Santa Rosa is studying whether to install solar panels on top of its five downtown parking garages, a move that could advance the city's climate protection goals and save it money, to boot.
A preliminary study indicates the arrays could generate 345 kilowatts of electricity, enough to offset most of the energy used to light the garages and remove the equivalent of 266 tons of carbon dioxide from the atmosphere annually.
The study, performed by Tim Holmes of Kenwood Energy, estimated that city could save from $550,000 to $1.5 million over 25 years depending on how it financed the $1.4 million installation cost.
If the city's parking district funded the project with cash, it would own the panels and generate more savings over their life span. If it financed the project with a partner who agreed to buy back the power, the upfront cost would be zero but the long-term savings would be lower, the study found.
The district has plenty of cash to fund the project, in excess of $10 million. The funds were raised from parking fees over many years to help build a new parking garage as part of a mixed-use project at the White House site on Third Street north of the U.S. Post Office building. Those efforts stalled several years ago as the housing market tanked.
The city already has solar arrays generating 543 kW of electricity, most of them at the Llano Road treatment plant. That means the new garage arrays would increase the city's solar footprint by 65 percent, said Colin Close, research and program coordinator for the city utilities department.
But it's unlikely all five garages will get solar panels, said Kim Nadeau, the city's parking coordinator.
The oldest one, Garage 5 on Third Street, has the smallest space available for panels, according to the report. It is also unclear what the future of that garage is. It needs upgrades to extend its life, and the City Council will have to decide whether to fix it up or pursue construction of a new garage, such as on the White House site.
Developing that city-owned property is a key economic development goal of the City Council now that construction of the Museum on the Square project at the former AT&T building is underway.
"They did put money in the budget next year to start doing studies to get that ball rolling again," Nadeau said of the White House site.
The city next plans to study the capital needs of the five garages, the demand for parking downtown, and the demand for downtown office and retail space to help make its decision about developing the White House site, Nadeau said.
The solar panels would be mounted on structures above the parking spaces on the roofs. Construction of the structures could result in the loss of some spaces, Nadeau said.
She stressed that the report is very preliminary. The next step is to put out a request for proposals and see what options solar vendors come up with.
In the report, Holmes suggests the city's aim is to offset 80 percent of the power needs of each garage. Doing more won't be cost-effective because the rates PG&E pays to buy back excess power generated from the photovoltaic panels, referred to as the feed-in tariff, are so low.
But there's a lot of flux in the industry right now, including falling prices for PV panels, the elimination of rebates and the advent of competitors like Sonoma County's startup public power agency, he said.
Sonoma Clean Power has yet to set a feed-in tariff rate, and once it does, it could very well affect the economics and size of the project, Holmes said.
"The rules are changing as we speak," he said.
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