100w Solar Panel Wiring Question

[ex-Gladys]

Good luck getting large (4mm/6mm) twin core. I was looking for some for running power to my new below deck autopilot, and couldn't get that at any of the usual suspects (although I didn't look at large wholesalers such as CPC Farnell)

 

[Pords]

Good luck getting large (4mm/6mm) twin core. I was looking for some for running power to my new below deck autopilot, and couldn't get that at any of the usual suspects (although I didn't look at large wholesalers such as CPC Farnell)

I looked online and 12v planet does 4mm cable and all the other bits needed. Baffling myself with how to mount on the stern. Toying with Noa turning panel mount 40mm or building an A frame.

 

[ex-Gladys]

I looked online and 12v planet does 4mm cable and all the other bits needed. Baffling myself with how to mount on the stern. Toying with Noa turning panel mount 40mm or building an A frame.

The largest tinned twin core on 12V Planet is 2.5sq.mm...

 

[duncan99210]

The largest tinned twin core on 12V Planet is 2.5sq.mm...

Yes but they do loads of single core stuff at reasonable prices. You'll have trouble getting twin core at that sort of gauge.

 

[aquaplane]

The stuff I used was single core. I put it in trunking to get the +ve and -ve cables from the panels to where I cut holes in the boat to get inside. When I got to the controller I trimmed thee XS off which produced the controller to battery cable with only a couple of meters extra, which is better than being 2 meters short. $mm nay have been big enough but 6mm was only £5 extra so I went large.

 

[Slycat]

I had similar questions, great thread.

Do you mind if I ask the most common way people connect a 100w panel (output) to two separate batteries for example engine battery/house battery?

I'm also not an expert so don't want one battery dragging the other down if they are connected all the time etc etc

 

[GrahamM376]

I had similar questions, great thread.

Do you mind if I ask the most common way people connect a 100w panel (output) to two separate batteries for example engine battery/house battery?

I'm also not an expert so don't want one battery dragging the other down if they are connected all the time etc etc

The most common and easiest way is to have 2 x regulators but, some allow back feed which will balance the batteries overnight so a split diode may be needed between the panel and the regs. Don't put it after a single reg to feed the batteries as the voltage drop will restrict charge.

There are some dual output regs on the market as well.

 

[VicS]

The most common and easiest way is to have 2 x regulators but, some allow back feed which will balance the batteries overnight so a split diode may be needed between the panel and the regs. Don't put it after a single reg to feed the batteries as the voltage drop will restrict charge.

There are some dual output regs on the market as well.

I dont think you could have two regulators connected to the same panel if they were MPPT regulators though.

 

[GrahamM376]

I dont think you could have two regulators connected to the same panel if they were MPPT regulators though.

I did that with a couple of cheap MPPT and it was because of reverse flow I had to fit the split diode, they seemed to charge reasonably well but a bit low voltage for the Trojans. When one bust recently I chucked the other into the junk box, paralleled the two banks and fitted a Victron SmartSolar which gives far better performance.

As a matter of interest, what do others do when leaving the boat for a couple of months - leave the 200w solar connected or not? The Trojans like quite a high charge voltage which the Victron gives them but wondering about water loss over the period. Maybe best to disconnect them?

 

[dk]

Good luck getting large (4mm/6mm) twin core. I was looking for some for running power to my new below deck autopilot, and couldn't get that at any of the usual suspects (although I didn't look at large wholesalers such as CPC Farnell)

Try Barden www.barden-uk.com

 

[RichardS]

I did that with a couple of cheap MPPT and it was because of reverse flow I had to fit the split diode, they seemed to charge reasonably well but a bit low voltage for the Trojans. When one bust recently I chucked the other into the junk box, paralleled the two banks and fitted a Victron SmartSolar which gives far better performance.

As a matter of interest, what do others do when leaving the boat for a couple of months - leave the 200w solar connected or not? The Trojans like quite a high charge voltage which the Victron gives them but wondering about water loss over the period. Maybe best to disconnect them?

This winter I've left the 600Ah house bank connected to the 400W panels through the Victron MPPT controller and the 200Ah start batteries connected to a 40W panel through a PWM controller - a twin output Photonic Universe one as mentioned by Pords below. In previous winters I've left the whole lot connected through the 40W/PWM so I'm into new territory now. :ambivalence:

Richard

 

[Pords]

I had similar questions, great thread.

Do you mind if I ask the most common way people connect a 100w panel (output) to two separate batteries for example engine battery/house battery?

I'm also not an expert so don't want one battery dragging the other down if they are connected all the time etc etc

Bought a charge controller which the solar panel plugs into, and in turn, regulates and charges 2 batteries. Check photonic universe website.

 

[Pords]

Furneax riddal do twin 4mm tinned cable. Have used them in the past so will droop them a line.

 

[GrahamM376]

This winter I've left the 600Ah house bank connected to the 400W panels through the Victron MPPT controller and the 200Ah start batteries connected to a 40W panel through a PWM controller - a twin output Photonic Universe one as mentioned by Pords below. In previous winters I've left the whole lot connected through the 40W/PWM so I'm into new territory now. :ambivalence: Richard

New territory for me as well with the Victron, BM1s were showing steady 14.9v this lunchtime, 13.8 now with 0.2a net charge. One possibility is to drop the charging voltage down to float value when away as in my case only the anchor light, radio memory and gas detector will draw a few ma. My start battery is trickle charged by a small separate panel regulated through the Aerogen reg and the Aerogen is tied up when boat left for a while.

 

[Mikedefieslife]

Any reason you guys don't have your charging sources all going to a bus? This then eliminates the need for multiple connections on the battery. Temp sensors excluded.

 

[GrahamM376]

Any reason you guys don't have your charging sources all going to a bus? This then eliminates the need for multiple connections on the battery. Temp sensors excluded.

I only have 2 daily charging sources, the battery charger very rarely used so no need to add anything extra.

 

[RichardS]

Any reason you guys don't have your charging sources all going to a bus? This then eliminates the need for multiple connections on the battery. Temp sensors excluded.

I have my MPPT controller connected by a short thick cable to the negative and positive bus bars mounted on the other side of the bulkhead from the house battery storage area.

The negative and positive bus bars for the two house batteries are a long way away so better served by tapping the smaller PWM controller into the engine battery connections at the bottom of the Victron shore-power charger.

When at anchor or sailing I don't bother to charge the engine batteries at all but use all the resources of my panels into the house set.

Richard