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Solar system isolator switches.


Cruiser_Boy

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Hello everyone,

I am close to buying all the parts for my solar system. Due to size constraints it will be a single panel 46V Voc type with MPPT controller.

I will put an isolator switch and fuse in the PV feed to the MPPT and I wanted to route the MPPT to Batteries cable to the existing services isolator switch via

a fused cable. Assuming the services to battery cables are up to it which I think they are.

Now comes my problem. If I have an isolator on both feeds which I think is sensible for safety then it is possible to have both Battery and PV off and then someone could turn the PV on first. The MPPT manual says Battery should be connected first. Its a Victron but I haven't bought it yet.

Is there an isolator switch which could be used that has say 3 positions which allows Battery ON / PV ON, Battery OFF / PV OFF and Battery ON PV OFF but not the 4th option?

Or conversely is it safe to have a switch which allows either both ON or both OFF only? I guess this would allow some minimal time where the PV could be ON and Battery OFF as the switch contacts operate.

Any thoughts ?

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I'd wire the controller directly to the leisure batteries with a fused cable. This way there's no risk of connecting the panel first. Unless the fuse has blown, of course. If you need to disconnect the controller from the batteries for any reason (there doesn't seem to be a likely reason?), simply remove the fuse. This is OK for BSS by the way. 

Edited by The Welsh Cruiser
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27 minutes ago, The Welsh Cruiser said:

I'd wire the controller directly to the leisure batteries with a fused cable. This way there's no risk of connecting the panel first. Unless the fuse has blown, of course. If you need to disconnect the controller from the batteries for any reason (there doesn't seem to be a likely reason?), simply remove the fuse. This is OK for BSS by the way. 

^^^^ This. Absolutely and completely.
 

Do NOT fit an isolator in the feed from controller to batteries. If it’s easier for cable routing the ‘battery connection‘ can be the battery side of the main isolator. 

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