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Catastrophic fuse size

March 03, 2022, 06:45:48 pm

OK, I intend to have 200W solar panel output on the roof of the coach at 26V this spring. Just enough to keep the batteries charged I hope.
Should I install catastrophic fuses? What size. if any?

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Re: Catastrophic fuse size

Reply #1 – March 03, 2022, 07:58:24 pm

I'd say 30 or 40 amp -- 1 on the hot line between the panels and your solar controller and one between the controller and the batteries. (another between the batteries and the inverter if you connect one)

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Re: Catastrophic fuse size

Reply #2 – March 03, 2022, 08:07:13 pm

I installed a 250 amp fusible link down where the solar goes into the battery connection at the electrical bus. I also have breakers up where the solar goes into and also out of the controller. You can't be too safe when a lot of amps are available. Northern Arizona Sun and Wind and Midnite tech recommended this.

Arrows point to the fusible link.

Pierce

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Re: Catastrophic fuse size

Reply #3 – March 03, 2022, 11:09:42 pm

Volts times  Amps equals Watts, Watts divided by voltage equals amps. 200w divided by 12v equals 16.67 amps. 25 amp fuse would protect. I think solar panels can be shorted out (please double check) and not be damaged.
Scott

is it ok to short circuit a solar panel - Google Search

No - you will not damage a solar panel by shorting it. Solar panels are designed to be continuously operated at very very close to their short circuit current. A good quick test of a solar panel is to run it short circuited into an ammeter.

is it ok to open circuit a solar panel - Google Search

Yes. It does not hurt them to be disconnected—open circuited. Leaving anything out in the sun and rain will cause eventual degradation.

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Re: Catastrophic fuse size

Reply #4 – March 04, 2022, 10:29:33 am

Trying to amplify Mr. Davidson's remarks, a circuit breaker can carry continuously about 75% of its rated current.  That being said, for protection multiply your maximum current by 1-1/3 and choose accordingly.

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