Truck driver
New Member
Interesting indeed.. but it works.. but figuring out what's causing it to not work better is frustrating.. I think it's in the 10awg wires.. BOTH pv and the wires that go to the batteries. I've tried to get anyone to come help me locally, but no success yet. So that 290w panel has been removed from the system. Yes.. it got a little morning sun but held back the others in the afternoon. So.. from here on out I want to get more production out of the side panels.. the 400w ones. I have tested each panel with a meter and they all put out about 42 volts. The panels are tilted at about 41 degrees now too. Today they did ok.. but were limited by the 45a controller. They are back in 2s2p and connected to the 150\100. I can swap the 400's with 4 of the 290 and see if that helps.This has been really interesting. A real shit show for me to follow and decipher...
I couldn't make heads nor tails of the wiring pictures, and this:
View attachment 148975
SCREAMS the array is either in 4P or the 290W in parallel with 2S is forcing a lower voltage. The only reason I think the latter is because there was ONE day at 88V.. makes me think you disconnected your 290W panel that day. This value should be your Voc first thing in the morning before it starts drawing current. Here's my 3S array:
View attachment 148976
I'll admit your solar may be so bad that it's always trying to pull current and you're just not seeing Voc like I do.
VRM advanced tab can be really useful too:
View attachment 148977
On a 12V system there is zero reason to go higher than 36Vmp unless you need to stay under a current limitation, i.e., wiring or the 70A limit on the MPPT input.
This is further bolstered by the fact that solar appears to be absolute garbage except for the 3 afternoon hours. If there's morning sun to be had, nab it with a 5P configuration. Yes. The 290W will cause some small losses, but the MPPT conducts a sweep every 10 minutes. It's going to figure out the 4 larger panels will contribute more closer to their Vmp than the 290W panel's Vmp. Furthermore, mid-day, the front panel will have very little to offer besides Voc. The MPPT will figure out where to get the max output will be. Since the 290W Voc is higher than the 400W Vmp, there's no risk of backfeeding and the operating voltage
This should optimize your production. The only issue is you need to be able to handle 50A in the wire down through the roof.
Alternatively, get another 290W panel out of the back of the truck, wire it 2S with the other 290W and join it to the 2S2P 400W for a 2S3P array.
Can 8awg PV wires handle 50A..? ok.. I'll connect a pair of the 290's with the 400's. 2s3p.. and post up with an update soon after I know.
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Wow.. your system is so stable... unlike mine.. the voltages drop to 40 and jump to 90..