Best Bang for the kWARRA Funded Small Solar Projects

John Schmadeke, Agua Fria UHSDSeptember 9, 2009

Funding Approval AZ received $55.5 Million ARRA (Stimulus) funding

for its Energy Grant Program.

$20 Million was allocated to K-12 School Energy Projects, including small school solar projects.

The SFB will administer and award grant funding to AZ public K-12 (non-charter) schools.

Grant process; requests due by November 6, 2009

Awards will be approved at the January 2010 SFB meeting.

ARRA Funded Solar

$5.5 Million will be dedicated to small solar electric systems for small (sf.) districts.

SFB will invite applications from those districts who qualify.

System size is limited to 30 Kilowatts (kW) per district.

Funding intended to cover 25 installations.

Speaking “Solar” Photovoltaic (PV) panels produce direct current

(DC), which like a battery, is not compatible with alternating current (AC) power systems.

PV panels are most common as crystalline or thin film technologies. Crystalline is 25% more efficient – smaller array, but more fragile.

An Inverter is required to convert the DC output of the panels to AC at the necessary voltage and frequency.

How Much is “30kW DC”?

In the Phoenix area 1 kW of solar PV capacity can produce up to 1700 kWh per year.

If your district’s power costs are about 10¢ per kWh, then the peak output would be worth $3 each hour - at today’s rates.

In the Phoenix area we can anticipate the value to be about $5,100 the first year. (30 kW x 1,700 x $ .10 = $5,100)

Lifetime Financials Panels degrade about ½ % per year.

Utility rates have escalated 3% historically.

Panels have a useful lifetime of 25-30 years.

A 30kW system will cost about $6,750 / kW, or $202,000.

A 30kW system will produce 51,000 kW per year when new, and about 45,200 kW in the 25th year.

First year electrical savings is $5,100.

Lifetime savings will be $173,900, excluding rebates.

30 kW System

Annual Panel Degradation 0.50% Annual Utility Escalator 3%  

             

Year kWh $/kWh Annual Savings Year kWh $/kWh Annual Savings

1 51,000 $ 0.10 $ 5,100.00 14 47,783 $ 0.15 $ 7,017.04

2 50,745 $ 0.10 $ 5,226.74 15 47,544 $ 0.15 $ 7,191.42

3 50,491 $ 0.11 $ 5,356.62 16 47,306 $ 0.16 $ 7,370.12

4 50,239 $ 0.11 $ 5,489.73 17 47,069 $ 0.16 $ 7,553.27

5 49,988 $ 0.11 $ 5,626.15 18 46,834 $ 0.17 $ 7,740.97

6 49,738 $ 0.12 $ 5,765.96 19 46,600 $ 0.17 $ 7,933.33

7 49,489 $ 0.12 $ 5,909.25 20 46,367 $ 0.18 $ 8,130.48

8 49,242 $ 0.12 $ 6,056.09 21 46,135 $ 0.18 $ 8,332.52

9 48,995 $ 0.13 $ 6,206.58 22 45,904 $ 0.19 $ 8,539.58

10 48,750 $ 0.13 $ 6,360.82 23 45,675 $ 0.19 $ 8,751.79

11 48,507 $ 0.13 $ 6,518.88 24 45,447 $ 0.20 $ 8,969.27

12 48,264 $ 0.14 $ 6,680.88 25 45,219 $ 0.20 $ 9,192.16

13 48,023 $ 0.14 $ 6,846.90 Totals 643,470 $ 173,866.55

25 Year Performance

Utility Rebates The AZ Corporation sets solar energy rebates as

part of the utility rate case. For the remainder of this year APS has requested

schools be treated as residential entities due to a surplus. $2.25 per watt, or $67,500 on a 30kW system.

Schools when classified by APS as a Commercial entity, earn production based incentives paid out quarterly. $ .22 per kWh up to 60% of installation cost over 10 years – maximum $101,000. (51,000 kWh x $.22 = $11,220 / year, over 9 years)

Other utilities – SRP, TEP, etc. ??? - TBD

What will it look like? PV panels are commonly mounted on

roofs, shade structures, on the ground, or elevated to create shade.

Tracking mounting systems follow the sun to produce more kWh each day.

Typical systems produce about 1 kW for each 100 square feet.

A 30 kW system thus is in the 3000 sf range, or about the size of 4 classrooms.

How can my District make the most of a small solar system?

It will not make up for the current economic downturn or loss of excess utilities!!

The systems do have beneficial economic results (stimulus) when considered as a distributed system of 815 kW.

25 small systems state-wide will allow widespread educational benefit and hands-on experience to many districts.

What are my options?

A district may elect to construct a system up to 30kW.

Economies of scale apply with increased size up to about 500kW, i.e. three 10kW systems cost more than one 30kW system.

A 30kW system might occupy about 50’ x 60’ on a roof above 4 classrooms; Or cover 15 parking stalls; Or provide 3000 sf of shaded outdoor dining space.

How will Students benefit?

Solar panel operating data is great real-world information useful in math and science courses. Ensure the installer provides current and historical data via the web or school network.

Students and families can see renewable energy at work and participate in the generational transformation from fossil to renewable sources.

Benefits to Adults

Administration and Board: Gain actual solar operating experience in your locale before considering a larger system.

Staff: Experience maintaining the system, from occasional panel cleaning, to trimming trees that might shade the panels.

Other Considerations Ensure the roof is in good condition before

installing panels – costs to remove and replace panels increase the reroofing cost. However panels also can extend roof lifetime.

Inverters have an expected lifetime of about 15 years, panels 25-30 years. Plan for these expenses. Consider a maintenance agreement or maintenance reserve fund.

Vandals could damage components – minimize climbing aids; consider a safe location; verify insurance coverage.

Questions & Comments

Thank you