New tech can make your house a solar microgrid
New version of support hardware can keep homes solar-powered during outages.
DOUG JOHNSON – 9/22/2022, 9:00 AM
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In 2020, the average United States resident experienced a little more than eight hours of electricity blackouts, according to stats from the Energy Information Administration. The report noted that this was the highest number seen since 2013 when the organization began collecting this data.
During huge storms or massive oppressive heatwaves, the power can go out, and many of the amenities—TV, the Internet, fridges, etc.—Americans enjoy simply go kaput. Currently, the primary options for avoiding this fate are batteries and backup generators. However, a company called Enphase says it has created a product that can let your house run directly off its solar panels if they’re producing, though it comes with some caveats.
Shouldn’t solar panels work during an outage?
You’d think so, but no—mostly. Solar panels affixed to homes (and other structures) that are connected to the power grid will also go kaput during power outages. The outage doesn’t stop them from producing power; the power just can’t be used in the absence of a functioning grid. That’s because the microinverters are part of an integrated system that includes the grid, power meter, and other associated hardware.
(There are two exceptions to this. The first is off-grid buildings that are set up to generate electricity from solar panels. The other exception is structures that have battery systems hooked up, though these can cost a lot—around $14,000 to install in some cases.)
To increase the number of exceptions, Enphase created the IQ8 Microinverter. Inverters convert direct current (DC) produced by solar panels to the alternating current (AC) supplied by the grid. A microinverter is just a small version of it. According to Enphase co-founder and Chief Products Officer Raghu Belur, microinverters function while attached to each solar panel instead of having many panels all fed into a larger inverter. This approach of having a distributed architecture has proven to work well in other applications, such as in computers and data centers, he said.
“The advantage [of putting inverters at every solar panel] is that, when you do power conversion at the panel itself—when you convert from DC to AC—you get better performance,” he told Ars. “The reason you get better performance is because the output of one panel is not dictated by the output of another solar panel, unlike in a centralized case.”
Another advantage is that there is no single point of failure; each panel and inverter acts as an independent energy producer. Further, the microinverters are all linked to software that, among other things, uses a mathematical model to predict power usage in whatever structure they’re attached to. That’s why its name includes “IQ.” Because it’s smart. (Maybe. We didn’t actually ask about that.)
OK, how does it power my house when the grid’s down?
A collection of these microinverters on a house can act as a microgrid. Each one contains a chip that—when the main power grid suffers a power failure—switches from an on-grid to an off-grid mode. In this mode, the microinverters ignore the grid and direct any power to the building they’re attached to. In essence, it can operate as part of a grid-integrated system or part of a microgrid.
Once in off-grid mode, if the sun is still shining, the solar panels will send their power directly to the house. But, if the power goes out because of, say, a huge storm, the panels wouldn’t be producing anyway, and the building would need to have a battery system to maintain power. However, according to Belur, the microinverters can extend the time the building would have power and make it so the owners wouldn’t need to purchase a particularly large battery setup.
There are two types of configurations that property owners can choose. The first is the Sunlight Backup System, which uses the microinverters without a battery. This setup requires the microinverters and a lot of other Enphase hardware: a combiner box like the IQ Combiner 4, a system controller like the IQ System Controller, a load controller, and a rapid shutdown switch. (To be clear, some version of all this hardware is needed for the panels to function.) The other configuration is functionally the same but also includes a battery or batteries.
According to Enphase’s website, one of the company’s more affordable systems can run between $6,000 and $8,000. This cost is potentially much cheaper than some higher-end battery systems.
So, it’s technically true—the IQ8 will increase the odds your house or business will have power during outages. Will it cover you 100 percent, regardless of the weather or time of day? No. Is it cheaper than many high-end battery systems? Yes.