Suspected failed solar panels

[Robert2891]

Good evening,
Having just replaced two batteries, i suspect my problem is with my solar panels. However, I have no idea how these are attached to the roof, and therefore how to test them. Any feedback welcome, photos attached

 

[Diabalo]

The feed will come into the van and connect to the controller, test at that point to start with

 

[Stealaway]

I suspect that you need to disconnect the solar panels at the solar controller. You always have to connect the solar panels last, after the batteries

 

[Raul]

Yes, disconnect from controller, ant test for short circuit current with a meter, in good light.
With all that yellow under the glass, I suspect the eva is shot, and allowed moisture in, creating corrosion high resistance.

 

[Lenny HB]

As said you can measure the voltage from the panels at the input to the controller input. If they are wired in parallel you should see 18 to 22v. You can check each panel by covering the panels and exposing one at a time.

If the voltage is a lot lower than 18v the controller is probably faulty. If the input voltage is OK and the batteries not charging again probably the controller.

Do you live in Spain?
If so, panels mounted like that the panels won't last very long as they will overheat they must be mounted with an air gap under them.

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[Otter Spotter]

They look as though they are just sikaflexed directly onto roof so would fail as they will get too hot, with no air circulation under panel. As others have said check the readings at controller.
If they have failed it looks an easy job to plug new ones into the cable box on roof after you have removed old ones and fit new with a gap underneath.

 

[tonka]

It Looks like the panels are sealed all the way around, that would not help as they need some airflow to cool. Maybe contributing to a failure ?

 

[CazPaul]

There’s no air gap is there, they will get too hot

 

[Robert2891]

Thanks for all the feedback. The Meter attached to the controller reads around 20V in the day, but the current is often under 1 amp. Yesterday was sunny all day and the panels output 12ah between midday Sunday and 1700 Monday.
I'll try test each panel separately by covering them.
Is it really possible that someone might have sikaflexed them to the roof!?

 

[Reallyretired]

It certainly looks like they are stuck to the roof without brackets.

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[Robert2891]

I'm guessing that will be tough to remove without damaging the roof! Is there a product for removing sikaflex or no nails?

 

[eddie]

I'm guessing that will be tough to remove without damaging the roof! Is there a product for removing sikaflex or no nails?

Yes a cheese wire.

 

[Lenny HB]

Thanks for all the feedback. The Meter attached to the controller reads around 20V in the day, but the current is often under 1 amp. Yesterday was sunny all day and the panels output 12ah between midday Sunday and 1700 Monday.
I'll try test each panel separately by covering them.
Is it really possible that someone might have sikaflexed them to the roof!?

Where are you at them moment as you are flying a Spanish flag, if southern Spain l would expect a lot more output.
Cover the panels and check each one like I said.

 

[Diabalo]

Unwound guitar string with 2 dowels has handles should do the trick same as cheese wire.

 

[MisterB]

I don't know if it will work with whatever they have used to 'stick' your panels to the roof (though sikaflex seems to be the popular view) but you can use a hairdryer on some types of silicone and it just peels off. Might be worth a shot before dismantling the cheeseboard ...

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[tonka]

I'm guessing that will be tough to remove without damaging the roof! Is there a product for removing sikaflex or no nails?

A cheese wire will cut through it (ebay) an alternative will be some strimmer wire
Option 2 may be the best as you will need a long stretch across a corner to start it off.

 

[Robert2891]

Thanks for the advice. Will give it a go!

 

[Robert2891]

Where are you at them moment as you are flying a Spanish flag, if southern Spain l would expect a lot more output.
Cover the panels and check each one like I said.

Yes, Southern Spain.

 

[Lenny HB]

Yes, Southern Spain.

Looks like 2 x 100 watt panels I would expect 30 to 50 ah a day where you are.

 

[Robert2891]

Looks like 2 x 100 watt panels I would expect 30 to 50 ah a day where you are.

If they are 2 x 100 and I was getting 50ah per day, is that enough for 3 leisure batteries? I've got 2 x 100ah in parallel on the main circuit and 1 x 90ah feeding the inverter. I'm asking because I don't want to change the panels like for like if there's an issue with that set up

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[Lenny HB]

At this time of year even in southern Spain you would be better with at least 300 Watts posibly 400 but with solar its always easy to add more later.
I take it with that arrangement you are only running a small inverter.

 

[VXman]

If they are 2 x 100 and I was getting 50ah per day, is that enough for 3 leisure batteries? I've got 2 x 100ah in parallel on the main circuit and 1 x 90ah feeding the inverter. I'm asking because I don't want to change the panels like for like if there's an issue with that set up

Well 390 amps would take 8 days to fill fully from empty at that rate. However, you should never let your batteries go below 50% as they will get damaged. So if you were to 50% that would take 4 days to charge.

However, whether you would ever use that much depends on what you are doing. Our leisure batteries use very little. LED lights don't use much, charge a few devices, water pump, that's about it. Plus the limited use of hair dryer/toaster from the inverter.

I have all 3 linked and parallel and the inverter connected to all 3. Shares the usage equally. Not sure of the reasoning of using one battery for the inverter - particularly as that may be the one that uses the most power?

 

[TDub49]

Whilst it is questionable that heat will damage the panels, it is a fact that the hotter a panel gets, the less efficient it will be. Sounds to me like the controller is dodgy rather than the panels. If there are connectors between the panels and the controller it is possible that they are malfunctioning somehow or, as I discovered when replacing what I thought was a shot panel, the soldered connection between the output cable and the panel was shot. Lesson learned and I now have a spare panel and controller . . . . . . .

Getting them off that roof, that's another thing altogether . . .

 

[Robert2891]

As said you can measure the voltage from the panels at the input to the controller input. If they are wired in parallel you should see 18 to 22v. You can check each panel by covering the panels and exposing one at a time.

If the voltage is a lot lower than 18v the controller is probably faulty. If the input voltage is OK and the batteries not charging again probably the controller.

Do you live in Spain?
If so, panels mounted like that the panels won't last very long as they will overheat they must be mounted with an air gap under them.

Ok, so the voltage seems fine - around low 20s mid day, was 19.6V at 1730 on a clear southern Spanish evening. However, meter showed 3.3A max and 0.3A at 1730 when I checked. Only 4ah all day. I covered the one panel and no change, then the other, no change, suggesting both working and in parallel. The dimensions are both 67cm x 148cm, and from what I've googled, panels this size are between 150-200W and so should be getting a lot more power overall. Before I go ahead and replace the whole system (which I really can't afford), does anyone have any idea why I might be getting such a low current. Could it be water ingress leading to high resistance? The one panel looks fine though

 

[Lenny HB]

I suspect the panels are OK but worth checking te current from them. Measure the current when you cover one panel it should drop by 50%, if it doesn't drop or drops to zero that would indicate one panel is faulty.

As I said the panels are probably OK so it is probably the Solar controller, If you discharge the batteries a bit the output of the controller should gradually rise throughout the day up to around 14.2v to 14.4v then depending on the controller it may drop to around 13.6-13.8v float charge or may hold at 14.2v for a few hours before dropping to 13.6v.

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[Robert2891]

I suspect the panels are OK but worth checking te current from them. Measure the current when you cover one panel it should drop by 50%, if it doesn't drop or drops to zero that would indicate one panel is faulty.

As I said the panels are probably OK so it is probably the Solar controller, If you discharge the batteries a bit the output of the controller should gradually rise throughout the day up to around 14.2v to 14.4v then depending on the controller it may drop to around 13.6-13.8v float charge or may hold at 14.2v for a few hours before dropping to 13.6v.

Thanks. Could you expand on your 2nd paragraph. I'm not sure what you mean

 

[Robert2891]

I'm wondering whether it could be corroded contacts? Would this result in me getting lower current but the correct voltage reading? The roof cover where the cables enter seems to have a failed rubber grommet which has probably let moisture in and it seems that they connected the two panels in parallel under this cover as 4 wires go in, but only 2 come through the ceiling.

 

[Lenny HB]

Thanks. Could you expand on your 2nd paragraph. I'm not sure what you mean

I was explaining what voltages you should see across the battery if everything is working OK.
You need to discharge your batteries to about 80/85% then monitor their voltage throughout the day.

 

[Lenny HB]

I'm wondering whether it could be corroded contacts? Would this result in me getting lower current but the correct voltage reading? The roof cover where the cables enter seems to have a failed rubber grommet which has probably let moisture in and it seems that they connected the two panels in parallel under this cover as 4 wires go in, but only 2 come through the ceiling.

Could be as the voltage would probably be OK but not much current would pass.
Did you check the current?

Also could be a poor or corroded connection in the junction box on the back of the panels.

 

[Robert2891]

Update: thanks for all of your help. I'm hoping that I've just been an idiot. It occurred to me that as the batteries are new and I haven't been using the van that the batteries are simply fully charged and so the controller has reduced the current. I turned my diesel heater on and straight away the panels showed an increase in charge current from 0.0/0.1 up to 10.8A. The panel voltage was reading around 20V. When I turned the power and heater off, the current crept back down to 0.0A and the batteries showed as fully charged again. Conclusion, everything is working??

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