Surge protection devices

Surge protection devices limit dangerous overvoltages, such as spikes on PV DC lines that are mostly caused by lightning. A DC SPD protects the inverter by blocking voltages above a safe threshold or shorting them to ground. Some string inverters have slots for type 1 and type 2 devices on both the AC and DC sides, and these devices can be added later as a retrofit. Some inverters have the SPD built in and report surge events and faults to the monitoring platform. Design the surge protection for the local site: put a separate arrester where measuring or network cables enter a building, include sensors and all networked devices in the lightning and overvoltage protection, and fit an arrester sized for the power transformer. Without surge protection, overvoltages can travel along network or data cables into buildings and other devices, and touching live parts can cause fatal electric shock. Only qualified licensed electricians should install or service SPDs, and only with the device de-energized and with proper protective equipment, because hazardous voltages are present inside them. The junction box failure sources describe arcing, burnt junction boxes and burnt bypass diodes, but they do not name surge protection as a fix for those failures.