[Bigbadfrankie]

Does any one know why a solar panel would have a diode  across the terminals. I can see no advantage to this, and mine has blown up !!!

[jimbeekeeper]

is it not effectivley a one way valve? So power does not feed back to the pannel?

[Bigbadfrankie]

I would think it would have to be inline for that.
  + diode>  -

 It looks more like quick short system 

[Snoop]

Each panel should have its own diode wired in series (so I'm told) for it to be wired correctly.

It's essential, otherwise your panel would be susceptible to reverse polarity glitches in the DC circuit. It is indeed a valve.

Apparently there are zillions of solar panel websites that give good advice about this.

[Bigbadfrankie]

this diode is in parallel and the panel works fine with out it. If it had one in seris the panel would not discharge the batteries in low light conditions.

[pairofacres]

If it's connected with the bar towards the positive side, it'll be to protect against reverse polarity connection. The diode will show a dead short when a power source is connected reverse polarity, resulting in a high current draw further down the line, blowing an in line fuse. By the sound of things, yours has probably been connected reverse polarity with no fuse, or a wrongly rated one??

[Digger Tom]

 If its in series (inline) then its for polarity protection.

 If its in parrallel it is probably a bypass diode, usualy used when more than one cell (panel) are in the system.

 hang on ill google it as its a bit complicated.

  Here it is

 ps -  by the way the PV = PhotoVoltaic.



 I hope this helps.