PV panel connections - assistance please!

[skyflyer]

I didnt think this though!

Bought a solar panel assuming that it would have a simple two core cable that I would route through the coachroof to the controller thence the batteries.

Of course it doesnt have a simple two core cable it has two single core cables with connectors on each end, which I now realise is designed to allow connection in series to other panels. I'm only using one panel, so these are my positive and negative cables, correct?

They're pretty thick and look as though they cant be bent to a tight radius without permanent kinking, is this OK to do or should it be avoided? I have no idea how the inner core is constructed.

The moulded plugs are going to need big holes in the coachroof, so i am minded to try and find some sort of waterproof connector into which they will plug, which can be mounted on the coachroof and then back to my original plan of a smaller pair of cables to route through to the controller.

Can anyone recommend a dedicated or adapted product to do this?

Thanks

 

[PaulRainbow]

Yes, one is positive and one is negative. If they are MC4 connectors (which they usually are), just chop them off and put the cables through something like this : https://www.photonicuniverse.com/en...pervans-boats-and-building-installations.html

 

[Puggy]

Yes as Paul says.

I have fitted panels with those connectors and if you have more than one panel you connect them in series, otherwise the leads just come back to the controller. To get through the coachroof, i used one of these waterproof cable glands (https://www.indexmarine.com/products/waterproof-glands/) then you can avoid cutting the plugs off. These glands seem to work really well. Resist the temptation to also use silicon as this mucks them up, and give the cable a wipe with acetone or similar and then it makes a really good seal.

Also, i found it hard to work out which is positive and negative on my panels and it would only register a charge one way round so took a little experimentation on a sunny day (make sure you have some load on the batteries to ensure the charger actually registers putting a charge into the batteries so you can tell).

Best wishes Puggy

 

[peteK]

Before you cut the plugs of check the panel with a multimeter to check that its giving its rated output,one I bought recently gave correct voltage but the amps were only 0.5 amps for a 30w panel.

 

[RichardS]

Yes as Paul says.

I have fitted panels with those connectors and if you have more than one panel you connect them in series, otherwise the leads just come back to the controller. To get through the coachroof, i used one of these waterproof cable glands (https://www.indexmarine.com/products/waterproof-glands/) then you can avoid cutting the plugs off. These glands seem to work really well. Resist the temptation to also use silicon as this mucks them up, and give the cable a wipe with acetone or similar and then it makes a really good seal.

Also, i found it hard to work out which is positive and negative on my panels and it would only register a charge one way round so took a little experimentation on a sunny day (make sure you have some load on the batteries to ensure the charger actually registers putting a charge into the batteries so you can tell).

Best wishes Puggy

I suspect the problem will be that the MC4 connectors are much larger than the cable so any hole in the gland large enough to push the MC4 through is not going to be a water-tight seal against the cable.

If the cables are long enough to reach to the batteries / controller then the MC4 will need to come off anyway. If the cables need to be extended then the extension section could be added either side of the gland depending upon the relative lengths. If the extension starts on the outdoor side of the gland then the MC4's can be retained.

The MC4's connected to some of my panels came with a red band on them for +ve and a grey band for -ve but this is not universal unfortunately.

Richard

 

[simonfraser]

Your cable has plugs at both ends ?
Going to have to cut one end anyway to connect to the controller ?
I extended mine and soldered the extension on, gas powered, heat shrink.
Pay attention to the polarity .......

 

[Puggy]

I suspect the problem will be that the MC4 connectors are much larger than the cable so any hole in the gland large enough to push the MC4 through is not going to be a water-tight seal against the cable.
Richard

The seal in the gland has a cut so you slip it around the cable

 

[RichardS]

The seal in the gland has a cut so you slip it around the cable

That's a good idea. The deck gland I used for my solar panel cables uses different sized rubber seals so you have to choose one that just fits over the cable.

Richard

 

[neil_s]

I found that the junction box on my panel had a removable lid. It was a simple soldering job to replace the two fat single core wires with a piece of round twin core that fitted through one of the glands. The other hole got blocked up with mastic.

After two years of happy battery charging though, my panel (e-bay cheapy) is now de-laminating and needs to be replaced.

 

[skyflyer]

After two years of happy battery charging though, my panel (e-bay cheapy) is now de-laminating and needs to be replaced.

Mine is also an ebay cheapie! Would it be worth trying to pre-emptively seal the edges, before installation, to prevent delamination, do you think?

 

[William_H]

I am guessing that OP solar panel is one made for domestic PV installations. ie 200w or so with 40 v open circuit. These can be excellent price and quality for a large market. The MC 4 type connectors are indeed for connecting panels in series which means that your DC volts from the PV array can be 320v (on my 8 panel 1500w array) or up to around 600 volts or more.
Hence the heavy insulation and well insulated connectors for ease of series connection. Not needed for a single panel boat installation. So as said cut the connector off. Of course it may be a panel made for lower voltage work ie 20 v open circuit voltage but the wiring just emulates the higher voltage versions. olewill