How to troubleshoot the GP-PWM-10-FM Solar Controller
How to Read this Section
Troubleshooting Problems is split into three 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.
NOTE: It is imperative all electrical precautions stated in the Warning Section 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.
Problems with the Display
Display Reading: Blank
Time of Day: Daytime/Nighttime
Possible Causes:
Battery or fuse connection and/or solar array connection (Daytime only) or battery or fuse connection (Nighttime only).
How to tell:
1. Check the voltage at the controller battery terminals with a voltmeter and compare with a voltage reading at the battery terminals.
2. If there is no voltage reading at the controller battery terminals, the problem is in the wiring between the battery and the controller. If the battery voltage is lower than 6 volts, the controller will not function.
3. For the solar array, repeat steps 1 and 2 substituting all battery terminals with solar array terminals.
Remedy: Check all connections from the controller to the battery including checking for correct wire polarity. Check that all connections are clean, tight, and secure. Ensure the battery voltage is above 6 volts.
Display Reading: Nighttime
Time of Day: Daytime
Possible Causes:
Panel is covered by something; PV panel is too dirty to supply a high enough voltage to charge the battery; PV panel is not connected.
Remedy: Check the panel and to ensure it is not obscured. Clean the panel if it is dirty. Check that PV cables are connected to the controller.
Problems with Voltage
Voltage Reading: Inaccurate
Time of Day: Daytime/Nighttime
Possible Cause:
Excessive voltage drop from batteries to controller due to loose connections, small wire gauge, or both.
How to tell:
1. Check the voltage at the controller battery terminals with a voltmeter and compare with the voltage reading at the battery terminals.
2. If there is a voltage discrepancy of more than 0.5 VDC, there is an excessive voltage drop.
Remedy:
Check all connections from the controller to the battery including checking for correct wire polarity. Check that all connections are clean, tight, and secure. Shorten the distance from the controller to battery or obtain larger gauge wire. It is also possible to double up the existing gauge wire (i.e. two wire runs) to simulate a larger gauge wire.
Voltage Reading: Controller flashes entire LCD for battery overvoltage
Time of Day: Daytime/Nighttime
Possible Causes:
1. Solar current is too large with respect to battery capacity
2. Electrical short
3. Unregulated charging source
4. Damaged/Old battery bank
How to tell:
1. Calculate the total solar array Isc. Find or calculate the battery bank capacity in amp hours (Ah). Divide the capacity by the total Isc. If this number is greater than 5, then consider increasing the battery bank size. (Note: This is a simplified rule of thumb and does not cover all system sizing situations.)
2. Have your battery bank tested.
Remedy:
Turn off any secondary charging sources such as a generator. If possible, turn off solar circuit breakers if the error does not clear after turning off secondary charging sources. If you suspect an electrical short, seek the help of a qualified professional or your dealer. Consider having your battery bank tested or replacing your battery bank. Battery capacity deteriorates with age and extreme use. Wait for the battery voltage to fall. Batteries self-discharge over time.
Problems with Current
Current Reading: 0 A
Time of Day: Daytime, clear sunny skies
Possible Cause:
Current is being limited below 1 Amp as per normal operation or poor connection between solar array and controller.
How to tell:
1. The State of Charge (SOC) screen is close to 100% and the Sun and Battery icon are present with an arrow between.
2. With the solar array in sunlight, check the voltage at the controller solar array terminals with a voltmeter.
3. If there is no reading at the controller solar array terminals, the problem is somewhere in the wiring from the solar array to the controller.
Remedy:
1. Check all connections from the controller to the array including checking for correct wire polarity. Check that all connections are clean, tight, and secure. Continue with the solutions below for additional help on low current readings.
Current Reading: Less than expected
Time of Day: Daytime, clear sunny skies
Possible Causes:
(1) Current is being limited below 1 Amp as per normal operation.
(2) Incorrect series/parallel solar panel configuration and/or wiring connections and/or wire gauge (for multiple panel systems).
(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) Battery State of Charge screen is close to 100% and the Sun and Battery icons are present with an arrow in between.
(2) Check that the modules and batteries are configured correctly. Check all wiring connections.
(3) 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 decrease the power output of the module.
(4) Disconnect one or both array wires from the controller. Take a voltage reading between the positive and negative array wire. A single 12-volt module should have an open circuit voltage between 17 and 23 VDC. If you have more than one solar module, you will need to conduct this test between the positive and negative terminals of each module junction box with either the positive or the negative wires disconnected from the terminal.
Remedy:
(1) Reconnect in correct configuration. Tighten all connections. Check wire gauge and length of wire run. Refer to Suggested Minimum Wire Gauge in the article GP-PWM Solar Controller 10-FM: Installation & Mounting.
(2) Clean modules, clear obstruction, or wait for conditions to clear.
(3) If the open circuit voltage of a non-connected 12-volt 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 the module.