How to connect solar panel charge controller

[moe58]

Hi

I am in the process of installing solar panels on my SO 389. Is connecting the solar panels' charge controller directly to the house battery bank the recommended way? Any advice is appreciated.

Cheers

[rene460]

Hi Moe,

The charge controller usually has six terminals on the connection strip, two for the panel, two for the battery and two for a load.

Ignore the load ones, they are not usually used in our application.  The other two pairs are then obvious.  Make sure you observe the correct polarity when you make the connections.

Connect the battery to the battery terminals first, this allows the controller to detect whether you are using it in 12V or 24V mode.  

Then connect the the panel wires.  It is not a bad idea to put a towel over the panel while you make the connections to avoid any sparking as the terminals first touch.  There should be a suitable fuse in the positive wire, between the panel and the battery.  If your charger has a display it should now show you that all is working as expected.

The boat systems all work directly from the battery, not through the charger.

I am one of those who turns off the battery isolators and remove the shore power connection when I leave the boat, so I want the panel to keep the battery charged while I am away.  This requires that I connect the panel and charge controller to the battery side of the isolating switches.

I have connected to the house batteries.  Then I also have a two way voltage sensitive relay which parallels to the engine battery when the voltage exceeds the threshold, so both are maintained on charge while I am away.  The two way feature of the VSR means that the alternator also charges both batteries when I am motoring.  The VSR replaces the simple relay that was originally installed on the boat.

Please come back and tell us how you go.

rene460

PS - by the way, did you ever sort out the length of that anchor rode?

[MalcolmP]

Good timing on your question. I am just installing a 100w solar panel in my camper, agree with all of Rene's great suggestions. The Victron mppt I am using also states that the battery must be connected before the panel www.victronenergy.com/solar-charge-controllers/mppt-100-30. 

On the boat I have my  360w panel connected to the house-bank permanently and don't intend disconnecting the solar very often, but on the camper install, I may well need to disconnect the leisure battery from time to time, so I wanted to be able to disconnect the solar feed simply so have just purchased this in line breaker - it is rather oversized at 20 amp.



www.ebay.co.uk/itm/DC-12V-20-100AMP-In-Line-Quick-Circuit-Audio-Breaker-Fuse-Holder-Inline-Circuit/372539240980

but I am quite impressed by the apparent quality, seems well moulded at least with good terminals, so hopeful the breaker circuit electrics are also good. Not I guess marine quality as designed I think mostly for high wattage car stereos, but if kept in a suitable location I imagine should be fine. I may well get a 40 amp one for the boat circuit now.

[moe58]

Thanks very much for the helpful tips 

[pbunning]

Important to make sure the fuse in the cable is close to the battery. The purpose of the fuse is to protect the cable.

[so40gtb]

Voyageur's Victron MPPT solar controller is connected to its charger/inverter (via smaller fuse) and thence to the house battery bank via a much larger fuse, so routed for wiring convenience, since the charger/inverter and the MPPT controller are both located in the starboard lazarette. This was a change from the factory location of the Cristec charger, when I extensively rewired and upgraded the DC power system in 2014. Effectively, the MPPT controller substitutes for the charger when the boat is away from shore power. But its contribution is miniscule when the inverter is activated, pulling big amperage from the Balmar alternator and house batteries.


--Karl

[chuckr]

SoulMates has 550w of solar and are connected to a BlueSky 3026 controller that leads directly to the house bank with a fuse before the batteries -

[NZL50505]

My marine sparky gave me a top tip recently after reviewing the poor performance of my two 100W solar panels installed only 12 months ago. He suggested rewiring them in series instead of parallel to double voltage - this is because my solar regulator can handle range 13-50V and by doubling voltage it will increase the amount of time that my panels make a contribution to house batteries when at anchor. Because they will only start charging once the voltage tips over a certain threshold (think it’s about 13.3V) and on cloudy days a panel might struggle to reach that threshold. But in series you will get above that more frequently. Current delivered will obviously be lower but a smaller current for more time might be better than a bigger current for very little time.

I’ll try it and report back.