The solar controller requires power from the battery in order for it to operate (9-14 volts) . The first step in troubleshooting any solar controller is to determine if you have 12 volts to the controller. This is done by measuring the input from the battery on the back of the controller. If the battery voltage is below 9 volts it will not power the controller. Check the inline fuse between the battery and the controller and your battery and terminal block connections on the controller.
If the controller is in an error state first try a soft reset. This is done by holding down all 4 buttons on the front of the controller for 15 seconds. If this does not work a hard reset is required. Remove all 4 wires from the back of the controller for 15-20 minutes, then reconnect the wires. Determine if this clears the error state.
Moon Symbol on Solar Controller
If there is a moon symbol appearing on the controller then the controller is not seeing voltage coming from the solar panels. The first step here is to remove the wires on the back of the controller coming from the solar panel. Use a multi-meter to measure across the two leads. In sunlight, you should see between 20-18 volts. (this number maybe lower on cloudy days). If you do not see this voltage at this point the next step would be to check your panels and work your way back down to the controller with the multi-meter.
Put the meter across the leads of each panel. The voltage should be very similar (20-18 volts based on the type of day). If one panel is lower than this then there is an issue with the panel. If all are the same then trace the wires back to the controller with the meter and determine if there is a connection issue.
Controller does not charge batteries/Controller shows "0.0" amps charging
1. Ensure batteries are not full, charging amps will drop to near zero if batteries are full (meter the batteries, don't trust the display from the controller)
2. Ensure solar panel is clean and is in direct sunlight. An obstructed/dirty panel will yield poor results
3. Check input voltage at controller from solar panel (~18V based on solar panel rating)
4. Check wiring from solar panel to batteries
5. Check for any fuse in-line in the system
6. Perform a hard reset on device. Disconnect all four wires from back of device and let sit for 15 minutes - reconnect all four wires and recheck
7. Replace controller
That behavior looks like the controller is trying to deal with a very high C-rate. Even though the controller can handle up to 30A, the battery capacity is too small for the panel input current. The voltage shoots up too high, too quickly, tripping the high voltage flashing. It will also flash if the battery voltage exceeds 15.5 volts.
If the problem was “fixed”, then it was because the user started using loads which divert some of the input current, because the panels became dusty or shaded, or because there was less sunlight.
Ideally, if this error occurs, the user should increase their battery bank capacity.