Another question about possible solar panel problem?

[Oscarpop]

As per another post, I think we have a problem with one of our 100w solar panels.

It is one of two identical ones, so I have a reference .
The good one puts out 5a in good sun.

The other doesn't.

So I went down the diagnostic routes, and is is where my question lies.

Yesterday it refused to put out any power at all, while the other was giving amperage.

This morning it is giving 1amp, but it's 8am so the sun is very low.
One day last week, it gave 3 when I angled it correctly ( while the other gave 5).

So I have an intermittent problem.

My questions therefore is: can solar cells work intermittently ? Or does this sound like a connectivity problem?

My next job is to open up the junction box on the panel and look for corrosion or bad connections. Then check the whole panel for possible breaks in the internal wiring.

All help gratefully received

 

[Tam Lin]

I have one for my caravan. I was surprised when the battery ran down so looked at the back of the panel. Mrs TL, looking over my shoulder said, "Shouldn't this wire be connected to something?"
Indeed it should, and once I fixed it the panel worked!
Funny as it had worked the year before but presumably a poor connection during manufacture. Worth checking.

 

[Oscarpop]

F

I have one for my caravan. I was surprised when the battery ran down so looked at the back of the panel. Mrs TL, looking over my shoulder said, "Shouldn't this wire be connected to something?"
Indeed it should, and once I fixed it the panel worked!
Funny as it had worked the year before but presumably a poor connection during manufacture. Worth checking.

Thanks. I checked the wiring this morning. All intact.

Am starting to suspect that the unit just failed, for no reason. Although I can't work out if this is com,on.

I know that output diminishes with time. However, to just go pop seems strange to me.

 

[Foolish Muse]

It is certainly possible that the wire to the panel has broken, right at the panel. Although your panel might have been "made for marine use", this does not mean it will stand up to salt water corrosion. It might have an intermittant connection. Or it is also possible that the cell connections inside the panel have broken. There has been tremendous pressure for solar panel manufacturers to reduce cost. This has resulted in significant deterioration in quality. It is not uncommon for panels to work fine for a year or two and then fail. It's caused by the normal expansion and contraction of the panel in temperature changes.

 

[srm]

Open up the junction box, when I did on mine I found the connections encapsuated in a lump of hard resin, which inevitably had failed at the panel face allowing water in and corroding one of the wires. A bit of creative soldering attached a new, heavier wire to the foil strips. I had to cut some of the facing plastic to get enough foil to work with. I then encapsulated the joint in clear, flexible sealant so that I can see if it starts to corrode again. Problem solved.

 

[William_H]

The test for the solar panel is simply putting an amp meter across the output. (disconnected from battery etc.
This can be done right at the panel junction box. There might be a diode in there too.
Solar panels can fail from failure of the connection of the cells to the interconnections. Usually all sealed up under the glass. I have had panels slowly die as a result of moisture/ corrosion of the cells them selves. This is seen as discolouration and strange material under the glass. That means essentially it is a throw away item. good luck olewill

 

[Oscarpop]

Just a quick update about our solar panel problems......

It appears to be that the panels both function correctly.

However we have 2 identical but faulty multimeters.
Purchased another on today and both panels are outputting perfectly.

There is also a lack of knowledge on my part as to how an mppt controller works.
I thought they dissipated excess solar energy as heat, thus showing a constant current across the ammeter I have wired in.
However, it would seem as if when the batteries are full , the mppt controller will not accept any more charge from he solar panels .thus the ammeter reading drops,

Thanks for all the help

 

[Sarnia]

As per another post, I think we have a problem with one of our 100w solar panels.

It is one of two identical ones, so I have a reference .
The good one puts out 5a in good sun.

The other doesn't.

So I went down the diagnostic routes, and is is where my question lies.

Yesterday it refused to put out any power at all, while the other was giving amperage.

This morning it is giving 1amp, but it's 8am so the sun is very low.
One day last week, it gave 3 when I angled it correctly ( while the other gave 5).

So I have an intermittent problem.

My questions therefore is: can solar cells work intermittently ? Or does this sound like a connectivity problem?

My next job is to open up the junction box on the panel and look for corrosion or bad connections. Then check the whole panel for possible breaks in the internal wiring.

All help gratefully received

Had similar problem with a 100w semi flexible, suddenly stopped working, nothing I did would make it work again, checked all connections etc, contacted supplier who wanted photos showing a meter 0 reading, boat in Greece I was back in the UK, anyway they sent me a new one, working fine.
Since then I have in conversation with others who use solar, been told that semi-flexible panels are more prone to sudden failure, something about the heat and their thiness, I also use a fixed 100w mounted on the rail which can be raised and lowered to face the sun, they are again I am told are much more reliable.

 

[William_H]

Quote "There is also a lack of knowledge on my part as to how an mppt controller works.
I thought they dissipated excess solar energy as heat, thus showing a constant current across the ammeter I have wired in.
However, it would seem as if when the batteries are full , the mppt controller will not accept any more charge from he solar panels .thus the ammeter reading drops,"



An MPPT controller actually "manufactures" the precise voltage that the battery needs for correct charge and not overcharge. So much like a modern battery charger or an alternator controller.
So if it manufactures 14.2 volts and presents this to the battery terminals then the battery will take a current dependent on the state of the charge. So as battery becomes more charged and has a higher inherent voltage the current in falls. The "excess power" of the solar panel is simply not used as opposed to controllers which dissipate it.
The clever thing about the MPPT controller is its ability to suck power out of the panel at the best voltage and current ratio (power) for the prevailing light conditions and to covert this in to what the battery needs.
good luck olewill