Solar to Controller to Battery

[Jev88]

Always looking to educate myself around the MH.
In an ideal world having solar panel, controller and battery all very close to each other is the goal?
In reality, what is the best ;
1) Longer cable from Solar Panel to Controller and get Controller next to Battery?
2) Shorter cable from Solar Panel to Controller and a longer one to Battery?

 

[andy63]

Option 1..
Keep the cable run from controller to batt as short as possible...?

 

[Raul]

No 1:
From the controller to battery the voltage will be lower, as close as possible. Mine in less than two feet.

 

[Jev88]

Is it a case of I can afford to lose some of the voltage from Solar (typically 20 volts approx) rather than losing a percantage of the 14 volts from the controller?

 

[Richard n Ann]

Is it a case of I can afford to lose some of the voltage from Solar (typically 20 volts approx) rather than losing a percantage of the 14 volts from the controller?

Exactly, and the controller will get the battery voltage more accurately.

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[tonyidle]

There's no reason to lose more than a very small amount. Simply use heavier cables. The higher voltage section will lose least hence the recommendations in previous posts. You can' 'afford' to lose anything you don't need to.

 

[Lenny HB]

Is it a case of I can afford to lose some of the voltage from Solar (typically 20 volts approx) rather than losing a percantage of the 14 volts from the controller?

Yes, but in the overall scheme of things it won't make much odds.
Solar panels produce their maximum output at around 18 volts (voltage drops with the load) 200watts of solar at 18v is 11 amps, the charging voltage out the controller will be 14,2v which is 14 amps. So there will be more losses drop per metre after the controller but when the solar is producing it's maximum the small drop won't worry you. In winter with the panels only producing 25% of their max so the current flow will only 25% and the losses very small.

 

[Raul]

Is it a case of I can afford to lose some of the voltage from Solar (typically 20 volts approx) rather than losing a percantage of the 14 volts from the controller?

Yes, because from controller to batt is crucial that no voltage drop happens. Your battery has to receive the voltage set in the controller to properly charge, voltage drop means no full charge.

 

[ShaKen]

Yes, because from controller to batt is crucial that no voltage drop happens. Your battery has to receive the voltage set in the controller to properly charge, voltage drop means no full charge.

Could you not then set the target voltage for the battery higher to offset any voltage drop of a long run? (Assuming you have a controller where you can change the settings).

I’m about to do an install in my Chausson that has preinstalled wiring for the solar.

If I do use the preinstalled wiring, then the controller will be fitted in a cupboard with the wiring running approx 3 or 4 meters to battery via the consumer / fuse unit.

The other option is to running completely new wiring, but that will be an interesting challenge to route from panels to controller which would be fitted nearer the battery.

Decisions, decisions....

 

[Richard n Ann]

Could you not then set the target voltage for the battery higher to offset any voltage drop of a long run? (Assuming you have a controller where you can change the settings).

I’m about to do an install in my Chausson that has preinstalled wiring for the solar.

If I do use the preinstalled wiring, then the controller will be fitted in a cupboard with the wiring running approx 3 or 4 meters to battery via the consumer / fuse unit.

The other option is to running completely new wiring, but that will be an interesting challenge to route from panels to controller which would be fitted nearer the battery.

Decisions, decisions....

Yes I suppose you could if the charger let's you tweek the settings like that. My optimate 4 has got a preset potentiometer on the PCB that sets the cut off voltage of 14.4v
I watched it charging a small car battery while I was fixing it (new transformer) and when the voltage gets up to 14v it rises quite quickly, about 5 minutes later it gets to 14.4 and switches off. So a small voltage drop of say 0.1v would make sod all difference in this case.

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[Raul]

Could you not then set the target voltage for the battery higher to offset any voltage drop of a long run? (Assuming you have a controller where you can change the settings).

I’m about to do an install in my Chausson that has preinstalled wiring for the solar.

If I do use the preinstalled wiring, then the controller will be fitted in a cupboard with the wiring running approx 3 or 4 meters to battery via the consumer / fuse unit.

The other option is to running completely new wiring, but that will be an interesting challenge to route from panels to controller which would be fitted nearer the battery.

Decisions, decisions....

Yes and no, because, voltage drop is not linear, is progressive with the resistance that it climbs and decreases with the power you try to push thru that cable. You will have a bigger percentage of drop on bigger power, and less percentage drop on very little power, so you will end up with a high voltage at the end of charge, if you up it on the controller settings to compensate for the drop. But a little increase will not be that bad; of course the correct way to correct this, is to have the right cable section for the power and distance you want to carry.