Energetica India Magazine January-February 2021

58 energetica INDIA- Jan-Feb_2021 ENERGY STORAGE For residential PV systems, the type Ⅰand 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 probabil- ity of these two lightning strikes will be higher. It is necessary to enhance and strengthen the lightning protection during the design stage. Metal equipment on the rooftop To enhance the effectiveness of lightning protection for resi- dential systems, in addition to normal lightning protection mea- sures, the following points should be considered: 1. If the system has a large capacity or is located in an area with high lightning strikes, it is necessary to install a lightning rod beside the solar array; 2. If there are other metal facilities on the roof, the DC side of the PV system should be kept as far from these structures as possible. Make sure the PV system mounting does not come into contact with these structures. It is also recommended to install a lightning rod on the roof. 3. Reduce the general PV system cabling cross-area to de- crease the strength of an induced lightning strike. 4. It is recommended to implement a separate lightning pro- tection solution for the PV system and avoid simply connecting to the building’s original lightning protection system. Enhanced lightning protection solution (inclined roof/flat roof) PART 3 Case Study This project is in Fenghua, China. According to statistics, the area’s annual average lightning days of more than 75 times defines it as a lightning-prone area. The on-site residential buildings have a large flat roof area, and the total installed ca - pacity is 28kW, with a GCI-25K-5G inverter, so the lightning protection system scheme shown in the figure below is what was implemented.. On-site lightning protection solution of PV system