The single solar panel we added to Campbell doesn’t have enough power to meet our needs when we are boondocking. So we added two more panels for a total of 300 watts of solar on the roof.
We need the extra power when we are off-grid for gear in the Land Cruiser and for charging the house battery in Cocoon, our Casita travel trailer.
Why on Campbell?
We could have added panels to our travel trailer, and these are the reasons we put them on the Land Cruiser:
- We park Cocoon in the shade.
- Ground deployed panels are prone to theft.
- They are available for overlanding excursions.
- The roof rack isn’t needed for extra cargo now that we have Cocoon.
Serial or Parallel?
Three panels can be wired either in series or in parallel.
Serially wired panels produce a higher-voltage output and can perform better in low light. The solar-charge controller has to be capable of handling the combined open-circuit voltage, about 75-volts for our three panels.
We will continue using the solar charge controller in our REDARC BCDC1250D. Its maximum solar input rating is 32-volts. It can’t handle the 75-volts from serial wiring, so we are wiring them in parallel.
We replaced the older AGM battery in the optional expansion box with four EXP12200 batteries.
We had two from the Alpicool test and added two more. They have good discharge and cycle performance. With it connected, we have a total of 160 amp-hours of auxiliary battery capacity.
Here is the article describing the expansion battery box.
To test the solar, I disconnected the DC-to-DC charging cable to the REDARC, so the batteries were charging only from solar. I set the Alpicool temperature to 20 degrees, battery safety to ‘M,’ the power to ‘Max.’ I added some ice cubes as a test indicator.
The weather was in the upper 80s during the day, 70s at night, and varied from mostly cloudy to mostly sunny. I parked it in an open parking lot and drove it some. The ice remained frozen.
The test ran from midday to midday for 68 hours. The TLC systems use 68 watts with the refrigerator compressor running and 9.5 watts when it cycles off. The total energy consumption was 2,576 watt-hours, and the average power draw was 38 watts.
Here is a list of the parts we used for the project: