CS6P-200 Canadian Solar PV / Xantrex C40 project

Xringer · 03-19-11, 02:16 PM

Tested the two new panels with the 10 ohm heater load and the clamp-on Amp meter.
It was very cloudy, but all 4 panels were showing about 2.5A each.

Installed the new PV on the outrigger arms. Needed some pulleys to get the array back up. (On the center support arm).

Hazy sunshine kicked it up to 757 watts (8.7A into 10 ohms).

That's about 94.6% of 800 watts, which is surprising, since I have not yet reconfigured the load to 20 ohms..

Better get to work on that load..

Edit:
I may have to build another load. I just realized that one can not get 20 ohms with four 40 ohm resistors.
I could get 20 ohms by putting two in parallel, but two of these (at 250w each) will only be good for 500w..
All four of them are 1kw. So, I'll be staying at 10 ohms for a while..

It seems very weird that the meter showed 8.7 Amps.
These panels are rated at 7.68 shorted. (6.93 Imp). Maybe it was Cloud Edge effect?
Tomorrow is going to be real sunny. I guess we will find out if 10 ohms
is too much of a mis-match for 4 panels.

If 10 ohms turns out to be a bust, I'll try reconfiguring the panels into series-parallel.
The voltage would be the 1/2 (or same as two panels in series), but double the amps.
That would increase the line loss a bit..
I know that 2 panels work pretty well into 10 ohms, (over 400w many times),
so changing the panel config might be the best way to go..

03-19-11, 02:16 PM	#28
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Cloudy, but still seeing 757 watts! Tested the two new panels with the 10 ohm heater load and the clamp-on Amp meter. It was very cloudy, but all 4 panels were showing about 2.5A each. Installed the new PV on the outrigger arms. Needed some pulleys to get the array back up. (On the center support arm). Hazy sunshine kicked it up to 757 watts (8.7A into 10 ohms). That's about 94.6% of 800 watts, which is surprising, since I have not yet reconfigured the load to 20 ohms.. Better get to work on that load.. Edit: I may have to build another load. I just realized that one can not get 20 ohms with four 40 ohm resistors. I could get 20 ohms by putting two in parallel, but two of these (at 250w each) will only be good for 500w.. All four of them are 1kw. So, I'll be staying at 10 ohms for a while.. It seems very weird that the meter showed 8.7 Amps. These panels are rated at 7.68 shorted. (6.93 Imp). Maybe it was Cloud Edge effect? Tomorrow is going to be real sunny. I guess we will find out if 10 ohms is too much of a mis-match for 4 panels. If 10 ohms turns out to be a bust, I'll try reconfiguring the panels into series-parallel. The voltage would be the 1/2 (or same as two panels in series), but double the amps. That would increase the line loss a bit.. I know that 2 panels work pretty well into 10 ohms, (over 400w many times), so changing the panel config might be the best way to go.. Last edited by Xringer; 03-19-11 at 04:30 PM.. Reason: Resistance to thinking ahead?