Coloradoans have seen the future and it’s bright. In a state that famously gets 300-plus days of sunshine a year, it is the optimal place for rooftop solar. Yet about 75 percent of households cannot take advantage of their surroundings because either they don’t own their house, can’t afford the upfront costs of adding a solar array to their home, simply live in too shady a spot for solar panels or have too small a rooftop. That’s where solar gardens come in.

The idea originated in the small town of Ellensburg, Wash. The municipal utility there partnered with community groups in 2006 to build a 36-kilowatt solar garden—an electric array that is owned by multiple subscribers and connected to the utility grid. The subscribers can purchase a portion of the power produced by the array and receive a credit on their electric bill. The idea is to allow all utility customers who want renewable energy to subscribe to the sun.

Solar gardens were first legalized in Colorado in 2010 in part because aside from signing up for green power with a utility, there wasn’t much folks could do to get renewable energy into their homes. If you owned your house and wanted clean energy, you had to install solar systems on your property. The 2010 law changed that by allowing people to buy into a solar array not on their property and receive credits from a utility for the resulting electricity. Ever since then, solar gardens have been growing wildly in the Centennial State.

One of the first solar garden programs in Colorado, run by the state’s largest utility, Xcel Energy, sold out in less than 30 minutes in the summer of 2012, receiving three times as many applications as it could fill. Late last year, Fort Collins’ municipal utility announced that it planned to start its first community-owned solar garden. “The aim is to allow people who don’t have the ability to install rooftop solar panels to get the same net metering benefit that they would have if they were able to put the solar on their roof,” Steve Catanach, light and power operations manager at the utility, says of the decision.

In addition to letting everyone participate, solar gardens also offer customers economies of scale they wouldn’t be able to achieve with individual rooftop projects. Minnesota, which passed a solar garden law last year and will soon launch its first project, caps the size of solar gardens at 1,000 kilowatts—much larger than an average 5-kilowatt residential system.

The size of solar gardens depends on state and local regulations. But an average single-family home would offset 100 percent of its electricity usage with just about 6 kilowatts of solar power, according to the Department of Energy.

So far, solar garden laws have been established in eight states—including California, Delaware, Maine, Massachusetts, Vermont and Washington—and the District of Columbia. But they aren’t without opponents. In Colorado Springs, the city council last year pulled the plug on a previously approved expansion of a municipal utility solar garden, citing costs to ratepayers.

Indeed, solar panels are expensive. A Coloradoan, for instance, can buy or lease a membership in an array project for between $600 and $3,500. The payback time on the investment ranges from 12 to 15 years. But that’s a bargain considering that the average cost of a residential rooftop array in Colorado runs between $15,000 and $30,000.

Only one-quarter of residential and commercial rooftops in America are suitable for solar panels, according to the National Renewable Energy Laboratory. That creates a big opportunity for community-owned solar. Clean Energy Collective (CEC), a Colorado-based community solar developer, says that shared solar could more than triple customer access to solar power in the U.S. To unlock its market potential, CEC says, a lot of regulatory and policy change is needed.

That’s where legislation is important. While gardens aren’t necessarily prohibited in states without laws, they can be legally and logistically more challenging without the legislation, according to the Solar Gardens Institute in Colorado. Laws help streamline the process of connecting solar gardens to the grid because they mandate that utilities accommodate them. So if solar gardens are to grow, the institute says, they need a little watering.