Is it necessary to install DC circuit breakers, lightning protection modules, etc. between photovoltaic modules and inverters?
With the increasing application of small-scale photovoltaic systems, especially in thunderstorm prone summer, the problems of photovoltaic systems have become more and more prominent. Recently, customers have often reported issues such as electrification on component brackets and low insulation impedance. After inspection, it was found that most cases were due to inadequate system grounding. Taking this opportunity, I would like to share with you the precautions for grounding photovoltaic systems.
1. The importance of grounding the photovoltaic system is to introduce lightning into the ground, ensuring the normal operation of photovoltaic system equipment; Prevent equipment or human health from being harmed by fault currents, lightning and influenza; To prevent voltage generation on the AC side N and PE terminals of the photovoltaic inverter, and to prevent errors in the photovoltaic inverter (we know that in the TN-S system, its N and PE lines are connected together at the neutral grounding point of the low-voltage winding of the power transformer, where the voltage is equal to zero, that is, the ground potential). The grounding of photovoltaic systems is divided into lightning protection grounding and electrical grounding
2. The lightning protection level of the grounded photovoltaic system is level three, and corresponding photovoltaic lightning protection equipment or measures should be selected. External lightning protection equipment mainly includes: 1. Lightning arrester: The lightning arrester includes lightning rod, lightning arrester network, and lightning arrester belt. 2. Downlead: 3. Grounding device
3. Attention
The burial depth of the grounding electrode shall not be less than 0.5m; The welded parts should be re treated with anti-corrosion and rust prevention measures; When the soil is loose, it is necessary to compact the soil. When the soil resistance value does not meet the requirements, spraying resistance reducing agents or charcoal chips can be used to reduce the grounding impedance.
4. Electrical grounding
1. Grounding of component frame, 2. Grounding of photovoltaic inverter, 3. Grounding of distribution cabinet
The grounding of a photovoltaic system is the least prominent but also the most important aspect. Reliable grounding can prevent direct lightning, induced lightning, and lightning waves from damaging the system. It can also prevent damage or even burning of photovoltaic modules or reverse photovoltaic converters caused by equipment short circuits and leakage. It can ensure that personnel come into contact with potentially live metal parts without being injured by electric shock. System grounding reduces the failure rate of the entire photovoltaic system, improves photovoltaic revenue, and plays a very important role in the reliability and stability of the entire photovoltaic system operation.
