Photovoltaic Solar Systems

8/10/2019 Photovoltaic Solar Systems

1/32

Photovoltaic Solar Systems

Manoj Kumar

Assistant professor

S.E.T Sharda University


2/32

What is a solar cell?

Solid state device that converts incident

solar energy directly into electrical energy

Efficiencies from a few percent up to 20-

30%

No moving parts

No noise

Lifetimes of 20-30 years or more


3/32

Cross Section of Solar Cell


4/32


5/32

Combining Solar Cells

Solar cells can be electrically connected in

series (voltages add) or in parallel (currents

add) to give any desired voltage and current(or power) output since P = I x V

Photovoltaic cells are typically sold in

modules (or panels) of 12 volts with poweroutputs of 50 to 100+ watts. These are then

combined into arrays to give the desired

power or watts.


6/32

Cells, Modules, Arrays


7/32

Rest of System Components

While a major component and cost of a PV system is

the array, several other components are typically

needed. These include: The inverterDC to AC electricity

DC and AC safety switches

Batteries (optional depending on design) Monitor(optional but a good idea)

Ordinary electrical meters work as net meters


8/32

Photovoltaic (PV) Terminology

Cell < Module < Panel < Array

Batterystores DC energy

Controllersenses battery voltage and

regulates charging

Inverterconverts direct current (DC )

energy to alternating current (AC) energy

Loadsanything that consumes energy


9/32

Solar Cells and the PV Effect

Usually produced with Semi-conductor

grade silicon

Doping agents create positive and negative

regions

P/N junction results in 0.5 volts per cell

Sunlight knocks available electrons loose

Wire grid provides a path to direct current


10/32

Series Connections

Loads/sources wired in series

VOLTAGES ARE ADDITIVE

CURRENT IS EQUAL

One interconnection wire is used between

two components (negative connects with

positive) Combined modules make series string

Leave the series string from a terminal not

used in the series connection


11/32

Loads/sources wired in parallel:

VOLTAGE REMAINS CONSTANT

CURRENTS ARE ADDITIVE

Two interconnection wires are used between two components(positive to positive and negative to negative)

Parallel Connections


12/32

PV was developed for the space

program in the 1960s


13/32

The PV Market

Solar Calculators

REMOTE POWER

Lighting Communications

Water Pumping

Mountain Cabins


14/32

Photovoltaic Array for Lighting


15/32

Telecommunications Tower


16/32

Remote Water Pumping


17/32

Recreation Vehicle Outfitted with

Solar Panels


18/32

A Solar Driven Band


19/32

NET METERING

In net metering, when the PV system produces

excess electricity, it is sent to the grid system,

turning the meter backwards. If you are usingmore power than is being produced, or it is at

night, the electricity is received from the grid

system and the meter turns forwards. Depending

on PV size and electrical consumption, you mayproduce more or less than you actually use.

Individual houses may become power producers.


20/32

Pole Mounted PV


21/32

Roof Integrated PV

If you are doing new construction or a

reroofing job, it is possible to make the roof

itself a solar PV collector. This saves thecost of the roof itself, and offers a more

aesthetic design. The new roof can be

shingled or look like metal roofing. A fewexamples follow.


22/32

Solar Roofing Shingles


23/32

Sizing a PV System to

ConsumptionA PV system can be sized to provide part or all of

your electrical consumption. If you wanted to

produce 3600 kw-hr a year at a site that had anaverage of 4.1 peak sun hours per day,

PV Size in KWp = 3600 kw-hr

4.1 kw-hr/day x 365 days/yr x 0.9 x0.98

= 2.7 KWp

Note: the 0.9 is the inverter efficiency and the

0.98 represents the loss in the wiring.


24/32

Thinking About Electrical

Consumption1 kW = 1000 watts = 1.34 hp (presumably

the maximum sustained output of a horse)

1 kW-hr = 3413 Btu is the consumption of a1 kW device operated for an hour (E=Pxt)


25/32

How Much Area Is Needed?

The actual area that you need depends on the

efficiency of the solar cells that you use. Typical

polycrystalline silicon with around 12% efficiencywill require about 100 ft2 of area to provide a peak

kilowatt. Less efficient amorphous silicon may

need 200 ft2 to provide the same output. Modules

are sold in terms of peak wattage and their areasare given so you can easily determine the total

roof area that is needed for a given size array.


26/32

Find the efficiency of a solar cell module

given its power rating and its areaAssume it is a 100 Wp module and its area

is 0.8 m2. Remember that the peak power

rating is based on an intensity of 1000watts/m2. So the maximum output with

100% efficiency is P = I x A = 1000 w/m2 x

0.8 m2 = 800 wattsThe actual efficiency = Pactual peak/Pmaximum peak

= 100 watts/800 watts = 0.125 or 12.5%


27/32

Larger Scale PV

Of course you dont have to stop with home

based PV systems. They make equally good

sense for businesses and corporations whowant to reduce their cost of electricity by

reducing their peak power consumption, or

who want to emphasize their greenness aspart of their image, or who need to operate

in a grid failure.


28/32

Details of Roof Installation


29/32

Large 57 KW Rural Installation


30/32

Solar Added to Flat Roofs

(can upgrade the insulation as well)


31/32

The Greenpoint, NY Building

T e sun s t e pr mary energy


32/32

T e sun s t e pr mary energysource for almost all energy

flows on the planet. Its time westarted using it.

Photovoltaic Solar Systems

Documents

Transcript of Photovoltaic Solar Systems