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The Future of Residential Solar PV

Texas A&M University

College Station, Texas, 77843

Solar Primer:

TR-2010-ECE689fall Group 10

December 10, 2010

Prepared by

Bjorne Skarboe

Chris Azeredo

Nate Ehsani

for

ECE 689 - 605

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EXECUTIVE SUMMARY

Arguably the greatest barrier currently facing solar photovoltaic (PV) energy and preventing it from

becoming viable is the political uncertainty surrounding a potential comprehensive energy bill, and the

lack of legislation that seeks to put a price on carbon while continuing increased funding of R&D. The

technological and economic barriers seem manageable as further improvements in efficiency and

production followed by cost reduction are expected. However, much will rest on whether Congress will

pass legislation that puts discourages the use of conventional energy sources. Despite the lack of a federal

policy, Texas and other states continue funding and supporting the further development and deployment

of solar energy through the use of financial incentives, tax breaks and renewable portfolio standards

(RPS). As we explore the various aspects of solar photovoltaic energy and its intricacies, the focus of this

primer will be on topics pertaining to technology, economic and financial viability, along with barriers to

growth. Specifically, we will focus on aspects in each of these three areas that will be essential in making

residential solar PV viable in the years to come.

Technological improvements must be made through increased efficiency for panels and inverters. It

appears that the technologies for making solar PV viable are already present or at least very close to being

available. As we move forward we should seek to utilize nano-solar cells to create thin film modules,

while further using micro inverters to overcome shading issues and making the system more reliable.

Economically, solar power remains expensive relative to traditional fossil fuels and certain renewable

energies. The cost of solar PV has seen a significant decline over the last decades. Texas possesses the

key components to a successful and prosperous solar industry, with an abundance of solar resources,

growing demand, financial incentives, and the technical expertise in place. Beyond 2020, regions with

suitable conditions, such as Texas could reach the point where solar is cost-competitive with electricity

produced from conventional sources of energy, without financial incentives. However, in order for that to

occur, the political and cost barriers mentioned must be overcome, along with additional problems

pertaining to intermittency and the lack of transmission infrastructure.

In order to overcome the barriers that solar PV faces, new technological advancements must be made in

order to reduce cost. Cost reductions are predicted to continue in the future, but should ideally be

followed by federal policies that put a price on carbon, while continuing to invest in renewable energy

R&D in order to make residential PV viable in Texas and to the nation as a whole.

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TABLE OF CONTENTS

Executive Summary 2

Table of Contents 3

1 Section I – Technology: Introduction 4

2 Solar Panels 4

3 Hybrid Solar PV / Thermal 6

4 The inverters 7

5 Storage 8

6 Meters 9

7 Material accessibility 11

8 Safety 11

9 Conclusion 13

10 Section II – Economic/Financial viability: Introduction 13

11 Cost of generating electricity by source 13

12 State and federal financial incentives 15

13 Conclusion 19

14 Section III – Barriers to Growth:Introduction 20

15 Federal Policies – Post 1973 20

16 Solar energy policies - Texas 21

17 The Federal Policy Debate – Moving forward 22

18 Barriers to Growth 22

19 Conclusion 25

20 Primer conclusion 26

21 References 27

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SECTION I – TECHNOLOGY:

1 INTRODUCTION

As we explore the various aspects of solar photovoltaic energy and its intricacies, the focus of this paper

will be on topics pertaining to technology, economics and barriers to growth of solar PV. Specifically, we

will focus on aspects in each of these three areas that will be essential in making residential solar PV

viable in the years to come. The first section of the paper will explore and describe current solar

technologies and projections for future development of these technologies. The second part of the primer

will further explore issues regarding economic viability, such as current costs, trends moving forward,

and incentives available for residential solar PV. The third section investigates barriers to growth and

further deployment of solar PV, specifically focusing on policy and regulatory issues, along with the most

commonly cited barriers such as cost, intermittency, transmission infrastructure and consumer concerns.

Lastly, final recommendations are made regarding how we can make residential solar PV viable.

The first section will explore the technological aspects of solar PV and seeks to cover the essential

components of a PV system, current and future technologies, the effects of cell degradation, material

accessibility, and safety and environmental impacts. Before we explore each of these areas, it is essential

that we review how a solar PV system functions and operates. First, in a PV system the PV panel sends

DC electricity to the inverter. The inverter can then either charge a battery if they are installed, or

otherwise it converts the DC to AC power and sends that to your home. Any excess power can then be

sent to the power grid. Your meter will further track the amount of power pulled from the grid and put

back into the grid. Next we will provide an overview of the most important aspects of a residential solar

PV system and the most promising technologies for the future.

2 SOLAR PANELS

Several different types of solar panels exist. Below, the most promising and prominent ones will be

discussed in further detail.

2.1 Silicon Crystal

Most solar panels developed use the crystalline silicon (c-Si) technology. It produces solar cells with

efficiencies ranging from 11-16 percent and utilizes knowledge gained from the microelectronics

industry. Its downsides include poor absorption of light and the thickness of the material needed.

Manufacturers use this technology in two different ways. Monocrystalline silicon involves using one

crystal boule to obtain wafers. The other, mutlicrystalline, takes one block of silicon and divides first by

bars and then into the wafer format. Though the trend in manufacturing leans more toward the

multicrystalline system, research shows the most efficient production cells come from a monocrystalline

system combined with laser-etched grid contacts.i

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2.2 Thin film Panels (Amorphous)

Since production costs of the c-Si technology remain relatively high, several businesses turn to

manufacturing thin film solar panels. These use materials such as cadmium telluride (CdTe) and copper

indium (gallium) diselenide, which cost less due to its lack of thickness and also provide strong light

absorption. The technology’s most well-developed form comes from amorphous silicon. However, even

with its low production costs, thin film cells have less efficiency percentages than c-Si cells (5-8 percent),

and some cells’ performances degrade over time. ii

2.3 Building Integrated

Building-integrated photovoltaic (BIPV) technology has become the newest competition to c-Si and thin

film technologies. BIPV takes photovoltaic materials and transforms them into parts used for building

homes. Four forms of BIPV exist currently. The first is a flat roof form, combining one layer of thin film

cells into the roofing membrane. Pitched roofs use solar shingles developed to appear as regular roof

shingles. Windows, skylights, and other parts created from glass can be replaced with glazing modules.

Finally, the façade form of BIPV covers the existing façade of a building. As opposed to c-Si and thin

film technologies, BIPV can decrease initial costs since labor and building material costs are reduced.

These technologies have potential immediate cost savings to the resident, which will be explored further

in section II of the paper.iii iv v

2.4 Future Cell and Panel Designs

Due to increasing knowledge about production efficiencies and development of photovoltaic cells, several

new cell and panel designs have emerged as a result of continued research. Next, the most promising

designs will be reviewed to better grasp the latest development within cell and panel design.

2.4.1 Multijunction Device

Multijuction devices use materials commonly seen in thin film technology (such as gallium arsenide and

amorphous silicon) to produce layers of solar cells that absorb different solar waves depending on the

layer. The most common form of multijuction devices contain a top layer receptive to short solar

wavelengths, while the other layers absorb energy form other solar waves. Though some two-junction

devices have successfully been built, these devices are still largely in the research and development

stage.vi

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2.4.2 Vaporware

Vaporware has been mentioned in the news on several occasions for its research in producing a plastic

spray on solar cell. However, it still remains largely in its research phase.vii

2.4.3 Group III-V

One future design involves using Group III and Group V elements from the periodic table in creating

semiconductors which respond to different solar energy wavelengths. Gallium arsenide is most commonly

used, and while it has shown to be very effective, costs remain too high. These types of cells typically

have and efficiency of 25%.viii

2.4.4 Nano-Cell

Developments in nano-cell technology provide an outlet for future solar panel designs. Because the

targeted film is micron-thin, the nanoparticles that create it are even smaller. The nanoparticles are

equivalent to 200 atoms in diameter. These particles are then created into an ink. The nanoparticle ink is

coated onto an alloy of metal foil using high-throughput coating/printing techniques that work in normal

atmosphere, with no cleanroom required. The cell is completed by adding fingers and a back contact

capable of efficiently carrying current with minimal optical and resistive loss. The solar-electric foil is

then slit and sheeted into pieces to form individual cells. Cells can then be cut to any size. There

currently exists a manufacturer on the market that has made large advances in nano cell technology. The

company “Nanosolar” has already begun the production of nano-cells.ix

2.4.5 Electrochemical PV

Electrochemical PV technology shows a potential decrease in manufacturing costs of solar cells by

absorbing light via a liquid phase layer rather than solid state layers. This is done through a dye sensitizer

in a nanocrystalline titanium dioxide semiconductor. Some consider that these cells will offer lower

manufacturing costs in the future because of their simplicity and use of cheap materials. Prototypes of

small devices are now appearing (120cm2 cells with an efficiency of 7%).x

3 HYBRID SOLAR PV / THERMAL

There is a new type of solar module being developed and already in use in certain areas. The module is

known as a solar PV/Thermal module. These modules produce both heat and electricity to be used by

your home or building. Below will in greater detail describe these modules and their function.

3.1 PVT Liquid Collector

The system has a liquid collector which is a water-cooled design and utilized conductive-metal piping or

plates that are attached to the back of a PV module. Further, a working fluid, which most commonly is

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either water, mineral oil or glycol is then piped through the pipes. The heat from the PV cells is lead

through the metal and absorbed by the working fluid and increases the cell efficiency.xi

3.2 PV/T Air Collector

This module is similar to the liquid collector described with the exception that air is considered as the

medium for transport of thermal energy.xii

3.3 PV/T Concentrator

A concentrator system uses relatively cheap concentrating devices to concentrate sunlight on relatively

expensive PV solar cells. A concentrating system has the advantage to reduce the amount of solar cells

needed. The main obstacles are to provide good cooling of the solar cells and a durable tracking system.xiii

4 THE INVERTERS

The inverter is the second most important part of a residential PV system and also the second most

expensive part next to the solar module itself. There are several types of inverters currently out there that

perform very specific functions.

4.1 Grid Ties Inverters

A grid-tie inverter is a unique type of inverter that is utilized in a renewable energy power system

to convert direct current (DC) into alternating current (AC) and feed back into the utility grid. Grid-

tie inverters are designed to rapidly disconnect from the grid if the utility grid goes down. This is

required by the National Electric Code in order to ensure that in the event of a blackout, the grid tie

inverter will shut down and prevent the energy it produces from causing harm anyone who is sent

to fix the power grid. xiv

4.2 Gird Tied Backup Inverter

Battery backup inverters are similar to grid-tied inverters with the exception of having an added function.

They are special inverters, designed to draw energy from a battery, manage the battery charge through an

onboard charger, before exporting any excess energy to the utility grid. The inverters are capable of

supplying AC energy to selected loads during an outage, but are required to have anti-islanding

protection. xv

4.3 Off Grid

Off-grid inverters are utilized in isolated systems in which the inverter gets its DC energy from a battery

charged by PV arrays along with other sources, including hydro or wind turbines. Stand-alone such as the

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Average Warranty

0

2

4

6

8

10

12

14

16

Grid-Tie Grid-Tie/Backup Inverter Inverter/Charger Micro-Inverter

Inverter Type

Years

Average Warranty

off-grid inverters additionally incorporate battery chargers that replenish the battery from an AC source,

when available.xvi

4.4 Micro Inverter

A PV micro-inverter converts DC power from a solar panel to AC power. As opposed to a central or

string inverter which takes all the power produced by the array of solar modules and converts it, the

micro-inverter takes the DC power and converts it to AC power from one single panel. Systems with

micro-inverters are connected in parallel as opposed to a central or string inverters which are connected in

series. The micro-inverter was designed to alleviate issues pertaining to standard central inverters. A

distributed approach in terms of the inverter technology lessens the effect of shade on the array, along

with dust and debris. Issues with any one single module will not affect the rest of the array, for the

important reason that they are installed in parallel via the AC connection only. Hence, they no longer face

the problem where removing one single point causes system failure.xvii

xviii

4.5 Longevity

Using the data gathered from

the standard warranties of

several manufacturers’ inverters

and looking at them by type, the

longevity of each type of

inverter was extracted (Fig. 1).

For grid-tied inverters the

standard longevity is about 10

years going by warranty. For

Grid-tied battery backup

inverters the longevity is 5

years. For off grid inverters the

longevity is about 2 years. For micro-inverters the longevity is 15 years. Most fail-periods are 0 to 5

years after the warranty expires so add 0 to 5 years to determine how long an inverter should last. This is

important information for the consumer to keep in mind and is an important factor to consider as they

decide whether to invest in a PV system.

5 STORAGE

Storage is the one area pertaining to technology that has shown the least amount of breakthroughs. For

the most part energy storage for a PV system is limited to batteries. In most systems your only choice is

sealed lead acid. However, a number of different barriers are offered and available on the market.

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5.1 Sealed Lead Acid Batteries

The oldest form of a rechargeable battery dates back to 1859 with the creation of lead-acid batteries.

Although having a low energy-to-weight ratio along with a low energy-to-volume ratio, because they

were able to supply high surge current, it also meant that the cell would have a large power-to-weight

ratio. These batteries are the cheapest you one get for a solar PV system, but to get enough to run your

home would still be quite costly.xix

xx

5.2 Fuel Cells

To put it in technical terms, “a fuel cell is an electrochemical energy conversion device. A fuel cell

converts the chemicals hydrogen and oxygen into water, and in the process it produces electricity.” xxi

There are some people who have set up systems where they use the excess generated electricity to convert

water to hydrogen and store it in order for them to later utilize it with the fuel cells. The problem is that

fuel cells are highly expensive to consumers and still not reliable enough.xxii

5.3 Longevity

Overall, fuel cells last on average about five years. The longevity of lead acid batteries falls between four

and eight years, and from a consumer standpoint we can expect to see further improvement in longevity

as the technologies improve.xxiii

xxiv

6 METERS

There are mainly five different meters and metering techniques that a company can use to measure power

usage by a homeowner.

6.1 Electromechanical

The electromechanical meter is the most prevalent type. The electromechanical meter operates by

counting the revolutions of an aluminium disc that is created to rotate at a speed proportional to the

power. The number of revolutions is therefore proportional to the energy usage.xxv

6.2 Electronic

Electronic meters show the energy usage on an LCD or LED display, but are also capable of transmitting

readings to remote places. Additionally, in order to measure the energy used, electronic meters are

moreover able to record other parameters of the load and supply such as maximum demand, power factor

and reactive power used. xxvi

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6.3 SMART Meter

A smart meter is an advanced meter which records consumption in intervals of an hour or even less,

before then utilizing this information and communicating it back to the utility on a daily basis via a

network in order to monitor the usage, but also for billing purposes (telemetering).xxvii

6.4 Net Metering

Net metering allows the customer to receive credit for some portion of their electricity generated.

This method allows for an accurate recording going in both directions, while keeping costs close to

zero and providing a method for banking superfluous electricity produced for future credit. As

opposed to a feed-in-tariff or time of use metering, net metering can be implemented strictly as an

accounting procedure, and therefore will not require any special metering, arrangement or

notification. When the Energy Policy Act of 2005 was passed, it was included in the act that all

public electric utilities must now make available upon request net metering to their customers. This

is an attractive option to consumers, and is an important incentive for the investment in a PV

system. xxviii

6.5 Variable Rate Meter

A variable rate meter allows public electric retailers to charge customers different tariffs throughout the

day in order to better reflect generation and transmission costs, and allows the consumer to reduce

consumption when electricity is the most expensive during peak hours.

6.6 Cell degradation

Though the silicon solar cells inside modules do not show degradation over long periods of use,

degradation can still occur with the module output. In particular two reasons explain the decrease in

output. First, the module encapsulant slowly stops functioning correctly. Module encapsulant protects the

cells and internal electrical connections against moisture ingress. Because it is impossible to completely

seal out moisture, modules actually “breathe” to a very small degree. Moisture that enters a module is, in

turn, forced back out on a daily basis, as module temperature increases. Sunlight slowly breaks down the

encapsulation materials over time and limits the ability of the module to force out moisture. The trapped

moisture ultimately causes corrosion to occur at the cell’s electrical connections. The second source for

output degradation happens when UV light breaks down the EVA layer between a module’s front glass

and the silicon cells. As time passes, this obscuration limits the amount of sunlight that can hit the cell,

which causes a slight but incremental decrease in cell output. xxix

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7 MATERIAL ACCESSIBILITY

Many of the materials needed to create a finished solar module can be accessed without too many

problems. In terms of the total mass of the module, about 65 percent of the total comes from glass. The

aluminum frame accounts for approximately 20 percent. The module encapsulant holds about 7.5 percent,

while the polyvinyl fluoride substrate and the junction box constitute 2.5 and 1 percent each. Silicon’s

accessibility is essential for creating the solar cell, even if they only represent the remaining 4 percent of a

module’s mass. While silicon remains the second most abundant element in the earth’s crust, its annual

production remains less than copper and costs more to extract than iron, and the price level of silicon is an

important factor as it has implications for the overall cost to the consumer. xxx

8 SAFETY

Lastly the issue of safety will be discussed as it is inherent with PV installation and PV construction.

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8.1 Material Gathering Safety

There are several safety concerns when it comes to gathering and processing silicon. The most harmful

by-product is crystalline silica dust. Silica dust has been associated with silicosis and cancer. Other health

concerns associated with regular, high exposure include chronic obstructive pulmonary disease,

rheumatoid arthritis, scleroderma, Sjogern’s syndrome, lupus, and renal disease. When upgrading silica

sand to metallurgical grade silicon the harmful byproduct is fume silica. If respiration occurs, fume silica

can pose the same health concerns as silica dust. When upgrading metallurgical grade silicon to

polysilicon, there are multiple hazardous materials and byproducts that without the proper safeguards can

pose a significant risk to human and environmental health. One of recent interest is silicon tetrachloride

which can cause skin burns and is along with an eye and respiratory irritant.xxxi

8.2 Manufacture Safety

There are not only safety concerns related to gathering the material, but also in the manufacturing and

assembling of solar panels. When cutting wafer into cells many different potentially hazardous chemicals

are utilized. The main health and safety concerns are related to the exposure to and inhalation of kerf

dust. Kerf dust is a byproduct of sawing the silicon ingots into wafers. Another health risk is the threat of

exposure to solvents, such as nitric acid, sodium hydroxide and hydrofluoric acid. During the assembly

of the module, individual solar cells are usually joined together with copper wire coated with tin. Some

solar panel manufacturers use solders containing lead and other metals could cause environmental

damage and pose a risk to human health if released.xxxii

8.3 Installation Safety

When installing a PV system there are many regulations that need to be observed. One agency in

particular is OSHA. There are several categories of OSHA regulations. These categories include:

Personal Protection Equipment, Electrical, Falls, Stairways and Ladders, Scaffolding, Power Tools,

Materials Handling, Excavation, and Cranes. However, there is general consensus that after a panel has

been installed it poses minimal risks to human health or the environment, and therefore health risks

should not be a concern as people look to invest in a system. xxxiii

8.4 Environmental Impact

The Brookhaven National Laboratory presented results from a study that came up with the conclusion that

“regardless of the specific technology, photovoltaics generate significantly fewer harmful air emissions

(at least 89%) per kilowatthour (KWh) than conventional fossil fuel fired technologies.” However, it is

important to note that if the solar modules are not correctly decommissioned, they pose a health risk

because of the lead containing solders. Lead could under the right circumstances leach into landfill soils

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and even into water bodies. Nevertheless, lead solder use only account for about 0.5 percent of lead use in

the USA. xxxiv

9 CONCLUSION

In conclusion, it appears that the technologies for making solar PV viable on a residential level to

consumers in Texas are already present or at least very close to being available. First, we must utilize

nano-solar cells to create the thin film modules needed for a solar shingle system. Further, the use of

micro inverters must take place in order to take care of any shading issues while making the system more

reliable. Finally, net metering can be used to meter all homes at close to zero cost to the electricity

companies, while providing an additional incentive to consumers. The solar PV system has a life-span of

least 20 years before it degrades, and by viewing the investment in residential solar PV as a long-term

investment, homeowners will be reaping environmental and utility cost savings. During that time period

they will reach the breakeven point for the investment in the residential system. After having explored the

technological aspect of a solar PV system and made recommendations regarding the most promising

technologies, we move forward in this primer, by investigating the economic and financial viability of the

investment in a residential PV system.

SECTION II – ECONOMIC VIABILITY:

10 INTRODUCTION

The cost of solar PV has seen a significant decline over the last decades. With every doubling of installed

capacity costs have fallen by 20 percent. The cost per watt for the system saw a reduction from $10.50 per

watt in 1998 to $7.60 per watt in 2007. Despite significant cost improvements over this time period solar

PV is still expensive relative to conventional sources of energy. However, the future of solar PV looks

promising, as beyond 2020, regions with suitable conditions, such as Texas that have abundant solar

resources and relatively high electricity prices could reach the point where solar is cost-competitive with

electricity produced from conventional sources of energy, without financial incentives from the state and

federal government. xxxv

11 COST OF GENERATING ELECTRICITY BY SOURCE

For the near-term, solar PV continues to be more costly than other renewables such as wind power and

conventional energy sources. At a levelized cost of 28 to 42¢/kWh, it is significantly more costly than

wind power (9 to 12¢/kWh) or natural gas (5 to 10¢/kWh). Higher cost remains the single most important

barrier to significant penetration of PV, and the levelized cost gap remains rather large for the time being.

What is not taken into account in these numbers is the true social cost which incorporates the

environmental benefits that solar PV possess. However, unless policy makers step in and put a price on

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the negative externality posed by conventional fuel sources, decisions will continue to be largely based on

market costs, rather than the true social cost.xxxvi

Solar PV will remain a niche technology unless the cost

comes down significantly, a price is put on carbon that would as a result drive up the price of fossil fuels,

or solar continues to be mandated through renewable energy portfolio standards or other financial

incentives as we have seen in Texas and other states.xxxvii

11.1 Current and predicted future cost

The cost of a PV system is made up of the module cost and the price of the balance-of-system (BOS). The

prices vary widely depending on several factors such as supplier, type, size and what country one

purchases the system.xxxviii

Total near term costs for crystalline silicon technologies for the complete

system lies between $3-8/Wp. Total system costs for thin-film technologies vary between $2-7/Wp. For a

stand-alone system the costs are much greater due to additional battery and charge controller costs, and

lies in the range of about $5-30/Wp for crystalline silicon and $4-30/Wp for thin-film technologies.xxxix

As depicted in the figure below (Fig. 2), a 30-year timeframe is shown regarding the global average

selling prices from 1976 through 2008 (in 2008 dollars). The figure shows an experience curve, which

depicts average sale prices versus cumulative sales volume. An interesting observation is that prices have

declined by roughly 20 percent for every doubling in sales. This supports the claim that if solar PV is

more widely adopted we can take advantage of economies of scale in order to reduce cost. Not only has

the price declined significantly with broader adoption, but the total market size globally has grown by 100

thousand fold, with prices dropping more than 90 percent. As we look to the future, the curve predicts a

continued growth averaging 20% per year through 2040, along with further price reductions. xl

Figure 2:

Source: Electric Power Research Institute xli

Many have predicted a bright future for solar PV and a continued growth and decline in costs over the

next years, and we could experience PV reaching grid parity with conventional sources of energy, with

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large-scale commercial and central-station utility scale PV dominating the growth in the market, while the

fairly high value displaced retail kWh will also stimulate growth in the residential and commercial

markets.xlii

As we look to the future and the cost predictions for solar PV, it can be concluded that rooftop crystalline

systems will become more cost-effective. As efficiency increases, system costs are expected to drop from

$6 or $7 per peak watt to $3 or $4. Thin film has advantages that crystalline PV does not have, due to

much lower manufacturing cost at larger volumes, along with a wider variety of applications. So far the

market for thin film is untapped and therefore makes estimations hard to present, but thin film is expected

to surpass traditional PV systems before 2015. xliii

12 STATE AND FEDERAL FINANCIAL INCENTIVES

Consumers are currently offered an array of financial incentives to pay for a residential PV system.

Different states and the local utilities offer various options. Some offer cash rebates in order to reduce the

up-front cost to the homeowner. The solar investment tax credit (ITC) is generally the most attractive tax

incentive for homeowners, while individual states and counties often have other tax-related mechanisms

to promote residential PV in their area. xliv

Texas homeowners are offered a variety of state specific

incentives. The programs put in place in Texas to promote solar PV and other renewable resources

include: loan programs, net metering, property assessed clean energy (PACE financing), gran programs,

state income tax credits and deductions for renewables, property tax incentives for renewables, rebate

programs for renewables and renewable portfolio standards with solar/DG provisions.xlv

Based on the

financial incentives available for promoting solar PV in Texas, we can conclude that in the case of

residential solar PV on the Texas state level, there is a great opportunity to lessen the cost and an array of

opportunities for consumers to take advantage of in order to reduce the cost of acquiring a residential

system.

When making the decision whether to invest and install a rooftop PV system, homeowners must

determine which of the many federal and state incentives are available to their project. The remaining

amount due after the incentives have been subtracted must be financed by the homeowner, and can still be

a significant amount of money. Traditionally, homeowners have financed the amount with a combination

of cash, home equity loans and/or refinanced mortgage loans. Estimates from a Texas based solar PV

company (Texas Solar Power Company), suggests that assuming a cost of $5.00/watt and the installation

of a 4kW system, the total cost will be $20,000. If installed in Austin (Texas), the utility company Austin

Energy would provide a rebate of $2.50/watt for a total amount of $10,000, along the with a 30 percent

federal tax credit totaling $3,000. The potential cost of the system would be roughly $7,000, with $50-60

in monthly utility savings and a payback period of about nine years.xlvi

It is essential that the customer

understands the economic payback for their investment in a solar PV system. The cost will depend on the

size of the system. It is important to keep in mind that the price you pay for the system varies based on

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local market conditions. Further, the energy generated depends on your local sunlight conditions and the

inclination of the solar module. xlvii

12.1 Payback period and financing options

The average price of retail electricity varies widely across the country. The prices range from $0.075 per

kWh to $0.209 per kWh. The electricity price to Texas consumers is above the national average. We can

conclude from the varying prices that the actual residential retail rate per kWh avoided by generating on-

site PV will depend on where the customer is located. As a result, it becomes more cost-effective for

residents to offset more expensive electricity in states such as Texas, as compared to cheaper electricity.

Hence, the value of on-site electricity generation has a greater value in higher priced markets. It is

important to note that generally state and federal incentive program play a larger and more important role

in determining whether or not to install solar PV, however, high electricity prices should and do play a

role as well. Despite lower utility bills and earned net metering credits, this tends not to be sufficient in

making the economic case for residential PV due to the high up-front cost. Currently consumers must

view the installation of a PV system as a long-term investment. As the graph below shows (Fig. 3), the

payback period varies greatly depending on the cost of electricity, but under these assumptions it

constitutes a significant timeframe. Hence, as stated above further cost reductions will continue to play an

important role along with government incentives, mandates and other policies in making residential solar

PV viable to a greater number of consumers. xlviii

Figure 3:

Source: Solar Buzz xlix

As mentioned above, the remaining amount left after the financial incentives are subtracted must be

financed directly be the homeowner. In order to get a broader understanding of the options available to

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the homeowner, we will review various financing options available to homeowners and an evaluation

each of them.

The first option is using cash out-of-pocket, which will reduce the monthly obligations of purchasing a

PV system, but not everyone can afford such an investment. For those homeowners, home equity loans

and property tax assessment models reduced the up-front burden, but require occurring payments for 10-

20 years in addition to system maintenance obligations. The solar REC loan program appears as a

promising option when combined with rebates, but an occurring amount must regardless be financed

monthly. The remaining options such as the solar lease and residential PPA will vary by program, but has

potential for combining low up-front cost and the opportunity to outsource maintenance responsibilities,

which makes it an attractive option. Each homeowner must determine what options are available in their

area and what is most suitable for their needs and financial situation. As mentioned, the traditional forms

of financing include cash, home equity loans or refinanced mortgage loans. However, four new financing

models have emerged in order to make the investment in residential solar more attractive and accessible.

First, the solar lease program, which is a third-party finance model that takes advantage of the tax credits

available for PV to non-residential owners and lowers up-front costs. The homeowners lease the system

and offset the lease payments with reduced utility bills. Second, the residential PPA model takes

advantage of tax incentives and sell competitively priced electricity to homeowners who hosts the system.

Third, the property tax assessment model is being tried out in cities across the country and provides long-

term financing for PV and addresses the transfer of ownership issue. Fourth, PSE&G solar REC loan

program is a program being utilized in New Jersey, which makes loans to its customers to install

residential PV systems. The loans will be paid back by selling back the renewable energy credits (REC)

the system generates. In addition to the numerous and exciting opportunities laid out above, there are a

number of local community-based projects that seek to promote residential PV, depending on the needs

and financial situation of the individual customer.l

In addition to financial incentives provided by the state and federal government, along with the various

financing options laid out above, solar PV can in the case of residential solar take advantage of several

near-term cost reduction options. PV panels can in fact be utilized as conventional building materials by

integrating PV into the building. One example is to use PV panels instead of granite facing on a

commercial building. There would be savings associated with not using the stone curtain wall, which

might be as much as $55 per square feet. Assuming 10 watts ac per square foot, this comes out to a value

of $5.50 per watt. Further, if we assume that the cost of the PV system is $8.00 per watt, that gives us a

net cost of $8.00-$5.50 = $2.50 per watt. This is a significant savings opportunity, but we must keep in

mind that the actual savings would depend on the specific location.li

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Another possible cost saving mechanism beside from using PV as building material, would be locating

the PV system at sites where certain parts of the system is already supplied by the facility and

infrastructure in place. For example, a house roof can provide parts of the support structure for a PV

array. It also becomes important and a great opportunity for new homeowners and designers to take

advantage of solar power, by designing a home or business optimal for PV. This can be achieved through

orientation, roof pitch, and landscaping. This occurs at a small additional cost, but makes future

installation of solar more cost-effective. A PV system remains expensive, and the cost of energy is about

one to three times higher than utility electricity in most areas; however, there is potential for greater cost

savings through economies of scale, innovation, financial incentives, as well as taking advantaged of the

cost saving mechanisms laid out above, while continuing to urge policy makers to make policies directed

at promoting solar energy and discouraging the use of conventional energy sources.lii

12.2 Solar PV in Texas: Benefits and job creation

A strong argument can be made to further support the growth of the solar PV industry in Texas. Texas is

one the states in the country with the most solar potential as it receives among the best solar radiance

(insolation).liii

Not only does Texas have the natural resources, but it also has the infrastructure and

resources in place that are necessary for a growing solar market. Specifically, “Texas has significant

installed natural gas capacity, its own electrical grid, and commitments to build additional transmission

capacity, all of which will help advance solar power as a viable investment in the state.” liv

Solar PV in

Texas has the potential to function as a hedge against peak demand, which is the most expensive energy

Texans use and takes place during the hottest part of the day. Solar energy generation is closely correlated

with peak demand and can in that aspect cost-effectively offset the need to operate less efficient

powerplants or build new capacity. Further, PV plants can be built more quickly than conventional

powerplants due to easier installation, while having the option of building PV plants where they are most

needed due to easier siting of PV arrays. As demand increases, these PV powerplants have the option of

being expanded incrementally as opposed to conventional plants. Lastly, PV powerplants consume no

fuel or pollution when in operation.lv We can conclude that Texas is geographically ideal for further solar

PV expansion. However, there are additional benefits to the Texas economy. Studies have shown that

there is potential for job growth and creation through the PV industry. “One study estimates that Texas,

under a scenario of “climate protection strategies” of reforms in the transportation, electricity generation,

and construction sectors, would gain 123,000 net jobs by 2020, second only to California’s 141,000 net

gain in jobs in the same time period.” lvi

Another study analyzed the state impacts of a national installed

PV capacity of 9500MW by 2015. In that case, it was estimated that Texas would capture more than 13

percent of all new jobs created and more than 13 percent of all new investment, with most of the growth

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coming from in Texas based manufacturing. As the economy rebounds from the recession, with the level

of Texas high-tech manufacturing jobs still below pre-recession levels, the PV industry is an opportunity

to generate employment for semiconductor and electric component workers across the state. lvii

The state legislature has been supportive and adamant in promoting renewable energy. The establishment

of renewable portfolio standards (RPS) however has yet to yield an increase in solar energy production.

The program was very successful in promoting wind power. There is no question that RPS works and the

policy has so far grown the wind industry in Texas at a fast rate, meeting the RPS goal four years ahead of

schedule. If the Texas legislature continues to utilize RPS to promote certain energy sources, it becomes

important for solar to take part in this development to a greater degree. Solar energy could complement

and contribute to the current energy supply with daytime production of renewable energy, providing

consistent supply and reducing the risk of shortages.lviii

As Texas moves forward with promoting solar

energy a few recommendations must be made in terms of improving the outlook and growth of the

industry. More funding must be provided to R&D from both public and private sources targeted at the

solar industry. Building PV companies in and attracting the settlement of firms in Texas should be a

priority in order to further the job growth and economic development of the state. Texas must take

advantage of the human capital and expertise developed in the field of the semiconductor manufacturing

sector. Texas already has certain PV assets in place, including a manufacturing plant for silicon

processors, currently accounting for 11.5% of the world’s silicon processing capacity in an industry

expected to see a 70% increase in processing capacity. Texas’ market share is declining, to a predicted

2010 level of only 4.9%. Therefore, Texas should seek to encourage the expansion of this industry.

Lastly, Texas should develop a strategy for high-surface-area electronics, since the next development in

design and engineering of PV cells and semiconductors will follow this trend. lix

13 CONCLUSION

Texas possesses the key components to a successful and prosperous solar industry, with an abundance of

solar resources, growing demand and the technical expertise in place. Consumers have an array of

financial incentives that reduces the cost of acquiring a residential solar PV system significantly. Through

state and federal tax breaks, along with financing options such as home equity loans and leasing

programs, consumers can select the financing option that best aligns with their unique project and

financial situation. Despite significant cost improvements over the past decades solar PV is still expensive

relative to other forms of electricity generation. However, the future of solar PV looks promising, as

beyond 2020, regions with suitable conditions, such as Texas that have abundant solar resources and

relatively high electricity prices could reach the point where solar is cost-competitive with electricity

produced from conventional sources of energy, without financial incentives from the state and federal

government.

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Part III: Barriers to Growth

14 INTRODUCTION

Despite more than three decades of renewable and solar energy incentives and tax breaks, the investments

have not been successful in making solar energy economically competitive with conventional sources of

energy. Despite the environmental benefits solar energy offers through reduced CO2 emissions, solar

power currently accounts for less than one percent of electricity production in the USA. Its growth has

and continues to be hindered by political obstacles, high cost, intermittency, the lack of transmission

infrastructure and consumer lifestyle issues.lx Solar photovoltaic (PV) energy is the most familiar solar

technology, which despite currently accounting for a marginal level of electricity production is predicted

an annual growth rate in the USA of 21.3 percent by 2030. lxi

First, we will briefly review the federal

energy policies directed at renewable energy sources since the energy crisis in the 1970s. Second, the

federal and Texas energy debate pertaining to solar and renewable energy as we move forward will be

discussed. Third, the greatest barriers to continued growth of solar PV energy will be presented. Lastly,

recommendations are made pertaining to overcoming the challenges currently facing solar energy and the

role of policy-making as the energy debate moves forward.

15 FEDERAL POLICIES – POST 1973

“Prior to the first oil embargo in 1973 the federal government's tax policy was designed to encourage

fossil fuel exploration and production.” lxii

The energy debate in the 1970s was highly influenced by the

energy crisis faced by the USA in 1973 and 1978. In response to the energy crisis the U.S. Congress

began realizing the importance of encouraging renewable energy production and funded research for

developing ethanol, biodiesel, solar and wind power.lxiii

In 1974, as the debate had shifted toward

renewable forms of energy, the Solar Energy Research Act was passed, recognized the importance of

solar energy as an energy source that could potentially help fulfill the energy demand of the nation going

forward. lxiv

Congress continued the promotion of solar energy with the Energy Tax Act (ETA) of 1978,

which included a 30 percent investment tax credit for residential solar to consumers. lxv

The 1980s saw the passage of the Energy Security Act which increased the credit for renewable energy

sources and the investment tax credit for solar.lxvi

The Energy Policy Act of 1992 (EPACT) established a

10-year $0.018 per kilowatt-hour (kWh) production tax credit for renewable energy production. During

the last decade, further policies directed toward promoting solar and renewable energy sources have been

passed. The Energy Policy Act of 2005 provided $250 million to federal officials to purchase solar

systems in public buildings. A total of $2.2 billion was allocated in FY2007 through FY2009 toward

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renewable energy research. In 2008, Congress renewed the tax credits for power generated from wind,

solar and other clean sources. Congress extended the credit to 2016 along with making it available to

residential and utility system owners. The American Recovery and Reinvestment Act of 2009 removed

the $2,000 cap on the residential investment tax credit for solar thermal installations, and allowed for up

to a 30 percent solar energy investment tax credit for homeowners. lxvii

16 SOLAR ENERGY POLICIES - TEXAS

On a state level, Texas ranks first in the nation in solar resource potential. The solar energy industry has

been aided by state and federal tax incentives. Currently, local, state and utility rebate programs are

available to eligible residents. Performance based incentives for systems with at least 90% roof-mounted

panels are eligible for the program. The state legislature established a renewable portfolio standard (RPS)

in 1999, which was later expanded in 2005 to set targets for the use of renewable energy on a state level.

In order to provide options for consumers, the state requires companies selling electricity to retail

customers to support renewable energy generation. lxviii

Texas currently offers various tax deductions and

exemptions to encourage the use of renewable energy sources, including solar. A law from 1978 exempts

solar-powered energy devices from the appraised value equal to the value increase as a result of the

installation of solar. lxix

Current policies on net metering technology does not guarantee that the consumer

will be paid a fair price for its surplus electricity from the installed solar panels by the electricity provider

for their supply back to the grid. During the last two years, rebates from individual electric providers and

stimulus money from the federal government has contributed to an increased number of installations of

small-scale solar on homes, businesses and schools. lxx

During the 2009 Texas legislative session, HB 1937 was passed, allowing homeowners to finance on-site

renewable energy systems or improvements in efficiency through municipal loans. The program is known

as PACE financing and is available upon the approval from municipal officials.

More than 60 bills pertaining to solar energy were introduced during the 2009 session, seeking the

creation of market incentives for solar energy development in Texas. Despite the large number of bills

that failed to pass, several may be reevaluated during the 2011 session. lxxi

The energy crisis in the 1970s spurred the call for development and investment in renewable sources of

energy to reduce the dependency on foreign sources of energy. However, despite the investments, solar

energy and other renewable energy sources in general still depend on financial incentives from the state

and federal government to be cost competitive with conventional sources of energy.

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17 THE FEDERAL POLICY DEBATE – MOVING FORWARD

The USA and the world as a whole desperately needs a comprehensive energy reform, that puts a price on

carbon which reflects the true cost of the negative externalities posed by conventional sources of energy.

In order to make solar and other renewable energy sources competitive among conventional sources of

energy on a national and Texas state level, we must continue to fund R&D alongside the implementation

of a federal policy that puts a price on carbon.lxxii

The current federal tax code provides investment tax credits for solar energy. There are two significant

problems with the current policies directed toward promoting solar energy. First, the subsidies for solar

generated electricity are not large enough to allow solar to compete with natural gas and other fossil fuels

when generating electricity. Second, these tax credits must be financed in some way, either through

higher taxes or reduced spending. Even if they are meant to discourage electricity production from fossil

fuels, the credits distort behaviors among non-fossil fuel power sources. A favorable approach would be a

tax on the sources of energy in which we want to discourage, such as a carbon tax. The current policies in

place pick political “winners” in the energy sector, when we should rather let the market decide which

renewable resource are able to compete and that are the most viable.lxxiii

With the implementation of a

carbon tax, the competiveness of solar PV would improve, however the amount of the tax and the rate at

which it would increase would determine if solar could become cost-competitive with traditional fuel

sources.lxxiv

A price on carbon does make renewable electricity more competitive with traditional forms of

energy, but in the case of solar PV, unless significant progress is made in reducing the cost, solar PV is

unlikely to become a least-cost generation option, even under a $50/ton CO2 price. lxxv

Under a “business-as-usual” forecast that occurs in the absence of significant new policies that seek to put

a price on carbon, renewable energy sources are only forecasted to supply 14 percent of U.S. electricity

by 2030, with non-hydro counting for only 6 percent. Currently solar is mandated through renewable

portfolio standards or feed-in-tariffs. With the support from tax incentives and subsidies by states and the

federal government, solar PV installations have experienced a rapid growth. However, it is important to

look at the policy goals and the functions of the market as we move forward in determining whether these

are viable and cost-effective policies. If the goal is a low-carbon policy at a reasonable cost, there are

alternatives that can provide low-carbon electricity in a more cost-effective manner than solar PV

currently is capable of doing. lxxvi

18 BARRIERS TO GROWTH

Among the obstacles faced by solar PV, the political challenges are often cited as one of the most

pressing barriers to further market penetration, if not the most important factor. lxxvii

We have looked at

commonly cited policy prescriptions for dealing with the promotion of solar energy and the need for an

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energy reform that puts a price on carbon. As we move forward in this paper, we will investigate

additional barriers to the continued growth and market penetration of solar PV. As stated in the previous

section, solar PV faces numerous and daunting political challenges. However, the solar PV industry must

also balance other obstacles such as cost, intermittency, transmission infrastructure, while making sure

consumer needs are taken into account. lxxviii

On a national and state level, solar has experienced a rapid

growth over the past decades (Fig. 4). However, despite the growth, technological improvement and

declining cost, solar PV will continue to face barriers of a political, technical, and economic nature that

must be overcome in order for solar energy to capture a significant share of the energy market in the years

to come.lxxix

Figure 4:

Source: NRELlxxx

18.1 Cost

In addition to the political uncertainty, cost remains the most important challenge to the further

deployment of solar PV. lxxxi

Despite the potential that solar possesses, solar PV cannot become a major

contributor in electricity generation unless more cost-effective methods for storage and distribution of

electricity are developed.lxxxii

However, without the support from policy makers, solar PV will be stuck in

a catch-22 situation, where due to its high cost it is not widely used, and the high cost comes as result of a

low level of adoption. The current growth of solar is dependent on subsidy programs. However, as the

federal and state governments continue to fund investment subsidies and other financial incentives, it

remains important that these policies require setting in motion a process of self-sustained growth, driven

by scale economies, while decreasing the subsidies over time. lxxxiii

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To put the cost issue in perspective, “the levelized cost of solar PV electricity is typically at 28 to

42¢/kWh without the investment tax credit, compared to, for example, 5 to 10¢/kWh for electricity from

natural gas combined cycle power plants.” lxxxiv

There remains not only political uncertainty in these

predictions, but costs are also highly dependent on various assumptions and are sensitive to the inclusion

of different tax incentives. lxxxv

The geographic location also plays an important role in determining the

cost, as more sunlight lowers the per kilowatt-hour cost. A solar PV system located in Texas has the

potential of producing up to twice as much electricity as one located in the northeast of the USA.lxxxvi

Due to its high cost, it seems unlikely that solar PV electricity will play a major role in energy supply

before 2020. However, beyond that point solar production could become significant, as we expect further

cost reductions and call for GHG reductions. Solar PV is a low-carbon option that in comparison most

fuel sources provides potential for environmental benefits through reduced emissions. “PV systems have

life-cycle greenhouse gas emissions in the range of 25-35 g/kWh (at S-European location) which is

relatively low in comparison with other energy options that have a large application potential.” We can

conclude that PV offers environmental benefits and a low-carbon energy technology.lxxxvii

Due to the unpredictable nature of Congress, climate legislation could pass and alter the time-frame.

However, we would still need to see technological progress that would reduce the cost, as even a $50/ton

carbon tax would not be sufficient in closing the current cost gap. lxxxviii

18.2 Intermittency

Solar PV systems face issues regarding intermittency due to weather conditions and the fact that daylight

hours are limited, along with an uneven geographic distribution of solar resources. Solar must rely on

advanced technologies such as demand responsiveness and improved energy storage capabilities to

overcome this problem. lxxxix

Since solar energy cannot be scheduled to deliver specific amounts of power

at exact times, it is at a disadvantage compared to fossil fuels, since the variability is viewed as a threat to

system stability and reliability. However, studies have shown that a 20 percent market penetration of solar

and wind electricity is achievable without posing a threat to system reliability, even though added

variability comes at an extra cost. xc

18.3 Transmission infrastructure

Solar PV is also held back by the lack of transmission infrastructure. xci

It is important to note that solar

powerplants are often located in remote areas, since this is often where the renewable energy source is the

most abundant. The placement of solar powerplants would therefore require the construction of additional

transmission lines, which has proven to be a challenge for several reasons. The building of new

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transmission lines is not only costly ($2-$4 million per mile), but face jurisdictional conflicts and overlaps

between states and the federal government, along with public opposition. xcii

18.4 Consumer lifestyle

Consumer knowledge and familiarity with solar PV will be important for further market penetration. Even

though the technology has been around for a few decades, only a small fraction of the population have

first-hand experience with the technology, which raises questions and uncertainty regarding credibility,

stability and reliability. Installing a solar system requires high up-front costs, but also faces other issues

on a local level including: “covenants, restrictions, and zoning considerations, particularly with residential

installations.” xciii

Some neighborhoods and developments might have issues with the esthetics and how

the panels look on the roof of residential homes. Solar PV industry stakeholders must be prepared to

overcome the shortcomings experienced by the consumers including reliability, performance, cost,

appearance and siting issues by providing the necessary information to the public.xciv

19 CONCLUSION


order to reduce cost. Cost reductions are predicted to continue in the future, but should ideally be

followed by federal policies that put a price on carbon, while continuing to invest in renewable energy

R&D. Transmission lines are needed in order to extend the transmission to remote areas where solar

resources are abundant, and allow for the flow of renewable electricity. The issue surrounding variability

and the matching of electricity supply and demand raises concerns about impacts on system reliability,

and with higher levels of solar energy and other renewable sources, it will require changes in system

operations. Lastly, consumer concerns must be dealt with through education and awareness.

The current financial incentives and tax breaks are expensive to the government, and should aim to be

faced out as the industry grows. Congress should discontinue selecting its renewable energy “winners”

and rather focus on putting a price on carbon that reflects the cost of the negative externalities posed by

conventional sources of energy. As cost continues to decline over time, and with the possibility of

Congress passing climate legislation to curb carbon emissions and promoting renewable energy sources,

we could potentially experience solar energy closing the cost gap beyond 2020 and playing a larger role

in meeting the energy demands of the future. xcv

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20 PRIMER CONCLUSION


order to reduce cost. Specifically on the technological side, we must utilize nano-solar cells to create the

thin film modules needed for a solar shingle system, while using micro inverters in order to take care of

any shading issues while making the system more reliable. Finally, net metering can be used to meter all

homes at close to zero cost to the electricity companies. Cost reductions are predicted to continue in the

future, but should ideally be followed by federal policies that put a price on carbon, while continuing to

invest in renewable energy R&D. The current financial incentives and tax breaks are expensive to the

government, and should aim to be faced out as the industry grows. Congress should discontinue selecting

its renewable energy “winners” and rather focus on putting a price on carbon that reflects the cost of the

negative externalities posed by conventional sources of energy. As cost continues to decline over time,

and with the possibility of Congress passing climate legislation to curb carbon emissions and promoting

renewable energy sources, we could potentially experience solar energy closing the cost gap beyond 2020

and playing a larger role in meeting the energy demands of the future. xcvi

Transmission lines are needed

in order to extend the transmission to remote areas where solar resources are abundant, and allow for the

flow of renewable electricity. The issue surrounding variability and the matching of electricity supply and

demand raises concerns about impacts on system reliability, and with higher levels of solar energy and

other renewable sources, it will require changes in system operations. Lastly, consumer concerns must be

dealt with through education and awareness.

Texas possesses the key components to a successful and prosperous solar industry, with an abundance of

solar resources, growing demand and the technical expertise in place. Consumers have an array of

financial incentives that reduces the cost of acquiring a residential solar PV system significantly. Through

state and federal tax breaks, along with financing options such as home equity loans and leasing

programs, consumers can select the financing option that best aligns with their unique project and

financial situation. Despite significant cost improvements over the past decades solar PV is still expensive

relative to other forms of electricity generation. However, the future of solar PV looks promising, as

beyond 2020, regions with suitable conditions, such as Texas that have abundant solar resources and

relatively high electricity prices could reach the point where solar is cost-competitive with electricity

produced from conventional sources of energy, without financial incentives from the state and federal

government.xcvii

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xlviii xlviii

Coughlin, Jason, and Karlynn Cory. "Solar Photovoltaic Financing: Residential Sector

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xlix Solarbuzz. "Economic Payback of Solar Energy Systems." 2010. Web. 5 Dec. 2010.

<http://www.solarbuzz.com/Consumer/Payback.htm>.

l Coughlin, Jason, and Karlynn Cory. "Solar Photovoltaic Financing: Residential Sector Deployment."



li li Electric Power Research Institute. "Assessment of Rooftop and Building-Integrated PV Systems for


lii lii Electric Power Research Institute. "Assessment of Rooftop and Building-Integrated PV Systems for


liii Kellison, Bruce, Eliza Evans, Katharine Houlihan, Michael Hoffman, Michael Kuhn, Joel Serface, and

Tuan Pham. "OPPORTUNITY ON THE HORIZON: Photovoltaics in Texas." The University of Texas at

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Austin, 2007. Web. 5 Dec. 2010.

<http://www.utexas.edu/ati/cei/documents/TexasSolarOpportunity2007.pdf>.

liv The State of Texas: Office of the Governor. "Texas Renewable Energy Industry Report." 2010. Web. 4

Dec. 2010. <http://www.governor.state.tx.us/files/ecodev/Renewable_Energy.pdf>.

lv Kellison, Bruce, Eliza Evans, Katharine Houlihan, Michael Hoffman, Michael Kuhn, Joel Serface, and


Austin, 2007. Web. 5 Dec. 2010.


lvi Bailie, Alison, et. al. “Clean energy: Jobs for America’s future.” World Wildlife Fund. 2001. Web. 5

Dec. 2010. <http://www.fypower.org/pdf/enews_docs/clean_energy_jobs_enews0923.pdf>.

lvii Sterzinger, George and Matt Svrek. “Solar PV Development: Location of Economic Activity.”

Renewable Energy Policy Project. 2005. Web. 5 Dec. 2010.

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lviii Kellison, Bruce, Eliza Evans, Katharine Houlihan, Michael Hoffman, Michael Kuhn, Joel Serface, and


Austin, 2007. Web. 5 Dec. 2010.


lix Kellison, Bruce, Eliza Evans, Katharine Houlihan, Michael Hoffman, Michael Kuhn, Joel Serface, and


Austin, 2007. Web. 5 Dec. 2010.


lx PEW Center. "Solar Power." Pew Center on Global Climate Change, 2009. Web. 6 Dec. 2010.


lxi EIA. "Annual Energy Outlook 2010." Energy Information Administration, 2010. Web. 5 Dec. 2010.

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lxii Metcalf, Gilbert. "Federal Tax Policy Towards Energy." Tufts University - Department of Economics;

National Bureau of Economic Research (NBER), 2006. Web. 5 Dec. 2010.

<http://papers.ssrn.com/sol3/papers.cfm?abstract_id=934763>.

lxiii Duffield, James A., and Keith Collins. "Evolution of Renewable Energy Policy." American

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lxiv The Library of Congress. Web. 23 Nov. 2010. <http://www.thomas.gov/>.

lxvEnergy Information Administration. "Policies to Promote Non-hydro Renewable Energy in the United

States and Selected Countries." 2005. Web. 2 Dec. 2010.

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lxvi The Library of Congress. Web. 23 Nov. 2010. <http://www.thomas.gov/>.

lxvii House Research Organization. "Solar Energy in Texas." Texas House of Representatives, 2010. Web.

3 Dec. 2010. <http://www.hro.house.state.tx.us/focus/Solar81-13.pdf>.

lxviii House Research Organization. "Solar Energy in Texas." Texas House of Representatives, 2010. Web.


lxix House Research Organization. "Solar Energy in Texas." Texas House of Representatives, 2010. Web.


lxx House Research Organization. "Solar Energy in Texas." Texas House of Representatives, 2010. Web. 3

Dec. 2010. <http://www.hro.house.state.tx.us/focus/Solar81-13.pdf>.

lxxi House Research Organization. "Solar Energy in Texas." Texas House of Representatives, 2010. Web.


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lxxii

Griffin, James M. "A Smart Energy Policy." Yale University Press, 2009. Web. 1 Dec. 2010.

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lxxiii Hassett, Kevin A., and Gilbert E. Metcalf. "An Energy Tax Policy for the Twenty-First Century."

American Enterprise Institute, 2007. Web. 3 Dec. 2010.

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lxxiv Bobvan Der Zwaan, Bob, and Ari Rabl. "The Learning Potential of Photovoltaics: Implications for



lxxv Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>.

lxxvi Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>.

lxxvii Fthenakis, Vasilis, James E. Mason, and Ken Zweibel. "The Technical, Geographical, and Economic

Feasibility for Solar Energy to Supply the Energy Needs of the US." Energy Policy, 2008. Web. 4 Dec.

2010. <http://solar.gwu.edu/index_files/Resources_files/Solar%20Plan.pdf>.

lxxviii Electric Power Research Institute. "Assessment of Rooftop and Building-Integrated PV Systems for


lxxix House Research Organization. "Solar Energy in Texas." Texas House of Representatives, 2010. Web.


lxxx Cory, K., J. Coughlin, and T. Jenkin. "Innovations in Wind and Solar PV Financing." NREL, 2008.

Web. 2 Dec. 2010. <http://www.nrel.gov/analysis/pdfs/42919.pdf>.

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lxxxi Lewis, Nathan S. "Toward Cost-Effective Solar Energy Use." SCIENCE, 2007. Web. 6 Dec. 2010.

<http://cepac.cheme.cmu.edu/pasi2008/slides/agrawal/library/reading/Lewis_N,_Science,_315,_798,_(20

07).pdf>.

lxxxii Lewis, Nathan S. "Toward Cost-Effective Solar Energy Use." SCIENCE, 2007. Web. 6 Dec. 2010.

<http://cepac.cheme.cmu.edu/pasi2008/slides/agrawal/library/reading/Lewis_N,_Science,_315,_798,_(20

07).pdf>.

lxxxiii Sanden, Bjorn A. "The Economic and Institutional Rationale of PV Subsidies." Solar Energy, 2005.

Web. 6 Dec. 2010. <http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V50-4CBVKP2-

1&_user=10&_coverDate=02/28/2005&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&

_docanchor=&view=c&_searchStrId=1569759685&_rerunOrigin=google&_acct=C000050221&_version

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lxxxiv Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>.

lxxxv PEW Center. "Solar Power." Pew Center on Global Climate Change, 2009. Web. 6 Dec. 2010.


lxxxvi Fthenakis, Vasilis, James E. Mason, and Ken Zweibel. "The Technical, Geographical, and Economic

Feasibility for Solar Energy to Supply the Energy Needs of the US." Energy Policy, 2008. Web. 4 Dec.

2010. <http://solar.gwu.edu/index_files/Resources_files/Solar%20Plan.pdf>.

lxxxvii ENVIRONMENTAL IMPACTS OF PV ELECTRICITY GENERATION - A CRITICAL

COMPARISON OF ENERGY SUPPLY OPTIONS – Alsema et al.

lxxxviii Bobvan Der Zwaan, Bob, and Ari Rabl. "The Learning Potential of Photovoltaics: Implications for



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lxxxix

PEW Center. "Solar Power." Pew Center on Global Climate Change, 2009. Web. 6 Dec. 2010.


xc Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>.

xci PEW Center. "Solar Power." Pew Center on Global Climate Change, 2009. Web. 6 Dec. 2010.


xcii Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>.

xciii Electric Power Research Institute. "Assessment of Rooftop and Building-Integrated PV Systems for

Distributed Generation." EPRI, 2003. Web. 6 Dec. 2010.

<http://my.epri.com/portal/server.pt?space=CommunityPage&cached=true&parentname=ObjMgr&parent

id=2&control=SetCommunity&CommunityID=404&RaiseDocID=000000000001004204&RaiseDocTyp

e=Abstract_id>.

xciv Electric Power Research Institute. "Assessment of Rooftop and Building-Integrated PV Systems for

Distributed Generation." EPRI, 2003. Web. 6 Dec. 2010.

<http://my.epri.com/portal/server.pt?space=CommunityPage&cached=true&parentname=ObjMgr&parent

id=2&control=SetCommunity&CommunityID=404&RaiseDocID=000000000001004204&RaiseDocTyp

e=Abstract_id>.

xcv Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>.

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xcvi

Komor, Paul. "Wind and Solar Electricity: Challenges and Opportunities." University of Colorado at


report.pdf>

xcvii Kellison, Bruce, Eliza Evans, Katharine Houlihan, Michael Hoffman, Michael Kuhn, Joel Serface,

and Tuan Pham. "OPPORTUNITY ON THE HORIZON: Photovoltaics in Texas." The University of

Texas at Austin, 2007. Web. 5 Dec. 2010.


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