Solar Panel System Troubleshooting - Charging Battery

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SUMMARY

The forum discussion centers on troubleshooting a solar panel system designed to power garden LED lights. The system consists of a 20W solar panel, a 12V 30A PWM solar charge controller, and a 12V 18Ah battery. Users concluded that the solar panel may be insufficient to fully charge the battery in one day, especially considering the load of 18W from the lights used for 3 hours daily. Recommendations include ensuring the solar panel is positioned correctly for optimal sunlight exposure and considering a larger solar panel or a deep discharge battery for improved performance.

PREREQUISITES
  • Understanding of solar panel specifications and performance metrics
  • Knowledge of PWM solar charge controllers and their operational limits
  • Familiarity with battery types, specifically deep discharge lead-acid batteries
  • Basic electrical measurement techniques, including voltage and current measurement
NEXT STEPS
  • Research the specifications and performance of deep discharge lead-acid batteries suitable for solar applications
  • Learn about optimizing solar panel placement for maximum sunlight exposure
  • Investigate larger solar panel options to meet energy demands more effectively
  • Explore the use of multimeters for accurate measurement of current output from solar panels
USEFUL FOR

Garden enthusiasts, solar energy hobbyists, and anyone involved in designing or troubleshooting small solar power systems for outdoor lighting.

  • #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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