Screen stays dark
Check battery supply, fuses and wiring.
MPPT Controller Troubleshooting Guide
Pick your symptom, check the screen as prompted, then take action.
What are you seeing?
Click one to jump straight to the steps.
PV not charging
Check alarms, PV input and stop-charging conditions.
Insufficient charging
Check PV, loads and cabling.
Battery overvoltage
Check alarms, battery type and charging sources.
PV abnormal
Check sunlight, switches, wiring and modules.
Look up the fault code
Enter the code to see the fix directly.
Not sure which one? Check these 4 readings first
- Short-press SELECT until "System Alarm" appears.
Write down the E code; normally it shows E0. - Keep short-pressing SELECT.
Record battery voltage, charging current, PV voltage and PV current.
Smoke, strange smell, battery swelling, leaking or melted terminalsStop immediately, keep away from the battery and follow your on-site emergency procedure.
How to read data with SELECT
Short-press SELECT = next pageYou can start from any screen; keep short-pressing until the reading you need appears. For daily troubleshooting, do not long-press SELECT, and do not press SELECT while in a settings screen, as this may change values.
Battery V→
Charge A→
PV V→
PV A→
Load A→
Temp→
E0 / E code
- Battery voltage
- Tells you whether the battery is under-volted, over-volted, or below the boost charge return voltage set for the current battery type.
- Charging current
- 0A means the battery is not being charged; if the value is small, continue with PV current and load current.
- PV voltage / current
- Tells you whether sunlight, the PV switch, wiring and modules are working normally.
- Load current
- A heavy load can consume the PV energy and prevent the battery from reaching full charge.
- Device / battery temperature
- When too hot or too cold, the controller may automatically limit current or stop charging and discharging.
- System alarm
- E0 is normal; for any other E code, go to the fault code table.
To view "Boost charge return voltage" onlyFrom any screen, press and hold ENTER for 3 seconds to enter parameter settings, then short-press ENTER to step through items until "Boost Charge Return Voltage" appears. Write down the value, then press and hold ENTER for 3 seconds to exit. Do not press SELECT while viewing, or you may change the parameter.
Screen stays dark / no response
- Confirm the battery is connected.
The controller usually starts from the battery; check that the battery switch, breaker and fuse are all on. Measure battery voltage with a multimeter — it must be above 9V. - If battery voltage is 0, check for loose terminals, reversed polarity, or wires clamped on insulation.
Do not disconnect wires while live; leave live-terminal measurements to qualified personnel. - If the screen is still dark, stop disassembling.
If battery supply and wiring are both normal but the screen stays dark, take photos of the wiring and contact support.
Once the screen comes backShort-press SELECT to "System Alarm", confirm it shows E0, then continue checking battery voltage and charging current.
PV not charging / battery not charging
The screen is on but charging current is 0A — check in this order.
- Check whether the main screen shows a flashing fault, then short-press SELECT to "System Alarm".
If there is an exclamation mark or an E code: look up the fault code and clear the cause first. After the fault indication disappears, perform an F01 system restart. - Short-press SELECT to "PV Voltage".
If PV voltage is 0, very low, or below battery voltage: make sure there is enough sunlight, then check the PV switch, fuse and wiring; measure PV voltage with a multimeter if necessary. - Short-press SELECT to "Battery Voltage".
Confirm the battery type first, then check the manual for the "Boost Charge Return Voltage" currently set for that type. The controller only starts a new charging cycle when battery voltage drops below this setting. - Go back to the main screen and check the charging stage.
If it shows FULL, FLOAT or a very small charging current: the battery is usually full or charging has stopped normally — this is not a fault.
Boost charge return voltage is not a fixed valueIt can differ between SLD, GEL, FLD, LI, USE, USE LI and custom battery settings. Always go by the value currently shown on the screen; never assume a fixed voltage.
Example for understanding onlyIf the return voltage for the current battery type is set to 13.1V: at a screen reading of 13.3V the controller may keep waiting; only after dropping below 13.1V does the recharging condition become true. If your screen shows a different value, judge by that value.
Battery not charging enough
There is charging, but current is small or the battery is still not full by end of day.
- Short-press SELECT to check PV voltage and PV current.
If values are clearly low: check weather, shading, dust on the modules, the PV switch and branch wiring. - Short-press SELECT to check charging current and load current.
If load current is close to or greater than charging current: turn off non-essential loads first, then watch whether the battery starts recovering. - Short-press SELECT to check battery voltage.
Write down the screen voltage; if terminals or fuse holders are hot, discolored or loose, stop. Leave battery cable voltage-drop measurements to qualified personnel. - After completing the checks above, you can perform an F01 restart.
The restart re-detects the system and re-scans for the maximum power point under the current sunlight.
How to perform the F01 system restartPress and hold ENTER for 3 seconds to enter parameter settings → short-press SELECT until F01 appears → press ENTER, F01 flashes → press ENTER again, and the controller restarts.
Battery overcharge / voltage too high
Battery swelling, leaking, overheating, smoking or a pungent smellStop immediately, stay away from sparks and open flames, and follow the battery manufacturer's and on-site emergency procedures.
- Short-press SELECT to "System Alarm".
Note whether E2 or another code is displayed. Check whether the battery protection board has tripped, and whether the controller system voltage matches the battery voltage. - Short-press SELECT to check battery voltage and controller temperature.
If voltage or temperature is abnormally high, stop charging and check whether any other charger is also connected to the battery. - Make sure the battery type on screen matches the actual battery.
A mismatched battery type applies wrong boost / equalization / float voltages; do not experiment on your own — configure it jointly per the controller manual and the battery nameplate.
PV voltage low / no voltage / overvoltage
- Short-press SELECT to check PV voltage.
If it is 0 or very low during daytime: check the PV switch, fuse, shading and wiring. - Keep short-pressing SELECT to check PV current.
If PV voltage is normal but current is very small: possibly weak light, shading, dusty modules, a full battery, or a dropped branch connection. - Short-press SELECT to check "Daily generation Wh".
Compare with a normal clear day without shading; do not judge the day by the nameplate maximum power. - If E10 is displayed, stop charging.
E10 means PV overvoltage — have qualified personnel verify the number of modules in series and the cold-weather open-circuit voltage against the maximum PV open-circuit voltage of your controller model.
Do not disconnect MC4 connectors or measure PV open-circuit voltage yourselfThese operations can expose dangerous DC voltages and should be left to qualified personnel.
Fault code quick reference
Read codes on the "System Alarm" LCD screen. Record first, then act. This table applies to controllers using the same E0–E31 code system; for other models, refer to their manuals.
No matching results. Check the code or try a shorter keyword.
Fault code clearing rulesFault codes do not need manual clearing. Protections such as load short-circuit and overload clear automatically after the required delay and recovery conditions are met; persistent abnormal conditions (battery voltage, PV voltage, temperature, wiring or sensors) only clear once the real fault is gone and the recovery threshold is satisfied. If the root cause remains, the code will stay or reappear.
About F01 / F02F01 is a system restart; F02 restores factory defaults. Use F02 only when normal troubleshooting has failed, all parameters have been recorded, and you are able to reconfigure everything per the battery manufacturer's requirements. Factory reset erases custom settings.
| Code | Meaning | LCD confirmation & action | Recovery |
|---|---|---|---|
| E0 | System normal | No action needed. You can still record current voltage, current, temperature and charging stage as a baseline. | Normal state |
| E1 | Battery over-discharge | Load output is off; record battery voltage and load current, reduce loads and restore charging as soon as possible. If the icon flashes slowly, verify system voltage detection. | Load restores after voltage rises above the return threshold |
| E2 | Battery overvoltage | Charging is off; check battery type, boost / equalization / float voltages and any other charging equipment. If there is overheating, swelling or leakage, treat as a hazardous state. | Auto-recovers after voltage drops |
| E3 | Battery low-voltage warning | Record battery voltage; this is a warning only. Reduce non-essential loads and confirm PV can recharge the battery. | Warning clears when voltage recovers |
| E4 | Load short-circuit | The controller has turned off load output; disconnect the load and check cables, polarity and shorted appliances. Wait for recovery only after the root cause is removed. | Auto-clears after the short is gone and recovery conditions are met |
| E5 | Load overcurrent | The controller has turned off load output; record load current, reduce loads and check startup surge currents. | Auto-clears after overload is gone and delay / recovery conditions are met |
| E6 | Controller over-temperature | Check device temperature, reduce loads, improve ventilation and clear obstructions around the heatsink. | Recovers when temperature drops below the threshold |
| E7 | Battery charging high-temp protection | Check battery temperature and sensor placement; stop charging and lower the ambient / battery temperature. | Stops above 65°C, auto-recovers below 60°C |
| Code | Meaning | LCD confirmation & action | Recovery |
|---|---|---|---|
| E10 | Solar panel overvoltage | Charging is off; qualified personnel should check array open-circuit voltage, number of modules in series and cold-weather Voc, ensuring they stay below the model's limit. | Auto-recovers below the safe value |
| E15 | Lead-acid battery not connected | In lead-acid mode, check whether the battery is missing, terminals / fuse are open, or the battery is damaged. | Restore the connection or replace the faulty battery |
| E16 | Battery discharging high-temp protection | Load output is off; check battery temperature, reduce loads and improve battery ventilation. | Load off above 75°C, recovers below 70°C |
| E17 | Battery discharging low-temp protection | Load output is off; check battery temperature and warm it per the battery manufacturer's instructions. Never heat with an open flame. | Load off below −35°C, recovers above −30°C |
| E18 | Charging overcurrent protection | Charging is off; check the array, charging current setting and battery connections. If it recurs, contact technical support. | Recovers about 10 seconds after battery voltage drops |
| E19 | Battery charging low-temp protection | Check battery temperature; stop charging and warm the battery per the manufacturer's instructions. | Stops below −35°C, recovers above −30°C |
| E30 | Charging/discharging disabled by system setting | Check TTL / RS485 / CAN host commands, BMS or EMS instructions and related registers. Do not bypass battery protection permissions. | Remove the external disable command |
| E31 | Charging overvoltage / overcurrent / reverse-polarity protection | Record battery voltage, PV voltage / current and charging current at the moment it appears; check polarity, array and wiring. | Device auto-recovers once the abnormality clears |
| E100 | Controller restart required | Indicates the controller needs to be restarted. | Auto-recovers after the device restarts |
Still not solved? Record these 8 items
Short-press SELECT to step through the pages, and take photos or fill in the values.
1. System alarm:
2. Battery type:
3. Battery voltage:
4. Charging current:
5. PV voltage:
6. PV current:
7. Load current:
8. Device / battery temperature:
Also take two photosThe product nameplate and the controller wiring area. Note the date, weather, and what changed before and after any restart.
Contact support immediately in these casesPower is normal but the screen stays dark; the fault reappears immediately after a restart; the device is scorched, water-damaged, broken or making unusual sounds; or the work requires opening the enclosure, disconnecting MC4 connectors or measuring live terminals.