Up to 4,000 energy-efficient homes are being planned by a developer in Arizona.

The shift toward renewable energy is a growing trend among builders and developers.

Developers are getting ready to cut the cord on electricity, and a battery may take its place, according to the Wall Street Journal.

Homes are incorporating batteries that resemble modern versions of outdoor neighborhood junction boxes, but these can be put inside the house, according to the Journal.

Up to 4,000 energy-efficient homes planned by developer Arizona Eco-Development and built by home builder Mandalay Homes will use 8 kilowatt-hour batteries from German maker Sonnen, according to the Journal. The majority will be in Prescott Valley, Arizona.

In Vermont, a partnership with Tesla Energy and Green Mountain Power is offering 2,000 of its customers a 13.5 kilowatt-hour battery called the Tesla Powerwall for $15 a month.

The batteries cost $5,500, according to the Journal, but GMP CEO and President Mary Powell said the utility can afford to put them in homes because it helps the company save on grid infrastructure. GMP also uses batteries from Sonnen, SimpliPhi and Sunverge.

The shift toward renewable energy is a trend among builders and developers as more residential buyers slowly consider environmentally-friendly options, despite the added cost. Popular states looking to revamp their grids include New York, California, Massachusetts, Hawaii, Vermont and Arizona.

Prices for solar panels in Florida have fallen by 64 percent over the past five years, according to the Solar Energy Industries Association. South Miami recently became the first Florida city to mandate the installation of solar panels on all new homes.