Solar power and electric can go together like a horse and carriage. That's the idea behind SolarCity's effort to market its solar energy system sales along with electric car charging installations.

The Foster City, Calif.-based company announced Tuesday a partnership with Rabobank to make electric car charging available for free to owners of Tesla Motors' vehicles traveling on Highway 101 between San Francisco and Los Angeles. Other cars that can make use of same charging technology are welcome. 

SolarCity has set up a fast-charging device at four of the bank's branches near the freeway as part of a larger charging technology development project by Tesla, which is headquartered just south of San Francisco.

The partnership with Rabobank is more than just a marketing strategy to win over more solar customers. Rive said his company is entering the business of installing charging stations for plug-in hybrid and electric cars because it, too, promotes the use of cleaner energy.

"We want to design systems for powering your home and car," said Lyndon Rive, CEO of SolarCity. "The key thing is we want to eliminate all the reasons we can't live a carbon-free lifestyle."

Rive is throwing out some incentives to entice home and business owners to install solar and charging stations: "If you get a PV system, then the EV system is free." (This deal won't likely last once more electric cars become available.)

SolarCity has been selling and installing solar energy systems since its founding in 2006. The company is one of few that offer financing options to both residents and businesses that don't want to pay the expensive upfront costs of owning a solar energy system.

Last week, it said it had finalized its purchase of Los Angeles-based SolSource Energy, whose business includes installing electric car charging stations. SolSource has been the North American distributor of Toyota Tsusho electric car chargers. Toyota Tsusho is responsible for the export, sales and marketing of Toyota vehicles and auto parts.

The four charging stations at Rabobank branches are part of a larger project by Tesla Motors to develop and deploy a car charging technology.

The San Carlos, Calif.-based electric automaker received a grant of $641,000 from the California Air Resources Board for the project in 2007, said Tesla spokeswoman Rachel Konrad.

Part of that money went into co-developing the charging device with ClipperCreek of Auburn, Calif., Konrad said. The result is a fast-charging device Tesla calls the "High Power Connector" that provides up to 70 amps, 240 volts of electricity, making it possible to fully charge a Tesla Roadster after 3.5 hours, Konrad added.

Tesla car owners can have an electrician install the High Power Connector, which costs an extra $3,000 and comes in a wall-mounted box with a power cord, in their garages. Tesla also has designed its cars to be able to charge with the standard 110-volt outlet, which could take 37 hours for a full charge.

About $80,000 of the $641,000 grant was set aside for setting up the charging spots, Konrad said. The money went into buying equipment for the installations, SolarCity said. Incidentally, Rive is a cousin of Elon Musk, Tesla's CEO.

The solar installer has built the charging stations at Rabobank locations in Salinas, Atascadero and Santa Maria. The Goleta location is scheduled to be up and running by Oct. 15, said Jonathan Bass, a SolarCity spokesman.

SolarCity also has erected a 30-kilowatt solar energy system at the bank's Santa Maria branch. Rabobank has signed a power purchase agreement with SolarCity to pay for the electricity generated from the 30-kilowatt system (SolarCity will own it). The bank is considering adding solar in its other locations.

The bank offers the sites and will be paying for the electricity while SolarCity owns and maintains the charging stations. The stations are located in or near shopping centers, so motorists have something to do while waiting for their cars to juice up.

The charging is free for now. Given the limited number of Tesla car owners, the bank isn't in danger of seeing a huge spike in electricity bills. The same deal isn't likely to last after major carmakers begin to launch plug-in hybrid or all-electric cars starting in 2010.

SolarCity does plan to add charging equipment from those companies, or install universal chargers when standards are in place, Bass said.

The company has installed a fifth station on land owned by the city of San Luis Obispo, which will operate it, Bass said.  

Image via SolarCity.