We were concerned to hear about recent news of fires at locations with large solar arrays. If you're interested in solar, you may be thinking is this a common thing and would a solar system pose a safety risk on your house?
There are a couple technical things about those systems that make a huge difference between the risk of how they operate compared to what an Ipsun Solar home installation looks like. We turned to our Deputy Director of Engineering Humza Arshad to break it down.
String inverters were used: what that means
Humza explains that those fires you've read about occurred with string inverters without rapid shutdown capability (RSD). Think of string inverters as if a row of solar pv modules (or in layman's terms, panels) were like a set of Christmas lights. While you can unplug a whole set of those light, there's no way to control a single Christmas light within a string. The thing is, string inverters run at extremely high voltages (with a dozen or more modules wired together) and do not have any way to shut down a single panel if there is an issue.
What's the solution? One-by-one individual panel shutdown capability
We use microinverters (1 per panel) that put out the same voltage that your home receives from the grid (240V AC). Every single microinverter we use has built-in protection, and will shut itself down as it alert us instantly if there are any issues.
Humza concludes, the short of it is that those fires were caused by poor installation and the use of cheaper, lower quality equipment, relative to what we would consider the minimum standards of materials and conduct that our industry should be following. Those installations would not comply with the 2017 electric code, the most recent edition. Ours do. He points out in closing: "Every Ipsun employee who owns a home has solar on it." It's true, and we all know the technology better than most and have confidence in solar with microinverters, which we endearingly refer to as "micros" for short.
Ever ride the Metro? You'll be familiar with the principle that DC arcing can cause fires. This could happen with solar systems set up in the older way. This just effectively does not occur on solar systems that use microinverters or DC optimizers and is primarily an issue with string inverters lacking proper arc fault interruption (AFCI) and Rapid Shutdown [RSD]. Microinverters are immune to DC arcing, and all of our systems are NEC 2017 code compliant, with rapid shutdown capability at each module. Rest assured that while troubling, the story of stores with solar that experienced fires don't mean that that's a risk for your solar home.