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Map: Western states lead the nation in home solar installations

More than 3 million households and businesses have connected their solar panels to the grid, but fights over pricing stymie growth.
Solar panels on a home in Hattiesburg, Miss.
Solar panels on a home in Hattiesburg, Miss.Bryan Tarnowski for NBC News

Home solar power usage has boomed in the U.S. in the past decade, but most of that growth has come from just two states.

The number of homeowners and businesses that linked up solar panels to utility grids has grown more than tenfold since 2012, rising from nearly 234,000 customers to about 3.2 million this year. Arizona and California account for half of those customers, according to an analysis of data from the U.S. Energy Information Agency, or EIA. 

When the numbers are adjusted for population, Hawaii leads the country with nearly 20 solar customers per 100 households, followed by California and Arizona.

Most states have little solar presence. Montana, Nebraska and Wyoming account for less than 1 percent of the country’s solar-powered customers. Alabama, Georgia and Mississippi collectively have about 1,500 customers with solar panels connected to utility grids.

The EIA data show only customers who participate in net-metering, a billing method that lets customers with solar panels or wind turbines earn credits on their bills by selling some of the generated energy back to local electrical grids. It doesn’t include those who use solar panels to live off the grid or the energy captured from large-scale solar farms that utilities can purchase and distribute to customers by traditional transmission lines.

Nearly every state has net-metering requirements, which mandate some form of payment for excess energy. The billing mechanism isn’t mandated in Alabama, South Dakota and Tennessee

Solar reimbursements are complicated. Not all states make it easy to get paid back for the contributed energy, and state legislatures and regulators have made moves to cut payments.

A patchwork of regulations allows customers to receive credit in most states, but some utilities have sought to limit what they pay back to customers for their excess solar energy. In Mississippi, the rates are so low that only 586 households have opted in to the service

Florida Gov. Ron DeSantis, a Republican, vetoed a measure last month to gut the state’s solar credits, saying it would hurt residents already reeling from rising gas and groceries prices. Florida ranks sixth in the country, with nearly 115,000 customers earning from solar.

Regulators in California delayed a decision last month to slash solar energy payments to customers.

Small installations accounted for about one-third of all solar energy generated in the U.S. last year, according to Energy Department data.