Microinverter manufacturers anticipate a growing balcony solar market

A new kind of small-scale solar is making its way to the US: plug-in, or "balcony," solar. Instead of a full rooftop system wired into your home's electrical panel, these setups use a small device called a microinverter that plugs straight into a regular outlet, similar to a major appliance. The power you generate gets used in your home right away, and any extra flows to the grid. It started in Utah last year after state lawmakers legalized it, and roughly nine or ten states now have similar laws, with more expected.

Two manufacturers, APsystems and Hoymiles, already make these microinverters for markets like Germany, where more than a million balcony systems are now in use, and have adapted them for US outlets and safety rules. New safety standards, UL 3700 and UL 1741, cover how these plug-in units interact with your outlets and guard against shock or circuit overload. APsystems' EZ1 can handle two small panels, while Hoymiles' HiFlow line can be chained together for a bigger system.

These systems cost much less than a full rooftop installation and produce far less power, but any electricity you make yourself is electricity you are not buying from the utility. Because the systems are just plugged in rather than professionally wired, they could make solar an option for renters or anyone unable to install panels on their roof. Whether your state allows plug-in solar, and what rules apply, depends on where you live.