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Lightning and Surge Protection for Building Installed Photovoltaic Systems |
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One of the more important safety considerations when installing a photovoltaic system is effective lightning protection because both direct and even nearby lightning strikes can damage components and endanger entire arrays. During the planning phase it is also important to determine what kinds of lightning and surge protection your system insurer requires.
A lightning protection system for photovoltaic arrays must include components that protect against direct lightning strikes (external protection) as well as mechanisms to protect system components from electrical surges (internal protection). External lightning protection involves intercepting direct lightning strikes using a lightning rod and diverting the energy to the ground without damaging the building or the photovoltaic components. Internal surge protection prevents dangerous electrical surges from travelling through the wires from the photovoltaic system into the building. Our new dedicated surge protectors provide effective lightning and surge protection on both the DC and AC current sides of your system and are easy to install and use.
Please follow the following guidelines and regulations:
- Lightning protection regulations: German Institute for Norms (DIN) EN 62305 / VDE 0185 305: Chapters 2-4 as well as appendicles 1-3
- German Institute for Norms (DIN) V VDE 0100: Parts 534 and 712
- VdS 2010: Risk oriented lightning and surge protection, guidelines of the German Insurance Association
Installation examples for MHH surge protectors and string boxes
A: Installation of main DC-Line input near system inverter
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1 Solar modules
2 DC main cable
3 Surge protector
4 Inverter with DC load break switch
5 Electrical distribution box and meter
6 Grid connection
7 Public grid
8 Electrical appliances
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If the DC cables between the modules and the inverter are installed along the outside of the building or run along the roof line, they first enter the building near the solar inverter. In this case, a dedicated MHH surge protector provides effective lightning and electrical surge protection when installed near the inverter. The surge protector box is installed on the line before the system inverter. This way the inverter is effectively protected from electrical surges from the modules as well as surges that might come from the public grid.
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B: Installation of the main DC-line input near modules
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1 Solar modules
2 DC string box
3 DC main cable
4 Surge protector
5 Inverter with DC load break switch
6 Electrical distribution box and meter
7 Grid connection
8 Public grid
9 Electrical appliances
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With larger photovoltaic systems it is often practical to connect multiple module strings together in a string box near the array and then simply run two DC-lines from the string box to the inverter. If the DC-input from the modules is located on near the roof and building is not already equipped with external lightning protection, we offer a string box with a built in DC surge protector and lighting arrestor. The inverter is shown here connected to a second, dedicated surge protector, similar to diagram A. In this configuration, the dedicated surge protector adds a second layer of protection from surges on both the DC and AC sides of the circuit.
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B2: Installation of the main DC-line input near modules and an inverter with multiple power stacks
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1 Solar modules
2 DC string box
3 DC main line
4 Surge protector
5 Inverter with DC load break switch
6 Electrical distribution box and meter
7 Grid connection
8 Public grid
9 Electrical appliances
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Our DC-string box ASK is designed for use with inverters that have multiple power stacks. The box is installed near the DC main line entry point and contains an integrated surge arrestor. As in examples A and B1, the inverter is shown here connected to a separate, dedicated surge protector; this adds a second layer of protection from surges on both the DC and AC sides of the circuit.
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