The Importance of Surge Protection Devices
The capacity of a PV array is directly related to its exposed surface area, so the potential impact of lightning events increases with system size. In the area that lighting occurrences are frequent, unprotected PV systems could suffer repeated and significant damage to key components. It results in substantial repair and replacement costs, system downtime and the loss of revenue. Properly designed, specified and installed surge protection devices minimize the potential impact of lightning events when used with engineered lightning protection systems.
Aside from the consequences of direct lightning strikes to the arrays, interconnecting solar cables are very susceptible to electromagnetically induced transients. Transients that directly or indirectly caused by lightning, and transients that generated by utility-switching functions, expose electrical and electronic equipment into very high overvoltages during very short duration (tens to hundreds of microseconds). Exposure under these transient voltages may cause a catastrophic component failure that may be noticeable by mechanical damage and carbon tracking or be unnoticeable, but still cause an equipment or system failure.
Long-term exposure in lower-magnitude transients deteriorates dielectric and insulation material in PV system equipment until finally breakdown. Additionally, voltage transients may appear in measurement circuits, control circuits and communication circuits. These transients may appear to be erroneous signals or information, rusult in equipment malfunction or shut-down. The strategic placement of Surge Protection Devices mitigate these issues because their function are shorting or clamping devices.