PV Logic Flexi Voltage Drop Problem.....

[capitanoooo]

Hi All,

I was wondering if anyone out there may help me with a solar panel problem that I am experiencing? The vehicle is a 2016 T6 converted by Autohaus.

I have an 80 watt PV Logic Flexi Panel from Solar Technology International which is Silkaflexed to the top rear of Reimo roof (please see photos). The flex from this panel runs to the underside of the roof, along to the front of the vehicle where it then drops into the headliner, it is then extended from here down the drivers B post to under the seat terminating into a STCC10 solar charger.

I have an intermittent problem with the panel that even when the panel is in direct sunlight and is super clean, it mostly sits at about 10 volts. Obviously at this voltage it will not charge the 12v leisure battery and becomes completely pointless. On just a couple of occasions it has measured around 18 volts, which in general light of day is what I would expect from this panel, and the light comes on at the controller charger informing me that it is charging the battery - which on testing it is! But as I say, most of the time it is around 10 volts - when panel is squeaky clean and in direct sunlight!

I have removed the headliner and checked the voltage (open circuit) with a multimeter at the end of the flex leading from the panel. There are no other terminals/connections before it enters the panel's moulded junction box (mechanical and chemically fixed on the panel) and there appears to be no damage to this flex. The voltage here is still at about 10 volts. So I have ruled out a bad connection or any earthing problems prior to the panel and its junction box.

I can't see any damage to the panel cells and I'm under the conclusion that if it has occasionally given me 18 volts that the panel cells should be okay and an intermittent fault would be unlikely from a cell?

I had some other advice that suggested the problem may be within the moulded junction box on the controller which supposedly contain diodes to prevent back feed into the panel's individual cells. It was suggest that if one of these are faulty and blocking a cell then I should expect to see a significant drop in voltage. I was wondering if anyone would agree with this or has experienced any similar problems?

I have contacted the manufacturer Solar Technology International but still awaiting to hear back from their support team. There is a 5 year warranty with the panel so thinking it should be covered but who knows with these things! I'm reluctant to pull the moulded junction box apart as if I am covered by warranty, then don't wish to null and void it in the process.

Can anyone think of any other possible causes or items that I should test first. Any advice would be greatly appreciated!

 

[VanDamMan]

This might have some bearing.... most solar panels are angled towards the sun (as seen on house roofs facing south) you get the suns rays from east to west..if it lays flat your not getting full exposure..might help

 

[oldiebut goodie]

First thing that I would do is chuck that controller away - that is the same one that they fitted to my van. I changed it a couple of months ago for a MPPT one and there was an immediate improvement to my charging. I was surprised when I found that they had used such a crap controller.
Just went out and checked mine - the panel is sat at 20.4v, panel is flat with the sun low in the sky. There must be a problem there somewhere if 10v is all that you are seeing most of the time. I have had solder connections that were bad in the junction box on previous panels a couple of times so I would get the panel checked as you still have warranty on it.

 

[travelvolts]

Sounds like a bad panel. See lots of them with the same problem.

 

[Phil_G]

I would try to disconnect the wiring as near to the panel as possible, maybe just inside the poptop, so you are measuring the actual panel voltage with no load, no possibility of shorts, chaffed & grounded wiring, or any back current. You only need to disconnect one of the two wires, the other you can connect your meter to by pushing a pin through the insulation. If at that point you see 10 volts, even without direct sunlight, then the panel is duff. Panels can be intermittent, and depending on the panels internal configuration just one bad cell could affect the whole panel. Another idea, before disconnecting anything is to use a DC current clamp-meter on one of the two wires, again as close as poss to the panel, whilst its in its '10v state'. Any short current will show. If its a 2-wire cable you'll need to split the outer to get at one wire (either will do).
Solar shorts arent like battery shorts, the power is coming from a resistive source (panels have a high ESR) and so they dont cause sparks or any of the pyrotechnics & heating/burning that usually results from a battery-powered short. Regarding a failed blocking diode (if it has one) Schottkys tend to fail closed so the panel could possibly have been damaged by reverse current, but any decent controller should prevent battery discharge through the panel even where (as can be the case in high-power solar) a diode isnt included.
Cheers
Phil

 

[capitanoooo]

Hi All, many thanks for your comments and words of advice.

VanDamMan, these panels are designed to be laid flat (can be installed on boat decks, etc) so don't think this would alter the voltage much. Do agree that directing the pop-top toward the sun would definitely achieve an improved output tho.

Phil and travelvolts, I cut back the wires to about 150mm from the panel junction box and only measured 10 volts so going with a conclusion that it is a faulty panel for one reason or another.

I have been in contact with Adrian at Solar Technology regarding the problem. His response and assistance has been exceptional and even though I've had a fault with the panel, their level of customer service has been brilliant - even with the ongoing dramas of COVID. They have replaced the 80 watt panel with 2 x 60 watt panels, received them yesterday. Unfortunately they didn't have the exact replacement in stock so offered the uprated version which was very kind!

I now have the issue of removing the duff panel which Sikaflex is proving to be a very tough adhesive to cut, especially when trying to not damage the roof in the process. However, new panels should cover most of the previous panels footprint. I have tried using cutting wire with little result so will resort to my trusted multitool next week.

Many thanks for all your feedback - I'm going to dismantle the junction box on the duff panel when I've got it removed. There are two physical fixings on the underside that need removing before I can pries it open. If I find anything interesting or work out the reason of the fault - I'll post some images on here shortly.

 

[Dellmassive]

have a look here.

more info:

Removing an old stuck down panel.

.

What Solar Panel/controller Dc-dc Leisure Battery - Have You Got ?

What Solar Panel/s & Controller/s . . . . ? There is a lot of talk about Solar at the moment, and with spring not to far away i wanted to get an idea of what kit we are all using . . . The main components are the Panels themselves, the charge controller (whether that be stand alone or...

www.t6forum.com

.

 

[capitanoooo]

have a look here.

more info:

Removing an old stuck down panel.

.

What Solar Panel/controller Dc-dc Leisure Battery - Have You Got ?

What Solar Panel/s & Controller/s . . . . ? There is a lot of talk about Solar at the moment, and with spring not to far away i wanted to get an idea of what kit we are all using . . . The main components are the Panels themselves, the charge controller (whether that be stand alone or...

www.t6forum.com

.

Thanks Dell - I will give it a go with some WD40. Mine is a flexible panel which I am hoping is only sikaflexed on the outer edges!

 

[Phil_G]

Before you remove it, you've nowt to lose so take the box apart first. It may well have a a crappy joint or a duff diode, though higher power panels tend to depend on the controller to prevent discharge.

If all else fails, heres my own panel removal adventure: Solar Panel Adhesive . It was a success, that same panel is now doing sterling service on his Austops poptop.

Mine is a flexible panel which I am hoping is only sikaflexed on the outer edges!

They will most likely have zig-zagged all over the panel too.

 

[capitanoooo]

Before you remove it, you've nowt to lose so take the box apart first. It may well have a a crappy joint or a duff diode, though higher power panels tend to depend on the controller to prevent discharge.

If all else fails, heres my own panel removal adventure: Solar Panel Adhesive . It was a success, that same panel is now doing sterling service on his Austops poptop.


They will most likely have zig-zagged all over the panel too.

Hi Phil, thanks for posting...

I was thinking of that at first but unfortunately the box is mechanically fixed (as well as chemically) on the underside of the panel so taking the box apart without removing the screws will likely right the box off completely.

Thanks for the link - I have purchased some windscreen cutting wire from Amazon but the Sikaflex is unbelievably strong! Is the lock wire any good compared to the others you tried?

 

[Phil_G]

Lock wire did it for us but its a long and miserable process Its a two-man job, one either side, take turns to pull, lumberjack style...
We wanted to re-use the panel though, in your case maybe you dont need to be so careful...

 

[capitanoooo]

Lock wire did it for us but its a long and miserable process Its a two-man job, one either side, take turns to pull, lumberjack style...
We wanted to re-use the panel though, in your case maybe you dont need to be so careful...

Yes I was worried that may be the case. The fella in the video above seems to cut through it like butter with a piece of string - very suspect!

Oh the wife is going to love me so much!

 

[Eclipse Custom Vans]

Hi All,

I was wondering if anyone out there may help me with a solar panel problem that I am experiencing? The vehicle is a 2016 T6 converted by Autohaus.

I have an 80 watt PV Logic Flexi Panel from Solar Technology International which is Silkaflexed to the top rear of Reimo roof (please see photos). The flex from this panel runs to the underside of the roof, along to the front of the vehicle where it then drops into the headliner, it is then extended from here down the drivers B post to under the seat terminating into a STCC10 solar charger.

I have an intermittent problem with the panel that even when the panel is in direct sunlight and is super clean, it mostly sits at about 10 volts. Obviously at this voltage it will not charge the 12v leisure battery and becomes completely pointless. On just a couple of occasions it has measured around 18 volts, which in general light of day is what I would expect from this panel, and the light comes on at the controller charger informing me that it is charging the battery - which on testing it is! But as I say, most of the time it is around 10 volts - when panel is squeaky clean and in direct sunlight!

I have removed the headliner and checked the voltage (open circuit) with a multimeter at the end of the flex leading from the panel. There are no other terminals/connections before it enters the panel's moulded junction box (mechanical and chemically fixed on the panel) and there appears to be no damage to this flex. The voltage here is still at about 10 volts. So I have ruled out a bad connection or any earthing problems prior to the panel and its junction box.

I can't see any damage to the panel cells and I'm under the conclusion that if it has occasionally given me 18 volts that the panel cells should be okay and an intermittent fault would be unlikely from a cell?

I had some other advice that suggested the problem may be within the moulded junction box on the controller which supposedly contain diodes to prevent back feed into the panel's individual cells. It was suggest that if one of these are faulty and blocking a cell then I should expect to see a significant drop in voltage. I was wondering if anyone would agree with this or has experienced any similar problems?

I have contacted the manufacturer Solar Technology International but still awaiting to hear back from their support team. There is a 5 year warranty with the panel so thinking it should be covered but who knows with these things! I'm reluctant to pull the moulded junction box apart as if I am covered by warranty, then don't wish to null and void it in the process.

Can anyone think of any other possible causes or items that I should test first. Any advice would be greatly appreciated!

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View attachment 66513

Hi, Sounds like a faulty /damaged panel. You need to be very careful with these panels to prevent damage when installing them. I assume it was working fully when first fitted, if so then it was not faulty when installed. Looking at the photos, there seems to be a bead of adhesive all the way around, this could lead to pockets of trapped air under the panel, this air when heated expands and can distort the panel leading to irreversible damage to the cells. This could be the cause of the panel becoming faulty over time. Or it could be a generally faulty panel.

Good luck
Rgds
Ian

 

[capitanoooo]

Hi, Sounds like a faulty /damaged panel. You need to be very careful with these panels to prevent damage when installing them. I assume it was working fully when first fitted, if so then it was not faulty when installed. Looking at the photos, there seems to be a bead of adhesive all the way around, this could lead to pockets of trapped air under the panel, this air when heated expands and can distort the panel leading to irreversible damage to the cells. This could be the cause of the panel becoming faulty over time. Or it could be a generally faulty panel.

Good luck
Rgds
Ian

Hi Ian,

The panel was installed by a professional fitter Autohaus 4 years ago. I obviously can only assume it was done correctly.

The installation instructions for this panel is to run a 6mm bead of Sikaflex around the outer edge and secure to a flat or slight curved surface - there is some flex in the panel (please see photo).

Do you have any further guidance on installing to avoid air underneath? it appears to have a flat flush fixing to the roof.

Thanks in advance!

 

[Eclipse Custom Vans]

As far as I am aware you cant leave trapped air underneath. Some of our suppliers even supply a raised open cell bed to allow dissipation of air. Pehaps PV have a different method, its up to you. We dont use PV, but have seen one previously with same problem. Customer received a replacement and was going to fit it over the old one. His call.

Here is an extract from a set of instructions:

One of the most important things to bear in mind when gluing the solar panel using adhesive is to ensure that there are no pockets of trapped air underneath the solar panel, i.e. no void spaces with air that are sealed all the way around with adhesive. If you leave trapped air under the solar panel (no matter whether it is between beads of adhesive or in various slots and holes of the uneven roof surface), such air will inevitably warm up when the solar panel is receiving good sunlight. When the air gets hot, it will significantly expand in volume, causing upward pressure to the solar panel surface and possible bulging of the solar panel during hot weather. This can result in permanent damage to the solar cells.

All te best,
Ian

 

[capitanoooo]

As far as I am aware you cant leave trapped air underneath. Some of our suppliers even supply a raised open cell bed to allow dissipation of air. Pehaps PV have a different method, its up to you. We dont use PV, but have seen one previously with same problem. Customer received a replacement and was going to fit it over the old one. His call.

Here is an extract from a set of instructions:

One of the most important things to bear in mind when gluing the solar panel using adhesive is to ensure that there are no pockets of trapped air underneath the solar panel, i.e. no void spaces with air that are sealed all the way around with adhesive. If you leave trapped air under the solar panel (no matter whether it is between beads of adhesive or in various slots and holes of the uneven roof surface), such air will inevitably warm up when the solar panel is receiving good sunlight. When the air gets hot, it will significantly expand in volume, causing upward pressure to the solar panel surface and possible bulging of the solar panel during hot weather. This can result in permanent damage to the solar cells.

All te best,
Ian

Okay thanks Ian.

Obviously I want to install it correctly - especially with the cost and it appears very difficult and time consuming to remove.

Beads in parallel and a break in the middle appears to be a good option to avoid this issue - will definitely be giving it some consideration

 

[capitanoooo]

Okay, so I've been having ago at removing the panel this afternoon and the good news is that it seems to be coming off quite easily, however the bad news is that it's bringing the paint with it. From what I can see at the corner where I have started, the entire underside of the panel has been Sikaflex'd to the roof - so absolutely zero chance of removing without the paint coming with it!

Obviously a respray is expensive - especially when I'm only going to put new panels on the top. I've heard vinyl wrap and then Sikaflex new panels to that - does anyone have any experience of this?

 

[Phil_G]

Just tidy it up and fit a slightly larger panel to cover the mess? Re the air thing, its ok to leave the roof channels open at the back, seal them at the front so wind cant get under the panel, but leave the channels clear and open at the back for cooling air:

 

[capitanoooo]

Thanks Phil for the picture and advice. Unfortunately my roof is flat with no channels for ventilation so will have to consider best option with new panels.

This next bit might be boring but thought some might be interested so decided to post it...

I had an opportunity to remove the old panel; unfortunately the wire cutting option was tedious and unsuccessful so ended up levering it off by tapping thin bits of plywood underneath the panel to break the sikaflex bond. This was still a very slow process as I had to be cautious not to damage the other parts of the roof. The footprint underneath the panel was left in a right state, the Sikaflex was not coming off without taking the paint with it so ended up with a horrible mess to contend with...




The old panel got pretty damaged trying to remove as I'm sure you can imagine...



The application method for the Sikaflex can be seen below which appears to show plenty of opportunity for air to be trapped on the underside of the panel, which could have had potential to be the cause of the fault, however...



I decided to remove the junction box and take a further look inside to see what I could find...



Initially I had to remove the mechanically fixings on the underside which were two small plastic screws...



Once these screws were removed the junction box literally fell away from the unit, the was no adhesion with the sealant used in the box and immediately noted corrosion around 2 of the 3 terminals, particularly on one...




I slowly removed most of the sealant from the junction box which was quite easy to remove and very fragile in parts. Water was clearly present inside (circled in blue), generally around the terminals and the diodes, there was obvious corrosion around the positive and negative terminals especially on the conductors. The sealant had greened slightly where water had been present...






My thinking it was the water ingress into the junction box which led to the fault occurring rather than the trapped air below the panel, although that wouldn't have been helpful. The water could of created a short between the diode connections which could have led to back feed into the panel.

I'm thinking about adding an additional layer of sealant around the edge of the junction boxes of the new panels just to try and mitigate this happening again.

Anyway so I have cleaned up the roof, removed all the remaining Sikaflex and loose paint, and applied a sheet of 3M 2080 vinyl wrap to cover the damaged area of the old panel and the footprint of the new panels. Thinking of using a combination of Sikaflex 252 and some 3M VHB RP45 tape to fix down the new panels in this formation but no rush with lockdown...

 

[Dellmassive]

Good job...

That's defo water ingress and corrosion cause the old panel to fail.

Vinyl wrap under panels is defo the way to go...

Yet so see an attempted removal though.