Energetica India Magazine January-February 2021

ENERGY STORAGE Residential PV Systems: Making Lightning Protection Design More Effective For residential PV systems, the type I and type II, two lightning strikes are the most common: direct lightning and induced lightning strikes. If the property is in a lightning-prone area or there are other high metal objects on the rooftop, e.g. solar thermal heaters, water tanks or satellite antenna, the probability of these two lightning strikes will be higher. It is necessary to enhance and strengthen the lightning protection during the design stage. 57 energetica INDIA- Jan-Feb_2021 Background Residential PV systems are generally installed on the rooftop of residential buildings, with a large metal surface area, high- er distance from the ground and exposed location. Therefore, PV systems are easy to become lightning targets in thunder- storms. If the power station does not have good lightning pro- tection & grounding, the probability of being struck by lightning is extremely high and could cause fire, electricity safety issues and losses to property and human life. The PV industry has matured and system design and construc- tion have become more standardized. However, there are still doubts about requirements for lightning protection: The whole design and construction of the system in this paper meet the requirements from components, brackets, inverters, electricity distribution boxes, and grounding cables. Why is lightning damage still a common occurrence? In order to answer this, we will share with you the problems that are eas- ily overlooked during installation and how to make the system protection more effective. PART 1 General Lightning Protection Solution Diagram 1_Standard lightning protection plan (Inclined roof on left and flat roof on right) For areas with relatively less lightning frequency, grounding methods shown in Diagram 1 are commonly used without in- stallation of additional lightning rods. If a system is installed on a flat roof, it usually tends to ground via the inverter cover or connect to the building’s existing lightning protection system. Such lightning protection is potentially inefficient for areas with high lightning probability. PART 2 Enhanced Lightning Protection Solution Before considering the effective lightning protection of a PV system, we need to understand the common types of lightning strikes.