Solar Panel; Toast?

[Salty Spuds]

I have a 130w semi flexible solar panel bonded to the poptop, it’s connected to a Victron smart 12/75 controller. I’m currently out in Portugal at the mo & I’ve noticed that the panel voltage is dropping from around 19v to 10v when the panel gets warm, which is about 10.30am. So at startup in the mornings it’s chucking out 50-60w @19v or thereabouts, after a couple of hours the voltage just drops off a cliff down to around 10V, it isn’t gradual, it’s as if a switch has been.....err switched. I don’t think it’s a cutoff/over heat device or the voltage would be zero if the panel had disconnected, I suspect it’s a row of cells on the panel that has a bad internal connection. When it cools down in the evening it comes back up to 19V or so. Any thoughts?

 

[t0mb0]

I agree, sounds like a dodgy connection to me. Assuming it’s in the panel itself, that could be a bit of a pain.

 

[Dilbert]

Which panel have you got there @Salty Spuds ? The 19V sounds low too especially as you will have good sun at 10.30am in Portugal....which may confirm a faulty cell (resistive) or more.

 

[Salty Spuds]

Which panel have you got there @Salty Spuds ? The 19V sounds low too especially as you will have good sun at 10.30am in Portugal....which may confirm a faulty cell (resistive) or more.

Dunno, it actually came factory fitted to the roof by Reimo. All I know is that it’s supposed to be 130W. According to the history on the Victron, the most it’s ever done is 105W@23.6V. Those are Pmax & Vmax. It looks like it was working fine up to a fortnight ago when the yields dropped dramatically despite glorious sunny weather.

 

[Dilbert]

factory fitted to the roof by Reimo

 

[Salty Spuds]

I’m thinking about removing it & fitting the same one as you have, the Carbest 160W one.

 

[Dellmassive]

Got any pics of your failing one,?

Also how is it fixed to the roof, and how do you plan to remove it?

 

[Salty Spuds]

Got any pics of your failing one,?

Also how is it fixed to the roof, and how do you plan to remove it?

No pics as yet. It looks like it’s Sika’d on. I’m thinking some dyneema fishing braid & a couple of bits of dowel & cheese wire it off. Not particularly looking forward to that, but hey ho!

 

[DXX]

No pics as yet. It looks like it’s Sika’d on. I’m thinking some dyneema fishing braid & a couple of bits of dowel & cheese wire it off. Not particularly looking forward to that, but hey ho!

Can you fit a slightly bigger one over the top of the failed one? It should lay pretty flat as they are very thin.

 

[Salty Spuds]

Can you fit a slightly bigger one over the top of the failed one? It should lay pretty flat as they are very thin.

I had considered that, but it offends the engineer in me & my OCD. I also want to fit a bigger panel.

 

[Dilbert]

I’m thinking about removing it & fitting the same one as you have, the Carbest 160W one.

I have been very pleased with it so far. Hopefully your removal techniques will work and you can clean up the remaining adhesive sealant with some sort of solvent.

 

[Dilbert]

I’m thinking about removing it

Presume you will do some double checks by placing the solar panel on a basic dummy load before trying to remove it. I would want to be completely certain the fault is not caused by another component; controller, wiring, etc, before you get the cheese wire out!

 

[DXX]

Presume you will do some double checks by placing the solar panel on a basic dummy load before trying to remove it. I would want to be completely certain the fault is not caused by another component; controller, wiring, etc, before you get the cheese wire out!

A good sharp 4” bolster would be quicker than cheese wire

 

[Dellmassive]

Have you thought about having a clear vynil wrap put on the roof.... so the sikaflex bonds to that and not directly to the paint work?

Thinking about this idea myself to aid removing a faulty panel or upgrading a panel.

 

[Skyliner33]

Have you thought about having a clear vynil wrap put on the roof.... so the sikaflex bonds to that and not directly to the paint work?

Thinking about this idea myself to aid removing a faulty panel or upgrading a panel.

Do you think that would be easy to remove then?

 

[Dellmassive]

well im going to do it on mine, the idea being that the vinyl should be easier to remove (than sikaflex or double sided tape direct on paintwork).

so still "cheese-wire" the solar panel off . . . . . but then the idea is that the sikaflex is bonded to the vinyl and not the paint work, so hopefully should peel-off leaving the paintwork undamaged.?

then just a new piece on clear vinyl and stick on a new panel . . . . . thats the idea anyway.

when i looked into this before some said about will the vinyl peel off when driving . . . . some pros said that you can get a heavy duty clear vinyl . . . and due to the total surface area of the vinyl to paintwork it should be a solid bond for the life of the panel . . . ?

 

[Skyliner33]

Ah that makes sense. I hadn't thought about 'cheese-wire' the panel off first.

 

[Salty Spuds]

Presume you will do some double checks by placing the solar panel on a basic dummy load before trying to remove it. I would want to be completely certain the fault is not caused by another component; controller, wiring, etc, before you get the cheese wire out!

Here’s a screen shot of the Victron. This is with the charger disabled so there’s nothing connected to the panel. It’s the same whether the charger is on or off tbh. I’m currently sat in full sunshine. The battery is charged so there’s no demand on the controller. Tonight when it cools down the panel voltage will go back upto 17-19V regardless of the load. Before I do anything drastic, I’ll disconnect the panel completely & do some testing.

 

[Salty Spuds]

Got any pics of your failing one,?

Also how is it fixed to the roof, and how do you plan to remove it?

Got a couple of pics

 

[Dilbert]

Got a couple of pics

Have you had a chance to check the voltage in the junction box on the roof? Connections in there would also be subject to heat/expansion movement.