Is my solar panel working?

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Nicholas123

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I have loads of documentation that came with the boat unfortunately it is all in forrin.
Basically there is a Sunware solar panel that I suspect stems from 1992 because I have seen that date quoted on some correspondence that appears to relate to the installation.A box inside the cabin marked Fox-D1 & another one marked Fox-40.The box Fox-D1 can be switched between volts & current but never goes up while switched to volts.
I charged up my battery the other day & it really took a pounding turning over the engine before I finally got it going.It started at over 13 volts but dropped bellow 13 volts & since the cold weather I notice it looses about a volt a day & yesterday stood at something like 12.6 volts.I suspect my battery would'nt stand another attempt to start the engine & would like my solar panel to do it's job so what can I do?
 
To start the ball rolling:
Id disconnect the solar panel and check its open circuit volts in bright light, preferably sun light. You should get 20 ish volts but check the tech spec for the panel you have.

If OK Id connect it to a suitable load via an ammeter to check that it can deliver the specified current.

If it is Ok you then have to consider the regulator.


( My first solar panel did not last much beyond 10 years ... and it was not cheap)
 
The obvious thing to do would be to check the voltage coming from the panel in daylight (open circuit & with a load). You really need to check each part of your system bit by bit (panel, regulator, batteries etc.).

Figures don't make sense wrt Voltage dropping 1V per day but still sitting at 12.6V. That figure isn't too bad for some types of battery that are close to full charge. However, unless you checked the voltage at night the panel should have pushed the Voltage up further than that.

However, you haven't given any details of your system.

1) Battery: Check labels, or even look at them as any information helps a bit (sealed, caps on top?).

2) Panel: Check the size
Do you know if it is 10W, 50W or 100W? Physical dimensions would help even if you don't have that information. Remember that it is December and you'll only get about 10%-20% of the max. summer output. So even if you have a largish panel of 100W you still might only get 5Ah back into the battery each day. If you only have a small 5W or 10W panel then it might not even meet the rate your batteries self-discharge.

Just noticed that panel is 20 years old so output will have dropped off by now (Zero output wouldn't surprise me much).
 
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Why not disconnect the cable from the solar panel and measure the open circuit voltage. In reasonable daylight you would expect about 18v. After that you need to ensure the regulator (if there is one) is outputting to the battery. The FOX D1 is a voltage / current measuring device so if it is not showing a current then the voltage output from the Panel / controller is below battery voltage. At a guess the D40 is a controller so you may be able to measure input and output there.

Yoda
 
The Fox D1 is just a volt meter Ammeter and should show some reading. I suspect there is a connection fault?

The Fox-40 is a 5 Amp solar panel controller which suggests that the panel is about 50 to 55 Watt output.

Obviously, from you description, something is amiss possibly a couple of small faults.

If you are near Gosport, give me a shout and I can take a look for you?

.
 
Solar panel

As said check the output of the panel. Use a volt meter across the disconnected wires + and - you should get 18+ volts. Now move you meter to amps range and connect across the output wires. You should see some amps.
NB the solar panel is peculiar in that it is OK to short out the panel with an amp meter for a short time unlike any other battery or generator.
A panel about 30cmX30cms is typically about 10w max. That means that in really bright sunshine with the panel square to the sun you should get .5 amp. If you connect it directly to a battery you should also get near .5 amp into the battery. Power increases with panel area. However I am in oz summer sun and in UK at this time of the year as said you might be lucky to get 10% of that power at midday sunny day.
The amp meter/ voltmeter and the regulator are both candidates for causing problems so test the solar panel itself with these out of circuit. However as said solar panels don't necessarily last for ever indeed you may even be able to see corrosion creeping under the glass.
Don't expect too much from solar and if you replace it you might need 20w or more just to keep the battery alive. good luck olewill
 
That's a pretty elderly solar panel to be working at all. How many cells does it have? 39 is common these days, giving open circuit voltages of up to 20. However, early ones had as few as 30 cells, giving 15 volts. Given that the wiring is probably as old as the panel, it may be that by the time the output reaches the battery it doesn't have enough oomph to put anything in.
 
Nicholas123 said:
I have loads of documentation that came with the boat unfortunately it is all in forrin.
Basically there is a Sunware solar panel that I suspect stems from 1992 because I have seen that date quoted on some correspondence that appears to relate to the installation.A box inside the cabin marked Fox-D1 & another one marked Fox-40.The box Fox-D1 can be switched between volts & current but never goes up while switched to volts.
I charged up my battery the other day & it really took a pounding turning over the engine before I finally got it going.It started at over 13 volts but dropped bellow 13 volts & since the cold weather I notice it looses about a volt a day & yesterday stood at something like 12.6 volts.I suspect my battery would'nt stand another attempt to start the engine & would like my solar panel to do it's job so what can I do?
Click to expand...
I read somewhere that output degrades at 10% per year. On that basis, a panel made in 1992 starting at 20v output would be down to 2.4v by now. Even at 5%, it would be only 7.2v so not much good for charging a 12v battery.
These things don't last forever which makes you wonder about the viability of roof-mounted domestic panels. I looked into these last year and as far as I recall (which these days isn't very far) degradation of output wasn't taken into account in the financial justification. By the time you had reached the end of the payback period, the panels would be producing b*gger all anyway.
 
Some very interesting info there gents,thanks.
I can see I will have to work through this methodically with a voltmeter/ammeter & check the connections first (which if anything like the rest of the boat will be shot to pieces & neglected).
The panel measures about 45 cm square & has 40 of those little cell things in it (some of them are a different colour to the others so I guess that is the corrosion you are talking about William?).
The battery that I have got down there at the moment is a 70 amp/hour (I think) AGM Banner type battery that I ordinarily use as the starting battery.While at home at the moment I have a 105 amp/hour "Freedom- Marine Stationary-maintenance free-calcium" type battery that I use for domestic.The whole system needs working through from fuse boxes to instrument panels & various bits of wires all over the place & I will get around to it eventually.......
Thanks for your very kind offer lensman but I only have a very small dinghy & you might change your mind if you saw it:D.I hesitate to put anyone to such a risk.
Hopefully I will be able to resolve this myself.
 
ghostlymoron said:
I read somewhere that output degrades at 10% per year. On that basis, a panel made in 1992 starting at 20v output would be down to 2.4v by now. Even at 5%, it would be only 7.2v so not much good for charging a 12v battery.
Click to expand...

I find that hard to credit based on my own experience. I have an eight year old rigid panel that so far as I can measure is as good now as when brand new (same can't be said for a succession of semi-flexible ones, which is why'll never buy another).

This from a non-marine solar panel outfit (even allowing for a degree of self-interest, it's a long way from 10%):

Solar panel manufacturers provide a 25 year warranty that your solar products will be producing solar power at 80% efficiency from there initial tested solar electrical output rating. This is based on the notion that modern crystalline photovoltaic solar panels will lose function at a rate of about 0.7% per year. This is a major reason why thin film solar panel technology is not ready for mass production. Solar powered thin film silicon technologies degrade at a rate of 5% during their first few months in exposed sunlight. After this initial degradation they level off to a rate of 1% a year.
 
Solar pael

Nicholas123 said:
Some very interesting info there gents,thanks.
I can see I will have to work through this methodically with a voltmeter/ammeter & check the connections first (which if anything like the rest of the boat will be shot to pieces & neglected).
The panel measures about 45 cm square & has 40 of those little cell things in it (some of them are a different colour to the others so I guess that is the corrosion you are talking about William?).

Don't despair so quickly. Those solar panel cells tend to be a very strange colour and pattern of blue and silver and often appear to be different coloured. Corrosion is very obvious creeping from the edge in a dull grey. In fact more obvious with the panels that have stripes wheras it seems like your's is the older type with many round cells. (still good). give it an electrical test. My guess is that it was 10 to20 watts when new. ie .5 to 1 amp max current. good luck olewill
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macd said:
I find that hard to credit based on my own experience. I have an eight year old rigid panel that so far as I can measure is as good now as when brand new (same can't be said for a succession of semi-flexible ones, which is why'll never buy another).

This from a non-marine solar panel outfit (even allowing for a degree of self-interest, it's a long way from 10%):

Solar panel manufacturers provide a 25 year warranty that your solar products will be producing solar power at 80% efficiency from there initial tested solar electrical output rating. This is based on the notion that modern crystalline photovoltaic solar panels will lose function at a rate of about 0.7% per year. This is a major reason why thin film solar panel technology is not ready for mass production. Solar powered thin film silicon technologies degrade at a rate of 5% during their first few months in exposed sunlight. After this initial degradation they level off to a rate of 1% a year.
Click to expand...

You're right. Further research has shown that loss of output is about 0.5%. So the OP can look elsewhere for a solution.
 
William_H said:
Don't despair so quickly. Those solar panel cells tend to be a very strange colour and pattern of blue and silver and often appear to be different coloured. Corrosion is very obvious creeping from the edge in a dull grey. In fact more obvious with the panels that have stripes wheras it seems like your's is the older type with many round cells. (still good). give it an electrical test. My guess is that it was 10 to20 watts when new. ie .5 to 1 amp max current. good luck olewill
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The cells are rectangular not round & I think it is semi-flexible so that has got me doomed if what macd has said is correct.......I have got the impression from somewhere that you can walk on them-sort of.
I think looking at the brochures that I have got which are extensive but all in foreign that it is an 18 watt panel or was when new.The measurements seem to tally roughly.Anyway in view of their antiquity it will be interesting to see if it is still working & producing anything :)
 
Disappointing semi-flexible panel

From experience, I agree with macd. The 5yr old 34W Solara semi-flexible panel fitted by the previous owner has corroded badly at the edges (nasty rust streaks on cabin top), connector block and the length of the output cable.

The output at the panel terminals in clear sunlight is still good, but with the slightest shading (front of sprayhood, boom..) the output is negligible so not rushing to repair and re-fit. A new replacement lists at £437.

Current solution is a 30W rigid panel (£70 with regulator in the Maplin sale) hung from the guardrail on the sunny side of the boat. Less convient but very effective.
 
I have just been down my boat & because the battery did'nt have enough clout in it to start the engine I oiked it in rediness to take ashore & re-charge.It was then that I noticed that the thingee Fox-D1 was still registering 9.5 volts & as the boat swang round it rose to 11.2.
I checked & the very low sun was covering maybe two thirds of the panel,what do you people make of it?
 
I still can't understand how it is registering 9.5/11.2 volts without any battery connected......I thought that unit Fox-D1 showed the voltage in the battery :confused:

On the good side I started up the engine this morning & it showed 13.8 volts which would appear to be a healthy alternator input.
 
Nicholas123 said:
I still can't understand how it is registering 9.5/11.2 volts without any battery connected......I thought that unit Fox-D1 showed the voltage in the battery :confused:

On the good side I started up the engine this morning & it showed 13.8 volts which would appear to be a healthy alternator input.
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Presumably still showing the output voltage from the solar panel when the battery is disconnected.

In full bright sunlight one might have expected a reading well in excess of 18 volts.

Your readings indicate that the panel is not totally defunct. They may well be satisfactory in the conditions you describe.

I d expect the output volts from the alternator to rise higher than 13.8 .
 
VicS said:
Presumably still showing the output voltage from the solar panel when the battery is disconnected.

In full bright sunlight one might have expected a reading well in excess of 18 volts.

Your readings indicate that the panel is not totally defunct. They may well be satisfactory in the conditions you describe.

I d expect the output volts from the alternator to rise higher than 13.8 .
Click to expand...

It was only partially in the sun Vic & the battery had taken a hell of a hammering to get the engine going this morning so maybe some of the charge was being dissipated into the battery?Anyway,when I got home I took a look at my Aldi battery & alternator tester & that puts it in the green range.Maybe if I had revved the engine it would have gone higher?
 
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