question

orangecowboy avatar image
orangecowboy asked

what size fuse between 200w solarflex panel and MMPPT 75/15 smartsolar charge controller

I have an Ampere Time 12v 200Ah battery
Renogy 2000w inverter
all for my tow trailer

One of your other replies was 15A DC rated circuit breaker or a 15a PV fuse with disconnect switch.


Many thanks

MPPT ControllersSolar Panelfuses
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1 Answer
Trevor Bird avatar image
Trevor Bird answered ·

Hello @orangecowboy .....The 200 watt panel can theoretically deliver 200/12 = 16.6 amps if it is operating at full capacity. I have seen panels deliver more than rated output if they are very cool and sun is high in the sky. For instance just after a sun shower of rain. Allowing for a posssible plus 10% lets say 220/12 = 18.3 Amps.

It is good practice to have a breaker between the panel and the MPPT controller to remove voltage from the input to the MPPT controller for trouble shooting. Provided the cable can carry the full rating of the short circuit current of the solar panel, I see no reason to fuse the line or put a breaker in for overcurrent protection. The circuit cannot deliver more than the short circuit rating of the solar panel and provided the cable can carry that current, nothing needs to be protected. A simple switch is all that is required in my view provded the cable is sized accordingly.


4 comments
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orangecowboy avatar image orangecowboy commented ·
Thanks for that feedback Trevor-bird. Ive seen a few videos saying to have the fuse so the power surge doesn't go back to the panels and destroy them. That is why I asked this question. Im grateful for you sharing this information.
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orangecowboy avatar image orangecowboy commented ·
Thanks Trevor-bird.

I wonder what is the cable size accepted in the charge controller. I have read from someone quoting from memory it is AWG10 6mm

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Trevor Bird avatar image Trevor Bird orangecowboy commented ·
Yes, according to the specs it is 6sq mm
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orangecowboy avatar image orangecowboy Trevor Bird commented ·
Thanks

Would I use a 20a circuit breaker between both controller & PV panel, & also between controller & battery?

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