Tesla self-consumption issue — mode & tariff fix
Your Powerwall should charge from excess solar and discharge to power your home. If it's exporting when it shouldn't, not charging during cheap rates, or draining overnight, one of six common misconfigurations is likely responsible. This guide covers Powerwall 2 and Powerwall 3 across all UK tariffs.
Tell us your Powerwall model, what the Tesla app shows for solar generation and house load, and whether you're on a smart tariff. We review app data and Gateway configuration remotely.
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⚡ 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.
6-step self-consumption diagnostic
Work through these steps in order. Step 1 catches mode misconfigurations. Step 2 addresses backup reserve settings. Steps 3–6 cover CT orientation, export settings, Octopus tariff configuration, and firmware issues.
Open the Tesla app → Settings → Customize. The mode should be Self-Powered for most UK homeowners without a smart tariff, or Time-Based Control for Octopus customers. Self-Powered mode charges from excess solar and discharges to cover house load. Time-Based Control follows a tariff schedule. If the mode is set to Backup Only or Cost Savings, the battery will not self-consume as expected during normal operation. Verify the correct mode is active for your situation.
In Self-Powered mode, the percentage slider sets the backup reserve — the state of charge below which the battery stops discharging for daily use and reserves power for emergencies. If set to 100%, the battery never discharges because all capacity is reserved and will not self-consume. Set to 20% for a balance of daily self-consumption and backup protection. Values above 50% will severely limit how much solar energy is used for daily loads.
A backwards load/site CT causes the Gateway to misread house consumption — it thinks the house uses less power than it actually does, so the battery won't discharge enough and will sit full, exporting excess instead. A backwards solar CT means the system thinks solar isn't generating. Check the energy flow diagram in the Tesla app — values should match your inverter's monitoring app and main meter. If readings don't match, the CT is likely reversed 180 degrees and needs rotating, which requires an electrician.
Go to Settings > Customize > Energy Exports. If set to "Everything", the system exports all excess once the battery is full — this is normal. If set to "Solar Only", only solar-generated energy exports and grid-charged energy is reserved. Check Grid Charging — if restricted, the battery cannot charge from grid for off-peak tariffs. For Time-Based Control with smart tariffs, Grid Charging must be enabled. Export may also be capped by G98/G99 compliance rules depending on your location.
For Octopus Go: use Time-Based Control with off-peak window 00:30-04:30 (or 23:30-05:30 for Intelligent Go). For Octopus Flux: Octopus controls the battery directly via their integration — you lose Tesla app control but gain VPP optimisation. For Octopus Agile: use Time-Based Control with a third-party integration like Home Assistant. Grid Charging must be enabled for any tariff that charges from grid overnight. Time windows must precisely match your tariff to avoid wasting cheap-rate energy.
Firmware updates can occasionally reset mode settings or introduce bugs. Check current firmware version in Tesla app > Settings. If the issue started after an update, a power cycle may help: turn off the Gateway circuit breaker, wait 30 seconds, turn it back on. Allow 5 minutes for reconnection. If the issue persists, the mode or schedule likely needs reconfiguring. Contact STS for a remote diagnostic — we review your Tesla app data, energy history, and Gateway configuration.
Self-consumption vs export — the difference
Self-consumption is the practice of using stored solar energy to power your home, avoiding expensive grid imports during peak times. When your solar panels generate excess energy during the day, the Powerwall stores it. When the sun sets or clouds pass over, the battery discharges to cover your household load, reducing reliance on the grid. Optimising self-consumption is the primary goal for most UK homeowners — it maximises the benefit of your solar investment and reduces bills. A misconfigured system can undo these savings by exporting excess instead of storing it.
UK smart tariff landscape: Octopus dominates the UK smart tariff market with flexible products like Octopus Go, Octopus Flux, and Octopus Agile. Tesla Powerwall integrates well with these tariffs, but configuration is complex — mode selection, time windows, grid charging, and export restrictions must all align. Incorrect setup can result in the battery charging when power is expensive, discharging when it should charge, or missing tariff opportunities entirely. STS helps homeowners configure these settings remotely, ensuring the Powerwall works in harmony with their tariff.
Self-consumption — common questions
This typically happens when the mode is set incorrectly, a CT clamp is backwards causing the Gateway to misread consumption, or the battery is full and excess solar is exporting — which is normal. Verify that Self-Powered mode is active and backup reserve isn't set to 100%. If the battery is not full and still exporting, check that your load CT is installed correctly. Compare your Tesla app energy readings with your inverter monitoring and main meter — they should match.
Self-Powered charges from excess solar and discharges to cover load, with no tariff awareness. The battery acts independently based on solar generation and house consumption. Time-Based Control follows a schedule — charges during cheap rate, discharges during peak, requiring tariff configuration. Most UK homeowners without smart tariffs should use Self-Powered. Octopus customers typically use Time-Based Control to optimise for their tariff windows and save on electricity costs.
Use Time-Based Control mode. Set the off-peak window to match your Go tariff — standard Go is 00:30–04:30, Intelligent Go is 23:30–05:30. Enable Grid Charging so the battery charges from cheap-rate grid during off-peak. Set the peak period to match your export window and test by checking the Tesla app shows grid charging during the off-peak window. Make sure the times are precise to your tariff — even 30 minutes out will cost you money.
Yes — Octopus Intelligent Flux integrates directly with Tesla Powerwall. Octopus controls the battery via their platform, optimising charge/discharge for their VPP. You lose direct Tesla app control of the battery schedule but gain automated optimisation and often higher export rates. To regain manual control, disconnect the integration through the Octopus app.
Common causes are mode misconfiguration (Time-Based Control without correct off-peak/peak windows), Self-Powered with a high house baseload that drains the battery, or automation tools like Predbat or Home Assistant sending discharge commands. Review the Tesla app Energy History to see exactly when discharge occurred and correlate with your tariff windows. Check if any automation is active on your network.
Still not self-consuming?
If you have checked the mode, backup reserve, CT orientation, and tariff settings — and the Powerwall still won't self-consume as expected — the issue may be a Gateway metering fault, a firmware bug, or a misconfigured automation. We review your Tesla app data, energy history, and Gateway configuration remotely. Independent from Tesla and your installer.