Solar Panel System Troubleshooting - Charging Battery

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Discussion Overview

The discussion revolves around troubleshooting a solar panel system designed to charge a battery for powering garden LED lights. Participants explore various factors affecting the system's performance, including the adequacy of the solar panel, the charge controller, and the battery's condition. The conversation includes technical details about the system's components and their interactions, as well as the impact of environmental conditions on solar energy production.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant questions whether the 20w solar panel is sufficient to charge the 12v 18ah battery in one day, given the system's usage of 18 watts for 3 hours each night.
  • Another participant suggests that the charge controller's capacity may be mismatched with the panel output, potentially causing inefficiencies in the system.
  • Concerns are raised about the battery's condition, with one participant noting that if the battery has been undercharged for an extended period, it may have become sulphated.
  • Some participants emphasize the importance of measuring actual current output and system efficiency rather than relying solely on voltage readings.
  • There is a discussion about the impact of latitude and seasonal variations on solar panel performance, with differing opinions on how these factors affect energy production.
  • One participant mentions that the green light on the charge controller may not necessarily indicate a fully charged battery, raising questions about the battery's actual charge state.
  • Another participant notes that the solar panel's positioning and exposure to sunlight are critical for optimal performance.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the adequacy of the solar panel, the efficiency of the charge controller, and the condition of the battery. The discussion remains unresolved, with no consensus on the root cause of the charging issues.

Contextual Notes

Participants highlight limitations in their measurements and assumptions, such as the inability to measure current accurately and the potential variability in solar energy production based on environmental conditions.

  • #151
Since your existing solar system has excess capacity, you could connect the pump to that as just an additional load. You may or may not need a way to keep the pump off at night. If the lights stay on long enough, just let the pump run. It is unclear if the lights are on continuously. If not, then replace whatever switches them with a device to select between lights and pump.

As an alternative, you might consider this pump. It has half the water flow but about 1/3 the power requirement. (Smaller panel and battery needed... or longer runtime.)
https://www.amazon.com/dp/B00JWJIC0K/?tag=pfamazon01-20

Wolst73 said:
Is there a controller without a delay?
No idea, I've never done a solar-electric system. Anyone out there, is there available a solar controller without a switching delay?

Wolst73 said:
how would you wire it so that pump is running directly off panel when there is enough sunlight and switch to battery when it's power output drops? (Jim's schematic pictures would be great!)
The instructions that come with the controller would show that... (or I suppose you could ask @jim hardy to do your research.)
 
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  • #152
Wolst73 said:
how would you wire it so that pump is running directly off panel when there is enough sunlight and switch to battery when it's power output drops? (Jim's schematic pictures would be great!)

Simplest answer is : Just parallel them. Strongest source, battery or panel, carries the load. But you probably want the low voltage cutout feature of a controller so as to not run the battery flat?

You'd have to let us read the controller's instruction manual. Probably you'll see it in there first, though. Is it linked earlier in the thread?
 
  • #153
My solar charge controller prioritizes battery charging, but then it automatically shunts any excess power to an auxiliary load. It is solid state, instantaneous, handles 40A, cost about $120, from Xantex.
 
  • #154
Sorry for being lazy about research. Have in my mind how I want it to work but don't know where to look to see if it will work or what devices are out there to make it work.

Tom.G said:
As an alternative, you might consider this pump.
I saw that pump but was worried the 400mA might be to low and fry the motor.

jim hardy said:
You'd have to let us read the controller's instruction manual.

IMG_0016.JPG
IMG_0014.JPG
IMG_0017.JPG


This might help. Hopefully you can enlarge and read. I have it set on 3. Lights on for 3 hrs but there is still a delay even though it says it should be off. 17 has the load on continuous when there is sunshine. Where does power for load come from in this case? Panel charges battery, battery powers load? When sun goes down, load shuts off and battery won't be totally drained? This is a cheap controller so may not be smart enough to alternate as @anorlunda stated. This would work although would be nice to run for the 3 hrs that the lights are on.
 

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