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bobf avatar image
bobf asked

Remote Wiring on 250/70 and other mppts

Greetings. I have already lost one MPPT because the circuit breaker supplying power to it opened under load when the sun was at its peak power. With the controller off, the incoming power from the panels fried it. I now have a new MPPT with the remote wiring provision. If a wire is run from circuit breaker protecting the battery side of the controller to the remote +, and a fault occurs on the charging side, shutting off the MPPT, will it now be protected from burning out? I do not see how it could, but perhaps something shuts off on the solar side at the same time. The other solution is to run a wire from the CB to a SSR on the PANEL input side, which would shut off the panels in case of a fault on the battery side. I look forward to your insights on this.

MPPT Controllers
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Paul B avatar image
Paul B answered ·

Without a full diagram and how the panels are connected and there specs, its hard to comment fully.

But as a Guess or suggestions the below maybe of help

In my opinion the only way it would have been fried is if the OCV voltage of the panels went over 250 volts.

anyway the unit is limited to 100 amp max output and it has a internal fuse as well so a output breaker is not really required (or put a bigger breaker in so it cant go open circuit on high load or remove it and put a on/off swich that can handle the 100amp output load. or have no switch of any type on its output line. this is really all up to how and what you want in the installation,

so if the OC voltage is going over the units max limit then you may damage it again. this is dependent on your panels instalation and could occur if the batteries are completly full and or the battery is removed by a breaker or switch when there is bright strong sunlight

look on your panels and check the OCV and as they will be I think wired in series then sum of them must not exceed 250 volts and thats at 25 deg C (or there about) if the temps in your area can go lower then there output maybe higher than there nominated specs so really dont go over 200 volts on the PV side, as this will give you room for spikes on cold days etc.



just some thoughts and others will also have other opinions.

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