Frequently asked questions about Solar Controllers

GP-PWM-30 / GP-PWM-25

FAQs:

1. 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.

2. 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 more full state of charge. Ensure they are in a well ventilated space.

3. My voltmeter shows a different reading than the GP-PWM-30 display. The meter value on the GP-PWM-30 display is an approximate reading intended for indication purposes only. There is an approximate 0.1 volt inherent error present that may be accentuated when compared with readings from another voltmeter.

There may be a slight difference between the battery voltage displayed on the GP-PWM-30 display and the battery voltage measured at the battery terminals. When troubleshooting using a voltmeter, check both the battery voltage at the GP-PWM-30 controller terminals and battery voltage at the battery terminals. If a difference of more than 0.5 volts is noted, this indicates a large voltage drop possibly caused by loose connections, long wire runs, small wire gauge, faulty wiring, a faulty voltmeter or all the above. Consult the Suggested Minimum Wire Gauge chart in the product manual for wiring suggestions and check all connections.

Troubleshooting:

How to read this section
Troubleshooting 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. It is imperative all electrical precautions stated in the Warning Section and outlined in the Installation Section of the product manual 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 Solar Controller Display

Display Reading: Blank
Time of Day: Daytime/Nighttime

Possible Cause:
(1) Battery or fuse connection and/or solar array connection (Daytime only).
(2) Battery or fuse connection (Nighttime only).

How to tell:
(1) & (2) Check the voltage at the controller battery terminals with a voltmeter and compare with a voltage reading at the battery terminals. 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. For the solar array, repeat steps 1 and 2 substituting all battery terminals with solar array terminals.

Remedy:
(1) & (2) 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.

Problems with Voltage

Voltage Reading: Inaccurate
Time of Day: Daytime/Nighttime

Possible Cause:
(1) 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. If there is a voltage discrepancy of more than 0.5 V, there is an excessive voltage drop.

Remedy:
(1) 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.

Problems with Current #1

Current Reading: 0 A
Time of Day: Daytime, clear sunny skies

Possible Cause:
(1) Current is being limited below 1 Amp as per normal operation.
(2) 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. 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:
(2) 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.

Problems with Current #2

Current Reading: Less than expected
Time of Day: Daytime, clear sunny skies

Possible Cause:
(1) Current is being limited below 1 Amp 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) Battery State of Charge screen is close to 100% and the Sun and Battery icon 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 cut to almost nil. Overcast days may also cut the power output of the module to almost nil.
(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 22 volts. 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 negative wires disconnected from the terminal.

Remedy:
(2) Reconnect in correct configuration. Tighten all connections. Check wire gauge and length of wire run. Refer to Suggested Minimum Wire Gauge in Section 5.
(3) Clean modules, clear obstruction or wait for conditions to clear.
(4) 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 module.