Tesla batteries will store sun power for SolarCity

• SolarCity is launching a new thrust aimed at luring businesses with a plan to store power
• The solar provider will use Tesla batteries to cut businesses%27 power bills
• Using stored electricity reduces power that needs to be bought from a utility

While Elon Musk is CEO of space launch firm SpaceX and electric car maker Tesla Motors, he is also chairman of solar power provider SolarCity. So how do you tie the businesses together?

When it comes to Tesla and SolarCity, he may have found a way. SolarCity has announced it is going to sell companies on a way to store electricity to meet their peak demands.

And guess where the batteries to store all the power will come from? You guessed it: Tesla.

We're not talking about emergency storage here, generators and such in case the regular power fails. Rather, SolarCity is trying to provide a way to cut companies' electricity bills on a day-to-day basis by storing power until they need it.

"It allows company to manage their demand better," says Lyndon Rive, SolarCity's CEO. "Peak demand at night or day."

In the process, it helps fix one of the big problems of solar power, and electricity in general: There has been no reasonable way to store it. Generally, whatever electrons get generated need to be consumed right away. For businesses that need spikes in their power use during the day, or those that want to avoid utilities' higher rates during certain hours, battery storage could be a boon.

Tesla is unusual among automakers in that its batteries come in packs made from cells of the same type used in laptop computers. Hundreds or thousands of these cells are bundled to make Tesla battery pack. If they work for cars, they should work for corporate storage purposes.

Even though Tesla has reported that its battery supplies have been tight, Rive says better supply will be available in the future about the time that the storage program will take effect.

Though SolarCity's trucks crisscross the sunbelt and it is known for home installations, about a fifth of its business, as measured in megawatts, has been from the commercial market, he says.

The compelling argument to business leaders: "It's just more savings."