This diagnostic guide covers every setting that can prevent charging. Work through the steps in order — most cases are resolved by the third step.
Book your free remote diagnosticSunsynk hubSafety: Isolate at the DC switch if you notice any error lights on the inverter or battery.
Brilliant support to get my solar battery working again. I didn’t expect help on a Saturday but Ron answered the phone, listened and sent me the information I needed to get it going, answered questions etc. A brilliant service I’d happily recommend.
Ron was brilliant. He really tried to help. He spent hours trying to fix our GivEnergy AIO and ultimately it became apparent that it needed parts to fix the BMS management system. As there appears to be no replacement parts available on the market, he gave excellent advice on what options are now available to move forward. He is incredibly helpful and knowledgeable.
Called back within a day and gave good advice.
Ron was extremely helpful and tried his best to repair/reset our GivEnergy inverter remotely. In the event he was unsuccessful but he couldn’t have been more helpful. If you have problems with a GivEnergy system please contact him. Highly recommended
Big thanks to Ron. He was incredibly patient and helpful over the phone, taking the time to walk myself and the installer through every troubleshooting step. Through lots of testing he figured out the issue was definitely a hardware issue, which allows us to consider our next steps. Support fees are clear and they operate a “no fix no fee” policy. It is rare to find that kind of honesty combined with dedicated phone support nowadays. I highly recommend Ron, if you need help with your solar system don’t hesitate to give him a call.
A superb service from Ron who went beyond the normal service received from other Tech support companies. I live abroad and was badly let down when my givenergy system failed (and the company went bankrupt) and the local supplier ran away from the problem. Ron sorted the problem and even accessed specialist coding for the inverter that would not be available for suppliers. Ron also ran a full diagnostic to insure that all was in good working order afterwards. Without Rons support and patient assistance I doubt I would ever have got the system back up and running. Well done and thankyou and you have a customer for the future.
Brilliant support to get my solar battery working again. I didn’t expect help on a Saturday but Ron answered the phone, listened and sent me the information I needed to get it going, answered questions etc. A brilliant service I’d happily recommend.
Ron was brilliant. He really tried to help. He spent hours trying to fix our GivEnergy AIO and ultimately it became apparent that it needed parts to fix the BMS management system. As there appears to be no replacement parts available on the market, he gave excellent advice on what options are now available to move forward. He is incredibly helpful and knowledgeable.
Called back within a day and gave good advice.
Ron was extremely helpful and tried his best to repair/reset our GivEnergy inverter remotely. In the event he was unsuccessful but he couldn’t have been more helpful. If you have problems with a GivEnergy system please contact him. Highly recommended
Big thanks to Ron. He was incredibly patient and helpful over the phone, taking the time to walk myself and the installer through every troubleshooting step. Through lots of testing he figured out the issue was definitely a hardware issue, which allows us to consider our next steps. Support fees are clear and they operate a “no fix no fee” policy. It is rare to find that kind of honesty combined with dedicated phone support nowadays. I highly recommend Ron, if you need help with your solar system don’t hesitate to give him a call.
A superb service from Ron who went beyond the normal service received from other Tech support companies. I live abroad and was badly let down when my givenergy system failed (and the company went bankrupt) and the local supplier ran away from the problem. Ron sorted the problem and even accessed specialist coding for the inverter that would not be available for suppliers. Ron also ran a full diagnostic to insure that all was in good working order afterwards. Without Rons support and patient assistance I doubt I would ever have got the system back up and running. Well done and thankyou and you have a customer for the future.
Work through these steps in order. Most battery charging issues are resolved by Step 2.
Log into SolarMan, navigate to Device → Settings → System Work Mode. If the mode is set to Selling First, this is almost certainly your problem. Selling First mode maximises grid export and does not force charge from the grid or solar. Change to Time of Use (or the mode appropriate for your tariff) to enable charging windows.
In SolarMan, check the State of Charge (SoC) settings: target SoC (maximum charge level) and minimum SoC (discharge floor). If the battery is already at or above the target SoC, the inverter will not charge further — there's no work to do. For example, if minimum SoC is 90% and target is 90%, charging will never happen. Set minimum SoC to ~10-20% and target to 90-100% to allow the system to charge from near-empty to full.
In SolarMan, on the Device page, check the battery status. It should display a valid percentage (e.g., 45% SoC, 78% SoC). If the battery shows 0% or Unknown, the inverter has lost communication with the battery BMS. This prevents charging entirely. Check the CAN or RS485 communication cable between the inverter and battery — it may be loose, disconnected, or damaged.
In SolarMan, check the Time of Use charge window times. The window must exactly match your tariff's cheap-rate period. Common windows: Octopus Go 00:30–04:30 · Octopus Flux off-peak 02:00–05:00 · Economy 7 approximately 00:30–07:30. Also check that the inverter clock is set to current local time. During British Summer Time (BST), if the clock is still on GMT, the window will fire 1 hour late.
In SolarMan, find the grid charge settings (usually under Device → Settings → Grid Charge). Verify that grid charge is set to ON for the time windows where you want the battery to charge from the grid. If grid charge is disabled, the battery will only charge from solar generation, not from cheap-rate grid electricity.
If your Sunsynk has a CT clamp installed (for import/export monitoring), check that it's oriented correctly. In SolarMan, at night with no solar generation, the grid reading should show a positive value (import). If it shows negative (export) while you're clearly consuming from the grid, the CT clamp may be backwards. This can prevent charging from activating correctly.
Sunsynk hybrid inverters (3.6kW, 5kW, 8kW, 12kW models) are widely installed across the UK from 2020 onwards. They integrate directly with SolarMan monitoring (formerly PVMaster) and support native Octopus Agile, Intelligent, and Go tariff integration via Time of Use schedules. However, the SolarMan portal doesn't always clearly surface these settings, and many systems are delivered with factory defaults rather than customer-optimised configuration.
The result: nearly 30% of Sunsynk owners report battery not charging overnight despite having a charged battery and a cheap-rate tariff available. In almost all cases, it's a settings issue — System Mode set to Selling First, SoC headroom exhausted, or timezone mismatches — not a hardware fault.
Tell us what you're seeing. We'll review your SolarMan data and settings to identify the exact cause — most cases are resolved in a single remote session.
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