Solar Photovoltaic

Cost Effectiveness of Photovoltaic Solar Panels on

Nonprofit Housing in Berkeley, California

Alfred Twu

Lothlorien Ministry of Waste Reduction

alfred@bsc.coop

November 26, 2011

Abstract

The installation of photovoltaic (electricity producing) solar panels facing southeast on nonprofit housing was found to generate a 4.83% annual return on investment. Higher returns can be achieved by southwest orientation of the solar panels.

These returns are less than that of insulation and furnace upgrades. However, solar panels have the ability to tap into streams of funding not available to other energy efficiency projects. Central Level Incentives could encourage other co-ops to purchase

PV with house level money.

Finally, continuing changes in solar panel and energy prices make the cost effectiveness of PV worth periodically reevaluating.

Methods and Materials

7.92 kW of PV solar panels were purchased and installed on the roof of Lothlorien South House at 2415 Prospect Street in Berkeley, California.

Timeline

March 2010: Solar installers contacted. Financial analysis completed.

May 2010: Approval with House Council, Central Office and Central Maintenance.

August 2010: City approval complete.

September 2010: Construction.

November 2010: PG&E Inspection & Meter Reprogramming.

December 1, 2010: Power generation begins.

Equipment

1 x Unirac Solar Mount Kit

1 x Grounding Circuit

33 x CEEG 240 Watt Solar Modules, SST240-60M

1 x AC Disconnect

1 x SunnyBoy SMA SB 7000W Inverter

Note 1: The original design called for 230 watt Canadian Solar modules; however, those were sold out by the time of city approval. The 240 watt panels were substituted at no additional cost.

Note 2: A redesign requested by the City necessitated that 12 of the panels be mounted on a high-tilt rack. Solar installer provided this at no additional cost.

Costs

Equipment $26,151 (after $6,800 PG&E rebate)

Installation labor $8,700

Partial re-roof: $4,760

Total cost: $39,611

Note 1: Half the house was re-roofed since the roof had only a couple years of life left and it would have been difficult to re-roof once the panels were on. The 4.83% return excludes cost of re-roof, since it would have had to be done anyway.

Note 2: The solar installer, Alter Systems, covered the cost of city and PG&E permits and fees.

Note 3: During the city approval process, available PG&E rebates were reduced by $2,345. The added cost was offset by house fundraising from members.

Funding

5 year loan from Central Level @ 5.25% $24,000

House level fundraising $2,345

House Approved Projects (HAPS): $13,266

Note: Energy Conservation Fund (ECF) funding was pursued but not granted as ECF prioritizes insulation,which has a faster rate of return.

Equipment Setup

Panel Orientation: 45 degrees East of South (due southeast)

Panel Tilt Angle: 30 degrees

Data Collection

The inverter data display on Lothlorien South House was monitored. The inverter displays kWh generated, current

output in watts, and estimated CO2 saved (1.7 pounds per kWh)

Results

Figure 4, Generation Report

Discussion

At 4.83%, the rate of return for solar PV panels on a southeast oriented roof is less than that of other energy efficiency projects available to the Berkeley Student Cooperative. A southwest oriented roof may have better results in the 5 or 6% range.

Thermal improvements, such as insulation, furnace upgrades, and double pane windows have calculated savings of 6-13% and may also provide health and comfort benefits.

Internal factors to consider

However, solar PV has the ability to access house level funds that insulation, furnaces, and windows cannot. The Loth PV array was paid for entirely by the house – all money was from House Approved Projects (HAPS), money borrowed from Central Level and paid back from the House Account, and house level fundraising from members. In contrast, insulation, furnaces, and windows have historically been paid for by central level money alone.

HAPS have been used in the past on luxury projects such as gargoyles and hot tubs. House Account spending, which has fewer restrictions than HAPS, can sometimes be even more dubious. Creating an incentive for houses to use HAPS money on solar PV

by providing matching funds could spur more houses to buy PV instead of hot tubs.

External factors to consider

PV solar panels continue to get cheaper, and additional savings could be achieved with a multi-house bulk contract. Changes to state incentives and rebates could also affect PV cost effectiveness.

Finally, if electricity rates increase faster than natural gas rates, then solar PV may become more cost effective than insulation.

It is recommended that the Berkeley Student Cooperative re-evaluate solar whenever there is a significant change in electric rates and/or solar panel prices.

Figure 5, Comparison to thermal energy efficiency projects

During the Kingman Seismic Retrofit of 2010, the cost of various energy efficiency projects to take place during the earthquake retrofitting construction was evaluated.

References

Berkeley Student Cooperative, Kingman Hall Retrofit Energy Efficiency Payback Calculations. Berkeley Student

Cooperative, 2010.

Pacific Gas & Electric Company, Electric Schedule A-6, Small General Time of Use Service.

http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_A-6.pdf

Pacific Gas & Electric Company, Electric Schedule E-CARE, CARE Program Service For Qualified Nonprofit Group-

Living & Qualified Agricultural Employee Housing Facilities.

http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_E-CARE.pdf

Pacific Gas & Electric Company, Current and historic electrical rates.

http://www.pge.com/nots/rates/tariffs/electric.shtml

Tracking the Sun III: The Installed Cost of Photovoltaics in the U.S. from 1998-2009, Barbose, G., N.

Darghouth, R. Wiser., LBNL-4121E, December 2010

Printable version of report is attached.