“There has been a huge takeup,” said James Basden, head of utilities at the Oliver Wyman consulting firm in London.

There is no doubt that SunEdison’s free installation plan proved popular. Since it began in March, the company said it had found about 1,000 takers. Among them were Julia and Chris Over, a retired couple living in a farm village called Dinedor in western England. Like many Britons, the two were attracted to solar energy as a means of saving money while reducing carbon emissions. But they were wary of the required investment of about 6,000 pounds, or about $9,200.

“It was something that was always in the back of my mind, but I wouldn’t have spent the money,” Mr. Over said.

Mr. Over said he was happy with the results, estimating that they are saving 20 percent to 25 percent on what had been a £1,500 annual energy bill.

The Overs and SunEdison have been sharing payments, called feed-in tariffs, that were introduced in 2010 to encourage the generation of low-carbon electricity on a small scale. Through these tariffs, subsidized by the government, homeowners can be paid around 12 pence per kilowatt-hour for the electricity their systems generate, whether or not it is fed back to the power grid.

That can reduce the average household energy bill by as much as £700 a year, according to analyst estimates.

Industry experts say there is no doubt that the subsidies, on which the government has been spending about £1.3 billion a year, have helped encourage the solar boomlet.