2 x MPPT controllers and fuse position

davethedog

davethedog

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Evening,

Looking at installing 2 x MPPT controllers (one is a combined solar and wind gen version) and a normal one. Each MPPT will control 250W of 12V solar (2 x 125W panels per controller, as well as the wind in the combined MPPT controller).

I believe best practice is to install a fuse/breaker between the MPPT outlets to the battery and the actual battery bank. Question is, do I fuse them separately or using just one bigger fuse/breaker.

Excuse the diagrams but option 1 or option 2?

20181015_183945.jpg

Thanks

DTD
 
davethedog said:
Evening,

Looking at installing 2 x MPPT controllers (one is a combined solar and wind gen version) and a normal one. Each MPPT will control 250W of 12V solar (2 x 125W panels per controller, as well as the wind in the combined MPPT controller).

I believe best practice is to install a fuse/breaker between the MPPT outlets to the battery and the actual battery bank. Question is, do I fuse them separately or using just one bigger fuse/breaker.

Excuse the diagrams but option 1 or option 2?

Thanks

DTD
Click to expand...

The wiring between the controllers and the battery should be as short as practicable because it is between controller and battery that volts drop in the wiring will affect the charging and the fuse(s) should be as close as possible to the battery.
Two separate fuses may allow lighter wiring between the controllers and the battery than will be necessary with just one fuse if the wiring can be kept very short but increasing the wiring size if that is necessary will be no big deal.
I'd fit separate fuses anyway

But what is your Marlec controller ? Will it support 250watts of solar ? Is it in fact a MPPT controller ?

The solar panels on the Marlec controller will also require blocking diodes ITYWF
 
Last edited:
Vic, the combined controller is the one that comes with the new 1200 windgen and supports 20A of solar as well as the wind gen.

Distance from the planned location for the MPPT controllers and the main battery bank/VSR is less than a metre.

Also plan to put blocking diodes in the positive line for each solar panel.

Still unsure of what option to go for, 1 or 2?
 
Last edited:
davethedog said:
Vic, the combined controller is the one that comes with the new 1200 windgen and supports 20A of solar as well as the wind gen.

Distance from the planned location for the MPPT controllers and the main battery bank/VSR is less than a metre.

Also plan to put blocking diodes in the positive line for each solar panel.

Still unsure of what option to go for, 1 or 2?
Click to expand...

Thanks for clarifying the type of controller .... Found the details now !

I'd fuse them separately. I cannot think of any valid reason not too. If fused together a fault on one circuit could put both systems out of action
 
VicS said:
Thanks for clarifying the type of controller .... Found the details now !

I'd fuse them separately. I cannot think of any valid reason not too. If fused together a fault on one circuit could put both systems out of action
Click to expand...

But read what it says about fuses, relays VSRs and switches in the battery connection in part 2 of the installation instructions for the Marlec controller !
 
Simple.....

Any cable that is connected to the positive terminal of a battery should be fused, as close to the battery as possible. Unless there is no possibility that it can short.
 
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