Solar Panels - What happened to the missing charge?

[BrendanChandler]

<span style="color:blue"> I have 2 Solara 85w solar panels on the boat. The first feeds its power to the second and then both feed power down on 2 core cable to a Prostar 15 solar controller.

I fitted these approx 3 years ago in accordance with the manufacturers instructions and have been very pleased with them until this week when the batteries (both heavy duty truck batteries installed in July this year and wired together) started to get low on power. Incidentally the reason that the batteries are wired together is that I do not have space for an additional starter battery. I carry a Power Pack as a backup in case I allow the power to drop too low to start he engine.

There has been almost no wind this week, so I could concentrate on the solar power.

Both solar panels show 20.2v at the output points on the panels.
The input wires to the controller show 20.1v when detached form the controller and show battery voltage when attached.

Today, a very sunny day the battery management system shows that the battery is receiving approx 3 Amps.

The controller is correctly set at type 3 battery, water filled.

I tried to connecting the input to the controller directly to the battery wires from the controller, bypassing the controller and the Battery Management system does not show a discernable difference, still about 3 amps.

As I type this, I notice that the voltage has now declined to 12.3 and with everything off, I am making 0.3Amp.

As you may gather, my knowledge of electrics is very limited.

Can I assume that the Solar Panels are ok because of the output voltage? Is it possible to gauge the Amps being supplied?

Can I assume that the Controller is ok as there was no discernable difference when bypassed?

If so, am I now looking for a power leak rather than lack of input and if so, where and how should I begin this process?

Help!!!
I am preparing for another Atlantic Crossing. The scurvy dogs will be even more revolting if they don’t have their Gin and Tonics cold!!

Thanks

Brendan </span>

 

[savageseadog]

Why did you bypass the controller, what prompted you to do that? You had a satisfactory 3 Amps before and after you bypassed the controller, there seems to be something missing in the narrative between bypassing the controller and the voltage going down to 12.3. Did it go dark?

 

[BrendanChandler]

I was trying to eliminate any fault in the controller and wondered whether connecting to the battery would give me the 7/9 Amps I expected. I am in Graciosa in the Canaries in very very bright sun, no wind, just washed the panels, so no sand or salt. I could be that I remade a poor connection poorly. The connections are spring loaded rather than screwed connections.

 

[arni]

When this happened to me, it was a loose connection of the main thick wire where it is attached at the solar regulator. Try all the connections by removing and re-fastening them.

 

[savageseadog]

easiest debug would be to disconnect the batteries and put an ammeter straight accross the panel output and see what you get. Whatever current you are expecting you should have it right there. Work towards the eventual battery connections and you should see more or less the same current. If you can find an old moving coil ammeter like an Avometer you stand a better chance of seeing fluctuations if you move any bad contacts,

 

[Gypsy]

Careful Savageseadog, this is NOT correct. You do not measure current by putting an ammeter ACROSS the solar panel. That is for measuring voltage. If you want to measure current you put the ammeter (or multimeter in "A" mode) in series with either the positive or negative wires which go to the load, in this case the load is the battery.

As others have suggested a step by step process is probably going to highlight the problem. More specific suggestions will come after some answers from the steps already suggested.
Ray

 

[savageseadog]

Sorry I'm absolutely correct. I'm suggesting measuring maximum short circuit current from the panel.

 

[BrendanChandler]

Hi Guys,

I would love to measure amperage but failed to do so.

My meter says that if I put it into Amp mode, connect probe to Amp (10A) out put and then attach it in series, I should get amperage.

I changed the 10A fuse in the meter, and tried adding the meter to a circuit which causes a bulb to light, but nothing registers on the meter and bulb does not light.
I am putting one probe on the + supply, the other probe on the bulb and the other end of the bulb to the - supply. I was hoping to measure the amperage this way but I do not get anything.

I am Irish, so all suggestions welcome ---- Not that one.

Brendan

 

[misterg]

Sounds like what you're doing is right, but I would agree with SSD that you can just connect ammeter across each panel in turn & check the short circuit current. (Don't try this with batteries, but OK for solar panels). Sounds like your meter is duff? Are there separate sockets for the test leads for the 10 amp range?

To answer the question about shadows - Yes, a small shadow can significantly reduce the output of a panel - even if it is just the shadow of a rigging wire.

Andy

 

[Gypsy]

Yes SSG I accept you are right for measuring the short circuit I of the panels. I didn't read that into your reply first and was worried that Brendan who has admitted limited knowledge of electronics may use that as a general current measuring technique. It seems his meter is faulty but a warning about the current but he could expect (app 5A per panel) is probably in order.
Ray