Solar panels test

[sailaboutvic]

Let's get some of our brains working again and take our minds of CV ..

A cruiser was doing some test yesterday on his panels .

We told its best to run panels in Parallel is better then series if there a shadow as it will kill both panels if run in Series .
So here the test .
2x 100w panels connected to a MPPT . In full sun light .
Connection in parallel if parts are covered on one panel the lost is about half of the Watts .
The test same test in Series , as soon as you partly cover the panel , W and V drop to almost nothing then with in a second or two they both end up about the same drop as the once in the Parallel test .

So what's going on ?

 

[Pete7]

Got any numbers because this is rather odd.

2 x 100w panels in parallel should produce about 12A at12v or 6A with one cell of one panel covered.

2 x 100w panels in series should produce 6A at 24v or ????? with one cell of one panel covered.

What was he seeing?

Pete

 

[sailaboutvic]

Pete agreed very odd .
I can't remember the numbers but basically, the % of drop was the same in both test ,
I.e. 2 x 5A panel in Series showing 5A partly 2.5A
I would had tho that covering part of the Series panel would had kill both panels .
Or am I got that wrong .

 

[sailaboutvic]

The other interesting thing is it depend a lot where the shade is over the panel how much is lost .
One sq can reduced most power then a shade across the middle in some cases .

 

[peteK]

[/QUOTE]

 

[peteK]

The panels are fitted with bypass diodes so if they are wired in series you dont loose all output.

 

[sailaboutvic]

Ok found the answer , sorry Peter seen nothing to do with diodes ,
the Victron MPPT some how compensation for the shading some how .
Or so Victron says