Independent solar and energy storage field services provider HelioVolta published a report claiming that commercial rooftop solar systems using rapid shutdown devices (RSDs) are 66% more likely to experience critical safety issues. The report, titled “Unintended Consequences: Rapid Shutdown Devices and Safety in Commercial Rooftop Solar Systems,” uses performance data from more than 500 commercial solar systems dating back to 2021. From that data, HelioVolta reports that it found 74 issues and thermal events in those arrays.
Credit: HelioVolta
RSDs are installed on solar projects to cut PV module voltage and de-energize a system, so that firefighters working on a rooftop will not be shocked by the system. They were designed in reaction to the adoption of the 2017 National Electrical Code in solar construction. Power optimizers and microinverters also offer rapid shutdown.
“Installing and maintaining safe PV systems is the best way for solar companies to protect first responders,” said Dennis O’Neil, assistant battalion chief of the California Department of Forestry and Fire Protection, in a press release. “Failure-prone solar equipment puts firefighters at risk and is frankly unacceptable.”
In the report, HelioVolta found that RSDs caused 21 rooftop fires since 2021.
“Faulty RSDs are operating on buildings across the U.S., unintentionally putting people at risk. As these devices age, worst-case scenario failures are more likely to occur,” said James Nagel, CTO of HelioVolta. “No one wants to acknowledge safety risks hidden in solar portfolios, but we can only eliminate the dangers of RSDs with transparent, informed technical discussions.”
The report also covers the conundrum of project insurance compliance requiring RSDs and the cost of retrofitting other rapid shutdown-enabled solutions.
“Our goal is not to promote a single technology pathway for PV systems,” commented David Penalva, CEO of HelioVolta. “It is to help the industry build safer, more reliable systems that benefit everyone. It’s what every community deserves.”
