From Fortune, by Katie Fehrenbacher

More American homes than ever before are getting solar panels.

The market to install solar panels on the roofs of homes in the U.S. set another record in the second quarter of this year, indicating a shift in the U.S. solar panel industry toward homeowners and consumers.

According to a new report from research firm GTM Research and the Solar Energy Industry Association trade group, the recent record beat out the amount of solar panels installed on home roofs in the first quarter of this year, which itself was a record at the time.

For years, the bulk of solar panels in the U.S. have been installed in big solar farms in remote areas, creating electricity to be sold to utilities. Utilities distribute this electricity to consumers through a centralized power grid.

That so-called utility-scale solar market is still significantly bigger than the one is for homes. In the most recent quarter, there were 729 megawatts worth of solar panels installed in solar farms for utilities.

At the same time there were 473 megawatts of solar panels installed on home roofs. One thousand megawatts is about the size of a large coal or natural gas plant.

But the amount of U.S. residential solar panels has been growing more rapidly, and has been expanding across more states than ever before. The amount of home solar roofs grew 70 percent year-over-year for the most recent quarter, and went from four states with vibrant residential solar markets in 2013, to 10 states today.

The growth in the market for residential solar is particularly interesting because by installing panels on roofs, consumers take more control over their own electricity generation. Energy generation becomes decentralized, in contrast to the traditional centralized model. In that model, utilities still provide the backbone for the grid, but don’t own the generation.

At the same time, the utility-scale solar market is growing, too. But there’s also potentially a boom and bust cycle happening for the biggest farms.

There’s an important subsidy, called the federal investment tax credit, that offers solar farm owners a 30 percent tax credit. That credit could drop down to a 10 percent tax credit starting in 2017.

As a result, power companies have been racing to build solar farms for utilities this year, leading to an over-inflated market in the short term and possibly an under-inflated one down the road. Another report from research firm IHS earlier this year found that as of this summer there were 32 gigawatts of solar farms, between about 20 and 100 megawatts in size, planned for the U.S. by the end of 2016.

The federal tax credit might get extended, particularly if a solar-friendly President such as Hillary Clinton is elected. But the uncertainty will still affect the solar industry.

Overall, the growth in both the utility-scale and residential solar markets in the U.S. this year has been impressive. There are now over 20 gigawatts of solar panels operating in the U.S., which can power 4.6 million U.S. homes. So far this year, 40 percent of all the new electricity-generating capacity came from solar.