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Overvoltage protection between PV Panels and MPPT

Hello,
What kind of overvoltage protection is recommended between PV Panels on the Roof and MPPT (BlueSolar 250/70-Tr) in the house?
Thanks!
overvoltage
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2 Answers
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ipirk answered ·

Hello, thanks for your answer.
Yes exact - overvoltage from lightning.
Can you reference me an DC Surge Protection (type) Devices that fits to my BlueSolar 250/70-Tr - i guess it shoud have a voltage of 250V?!

DC isolator shoud be no problem - my Setup is:
PV Panel, Fuse, Overvoltage Protection, DC isolator - so the DC isolator is protected from the fuse.

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@ipirk

How are you combining your strings? Is each string dc fused?

Sometimes just buying a pv combiner box for the number of strings and pv power you have is simpler than sourcing all the parts.

https://www.google.com/url?q=https://www.amazon.com/ECO-WORTHY-String-Combiner-Circuit-Breakers/dp/B01N96GJFT&sa=U&ved=2ahUKEwjwudaxpcvvAhX0mFwKHbqfDuIQFjAJegQIAhAB&usg=AOvVaw1LNEPT98wlXw_tYM0RLM7Q

Thanks - yes every string is dc fused - so exactly as in your link.
But in your link the overvoltage protection is a 1000V Protection - and i think this is way to much for the Victron or?

No. You can lower it to 750v or 500v if you like. The voltage is not really the important thing rather the class type (based on if you have other lightening protection and more the KA rating than the voltage)

Remember it is not for the normal panel production, it's for the just in case of lightning or transient spikes of voltage or an induced current from such things, those will usually be much more than normal panel production.

The voltage from panel production should be sized at the minimum temperature for your area so they don't overvolt in normal operation.

@ipirk

Are there regulations for your area? Often this is the best place to go for recommendations. There are none where we are so we have just been following best practice and international standards.

Alexandra avatar image
Alexandra answered ·

@ipirk

By overvoltage are you referring to overvoltage from lightning? You can ground the array.

You would need DC Surge Protection Devices for that. Example linked.

https://www.sonopsolar.co.za/product-category/solar-products/accessories/1-8-surge-protectors/dc-surge-protector/

But as for panel voltage, 250v at minimum temperature for your location is the hard install limit for the mppt. You would need a pretty decent DC isolator for that as well.

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