Secure your power systems with lightning protection
Lightning is the number one cause of catastrophic failures in solar electric systems and components because many PV systems are poorly grounded and poorly protected.
Lightning protection controls the path of the lightning after it hits. Like it or not, that is about the best you can do. It’s not lightning that causes the damage, it’s lightning going through places you don’t want it to.
The fact is that almost nothing can offer 100% protection from lightning strikes or damage – but risk can be reduced significantly with simple precautions and relatively inexpensive installation methods.
Solar panel frames and mounts are grounded in order to provide the easiest path for lightning to get to the ground. You would much rather have it go down the mounting pole or your ground rod than down your wiring to the controller, inverter or new wide screen TV. Without proper grounding, lightning can do some really strange things and can jump around while trying to get to earth. If the inverter happens to be in the way, you will probably be buying a new one. You cannot stop lightning, but you can usually direct where you want it to go. Please note that fuses and circuit breakers offer no protection at all to lightning strikes.
Sometimes also called Surge Protectors (SPD) such as the MidNite Solar MNSPD’s, act like “clamps” in most cases. They go across the live wires with another wire going to the ground. Normally they just sit there, but if the voltage goes above a certain level, they start to conduct, shorting the higher voltage to the ground. For most DC coupled systems to get the best protection, you should have a DC surge arrestor on the INPUT to the charge controller. It should be as near the charge controller as possible. On the AC side you should have AC Surge arrestors on BOTH the inverter AC input and AC output for generator and/or grid tie systems.
Most inverter damage is caused by surges on the AC side coming in through house or generator wiring. In many systems with a backup generator, the generator is located outside, quite some distance from the inverter, and is a common hit point for lightning strikes.
It may seem a lot to spend over $300 on an SPD, but the typical repair bill for a mid to large size sine wave inverter that has been hit by lightning can come in at between $1,500 and $2,000.
Please refer to section 3.5 of the AS/NZS5300:2014 standards for more about the installation of Surge Protection Devices