Who has the diodes?

[mjchee]

 Anyone out there that can answer or knows, please help. I got some old Arco solar panels,Carrizo solar panels. Were these panels made with diodes or not and how can I tell if they were? Thanks.

[ghurd]

Connect the output wires to a battery. Wait for dark.

If the battery is discharging through the batteries more than a couple ma, the diode is not included or the diode is shot.

Do not use the battery voltage as a gauge.

The battery voltage will be lower in the morning than the previous evening.

Those PVs are not great. Many are failing.

G-

[henjulfox]

Or, if there is a connection box try popping it open. The diode is visible on panels I've seen. The ones I've seen are maybe 1/2 the diameter of a pencil, 1/4" long, connected between the output of the panel and the connector for the wire.

-Henry

[dinges]

And if there isn't a diode in them, or it's defect (shorted, that is), you can simply put an external diode in series with the PV panel. Anything that can handle the voltage (100V should be fine) and the current, with some safety margin (factor 2?).

It doesn't even hurt if you have 2 diodes in series, it just means you'll lose about 1V (not the usually assumed .7V!) as voltage drop.

Peter.

[mjchee]

 As long as I have a good working charge controller, I should be alright, right?

[ghurd]

Yes