Adele Peters for Co-Exist:  Less than a year after Tesla unveiled its Powerwall battery for storing electricity at home, a startup has designed a much cheaper alternative that you can plug in yourself, without an electrician.

The modular batteries, called Orison, can be hung on the wall or set on the ground to double as an LED lamp. If you want more power, you just add the units together.

"Think of Orison like Legos," says co-founder and CEO Eric Clifton. "The 2.2 kilowatt-hour unit is really just one piece, so you can actually add as many as you need." The 2.2 kilowatt-hour version is as large as the company could make one unit and keep it under 40 pounds, so it could be easily shipped and moved.

With one unit, if your power went out in a storm, you could keep an energy-efficient refrigerator running for about two days. If you want to back up everything in your house, you'd connect a long series of batteries together.

For someone with solar panels on the roof, the batteries can store power to use at night. Right now, most people can sell extra solar power back to the grid when they're not using it, but many state laws are about to change so people will make less money. Batteries can help solar homeowners save money by making use of the power they've generated.  Cont'd...