Few places in the country are so warm and bright as Mary Wilkerson's property on the beach near St. Petersburg, Fla., a city once noted in the Guinness Book of World Records for a 768-day stretch of sunny days.

But while Florida advertises itself as the Sunshine State, power company executives and regulators have worked successfully to keep most Floridians from using that sunshine to generate their own power.

Wilkerson discovered the paradox when she set out to harness sunlight into electricity for the vintage cottages she rents out at Indian Rocks Beach. She would have had an easier time installing solar panels, she found, if she had put the homes on a flatbed and transported them to chilly Massachusetts.

"My husband and I are looking at each other and saying, 'This is absurd,'" said Wilkerson, whose property is so sunny that a European guest under doctor's orders to treat sunlight deprivation returns every year. The guest, who has solar panels on his home in Germany, is bewildered by their scarcity in a place with such abundant light.

Florida is one of several states, mostly in the Southeast, that combine copious sunshine with extensive rules designed to block its use by homeowners to generate power.

States like Massachusetts, New Jersey and New York — not known for clear, blue skies — have outpaced their counterparts to the south in the installation of rooftop solar panels.

While the precise rules vary from state to state, one explanation is the same: opposition from utilities grown nervous by the rapid encroachment of solar firms on their business.

The business models that have made solar systems financially viable for millions of homeowners in California, New England and elsewhere around the country are largely illegal in Florida, Virginia, South Carolina and some other Southern states. Companies that pioneered the industry, such as SolarCity Corp. and Sunrun Inc., do not even attempt to do business there.

"We get all kinds of inquiries every day" from the South, said Will Craven, spokesman for SolarCity. "People there want to be our customers."

Florida, in particular, is known as the "sleeping giant" of his industry, Craven said. "It has a ton of sunshine, a ton of rooftops," he said. "But there is no rooftop solar industry in Florida."

In South Carolina and Virginia combined, only a few hundred homes have solar panels, according to the Solar Energy Industries Assn. New Jersey has 21,500; California, 234,600.

Under the typical business model for the solar industry, homeowners sign lease agreements with installation companies. The homeowners pay the cost of the panels over time and sell any excess power the systems generate.

Along with tax breaks and other government incentives, the lease agreements have made solar installations increasingly affordable.

States where solar thrives typically pay homeowners attractive rates for the excess power they generate and require utilities to get a considerable share of their power from renewable sources. That gives companies an incentive to promote use of solar.

Southern states, several of which cherish low electricity rates afforded by extensive use of coal, typically have far fewer solar incentives.

This story was originally published by Governing.