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Robert M.O. Seidel avatar image
Robert M.O. Seidel asked

blocking diodes in 6 parallel VE Panels. need it or not!?

I would like to wire 6 x 215 W VE panels in parallel. Should I or should I not mount additional blocking diodes to the panels or are the panels sufficiently protected against reverse currents with the diodes in the box? I am never sure about that.

Solar Panel
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4 Answers
klim8skeptic avatar image
klim8skeptic answered ·

You will need to put diodes (or fuses) in the pos and neg lead of every panel.

Should one panel have a fault, the other five panels will dump all of their energy into the faulty panel, setting it on fire.

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jetlag avatar image
jetlag answered ·

Please check what is the max. allowed reverse current of these panels and then install DC fuses with a bit less rated current instead of such diodes. The diodes always cause a power loss and can heat up to a dangerous value. There are some youtube guys that had almost burning MC4 diodes on their roof, - not that funny...

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Robert M.O. Seidel avatar image Robert M.O. Seidel commented ·

Thank you for your prompt response. So you mean that if the panels have a short -circuit current of 6.3a ISC, I should install a 6a backup.

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renaniv avatar image
renaniv answered ·

I have the same question.

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jetlag avatar image
jetlag answered ·

@Robert M.O. Seidel

You should find out the allowable reverse current through the module. Isc is the max short current that the module can produce by itself.

I searched a little bit with the data you gave us, and I guess it is this module: SPM042152400 right?

Unfortunately I was not able to find this information within 5 min, but in general I would recomment to choose a fuse that is rated a little above Isc as the allowable reverse current should be normally higher.

Please check this type: OEZ Minia 41850.

This is a DC Fuse/Breaker with 8A and should fit into your application. Nevertheless it would be good to get a value for the max. allowable reverse current to be sure on that.

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