Internal and External Lightning Protection
In PV systems, the PV arrays are outdoors, frequently on buildings. Depending on the situation, the inverters are also installed outdoors. For this reason, even at the planning stage of the PV system, you should determine whether measures need to be taken to deal with flashes of lightning and overvoltage. These measures can be required for various reasons. In addition to national technical standards and building regulations, the system insurer can also require overvoltage protection. An expert on lightning protection must determine for each PV system which measures are necessary.
Lightning protection systems are intended to prevent damage to buildings from lightning strikes. We distinguish here between internal and external lightning protection:
The external lightning protection serves to collect the lightning and conduct it into the ground. In this way, buildings and systems to be protected are saved from the effects of a direct lightning strike. The external lightning protection consists of air-termination systems, conductors, and the associated grounding arrangement.
The internal lightning protection provides equipotential bonding between installations with touchable parts made of metal and lines within the system. Metal and conductive system parts, e.g. water pipes, are connected directly with each other for this purpose. Live cables such as the grid connection or telephone lines are connected indirectly to the grounding arrangement using a surge protection device.
Overvoltage protection serves to prevent damage to electrical and electronic devices as a result of excessive voltages. Overvoltage protection devices (surge protection devices, or SPD for short) generate equipotential bonding between the connected conductors when excessive voltage is applied. This prevents voltage peaks from destroying connected devices.
Information on the topic of lightning and overvoltage protection in general as well as specifics when combining overvoltage protection devices with SMA inverters can be found under the following link: Technical Information "Overvoltage Protection - Lightning Protection and Overvoltage Protection for Sunny Boy and Sunny Tripower" and at www.SMA-Solar.com.