Make your solar PV system safety

You have probably seen a number of systems that were incorrectly wired, and hopefully they haven't caused any serious fires.

In recent years, fires have been attributed to: 1. PV module defects and; 2. Incorrect installation. Both causes resulted in fires that continue to burn due to DC arcing from the PV arrays continuing to generate power in sunlight even though they were disconnected from the inverter.

Having attended a number of safety seminars that were presented by a number of fire marshals, well known national electrical experts, etc., in the US, it was disturbing to find out how many people think that a DC disconnect switch, relay, or some other switch can deactivate a PV array during a fire. Even if you turn off the switch, the array itself is still producing power, so a sure way of deactivating the array is to cover the panels and keep light from reaching the modules. Once done, the individual panels need to be individually disconnected, or at least significant numbers of each string disconnected so that lethal voltages cannot be generated.

It was also acknowledged that AC modules (integrated microinverters) are safer as the modules aren't in series and therefore generating the high voltage DC which can arc and perpetuate a fire.

Many fire fighters in the US have received training on fighting PV fires, and understand the dangers of PV systems. They should be aware of the limitations of DC shutoffs, that the panels are still live, and will shade the panels to stop the production of power before going near them.

While covering the array is possible for a small home system, larger commercial systems fires can be extremely difficult to fight. Sometimes the fire fighters are forced to watch it burn itself out, or wait until dark! Many will not remember to cover the panels before the sun rises the next morning, and the trouble may start again.

It is very important for installers and designers to understand how dangerous a PV fire can be, so they should take extra care to ensure that their systems are designed and installed correctly. In the US, PV fires got a lot of negative publicity and damaged the reputation of PV solar.

I also cringe on the number of "amateur or inexperienced" designers here on these forums that are soliciting others to provide information for systems design, instead of attending PV design and installation training and certification through organizations such as NABCEP.

While PV is great, it can also create new challenges. We should continue to ensure that only properly trained persons are allowed to design, install, and inspect the systems. The home owner, or commercial property manager should also take interest in how to deal with a fire should that time ever comes.