SolarCity is to offer business customers an energy storage unit option using technology from electric car manufacturer Tesla.

The largest solar installer in the US will offer the system on a ten-year system contract with no initial outlay.

“Utilities have altered their rate structures such that demand charges are rising faster than overall energy rates, and businesses are bearing the bulk of those increases,” said Peter Rive, SolarCity’s chief technology officer and chief operations officer.

“Time is money, but so are control and predictability. Our storage systems can give businesses the tools to address all three – delivering immediate savings, protection against escalating demand charges and optional, grid-independent backup power in case of outages,” he added.

Rive and his brother, SolarCity CEO Lyndon Rive, are the cousins of Tesla Motor’s co-founder Elon Musk.

The company does not expect the DemandLogic system to give businesses independence from the grid but it will provide back-up against power shortages and enable companies to reduce their need for expensive grid energy during peak demand.

California became the first market in the world to set a significant energy storage target and falling costs are expected to give the market a major boost.

“The economics and scale that Tesla has achieved in the automotive market now make stationary energy storage more cost effective and reliable than it has ever been in the past,” said JB Straubel, CTO and co-founder, Tesla.

“We expect this market to grow very rapidly now that we have crossed this economic threshold,” he added.

The system will initially be available in parts of California, Massachusetts and Connecticut.

The two companies combined on a residential storage unit in 2012.