Solar panels not working

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eddystone

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I have 2 × NASA 20w panels charging domestic batteries via Victron PWM controller. Worked perfectly for last 18 months. Just noticed before leaving the boat on Tuesday that only the battery light was on (controller hidden in top of engine box). Checked with meter voltage on battery outlet is normal but voltage on panel input is effectively zero. Conceivable that pulling wires through to fit AIS receiver I have broken a connection but any other possible causes?
 
It seems unlikely that both panels have decided to turn up their toes at the same time. Check the wiring.

As for winter, my pair of 20w panels normally manage to top up a weekend's use by the next weekend even in December.
 
If you have any local connections by the panels, check the voltage at these points which will show if the panels are producing anything. Solar panels only need daylight to produce a measurable and useful output.
 
Stop thinking about the voltage and check the amperage (current) coming from the panels. Bad panels will still put out the same voltage, but will have much lower amperage. It's possible that one of your two panels is shot competely, or that cells inside the panels are shot. Checking the amperage will tell. Remember that power (watts) is the product of voltage and amperage.
 
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Don't have experience of your panels, but my cheap eBay Chinese ones had the wire connections to the panel embedded in a hard resin. This failed after a couple of seasons and the wires coroded and broke. A bit of creative soldering and new heavier wire was the remedy, then encapsulated the joint in clear flexible sealant so I can see the green stains from any future corrosion. Incidentally, I was expecting blocking diodes in the panel connector but nothing, just the feed wires onto the metal foil.
 
Quel surprise!
Went to boat today to meet sailmaker to measure for new genoa. Before I left I was checking the wiring route from the panels and noticed the controller was showing normal operation; quick check with multimeter showed same volts at pv input as battery which is as should be.(c13v)
Mystified!
 
I'll tell you again to check the current (amperage). What you are describing is exactly what you would see if one of your panels is not putting out enough current. This will happen if some of the cells inside the panel are damaged, or if the wiring from one of your two panels is damaged. I have 9 smaller panels on my boat rather than 1 large panel. The voltage that I measure at the controller will stay high, but the current drops low if the cells or wires from one panel are damaged. Measure the current from each of your two panels separately.
 
As said it is amps into the battery that matter with a solar panel set up. Under usual conditions of battery not fully charged a pulse width controller is effectively a switch that connects the solar panels to the battery so solar panel voltage can not exceed the battery voltage. It is unlikely that the battery voltage is feeding back to the voltage you measured at the solar input because they usually fit a blocking diode.
Nevertheless only an amp meter will confirm if and when your panels are working. (in good sunlight of course). Just in case the PWM controller has decided batteries are charged you can turn on some battery load like lights etc. Inw hich case solar should not be throttled back but running flat out.
good luck olewill
 
What type are they?? Mono or Polycrystalline? Was it a dull day? Monocrystalline panels produce virtually no power in dull conditions but Poly's do. If you are running a controller polycrystalline panels are better wired in series as they work better on dull days and the controller will sort our the amps/volts to suit. They are less efficient in sunlight than mono's though. One mine I have have 2 polycrystalline in series and 2 mono crystalline in parallel for the best of both worlds.
 
I think they are poly - they are semi-flexible. I'll test again with a load applied when i get the chance. I don't really know where to test the panels themselves for amps as there is no junction I can see to undo - the cables seem to be moulded on. Also don't you need a sunny day to do this test - well that's what one of those videos said - another said you have to connect the multi-meter in the shade. I can always read up on the difference between volts, amps and watts (which i failed to understand in O level physics 50 years ago so no logical reason I should be any better now), it's the practical issues of where to stick the multimeter probes that stumps me.
 
eddystone said:
........Worked perfectly for last 18 months......... any other possible causes?
Click to expand...

My 60W panel failed recently. I was going to post when all the facts were in but with two recent post on this subject, I thought I would throw my information into the pot.

I had full volts (~19V) but no current as measured by the HRDX Wind/Solar charger. As I dismount the panel during the winter months (when I go alongside and have access to 240V ac), I took the panel home to investigate. The panel has had less than 18 summer months exposure to the elements. Its position is well away from salt spray. It is flat when installed and therefore liable to rain accumulation.

My panel has a termination box on the cell face. I prised off its lid to reveal extensive rust dust. Once that was brushed out. the lightest touch on one of the spade terminals caused it to separate. Stamped on the cover is IP65, which is not the best of protection.

I have notified the supplier about the problem and they say they have written to the manufacturer. That was a couple of weeks ago. I'll repost as and when a reply arrives/does not arrive.

It was a little surprising that a product intended for use outdoors should rust so easily.

Cheers
Bob
 
eddystone said:
Quel surprise!
Went to boat today to meet sailmaker to measure for new genoa. Before I left I was checking the wiring route from the panels and noticed the controller was showing normal operation; quick check with multimeter showed same volts at pv input as battery which is as should be.(c13v)
Mystified!
Click to expand...
Not at all, if you have a PWM controller. if the panels are charging then the output voltage is the same as the batteries. Before I had a remote meter on the controller, I always measured the voltage at a convenient point and got exactly what you describe.
 
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