Residential Inverter Quality: An O&M Headache


Perhaps the residential solar component with the shortest life expectancy is the inverter, which is typically covered for only 10 years within a total system lifetime expectancy of 20 or more years.

However, many inverters fail to hit the 10-year mark. The Solar Engineering & Manufacturing Association (SEMA), based in Santa Ana, California, found several years ago that about 10 percent of all solar inverters had failed within seven years.

Such a failure rate could bode poorly for mega-installers that package large groups of residential installations as a securitization sold to unknowing investors. Who carries the warranty in such cases? Perhaps the installer, perhaps the insurer and perhaps it’s just hard to get satisfaction.

One residential installer highly focused on quality claims not to be a fan of either microinverters nor power optimizers. “I don’t have the metrics to confidently quantify specific failure rates, but let’s just say that they are often enough to create a challenge for the service department,” Steven Kane, the customer service and O&M engineer for Boulder, Colo.-based Namaste Solar, told pv magazine.

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“I do see more stability with DC optimizers — like SolarEdge, which is very good — and failure do not occur with them too often,” he says. “The DC optimizers have ceramic capacitors, while the microinverters have electrolytic capacitors; the ceramic models are more stable and have a lower failure rate,” he says.

Better communications will help. “One problem with detecting failures is a breakdown in the network based data communications on the customer side; I’m more of a fan of cellular connections independent of the customer line,” explains Kane.

“I don’t know if it is a funding problem for the suppliers, but some companies do have extra hardware in stock, whether it is the same model or a newer, better one. It is absolutely a problem to get returned merchandise authorizations; you just can’t get them from some manufacturers even if the equipment is still under warranty.”

The cost of servicing residential solar systems will only rise as time goes on. “We charge $200 for the first hour of a truck roll with two guys, then after materials costs, it can be significant to replace inverters and wiring on arrays,” he says.


Editor’s Note: These issues and others will be explored at pv magazine‘s Quality Roundtable at the Solar Power International trade show in Las Vegas on September 14.

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