Tuesday, Apr 23, 2013 at 14:32
Hi Ron,
Apologies for not being clear in my descriptions.
There are 2 types of diodes used in solar applications - blocking and bypass. Blocking diodes are used to stop current flowing backward through the panel at night and are installed in series with the panel. Bypass diodes are used to allow the current from a fully lit panel to bypass the high resistance presented by a panel that is shaded. Bypass diodes are installed in parallel.
In my post, I was referring to the blocking type (as per your manual) which are in series. Being in series, the Anode of the Diode will be connected to the positive terminal of the panel (inside
the junction box) and the Cathode will be connected to the positive lead going to your regulator (also inside
the junction box).
I would try Ted's idea first as that is much easier than
mine, but I am expecting that you may not get much if any light from a globe. If this is the case, open up
the junction box, identify the type of diode you have, if it is wired in series or parallel and which terminal is the anode and which terminal is the cathode. If it is in series, happy days, keep reading below. If not, then my idea isn't going to work for you and I'm back to the drawing board!
If in series...
The "panel side" is the anode and the "regulator side" is the cathode. Given the age and size of your panels, I also wouldn't be surprised if you have the old style diodes that are a little black cylinder with a white band at one end and the leads sticking out of either end. The white stripe is closest to the the cathode terminal. (sorry if this is obvious to you).
With the panel connected to a load, measure the voltage on both sides of the diode. If the voltage is more than 1 Volt different (I am expecting you will read close to 20 Volts different, the diode has failed. Go to an electronic component retailer and buy an new one (rated for the max current of your panel) They should only cost you a few $ at the most.
Hope this helps
Jason
FollowupID:
787532