Solar panels (again, sorry!)

[tomandsophie]

I installed the panels yesterday in the dark. I wired them in parallel (2 64w uni-solar triple-junction panels) to my 12v system via a Steca charge controller (the pretty one with the LCD).

An overcast day today but I nipped home at lunchtime, checked the output at the panels and at the controller and it measured 10.45v. The controller was showing an error code that, according to the manual, means that it hasn't detected a panel connection. Very odd. I followed the instructions to the letter. I'm concerned. help?!

Is that the kind of voltage you'd expect?

Edited January 15, 2007 by tomandsophie

[Alastair]

Nope, that's defn a fault.

 

At a guess, I'd say you have a loose wire somewhere.

[Theo]

I installed the panels yesterday in the dark. I wired them in parallel (2 64w uni-solar triple-junction panels) to my 12v system via a Steca charge controller (the pretty one with the LCD).

An overcast day today but I nipped home at lunchtime, checked the output at the panels and at the controller and it measured 10.45v. The controller was showing an error code that, according to the manual, means that it hasn't detected a panel connection. Very odd. I followed the instructions to the letter. I'm concerned. help?!

Is that the kind of voltage you'd expect?

 

 

Don't apologise. I am most interested to hear how you get on.

 

Nick

[Alistair]

I installed the panels yesterday in the dark. I wired them in parallel (2 64w uni-solar triple-junction panels) to my 12v system via a Steca charge controller (the pretty one with the LCD).

 

 

Make sure you've got the panels wired +ve to +ve if they're in parallel.

 

Try just one at a time and let us know how you get on.

 

Sounds like a loose connection to me too.

 

Cheers

[chris w]

I installed the panels yesterday in the dark. I wired them in parallel (2 64w uni-solar triple-junction panels) to my 12v system via a Steca charge controller (the pretty one with the LCD).

An overcast day today but I nipped home at lunchtime, checked the output at the panels and at the controller and it measured 10.45v. The controller was showing an error code that, according to the manual, means that it hasn't detected a panel connection. Very odd. I followed the instructions to the letter. I'm concerned. help?!

Is that the kind of voltage you'd expect?

If you inserted a diode in series with each panel (to stop battery discharge at night through the panels) did you wire the diodes the correct way round? The band on one end of the diode should be nearest to the battery. ie: the non-band end of the diode should be closest to the panel.

 

If the diodes are the incorrect way round, you won't get any charging at all.

 

Chris

Edited January 15, 2007 by chris w

[Nemesis]

If you inserted a diode in series with each panel (to stop battery discharge at night through the panels) did you wire the diodes the correct way round? The band on one end of the diode should be nearest to the battery. ie: the non-band end of the diode should be closest to the panel.

 

If the diodes are the incorrect way round, you won't get any charging at all.

 

Chris

Assuming the diodes are connected in series with the +ve leads. If they are in series with the -ve leads, the bar should be to the panel side.

[tomandsophie]

Will check all the connections when I get back, and will try what happens with just one panel connected.

No diodes in the wiring, as the charge controller does all that for me.

[Bones]

Will check all the connections when I get back, and will try what happens with just one panel connected.

No diodes in the wiring, as the charge controller does all that for me.

 

 

and make sure you have put the panel cables in the panel connection on the controller rather than the battery bit....

 

Did you send the wires directly from the controller to the battery or did you go via an isolator switch?

[tomandsophie]

and make sure you have put the panel cables in the panel connection on the controller rather than the battery bit....

 

Did you send the wires directly from the controller to the battery or did you go via an isolator switch?

 

The panel cables are definitely in the panel connection on the controller. The wires go from the controller to the battery via an isolator switch.

 

I measured the voltage actually coming directly out of the panels, and when they are not connected to anything (i.e. I have disconnected them from the controller) they read 0.0v, and then when I connect the wires to the controller it goes up to 10.45. This reading of 10.45 is the same at the panels and at the controller. Odd.

Edited January 15, 2007 by tomandsophie

[tomandsophie]

What kind of voltage would you expect to be reading at the panel end of things?

Edited January 15, 2007 by tomandsophie

[chris w]

Assuming the diodes are connected in series with the +ve leads. If they are in series with the -ve leads, the bar should be to the panel side.

Quite right

 

Chris

[Carrie]

Mine usually says between 13.3 and 15V. Today, around midday, it read 13.8v

[Ricardo]

I measured the voltage actually coming directly out of the panels, and when they are not connected to anything (i.e. I have disconnected them from the controller) they read 0.0v, and then when I connect the wires to the controller it goes up to 10.45. This reading of 10.45 is the same at the panels and at the controller. Odd.

 

What reading are you getting from the panel input connection on the controller when the panels aren't connected, if this is 10.45 volts then this must be coming from the batteries and not from the panels.

 

The volt readout on the controller is the battery voltage, what does this say?

 

IIRC I got about 18 volts from my panel when it wasn't connected.

[charles123]

The panel cables are definitely in the panel connection on the controller. The wires go from the controller to the battery via an isolator switch.

 

I measured the voltage actually coming directly out of the panels, and when they are not connected to anything (i.e. I have disconnected them from the controller) they read 0.0v, and then when I connect the wires to the controller it goes up to 10.45. This reading of 10.45 is the same at the panels and at the controller. Odd.

 

 

As you measured the voltage coming out of each panel (presumably in daylight) and they are reading 0.0v this would apear to be where the problem is as they should be producing a healthy voltage on your volt meter. Looks like the connections are wrong at the panel end to me, which is a puzzel since there is not much to get wrong

 

Good luck with them

 

Charles

[Alastair]

Both panels are in sun, aren't they?

 

If one is shaded, it will drag the voltage down.

[Gibbo]

I measured the voltage actually coming directly out of the panels, and when they are not connected to anything (i.e. I have disconnected them from the controller) they read 0.0v,

 

There's your problem then!

 

Gibbo

[DHutch]

Yeah, with my very limited knowlage, open circurt (not wired to anything) you should get a meter reading of around 20volts acrooss the pannels.

 

 

Daniel

[tomandsophie]

Looks like the connections are wrong at the panel end to me, which is a puzzel since there is not much to get wrong

Good luck with them

Charles

 

You are all so kind with your helpful suggestions, thanks.

I have a confession to make. When I fitted them, I must have only pushed the connections so far and not all the way. When you push in the leads on the backs of the panels, they click quietly into place. What I didn't realise is that if you then twiddle them around and push them, they clunk heartily into position. So the leads were only half in. When I clunked them properly into place last night, the charge controller immediately recognised that there were some panels connected.

 

On the LCD on the controller there are several bits of information. The status of the panels (as in if they are working) is shown by a little smiley face. Up until now he has looked like this and now he looks like this and we look like this

 

Will post tonight or tomorrow once I have seen how much power we have when we get home...

[Bones]

You are all so kind with your helpful suggestions, thanks.

I have a confession to make. When I fitted them, I must have only pushed the connections so far and not all the way. When you push in the leads on the backs of the panels, they click quietly into place. What I didn't realise is that if you then twiddle them around and push them, they clunk heartily into position. So the leads were only half in. When I clunked them properly into place last night, the charge controller immediately recognised that there were some panels connected.

 

On the LCD on the controller there are several bits of information. The status of the panels (as in if they are working) is shown by a little smiley face. Up until now he has looked like this and now he looks like this and we look like this

 

Will post tonight or tomorrow once I have seen how much power we have when we get home...

excellent!!! an easy solution... well done!

[Keeping Up]

Hooray! I do like to read a story with a happy ending

[Theo]

Hooray! I do like to read a story with a happy ending

 

 

And, following on from my one comment in this thread, thank you for asking. I have learned a bit more about solar panels from all the helpful replies.

 

Nick

[tomandsophie]

Got home this evening (in the dark of course), looked at the control panel and it has recorded a measly 3ah input today. Now I know it has been overcast (with about an hour of clear sun down here) but the panels are facing south, tilted at an angle of 45 degrees, and no shade anywhere near. So surely I can expect more than 3ah a day from 128w triple-junction panels?!

Will nip home in my lunchbreak tomorrow and do a quick test on them in the light...

[tomandsophie]

How many ah do you reckon you should get out of 128w of panels on a typical overcast January day?

[chris w]

How many ah do you reckon you should get out of 128w of panels on a typical overcast January day?

 

 

I don't know the answer to your specific question, but be aware that charging is only about 70% efficient typically so, in other words, you only utilise 70% of what appears to go into the batteries. This means that you have to charge for nearly 1.5 times longer than you might think from simple calculation. How is the 3AH being measured? Is it an indication on the Steca controller?

 

Without anything other than (intelligent) guesswork, let's assume that the power output is only 10% of that on a bright sunny July day. I base this on the fact that around the south of England, where I live, the maximum to which the sun rises in summer is about 61 degrees and the highest in winter is about 13 degrees. The ratio of the sine of these angles is about 2: 1 so, since the sun radiates in all directions there is a cube law attached to these figures so 1/2^3 = 1/8th or pretty close to 10%. On top of this the days are cloudy and overcast in winter so the sun's intensity is further greatly reduced.

 

So let's say 12W is being produced due to relative brightness (angle of sun) and this is further reduced by 50% due to cloud thickness. This means that about 6W may be reaching your batteries of which about 70% is actually used in charging as explained above. This equates to 4W average. Over 8 hours this is about 3AH which is what you saw.

 

I have no way of knowing if this "theory" is absolutely correct but it does show within reasonable bounds that 3AH is not entirely out of kilter.

 

Chris

Edited January 16, 2007 by chris w

[Gibbo]

How many ah do you reckon you should get out of 128w of panels on a typical overcast January day?

 

This was answered in an earlier post in the other thread I think. About 3 to 5Ahrs per day would be about right at this time of year.

 

Gibbo