Solar adds up to savings for busy San Francisco service station

August 2004

Solar panels cover the Divisadero Street Shell Station canopy.

San Francisco, Calif. -- The electricity blackouts during the summer of 2002 and the present threats of new blackouts, as well as compelling cost-savings and quick payback, lead the owners of the busy Divisadero Street Shell Service Station to install solar. The 30.4 kilowatt, grid-tied solar photovoltaic system is now the city's largest private, commercial solar installation and also Cooperative Community Energy's largest San Francisco project to date.

The eye-catching solar array spans the roof canopy of the bustling service station and carwash complex located at the busy Divisadero and Oak street intersection, visible not only to passersby but also to a nearly constant stream of customers lined up either to fuel or wash their cars.

Business owners Roy and Patty Shimek didn't exactly set out to make a political or environmental statement. "It is our small pioneering effort to prevent peak time blackouts in our neighborhood and it is our hope that Shell Oil Co. will follow our lead and put solar panels on their other stations," Roy Shimek says.

Olov Sundstedt, the Bay Area energy and utility rate consultant who recommended the idea of solar to Shimek, approached CCEnergy's San Francisco field representative, Max Mayer. "I am always looking for ways to lower the energy costs for my clients," Sundstedt says. "With those huge canopies basking in the sun, why not soak up the sun's energy?"

"The owner was looking for a way to offset his operating expenses," Mayer adds. "State-of-the-art PV systems provide lower-cost power than the utility, making this a logical, easy business decision." Before designing the system, Mayer conducted a detailed energy analysis of the service station's power usage, estimated at 53,000 kilowatt-hours annually. Mayer and Sundstedt also did a thorough financial analysis to address the property owner's twin goals of reducing energy costs while optimizing his return on investment.

As a result, the system installed will offset 51% of the service station's electricity consumption, and 79% of electricity costs. Furthermore, a combination of financial incentives currently available for commercial solar systems 30kW and larger in California cut the bottom line cost of this installation by more than half. The service station not only will be saving an average of $10,000 annually on its utility bills but also repaying its solar investment entirely within about eight years.

Design and installation challenges

CCEnergy Field Rep Max Mayer inspects the platform constructed on the canopy to support the solar system's weight.

The service station canopy's I-Beam construction with a standing seam metal roof presented special structural considerations for supporting the solar array's weight. Mayer brought Miguel Silva and Ernesto Montenero of Sustainable Technologies, the installers for the project, as well as structural engineers into the system design process. The project team was able to collaboratively design a levered platform with a system of trusses using angel irons and steel members to accommodate the canopy span and fulfill city building permit requirements. The team managed to achieve this while keeping costs within budget.

Structural issues also necessitated mounting the system's 216 Kyocera 167G PV panels closer together than usual, which meant that standard clamp mounting for individual solar panels would not work. Instead, the installers built 44 sets of five panels and four sets of six panels in their shop and then mounted the "panelized" arrays using bolts attached to the backside of the panels. The system's 12 SMA America SunnyBoy 2500U inverters were also mounted on the backside of the structure.

Because the service station is constantly busy and located in densely populated area, the platform trusses and solar panels had to be lifted onto the canopy by a large crane during the middle of the night. "We had a lot of engineering challenges to work out and a lot of people to work around, but the installation went very well," Montenero says. "Hopefully other businesses will see the results and find out what a good deal commercial solar is."

The design also enabled the PV panels to be tilted and oriented for optimal solar exposure. "When we first switched it on, the system was generating 14kW on a cloudy day. The next day, when it was partially sunny, the system went right up to 26.6 kilowatts," Montenero says. The system passed city building department and PG&E inspections with flying colors in late August 2004.

Maximizing return on investment

The financial incentives line-up that made solar a common sense business investment for the Divisadero Street Shell Service Station include:

• A rebate through Pacific Gas & Electric's Self-Generation Incentive Program at $4.50 per watt for solar systems 30kW and larger, up to 50% of the installed system cost


• Federal business tax credit of 10%


• State tax credit of 7.5%


• Five-year accelerated business depreciation, including a 50% first-year bonus depreciation allowance (until Jan. 1, 2005)


• A Net Metering or Interconnection agreement with PG&E, coupled with a "Time-of-Use" utility meter. Net-metered solar systems are connected to the property's utility meter to feed electricity back into the power grid during times of excess power generation. Solar systems produce the most electricity during the midday hours when demand on the grid is highest. Net metering allows grid-connected solar customers to receive credit from PG&E for the excess power generated. The Time-of-Use utility meter enables the business to pay lower rates for electricity used during PG&E's lower demand hours during the evening, which in this case coincides with the business's greatest power requirements.

More about financial incentives and resources for solar »
See more photos of Divisadero Street Shell Station's solar installation »