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VOC panneling question

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RodKnock

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Oct 17, 2021
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I have searched the forums and ran across a couple Bluetti threads with similar questions but different enough that they don't give me the answers I'm looking for.

Worried about the VOC in this setup. Is there a way around it besides removing a pannel or going with a different one?

Bluetti AC200 Max
900W solar input rate
VOC 10-145
12amp

Looking at running 3 REC315PE 72 pannels because I can buy them new locally for $125/pannel.
Peak Power 315 w
VOC 45.8v
Impp 8.40a

Wired in series
3x315 = 945w -- Over panneled by 45w which should be fine because thats under theoretical perfect conditions right?
3x45.8 = 137.4v -- Meets VOC limit until temp goes less than 40F which is a problem in MN when we regulary see -30F.
diysolarforum.com

Adjusting Solar Panel Voc for temperature

When designing you solar panel system, it is important to adjust you solar panel Voc for temperature in order to ensure you do not over-voltage the PV inputs of your solar charge controller. This paper shows how to calculate the Temperature...
diysolarforum.com diysolarforum.com

Winter 3x45.8x1.25= 171.75 POP goes the weasel.

As I understand it, surpassing the VOC limit is a BIG no no and can damage the charge controller.

I can't run them in parallel or I go over the 12amp limit right?

Can I run a 3rd smaller pannel like a 200w Rich Solar to make up the difference?
315+315+200=930w
45.8+45.8+24.3x1.25(Temp correction factor)= 144.875 VOC

Feel like i'm running in circles.

Thank you for any insight you can give.
 
Sorry, its 15A.
Listed as input limit.

Solar input: 900W (10-145), MAX 15A.
www.bluettipower.com

BLUETTI AC200MAX Expandable Power Station

AC200MAX is BLUETTI®'s first expandable solar generator that can be connected to B230 or B300 batteries, enabling up to 8,192Wh! Order yours right away!
www.bluettipower.com www.bluettipower.com
 
Well, first thing is that you don't want to go mixing and matching panel voltages, so don't put the 200w in there.

Your thinking is correct on the 3s setup, winter hits and poof is a very likely thing. (y)

If you can get a 4th panel to match the 3 you have now, you should be able to safely put them in a 2s/2p setup as each string will only be putting in 8.4a under perfect conditions, so you're right under that max PV Amperage line.
 
RodKnock said:
Can I run a 3rd smaller pannel like a 200w Rich Solar to make up the difference?
315+315+200=930w
45.8+45.8+24.3x1.25(Temp correction factor)= 144.875 VOC
Click to expand...
Yes but the overall array will be limited to the lowest amp panel. For example, if your lowest amp panel is 5A, your array (using your pre-temp corrected Voc):
(45.8V + 45.8V + 24.3V) x 5A = 115.9V x 5A = 579.5W.

It will work but if there is a large amp mismatch (for series connection) will cause a lot of lost array production.
 
If you can find a panel with a VOC of around 41, then it should be good to -45C (-49F) and 60C (140F) cell temperature.

The Solarever 360W panels were the only ones I've found that were stable over that large of a range.
 
I thought about 2S2P but I would be at 630w and 17a which would surpass the 15 amp limit.
Would I just put an inline 15a fuse at the parallel connector and just expect to replace it if and when it pops?

The supplier I will be using also has some Ureco panels I'm waiting to get the exact details on.
 
One thing is that the panels won't perform like STC anyways. The NOCT numbers will probably be closer to what actually happens.

Though I would plan to STC and then you have headroom.
 
Going with a couple 390w split face pannels. Gives me head room so I don't have to worry about letting the magic smoke out.

Thank you everyone for all your help.
 
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