Does this seem right to you?

RodKnock

New Member
Joined
Oct 17, 2021
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Just got my solar setup going and want to make sure I am understanding things correctly.
I have 2 390w panels in series running to a Bluetti AC200MAX solar generator.

URECO solar panel specs:
Model - D7K390H8A
Pmax - 390w
VOC - 48.53v
ISC - 10.16a
Vmpp - 40.39v
Impp - 9.66a

The Bluetti charge controller shows input voltage of 91.0V and input power of 72W on this over cast day.
Panels are at a 23 degree angle due to being in MN. Temp is 25F outside.

Do I use the VOC or Vmpp rating to see the theoretical maximum volts the panels will generate?

Also, I have 780W of pannels yet its only producing 72W of input power?
Something doesn't seem right to me.

Any assistance is greatly appreciated.
Thank you.
 
Last edited:

rmaddy

Full-time Solar-powered Trailer Life
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Your 97.06Voc, then adjusted for the cold, needs to be less than the max input voltage of the AC200. Since the cold adjusted Voc could be closer to 115V make sure the AC200 allows at least 120V or more.

72W on an overcast day isn't bad. See what you get on a sunny day midday.
 

RodKnock

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Oct 17, 2021
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Manual says it will take 10v-145v so that shouldn't be an issue.

Thank you!
 

GLC

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On an overcast day you may be making voltage but you may not be making amps. My panels generate volts with a full moon but it will not generate any amps so the watts will register very low or nonexistent. You have to have amps and volts to create watts.
 

RodKnock

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Oct 17, 2021
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I noticed on a good winter sunny day it only makes 1.5- 3A when I was testing the connectors before I got the generator.
I assume spring/summer will show drastically more.
 

GLC

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Yep at 3 amps thats 242 watts. that is very low for new panels. Where and how are the panels attached? Is the sun ever at 90 degrees over the panels?
 

RodKnock

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Oct 17, 2021
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Facing south. Wired in series. with about 110ft of 10ga solar cable. If my angle calculation is correct they are at 23degrees.20211119_161026.jpg
20211121_114228.jpg
 

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GLC

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Wow, i am guessing that the sun is pretty well on the horizon all day long? Will your controller let you over panel? How long have you had it up? Best readings in the summer? Model of your controller? Max amps and voltage of your controller? You will probably be buying more panels. Does not matter what your panels are rated at it. The controller looks at what actual amps and volts it puts out.
 
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RodKnock

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Oct 17, 2021
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Central MN. Yeah it doesn't get to high right now.
Having a loop of service cable doesn't affect it, does it? Usually no with anything but antennas.
 

GLC

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No, excess cable does not effect it. Have you ever made something like a shadow box to actually see where the sun is hitting at the suns highest point just to verify correct best panel angle? Easy to do with a card board box, marker, ruler and pencil.
 

GLC

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Hard to explain, i will see if i can make one this next weekend and try to explain how to use it. Simple and next to no cost but it helped me out when i installed panels on my roof to verify that i had the best angle of my panels.
 
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