Problem diagnosis · LuxPowerTek

Lux Power Octopus Charging Not Working — TOU Schedule, Clock Offset & Grid Charge Fix

Your Lux Power battery should be charging overnight on the cheap rate, but it's not. The portal shows the schedule is set, the battery has capacity, and the inverter is online — but no grid import happens during the off-peak window. This is almost always a TOU configuration issue, not a hardware fault.

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LuxPower portal TOU schedule specialist
Octopus Go, Flux, Agile & Intelligent
BST/GMT clock offset resolution

Battery not charging on the cheap rate?

Most LuxPowerTek charging failures are TOU schedule configuration errors. We diagnose and fix them remotely via the LuxPower portal — usually same day.

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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.

Steve M · Jun 2026 Google

Brilliant service from Ron - our GivEnergy inverter stopped working on Tuesday what a nightmare seen as the company who installed it are no longer in business. Through social media I found STS (Ron) he had a new inverter and it was fitted and working by Friday - what I thought was going to be a nightmare turned out not to be!!! Great guy great company - def my go to now for anything solar related - Thank you so much

Jane Thomas · Oct 2026 Google

We reached out to Solar Technical Support after our solar energy system stopped working. As GivEnergy 'solar orphans,' we have been extremely pleased with the service from STS - our system was back up and working within a day of us contacting them. We found other solar engineers reluctant or unable to help us, so it has been great to find this organisation. We would definitely use them again and would recommend them to anyone, especially GivEnergy orphans!

Fiona Ford · Aug 2026 Google

Great experience with STS great communication from Ron, very helpful and knowledgable. Installed me a second Givenergy battery to help take the strain off my original 9.5 that needs refurb due to a weak cell. They secured me an 8.2 arranged install. Levi arrived the whole install was done within 1.5 hours - great tidy job. Worked with me to alter my setup to allow easy removal of my 9.5 when i can get it away for refurb - very happy with their service and its reassuring to know there is a company out there that can help look after my givenergy system

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Having had a recent solar instal and being concerned about various aspects of the work, I reached out to Solar Tech for advice. I received immediate engagement and first class advice. This was late evening and the company went above and beyond in providing assistance to me - high recommended.

John Szram · Jul 2026 Google

Had a fault on a GivEnergy AC coupled 3kW home battery and was getting no joy from multiple companies I contacted, as well as the original installer. Contacted Solar Tech Support and they sorted it really quickly, now working perfectly again, can’t recommend them highly enough, professional and very responsive!

John Jones · Jul 2026 Google

Steve M · Jun 2026 Google

Jane Thomas · Oct 2026 Google

Fiona Ford · Aug 2026 Google

Alan Glaister · Sep 2026 Google

Written by Ronald · Independent Solar Engineer Last updated 28 October 2026

Key point: LuxPowerTek cheap-rate charging relies entirely on the TOU schedule in the LuxPower portal. If the schedule is wrong, the battery will never charge from the grid during off-peak hours — even though the inverter and battery hardware are working perfectly.

Diagnostics

5-step Lux Power charging diagnosis

When a LuxPowerTek battery fails to charge on a cheap-rate tariff, the problem is in the TOU schedule configuration — charge window timing, grid charge enable, clock offset, SoC target, or charge current limit. Work through these steps in order.

Check the TOU charge window in the LuxPower portal

Log into the LuxPower monitoring portal and open the Time of Use schedule. Verify that a charge window exists for the correct cheap-rate period:

Typical UK smart tariff windows

Octopus Go: currently 00:30–05:30. Legacy and regional variants exist, including the older four-hour 00:30–04:30. Check your tariff agreement

Octopus Flux: 02:00–05:00 (cheap import window)

Octopus Intelligent: 23:30–05:30 (extended window)

Octopus Agile: Variable — cheapest half-hours change daily

If no charge window exists, the inverter has no instruction to charge from the grid. The most common error is a schedule that was edited but never properly saved.

Confirm grid charge is enabled in the TOU settings

LuxPowerTek inverters have a separate grid charge toggle within the TOU schedule. Even with a correctly timed charge window, if grid charge is disabled the inverter will only charge the battery from solar — no grid import will occur during the cheap-rate window.

This toggle is frequently missed during initial setup or accidentally disabled after a firmware update. In the LuxPower portal, check the TOU settings for each configured time period — grid charge must be explicitly enabled on the period covering your cheap-rate window.

Some LuxPowerTek firmware versions have separate charge and discharge toggles per TOU period. Ensure the charge toggle is on and the source includes grid.

Check the BST/GMT clock offset on the inverter

This is the single most common cause of seasonal charging failures. The LuxPowerTek inverter has its own internal clock that may not follow UK daylight saving time automatically:

What happens in BST (March–October)

If the inverter clock stays on GMT, a charge window set for 00:30–05:30 actually fires at 01:30–06:30 BST. The first hour of cheap rate is missed, and the last hour of charging runs on at the standard rate.

What happens in GMT (October–March)

If someone corrected the clock in summer by adding an hour manually, it will now be one hour ahead in winter — charging starts at 23:30 instead of 00:30, potentially at a higher rate.

Check the inverter time in the LuxPower portal under device settings. If it shows UTC or is one hour out, the clock offset needs correcting.

Verify the SoC target and minimum SoC threshold

The TOU charge window has a target SoC that tells the inverter when to stop charging. If the battery is already at or above this target when the cheap-rate window starts, the inverter will not charge:

• Charge SoC target: Set to 100% for Go and Flux to maximise cheap-rate import

• Minimum SoC threshold: If set too high (e.g. 50%), the battery may not discharge enough during the day to create headroom for overnight charging

• Battery already full: If solar production fully charges the battery during the day and the minimum SoC prevents discharge, the battery arrives at the cheap-rate window already at 100%

For Octopus Go and Flux, the standard configuration is 100% charge target with a 10–20% minimum SoC. Adjust minimum SoC based on your evening consumption needs.

Check the charge current limit and battery BMS status

If the schedule is correct but the battery still doesn't fully charge during the window, the issue may be the charge rate:

• Single UHome module: Maximum charge rate is approximately 1.44kW (30A at 48V) — a 2.4kWh module takes roughly 1.5 hours from empty to full

• Stacked modules: Combined charge rate increases, but the inverter charge current limit must be set to match the stack size

• Charge current too low: If the inverter's grid charge current is limited below the available stack rate, the battery may not reach 100% before the window closes

Also check the UHome BMS communication status in the portal. If the battery has a BMS communication fault, it will reject charge commands regardless of the schedule configuration.

Safety: Do not open the inverter or touch DC cabling. If the BMS is in a fault state, isolate at the DC switch and contact an engineer.

Why Lux Power cheap-rate charging breaks so often

LuxPowerTek systems rely entirely on the LuxPower monitoring portal for TOU schedule management. Unlike some inverters that have on-screen schedule configuration, Lux Power systems are configured remotely — which means the portal must be online and correctly synced for any schedule changes to take effect. If the portal connection drops or the inverter's WiFi logger loses connectivity, schedule updates may not reach the inverter.

The BST/GMT clock offset problem affects Lux Power owners twice a year. We see a spike in charging complaints every March when the clocks go forward and again in October when they go back. The fix is straightforward — correct the clock offset in the portal — but many owners do not realise the inverter clock is independent of their phone or computer time. Combined with the grid charge toggle (which defaults to off on some firmware versions), these two configuration items account for the vast majority of cheap-rate charging failures on LuxPowerTek systems.

Lux Power cheap-rate charging — common questions

Why isn't my Lux Power battery charging on Octopus Go overnight?

The most common causes are: no TOU charge window configured in the LuxPower portal, the grid charge toggle being disabled, or a BST/GMT clock offset causing the window to fire at the wrong time. If the inverter clock is one hour behind during British Summer Time, the charge window starts an hour late and runs an hour past the end of the cheap rate.

What is the BST clock offset issue on LuxPowerTek inverters?

LuxPowerTek inverters do not always follow UK daylight saving time automatically. When the clocks go forward in March, the inverter clock may stay on GMT — meaning a charge window set for 00:30 actually fires at 01:30 BST. This is the single most common seasonal charging failure. Correcting the clock offset in the portal device settings resolves it immediately.

How do I set up Octopus Flux on my Lux Power system?

Octopus Flux has three key windows: cheap import (02:00–05:00), peak export (16:00–19:00), and standard rate outside those times. Configure a charge window for 02:00–05:00 with grid charge enabled and 100% SoC target. Then configure a forced discharge window for 16:00–19:00 to export at the peak rate. The minimum SoC threshold controls how much the battery retains for evening use.

Can you configure my Lux Power system remotely for a smart tariff?

Yes. We configure LuxPowerTek TOU schedules remotely via the LuxPower portal — Octopus Go, Flux, Agile, Intelligent, or any time-of-use tariff. Tariff setup is a fixed £45 per session, with no site visit required. We verify the clock offset, grid charge toggle, SoC targets, and charge current limits as part of the setup. If cheap-rate charging was set up and has stopped working, that is a fault, not setup: the diagnostic is free and the remote fix is £125, only if we fix it.

What SoC target should I use for overnight charging?

For Octopus Go and Flux, set the charge SoC target to 100% to maximise cheap-rate import. This fills the battery completely during the off-peak window. For Octopus Agile where prices vary by half-hour, you may want to adjust the target based on expected solar generation — but for fixed-window tariffs, 100% is the standard recommendation.

Book

Lux Power battery not charging on the cheap rate?

Tell us your tariff and what the LuxPower portal is showing. We'll review the TOU schedule, clock offset, grid charge settings, and SoC thresholds — and fix it remotely.

No fix, no fee
TOU schedule configuration included
All UK smart tariffs supported

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