diy solar

diy solar

400 watt solar on a ProMaster Van

I'm testing two panels in series right now, and have a minivan filled with cardboard. I think I will go out and test it in a few minutes.
Well, it went to zero amps when I covered the panel, but, when I uncovered the panel, it didn't come back, and I started thinking about my system- 24V battery, with a Tracer AN 20A solar controller, and I just took, at best, my solar input voltage from about 34 to about 17. So, I guess I proved nothing about diodes, but, may have gained some useful information about the Tracer's behavior- it went literally to zero and the solar power indication was gone, but before I came in to write this (after a couple of minutes staring at it), it was indicating solar charging, and a couple of milliamps. Perhaps the computer in the Tracer will sort things out in time.
 
Well, it went to zero amps when I covered the panel, but, when I uncovered the panel, it didn't come back, and I started thinking about my system- 24V battery, with a Tracer AN 20A solar controller, and I just took, at best, my solar input voltage from about 34 to about 17. So, I guess I proved nothing about diodes, but, may have gained some useful information about the Tracer's behavior- it went literally to zero and the solar power indication was gone, but before I came in to write this (after a couple of minutes staring at it), it was indicating solar charging, and a couple of milliamps. Perhaps the computer in the Tracer will sort things out in time.
OK, it's back to about 34V and 2A (what it was before I covered one of the two panels). I think what happened is that I threw the controller's MPPT an edge case, and it took a while to sort it out. I guess I've proved that, if the diodes do what I think several sales blurbs claim, it won't do me (running 2 12V panels in series and a 24V battery) any good in the extreme case, at least.
 
OK, it's back to about 34V and 2A (what it was before I covered one of the two panels). I think what happened is that I threw the controller's MPPT an edge case, and it took a while to sort it out. I guess I've proved that, if the diodes do what I think several sales blurbs claim, it won't do me (running 2 12V panels in series and a 24V battery) any good in the extreme case, at least.
I just finished one more test, this time shading one panel significantly, but not 100% This time, the voltage held, but the amperage dropped by about 1/2 (as expected). I'm going to say that shading of one panel of my two panel string does not shut down the output of the other panel, unless it's a perfect shading storm.
 
I thought I made two comments on the result of my test, but don't see them now. So, to recap:

On my test setup (2 100W 12V Newpowa panels in series charging a 24V battery through a Tracer AN 20A), completely covering one panel causes the Tracer to show no panels and 0 Amps, and uncovering that panel causes the tracer to _slowly_ recover to the 2 amps or so it had been charging (a full battery, with not much load). a substantial covering of one panel (call it 90%) causes the current to drop by about 1/2, not to 0, and the Tracer to recover more quickly when the panel is uncovered.
 
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I'm testing two panels in series right now, and have a minivan filled with cardboard. I think I will go out and test it in a few minutes.

That's what I like to see!

I have a couple 100w panels I use as portables and wire them variously in serial v. parallel depending on conditions (my mppt controller and bank voltage will tolerate both arrangements). I typically leave them in series except in uneven shade or different orientations, since in in those scenarios my unscientific testing suggests parallel tends to make more power.

shading of one panel of my two panel string does not shut down the output of the other panel,

Agreed, that's what I see in series arrangements. There is a big hit but it doesn't fall to 0w,
 
That's what I like to see!

I have a couple 100w panels I use as portables and wire them variously in serial v. parallel depending on conditions (my mppt controller and bank voltage will tolerate both arrangements). I typically leave them in series except in uneven shade or different orientations, since in in those scenarios my unscientific testing suggests parallel tends to make more power.



Agreed, that's what I see in series arrangements. There is a big hit but it doesn't fall to 0w,
Well, in series, there is presumably loss from the forward voltage of the diode, when one is shaded. Assuming Shottky (I really don't know, but that's what I would use), around 1.5%, for a 12V panel, I calculate.
 
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