This diagnostic guide walks through every setting. Most cases are resolved by Step 2 — the BST/GMT clock offset.
Book your free remote diagnosticOctopus tariff guideWe configure Sunsynk for all major UK tariffs remotely in a single session.
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.
⚡ Safety Warning
Do not open your inverter or interfere with DC cabling. Solar panels produce live DC voltage whenever exposed to light. Always use your DC isolator switch and contact a qualified solar engineer for hands-on fault diagnosis.
Work through these steps in order. Most cases are resolved by Step 2.
Check your energy supplier's portal or your latest bill for the exact cheap-rate hours. Common windows: Octopus Go 00:30–04:30 (GMT/BST) · Octopus Intelligent 23:00–06:00 plus peak windows · Octopus Flux off-peak 02:00–05:00 · Economy 7 approximately 00:30–07:30 (varies by region). Write these times down exactly — you'll need them for Step 2.
In SolarMan, go to Device → Information and check the inverter's current clock time. Compare it to your local time right now. If the inverter clock is 1 hour behind (e.g., showing 23:00 when it's actually 00:00 BST), this is the problem. During British Summer Time, many Sunsynk inverters don't auto-adjust the clock. The charge window will fire exactly 1 hour late as a result.
Navigate to Device → Settings → Time of Use. Find your charge window and verify the start and end times match your tariff window exactly. Common mistake: if Octopus Go is 00:30–04:30 but SolarMan shows 23:30–03:30, the window is offset by 1 hour. Correct it to 00:30–04:30.
In SolarMan, check the grid charge settings (usually Device → Settings → Grid Charge). Confirm that grid charge is set to ON for the charge window. If disabled, the battery will only charge from solar generation, not from cheap-rate electricity. Grid charge must be ON for the system to force charge from the grid.
In Device Settings, find the charge power limit (if set). If too low (e.g., 500W), the battery will charge very slowly during the window — a 5kWh battery might only gain 500Wh in 4 hours. Set charge power to the inverter's rated capacity for maximum charging during the window. Also verify SoC target is high (e.g., 90-100%) and minimum SoC is low (e.g., 10-20%) to allow meaningful charge/discharge cycles.
After making any adjustments, check SolarMan's battery SoC graph the following morning. Look for: battery SoC increasing during your charge window, grid power showing as positive import during the window, and battery reaching your target SoC by the end of the window. If charging still hasn't started, book a remote diagnostic — there may be a secondary issue.
Octopus Energy grew explosively across the UK from 2020 onwards, and many Sunsynk systems were installed without proper tariff-specific configuration. The combination of BST/GMT clock confusion, unclear SolarMan UI, and inconsistent Time of Use scheduling has created a situation where the majority of Sunsynk owners report that their cheap-rate charging doesn't work reliably. In reality, nearly all of these systems can be fixed in a single 30-minute remote session.
STS is a Sunsynk and Octopus specialist. We've configured hundreds of Sunsynk systems for Octopus Go, Agile, Intelligent, and Flux tariffs. The fix is always the same: correct the clock, verify the TOU window times, enable grid charge, and set appropriate SoC targets.
Tell us your tariff and what you're seeing. We'll check your SolarMan data and configure your system to work correctly with your Octopus tariff — most cases are fixed in a single session.
We use cookies to measure traffic and improve our ads — including sharing limited, hashed details with Meta (Facebook) to measure ad performance. Accept, or decline for essential cookies only. Privacy policy
