Problem with panel

[mettleramiel]

I have a 15 watt panel that works just fine by itself, giving me about 0.7 amps in some sood sun, but when I hook it up in parralel with any other panel, it stops making power. It is just the one panel doing it, I am sure. Any ideas? It would be nice to get this panel working along with the others.

[Flux]

You need to do some investigation and really find out what is happening.

Ideally you need more than one ammeter and you need to find out if that panel fails to produce current when in parallel with another or whether the combined current of both is coming out close to one panel on its own.

I see no reason why a panel should fail to produce current when in parallel with others.

Are all the panels in this discussion the same or is the suspect one different from the others. You probably need to take short circuit current in each case to see what the impedance of the panels are and to check that you don't have strange circuit resistances.

Do all panels have series diodes and is there some shading on the suspect panel when it is connected to the rest.

You have to check from first principles, if your circuits are right there is no reason for that panel to fail to produce current, why does it know that others are connected?

Flux

[snowcrow]

If the 15 watt panel has a much lower voltage than the other panels, it will not work. Are the other panels much higher in wattage? That can have an effect too!! Check the diodes too, make sure there isn't a shorted one.

Blessings, Snow Crow

[AbyssUnderground]

Higher wattage panels would only affect the output in series. Judging by what the author has said, he may be confusing parallel with series and vice versa, hence the problem and the confusion.

Like you say in series it becomes a problem of the smallest panel limiting the others.

[mettleramiel]

I know the diference between series and paralell. I am hooking them up with all of the positives together and all of the negatives together. parallel. The other panels are not being limited, just this one. I even hooked up this panel with another one up to the same battery each with their own multimeter. The panel works fine until I add the second one. The amps go down instantly. My other 3 panels work just fine, however. They are all rated at 15 watts, they are even the same brand. I took the panel apart and the diode seems to be working. I took it out and connected it to a small battery. It would only let the power flow one way.

[Flux]

You seem to be violating Kirchoff's law.

If you are really doing what you say I can offer no explanation.

Check open circuit voltage and short circuit current of each panel, I can't think of anything else, that may show something odd about the rogue panel. I still suspect a wiring problem.

Flux

[snowcrow]

I'm assuming that you are putting the multimeter in the circuit between the two panels, and not just across the terminals of the new panel while taking your amp reading, am I right? If I'm not right and the latter is true, then you will see the amps drop off instantly.

Blessings, Snow Crow

[ghurd]

Are these thin-film China PVs?

Does it put 0.7A into a battery or is the 0.7A Isc?

I have seen some that will supply reasonable amps shorted, and proper voltage open, but will not charge a battery at all.  They are usually `old' by thin-film standards.

I have seen the same thing in crystalline PVs.  I decided it was poor internal solder connections, cracked cells, or indirect lightning damage, depending on the PV.  Some worked OK when cold.

Sometimes faulty diodes can do some strange things.  Try changing the diode.

The wattage will have no effect.

G-