Solar Power Switch.

[GWAYGWAY]

Have just installed a 140 watt panel on the roof of my van and between the panel and the controller I have put in a switch on the live side to turn the panel off when the engine is running and the alternator is charging the leisure batteries. My idea is that if the batteries are low and it is bright light the van alternator would "sense" the 13.8 volt the panel puts out and cut back as it thinks the batteries are fully charged leading to a slow charge. Am I wrong here or is there a better charger/ controller that can control both inputs without cutting back the biggest one from the engine .

 

[Terry and Jan]

Hi, just had 140w panel fitted by auto solutions ltd, no switch in circuit just an in line fuse. Been away this weekend to Carnon Down Truro, on mains hookup, no prob's.

 

[tonyidle]

Have just installed a 140 watt panel on the roof of my van and between the panel and the controller I have put in a switch on the live side to turn the panel off when the engine is running and the alternator is charging the leisure batteries. My idea is that if the batteries are low and it is bright light the van alternator would "sense" the 13.8 volt the panel puts out and cut back as it thinks the batteries are fully charged leading to a slow charge. Am I wrong here or is there a better charger/ controller that can control both inputs without cutting back the biggest one from the engine .

Whatever output is available from panels, alternator, or both the battery will accept charge until its terminal voltage has risen to whatever is determined by the panel controller or alternator. Whichever charge source has the higher voltage output will win the race to fully charge the battery. A switch is not needed and might harm the panel controller - most controllers require the battery to be connected before the panels are connected.

 

[Reallyretired]

I have put a switch between my panels and the controller so it can be easily disconnected in order that the batteries can be worked on or replaced. A fuse can be used but my fuse is not easily accessible. The switch needs to be rated to carry the current from the panels, in the case of mine 400w, often 20A if the sun is shining, or use a relay.

 

[tonyidle]

I have put a switch between my panels and the controller so it can be easily disconnected in order that the batteries can be worked on or replaced. A fuse can be used but my fuse is not easily accessible. The switch needs to be rated to carry the current from the panels, in the case of mine 400w, often 20A if the sun is shining, or use a relay.

That is where an easy disconnection is needed for the reasons you state.

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