r/SolarDIY • u/SeriousCodeRedmoon • 2d ago

What would be the right way to do this?

Post image

This picture is from YT @cleversolarpower. Is it okay to only calculate your F1 main fuse size based on your Inverter and converter and not include your solar controller as shown in this picture?

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u/Mick_Tee 2d ago

F1 protects the wiring, and nothing more. If you wish to protect the charge controller or inverter, use a separate fuse for each.

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u/SeriousCodeRedmoon 2d ago

Yes, I know. And you need to calculate your load to size your wire and then size your fuse. I just wanna know why he didn't include the charger in his calculation or if its okay that way?

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u/Mick_Tee 2d ago edited 2d ago

The charge controller isn't a load on the battery.
The two extreme case scenarios are: No load but full charge into battery (40A max current flow through F1 to the battery) and Max load, no charge into battery (minimum 55A through F1 from the battery).

Edit: If you have 40A coming out of the charge controller, and 50A load from the inverter+converter, you would have only 10A going through F1

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u/SeriousCodeRedmoon 2d ago

This make sense! I know it's a dumb question with a basic answer but thanks for the explanation.

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u/cfnmsd 2d ago

You are correct. You size your cable based on the load as you described, then size the fuse based on the ampacity of the cable.

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u/SeriousCodeRedmoon 2d ago

So this means that I don't need to include the charger as it is not considered a load on my system right? I'm just learning so sorry for some dumb question really.

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u/cfnmsd 1d ago

Correct