When Greg Hare looked into putting solar panels on his ranch-style home in Magnolia, Tex., last year, he decided he could not afford it. “I had no idea solar was so expensive,” he recalled.

But the cost of solar panels has plunged lately, changing the economics for many homeowners. Mr. Hare ended up paying $77,000 for a large solar setup that he figures might have cost him $100,000 a year ago.

“I just thought, ‘Wow, this is an opportunity to do the most for the least,’ ” Mr. Hare said.

For solar shoppers these days, the price is right. Panel prices have fallen about 40 percent since the middle of last year, driven down partly by an increase in the supply of a crucial ingredient for panels, according to analysts at the investment bank Piper Jaffray.

Image Greg Hare recently installed solar panels on his home that he hopes will cover between 50 and 80 percent of his electrical bills in Magnolia, Texas. Credit... Michael Stravato for The New York Times

The price drops  coupled with recently expanded federal incentives  could shrink the time it takes solar panels to pay for themselves to 16 years, from 22 years, in places with high electricity costs, according to Glenn Harris, chief executive of SunCentric, a solar consulting group. That calculation does not include state rebates, which can sometimes improve the economics considerably.