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Photovoltaic systems, whether large ground-mounted systems or rooftop systems on a residential building, are at risk of lightning surge voltage due to the coupling surfaces and installation locations. With our string combiner boxes and surge protective devices for photovoltaic systems, you not only ensure availability and high performance. At the same time, you also keep the amortization time of the system as short as possible. Use our lightning and surge protection for photovoltaic systems to ensure availability and your yield.
Separation distance “s” is the minimum distance needed between the lightning conductor and photovoltaic system to prevent the lightning flashing over. Experts need to help determine this because the distance is difficult to calculate. All PV components should be installed with a clearance of at least this distance. If the distance is not maintained, the photovoltaic system is connected to the lightning protection system, which places increased requirements on surge protection.
In addition to the separation distance, the sag is important, especially when retrofitting PV systems. The area below an imaginary line between the tips of the lightning rods should be protected, as lightning can easily penetrate underneath. PV panels must be located below the sag. If they are located above, you can either install the panels in a flatter orientation or adjust the lightning protection system. The size of the sag can be determined by the installer of the lightning protection system.
The PV panels are connected in series. They form a cable ring that acts as an antenna and is sensitive to couplings. These couplings can damage the inverter and the photovoltaic system. The spanned area of the cable ring must be kept as small as possible. A larger area couples more energy. Lightning strikes act as powerful transmitters. In the event of a nearby impact, they can generate significant currents that endanger the system.
A lightning strike on the building has not been taken into consideration. A photovoltaic system also does not increase the risk of being struck by lightning. The photovoltaic system is integrated into the equipotential bonding.
The PV panels are installed a sufficient distance from the lightning protection system in the protection zone. The photovoltaic system is optimally protected in the event of a lightning strike. The photovoltaic system is integrated into the equipotential bonding.
The PV panels are installed close to the lightning protection system. Therefore, in the event of a lightning strike, there could be a dangerous sparkover to the photovoltaic system. To prevent this, the PV panels and/or the PV mounting frame are connected properly to the lightning protection system. Please note here that partial lightning currents are introduced into the building. The equipotential bonding must be able to handle lightning currents.
Ideally, the surge protection is installed in the vicinity of the inverter. Integrate protection using our surge protective devices for the AC and DC side of the inverter. Alternatively, you can also use our preassembled solutions for string combiner boxes.
For the installation locations and installation conditions, please refer to the table below.
Our product recommendations for the installation locations can be found here:
| AC voltage 1 | AC voltage 2 | DC voltage 1 | DC voltage 2 | |
|---|---|---|---|---|
| Installation location | Main distribution | AC side of the inverter (cable length to the main distribution ≥10 m) | DC side of the inverter (cable length to the PV panels ≥10 m) | Near the PV panels or the entrance to the building |
| Without external lightning protection | Type 2 SPD | Type 2 SPD | Type 2 SPD | Type 2 SPD |
| With external lightning protection, separation distance is observed | Type 1 SPD | Type 2 SPD | Type 2 SPD | Type 2 SPD |
| With external lightning protection, separation distance is not observed | Type 1 SPD | Type 1 SPD | Type 1 SPD | Type 1 SPD |
In addition to the four installation locations of surge protective devices for PV systems that have been highlighted so far, there is another area that you shouldn’t forget:
The protection of communication interfaces is not necessarily required by standards, but is nevertheless highly recommended. The inverter electronics can actually be damaged by overvoltages via a network cable or a thin control line, thus disrupting the operation of the photovoltaic system.
Digital inputs for power regulation, a weather station, Ethernet, RS-485: all of these are examples of common interfaces that need to be protected.
