Photovoltaic cell modules are installed on the outdoor ground or on the roof. The distribution lines in the system are exported from the outside to the outside and output to the outside. This will increase the lightning strikes of the line. In order to ensure that the photovoltaic system can be normal. Work, the lightning protection of the entire system including solar modules and their supports, inverters, power distribution rooms and other systems is a very important security measures.
Lightning protection object for solar photovoltaic system
1. Lightning electromagnetic pulse protection: Lightning flashing electromagnetic pulse is transmitted by space, which will induce surge overvoltage on photovoltaic power generation system equipment and lines, and damage electrical equipment;
2, direct lightning protection: solar energy panels are installed on the outdoor roof or open space, so lightning is likely to directly hit the solar panels, resulting in equipment damage;
3. Ground potential counter-attack protection: As the external lightning protection device discharges the lightning current into the ground, the ground potential will rise, and the high voltage will enter the equipment through the grounding line of the equipment, thus damaging the photovoltaic power generation system equipment.
From the seasons, lightning activity is the most active in summer and the least in winter. From the regional distribution, it is the most active near the equator, with the latitude increasing and decreasing, the polar minimum.
The main methods of lightning protection:
(1) Using direct lightning protection;
(2) Eliminate lightning overvoltage, overcurrent and lightning electromagnetic pulse on the periphery of the device by means of isolation, clamping, voltage equalization, filtering, shielding, grounding, overvoltage and overcurrent protection;
(3) Use the grounding to pull a certain safe distance.
Direct lightning protection:
1. According to the scope, height and installation position of the solar cell array, according to the requirements of GB50057 “Lightning Protection Design Code for Buildings”, anti-direct lightning strike flash pins, lightning strips, flashing lines and lightning nets should be installed. The flashing pin should be calculated according to the ball method to determine the height and number of lightning rods and install them in a reasonable layout.
2. Large-scale photovoltaic power stations can be installed with flash pins and towers to prevent direct lightning strikes.
3. The flashing needle installed in the large-scale photovoltaic power station should be greater than or equal to 3m from the edge of the photovoltaic module.
4, anti-direct lightning strike down the line and the safety protection ground down the grounding point on the ground should be more than 10m.
5. Schematic diagram of flashing needles and tower anti-direct lightning strikes installed in large-scale photovoltaic power stations
6, large-scale photovoltaic power station can also be installed to connect the flash line, the flashing line pole should be greater than or equal to 3m from the edge of the photovoltaic module.
7. The cross-sectional area of the flashing line should be determined from the length and width of the PV module group, generally not less than 25mm2.
8. Schematic diagram of the flashing belt installed in a large-scale photovoltaic power station
9. When the photovoltaic cell module is installed on the roof slope, the flash band should be installed. The flashing strap should not be connected to the aluminum frame and bracket around the solar panel. The lightning strip should be connected to the ground net every 18m.
10. The aluminum alloy frame and PV solar mounting bracket around the solar panel should be connected to the equipotential bonding. Depending on the size of the battery pack, two or more grounding wires should be installed to pass through the steel pipe or be connected to the grounding net with a shielded wire as a safety protection ground.
11. Anti-direct lightning strike downline and safety protection. The entry point on the ground should be more than 10m away to prevent lightning strikes.
12. When the photovoltaic battery pack is installed on the sloping roof, the installation of the flashing belt is schematic.
13. When the photovoltaic cell module is installed on a flat roof, the anti-direct lightning strike flash pin installation diagram is shown
14. The battery plate with the automatic solar tracking system should be within the protection range of the lightning protection needle in different directions and angles.