diy solar

diy solar

New wondering if this is a good deal

Hmm, i see for 4S5P array, iused 40a for 5x 9.45a. That should have been 47.25a total.

So rerunning numbers, 10awg shows over 10% voltage drop (heat produced in wire!).
8awg shows 6.6% loss.

My understanding is that 3% should be the worst case for voltage drop.
Screen Shot 2021-06-10 at 12.16.31 PM.pngScreen Shot 2021-06-10 at 12.16.04 PM.png
 
Hmm, i see for 4S5P array, iused 40a for 5x 9.45a. That should have been 47.25a total.

So rerunning numbers, 10awg shows over 10% voltage drop (heat produced in wire!).
8awg shows 6.6% loss.

My understanding is that 3% should be the worst case for voltage drop.
View attachment 52329View attachment 52330
I’m doing a 4s3p per channel on the growatt if I’m allowed to over panel 4020 watts
26.91 amps
210 voc at 0 degrees 187 vocC736EA86-6CD7-4D3A-939F-688EC7A1B116.jpeg
 
Does the 520 watts of over paneling per input help with the loss?? Saves like $600 in wire
 
335w x 12 panels = 4020w
Your wires will absorb ~300w = 3740w at the SCC.
3740w / ~54v charging = 70a charge capability.

Which SCC model? I see either 5000w or 7000w max (usable) array. It won't be over paneled and you will lose the 300w into your wire.

I would be most concerned about your wires being undersized! Safe? I dunno.
 
47A exceeds NEC rules for 10 awg, but is within 8 awg depending on insulation rating and ambient temperature.
That power dissipation in the wires goes as current^2, so drops off rapidly when sun is off-angle during other hours or seasons. Not much is lost those days when production is low.
Orienting multiple PV strings 90 degrees (6 hours) apart reduces peak to 0.7 as much, power dissipation to 0.5 as much (but extends the hours both of production and of high I^2xR loss.)
 
47A exceeds NEC rules for 10 awg, but is within 8 awg depending on insulation rating and ambient temperature.
That power dissipation in the wires goes as current^2, so drops off rapidly when sun is off-angle during other hours or seasons. Not much is lost those days when production is low.
Orienting multiple PV strings 90 degrees (6 hours) apart reduces peak to 0.7 as much, power dissipation to 0.5 as much (but extends the hours both of production and of high I^2xR loss.)
It’s 26.91 amps
 
FAC8C1AD-082E-4BD2-A23E-6CAB5361B001.jpeg
Got 24 getting them washed up and hope it’s sunny tomorrow for some testing
 
Got 24 getting them washed up and hope it’s sunny tomorrow for some testing

Voc and Isc are a start, but don't tell the whole story. There are some forms of damage that show up primarily as a reduction in power, current at an intermediate voltage.

I have an idea that I haven't tried out yet.
What if we connected three panels 3s, kept them in the dark. These will serve as a "load", sinking current and dissipating power.
Connect 4 panels 4s, to be exposed to sunlight
With 4s (illuminated) wired in parallel with 3s (dark), the 4s will be pulled down to about Voc x 3.
That allows a voltage/current measurement somewhere near Vmp.

(Cover the 4 panels while making the parallel connection, so current near zero.)

I used the specs posted earlier, 46.81 Voc, 37.33 Vmp, so Vmp is ~ 75% of Voc.

It could be repeated with the load being 2s, 1s to get additional points on the IV curve. So long as they are kept in the dark, the forward biased PV cells will never carry more than Isc x 1, which is what they do when exposed to sunlight by themselves open-circuit.
 
55239E03-960F-4412-BECC-DD9FBDF5FC0F.jpeg
Crap what am I doing wrong or are these panels really that bad?
 
What is your test configuration?
I would rotate the panel right angles to the sun (so zero current), short PV+ to PV-, rotate back to the sun and measure current.
It is not uncommon to have current reduced 33% due to less than full sun, but I don't expect 30% of Isc like you're showing.
 
"~" :ROFLMAO:

Don't know how you got that high a reading, but you've got the wrong meter !!!

If I was you, I wouldn't be worried about the panels, I'd be worried about biological effects of EMF! ?
 
"MS2033C AC Clamp meter"

Here are the ones I considered. I bought the HF one for $100

 
"~" :ROFLMAO:

Don't know how you got that high a reading, but you've got the wrong meter !!!

If I was you, I wouldn't be worried about the panels, I'd be worried about biological effects of EMF! ?
Got it figured out shortly after that post 3C3F0E09-61B0-454C-A516-3C0C97A5DE5C.jpeg78266DA3-D381-41D1-9624-8C99BD5080A6.jpeg
 
BD7BD6B3-869C-47B4-8781-4416B5094E7A.jpeg12016E30-8151-4EBD-A680-FD1974A409BC.png
Only tested 3 so far with the new meter and 2 had over 10 a this one climbed to 10.75 as a cloud cleared
 
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