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Old 11-11-2018, 09:25 PM   #1
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Need Help Trouble-shooting Solar

Had our Geo Pro out boondocking this weekend only to find something went wrong with our solar system.
Have a 160W panel on the roof (not sure of brand), a Go Power 30amp controller and 2 6v interstate flooded batteries. Everything in its first season of use.
Had a less than optimal exposure, ie faced in a way that the roof top ac unit always cast some shade on the panel, but located in AZ and had cloudless skies with a good 8+ hrs of sun daily.
The main symptom I observed was that the Go Power controller would show .5amps by 8:30 am but would never go higher even as the sun rose and panel shadowing reduced. volts never rose higher than 12.6. Over 3 days of camping with very conservative use of 12v, according to the Go Power, batteries dropped to 73%. After a 2 hr drive home, batteries were at least 90% again.
My theory is that the controller is failing to recognize when the batteries drop and is not directing the power to recharge them.
I need some help and suggestions in trouble shooting this to determine exactly what is wrong and then how to fix if possible, or what to replace.
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Old 11-11-2018, 09:47 PM   #2
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If you have any shadows on the panel, you will basically get no output.


Show us a picture of your panel on your roof.


If you only have one panel, why is it next to your AC or is it because your roof is very small?



I was going to have a shading issue on one of my panels but I just made a taller mount to clear a vent and I was able to mount it away from the AC. You can also make a really tall mount and put it above your AC. Just has to be a strong mount.



Have you measured the panel voltage where it enters the controller?
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Old 11-11-2018, 10:06 PM   #3
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I've had some good experience with this setup.
Even with some shadowing, worse than I had this weekend, I'll still get between .9 and 1.5 amps.
I did pull the controller off the wall and put a self ranging digital multi meter set to DCV but couldn't get a reading. I found that odd being the controller indicated some current was flowing so I expected to be able to measure some voltage
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Old 11-11-2018, 10:33 PM   #4
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Hi,

A partially shaded, presumably flat mounted panel (with presumably nice tight connections).

Before I tinkered around too much, if it were me, I would find some way to get that panel in full overhead sun and then get some fresh amperage and voltage measurements.

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Old 11-12-2018, 12:15 AM   #5
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Quote:
Originally Posted by lamokadave View Post
Had our Geo Pro out boondocking this weekend only to find something went wrong with our solar system.
Have a 160W panel on the roof (not sure of brand), a Go Power 30amp controller and 2 6v interstate flooded batteries. Everything in its first season of use.
Had a less than optimal exposure, ie faced in a way that the roof top ac unit always cast some shade on the panel, but located in AZ and had cloudless skies with a good 8+ hrs of sun daily.
The main symptom I observed was that the Go Power controller would show .5amps by 8:30 am but would never go higher even as the sun rose and panel shadowing reduced. volts never rose higher than 12.6. Over 3 days of camping with very conservative use of 12v, according to the Go Power, batteries dropped to 73%. After a 2 hr drive home, batteries were at least 90% again.
My theory is that the controller is failing to recognize when the batteries drop and is not directing the power to recharge them.
I need some help and suggestions in trouble shooting this to determine exactly what is wrong and then how to fix if possible, or what to replace.
Quote:
Originally Posted by lamokadave View Post
I've had some good experience with this setup.
Even with some shadowing, worse than I had this weekend, I'll still get between .9 and 1.5 amps.
I did pull the controller off the wall and put a self ranging digital multi meter set to DCV but couldn't get a reading. I found that odd being the controller indicated some current was flowing so I expected to be able to measure some voltage
Any shadow on your solar panel will cancel any power from it. See this youtube video:
What effect does shading have on Solar panels?

I have six 100 watt solar panels in parallel to avoid shadow. At least one will not be in a shadow.

My roof panels:
Click image for larger version

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The panels on the right will not produce any power because of the shadows on them.
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Old 11-12-2018, 02:26 PM   #6
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This is exactly why I chose to put all 6 of my panels in parallel rather than series. Shading can eliminate all panel output. As suggested, you need to get this panel in full sun, unshaded, and check the output then. Your charger will not decide whether or not to charge. It will provide a charge voltage if it can, although it should slow to trickle charge as the battery is full.
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Old 11-12-2018, 03:33 PM   #7
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watching this
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Old 11-12-2018, 04:03 PM   #8
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X2. Good info.
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Old 11-12-2018, 04:03 PM   #9
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Thanks for the video as it has convinced me to agree that my problem is simply shadowing as several have suggested. I was reluctant to accept that as in the past I'd have shadowing but always got an amp or more under that condition. The difference now though is the angle of the sun in Nov vs summer.
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Old 11-12-2018, 04:09 PM   #10
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Here's a shot that is only producing .4 Amos
https://photos.app.goo.gl/xALYUHyYxtENJ6BW9
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Old 11-12-2018, 05:47 PM   #11
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Would the controller also limit output if the batteries were fully charged or close to full?
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Old 11-12-2018, 06:14 PM   #12
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Quote:
Originally Posted by lamokadave View Post
Here's a shot that is only producing .4 Amos
https://photos.app.goo.gl/xALYUHyYxtENJ6BW9
Your panel has 36 solar cells. (9x4=36) 12 cells are in a shadow. Result no power.

The high sun angle will reduce the power by as much as 50%. I have six panels and plan to increase that to 10. I have a 50 amp MPPT that will support 750 watts. With a 60 degree angle to the sun I was able to get 355 watts of power to my batteries.


See my thread: Solar panel over sizing with rigid roof mount.
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Old 11-12-2018, 06:21 PM   #13
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Quote:
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Would the controller also limit output if the batteries were fully charged or close to full?
Yes.
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Old 11-12-2018, 07:01 PM   #14
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There are panels that use bypass diodes along various numbers of the cells so that cells that are shaded are bypassed. These particular panels are pretty much useless in a parallel configuration and only work in series configs in residential applications and RVs that use residential panels.

I am pretty sure the Renogy panels don't use these diodes. My panels do have them and I will still get output with some shading.

These diodes are different than the diodes that are sometimes used to prevent discharge at night.
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Old 11-12-2018, 07:56 PM   #15
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Renogy panels do have bypass diodes.
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Old 11-12-2018, 08:12 PM   #16
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Renogy panels do have bypass diodes.
And you know this how? There is a guy that tested dozens of panels for shading performance and he didn't find that to be true.

BTW, if a panel only has one bypass diode, shading still wipes out the entire panel but it does allow a series of panels to still work.
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Old 11-12-2018, 08:55 PM   #17
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You should not believe everything you read
That guy doing the testing can not know what he is doing.

"I know this how" from their website.

Quote from Renogy website.

"Junction Box (2.1.1.1): The junction box is generally located on the back of the panel. It contains bypass diodes to help with power loss due to shading. Also it serves as a connection and a holder for the panel wires."
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Old 11-12-2018, 09:13 PM   #18
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You should not believe everything you read
That guy doing the testing can not know what he is doing.

"I know this how" from their website.

Quote from Renogy website.

"Junction Box (2.1.1.1): The junction box is generally located on the back of the panel. It contains bypass diodes to help with power loss due to shading. Also it serves as a connection and a holder for the panel wires."
LOL...if the diodes are in the junction box, that means it is only a bypass for the whole panel.
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Old 11-12-2018, 09:33 PM   #19
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Don't know ? , just going by what they say on their website.
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Old 11-12-2018, 09:52 PM   #20
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Don't know ? , just going by what they say on their website.
I guess its's possible they could have them in the junction box. If the panel had 6 rows with a pair of rows tied at the bottom, there would only be 2 diodes needed at a minimum and they could probably do that in the junction box. 4 rows would only need one diode at a minimum.

So basically, if you are only shading the first 2 rows(when I say rows, that's the length of the panel)the remaining rows should output if the panel has individual bypass diodes. However, if you only have one panel, shading is going to essentially kill your output since the voltage will be too low to do anything. That is why you want to run series if possible. There is no good reason to run in parallel with an MPPT controller.
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