Solar charging basics

Solar puts power into the battery through a charge controller. Most problems are connections, settings or shade.

The short version

• Check panel voltage at the controller input on a sunny day.
• Make sure the controller is set for the battery type. Lithium and lead-acid need different settings.
• Check fuses and connections between the controller and the battery.
• Shade, dirt and a bad panel connector all cut output.

On the job

1. Midday, panels in sun. Open-circuit panel voltage at the controller input: 18 to 22 V per 12V-nominal panel.
2. Controller output at the battery: 13.5 to 14.6 V and amps flowing on the positive wire.
3. Battery side fuse and connections; the controller powers from the battery.
4. Set the battery type. Clean the panels. Shade on one cell kills the panel.

Try it on a service call

Put the lesson to work on a hands-on troubleshooting case.

• Solar quit charging

Keep going on 12V and batteries

Learn it

• Volts, amps and ohms, the simple way
• Voltage drop: the test that finds bad grounds
• Practice: find the bad connection
• Batteries: lead-acid vs lithium
• Fuses, breakers and grounds

Prove it

• Back lights are dim
• Battery dies even on shore power
• Lithium won't charge on cold mornings
• Coach is dead, battery is fine
• Batteries dead after storage

On the job

• 12V system
• Converter / charger
• Lithium battery
• Coach dead, battery good
• Solar not charging