Before a problem is suspected with the system, read this section. There are numerous events that may appear as problems but are in fact perfectly normal. Troubleshooting Problems is split into four sub-sections, grouped by symptoms involving key components. Components considered irrelevant in a diagnosis are denoted ‘Not Applicable’ (N/A). A multimeter or voltmeter may be required for some procedures listed.
Check the controller LED display as the first step.
NOTE: It is imperative all electrical precautions stated in the Safety Instructions and outlined in the Installation Section are followed. Even if it appears the system is not functioning, it should be treated as a fully functioning system generating live power.
Blank LED Display
Display Reading: Blank (no LEDs) | Time of Day: Daytime/Nighttime
Battery voltage or connection, blown fuse/breaker, wiring/connector problems
How to tell:
1. Check the battery voltage. If battery voltage is <9V, the controller will not charge, and the LEDs may not function correctly.
2. Check wiring polarity.
3. Check all fuses/breakers, wires, and connections. A blown fuse/breaker, damaged wire, or loose connection will prevent battery power from reaching the controller.
1. Use an external charging source to charge the battery voltage above 9V. Consider battery replacement.
2. Correct any reverse polarity connections.
3. Check that all connections are clean, tight, and secure. Check that all wires and insulation are intact. Check for possible shorts or damaged equipment. Replace blown fuses or reset breakers.
Red Battery LED On
Display Reading: Red battery LED on | Time of Day: Daytime/Nighttime
1. Battery voltage is too low because of excessive voltage drop from battery bank to controller or insufficient solar power.
2. Battery voltage is too low because of excessive load power draw from battery bank.
3. Battery voltage is too high because of secondary charging source.
4. Battery voltage is too high because of a short.
How to tell:
Check the battery bank voltage with a voltmeter. Less than 11.9/23.8V is a low battery voltage. Above 15.5/31.0V is a high battery voltage.
Check the battery voltage when loads are on and recheck when loads are off. If there is a voltage discrepancy of more than 1V, the loads may be too large.
1. Check all wiring and connections from the controller to the battery bank. Ensure that all connections are clean, tight, and secure. Shorten the distance from the controller to battery bank or obtain larger wire. It is also possible to double up the existing gauge wire (i.e. two wire runs) to simulate a larger wire. Wait for system to charge battery. Turn off loads for faster charging.
2. Increase the battery bank capacity. Consult your dealer or installer for assistance.
3. Remove any secondary charging source. GP-MPPT-85/20 will only begin charging after battery voltage has fallen to a normal level. Use a voltmeter to check if voltages are in correct range.
4. De-energize system and disconnect equipment. Use a DMM with a connectivity setting to check for shorts in wiring or equipment. Otherwise, use a voltmeter to check if voltages are in correct range.
Red Solar LED On
Display Reading: Red solar LED on | Time of Day: Daytime/Nighttime
1. PV array voltage is greater than 85V.
2. PV array current is greater than 20A.
How to tell:
Measure PV array voltage. If it’s greater than 85V, the controller will not charge. Check PV module nameplate for ratings.
Change PV array wiring configuration. Consult your dealer or installer for assistance.
Problems with Charging
Problem: Controller doesn’t seem to be charging | Time of Day: Daytime, clear sunny skies
Current is being limited as per normal operation or poor connection between solar array and controller.
How to tell:
The green LED will flash if controller is charging. The green LED is on continuously if controller isn’t charging or if there’s insufficient solar voltage.
With the solar array in sunlight, check the voltage of the solar array terminals with a voltmeter.
Check all connections from the controller to the array including checking for correct wire polarity. Check that all connections are clean, tight, and secure.
Wait 5 minutes and recheck charging status. A delay is present to prevent erratic behavior.
Problem: Charge current is less than expected | Time of Day: Daytime, clear sunny skies
1. Current is being limited as per normal operation.
2. Incorrect series/parallel configuration and/or wiring connections and/or wire gauge.
3. Dirty or shaded module or lack of sun.
4. Blown diode in solar module when two or more modules are connected in parallel.
How to tell:
1. Check battery voltage. If battery has reached the target charge voltage, then current is being limited per normal operation.
2. Check the heatsink temperature. Controller will limit charge current when internal temperatures are too high.
3. Check that the modules and batteries are configured correctly. Check all wiring connections.
4. Modules look dirty, overhead object is shading modules or it is an overcast day in which a shadow cannot be cast.
NOTE: Avoid any shading no matter how small. An object as small as a broomstick held across the solar module may cause the power output to be reduced. Overcast days may also cut the power output of the module.
Reconnect in correct configuration. Tighten all connections. Check wire gauge and length of wire run. Clean modules, clear obstruction or wait for conditions to clear. If the open circuit voltage of a module is lower than the manufacturer’s specifications, the module may be faulty. Check for blown diodes in the solar module junction box which may be shorting the power output of module.
It seems like my flooded batteries are losing water over time.
Flooded batteries may need to have distilled water added periodically to replace fluid loss during charging. Excessive water loss during a short period of time indicates the possibility of overcharging or aging batteries.
When charging, my flooded batteries are emitting gas.
During charging, hydrogen gas is generated within the battery. The gas bubbles stir the battery acid, allowing it to receive a fuller state of charge.
IMPORTANT: Ensure batteries are in a well-ventilated space.