How Do You Know Your Solar Panels Are Working Correctly? You Probably Don’t

February 18, 2015

A new study finds that real-time data doesn’t always uncover issues with PV systems.

Katherine Tweed, Greentech Media
February 18, 2015

As Brewster McCracken and his team at Pecan Street were gathering solar photovoltaic data from houses in their ongoing research, they were surprised by how many PV systems had gaps in their energy production. It was even found that one set of panels had been down for months.

The findings compelled Pecan Street, an Austin, Texas-based organization that investigates water and energy use behavior, to take a deeper dive.

new study from Pecan Street has found that most solar PV systems only experience minor issues and that solar PV is largely maintenance-free. But the minor issues can often impede power production for days, weeks or even longer. In most cases, the homeowners had no idea there was a problem.

“It’s a minor issue. But by not detecting it, it becomes an issue where you’re losing value on your solar panel even though it’s a $5 issue to fix,” said McCracken, CEO of Pecan Street.

In the study, 54 of 255 homes experienced minor issues, such as blown AC fuses and ground fault interruptions. Many of the problems required less than $25 in parts and less than an hour of an electrician’s time to be resolved, if an electrician was needed at all. Only two homes had more serious issues, inverter failures in both cases.

The study found that most homeowners had no idea their panels were malfunctioning, even though they may have real-time data from their solar installer. In many cases, they were down for weeks to months, Pecan Street found.

“Data is just data,” said McCracken. “Odds are it’s very hard to figure out” problems by just looking at raw, real-time data, he said. Many of the problems, especially ground fault interruptions, can look like the dips in production from weather changes. For people who are only looking at 30-day bills, it’s even harder to tell.

The study also found that while the average solar PV owner is more of an energy geek than the average person, there are limitations. “There’s car guys, and then there’s the rest of us,” McCracken said. And for the rest of us, there are “check engine” lights.

Despite the move to real-time energy data, disaggregation services and utilities providing alerts for high bills or outages, solar PV owners do not often have the same alert services for their panels. As solar becomes more and more mainstream, such services become even more necessary.

To meet the needs of the market, Pecan Street is launching Pecan Street Sol, an alert system for PV systems. The service is free and available to PV system owners who have an eGauge-compatible energy monitoring system available with their panels. For those without an eGauge device, another piece of hardware is needed to use the app.

EGauge takes data from panel circuitry. Devices that are eGauge-compatible have various names, including LightGauge (Lighthouse Solar), Hot Purple Energy, and Revolve Solar. A list of eGauge installer partners can be found on the company’s website.

Missing from that list of names are the two largest installers in the U.S., SolarCity and Vivint. SolarCity recently launched MySolarCity app, but it does not come with alerts. For customers with systems that are not eGauge-compatible, the devices cost about $500, plus the cost of installation, which will vary. Pecan Street can recommend contractors and electricians that can install the devices, or a solar installer could also be a resource.

For utilities that are looking to get into the rooftop solar business, offering access to such an app should be an obvious customer service tool. While customers may not engage more frequently with the utility because they have it, they’ll be glad to have it if they need it. “Alert services are low-engagement platforms,” said McCracken, “but that doesn’t mean they’re not valuable.”

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