This month we signed up for the Intelligent Octopus Go 12M Loyal Fixed tariff, which brought our unit rate down to 6.60p and gave us five hours of free electricity. We utilised four of those hours to charge the car and top up the house batteries, saving us £7.72 so far while the final hour is still being calculated. The real headline was a new record for October solar production; although it only beat our previous best by 9 kWh, it marks yet another milestone as we continue to see great solar generation in 2026.
Solar Generation
We produced 235.20 kWh of solar energy this month, which is an increase over the 185.10 kWh we recorded during the same month last year. However, this represents a drop of 154.80 kWh compared to September’s 390.00 kWh. Our solar coverage of the house stood at 34.75% this month. It is worth noting that we had zero days where we generated more solar than the house consumed, and zero days where we generated more than we imported from the grid.
Battery Performance
Our battery management continued with 275 charging slots used and 121 suspended slots. This allowed us to achieve an average grid slot cost of 9.34p, which is lower than the 9.79p average we saw in September. During this period, the cheapest import slot was 6.60p and the most expensive reached 35.89p. To maintain our storage levels, the battery charged 496.40 kWh and discharged 520.50 kWh throughout the month.
Grid Usage
The smart meter measured a total grid import of 745.88 kWh including the car charger. Of this total, 86.68% was charged at the low overnight rate, 4.36% during Smart Charge slots, and 8.96% at the high peak rate. Compared to last month, our house consumption rose by 37.90 kWh to reach 676.90 kWh, driven primarily by the heat pump which used 83.73 kWh (an increase of 27.78 kWh over September).
Cost Savings Summary
We achieved significant savings when comparing our imported kWh to the price cap, totaling £139.15, while our house consumption compared to the price cap saved us £131.52. Our export savings were £35.03, which is a decrease of £13.44 from the £48.47 we saw in September. This month's bill including export came to £46.27.
Grid Usage by Rate
Electricity Usage By Kind
As solar panels output declines over the years I have added the previous years generation to the table at the bottom. Of course weather comes into it as well, but I thought it would be interesting to track. I have added this post that shows each year as a graph.
For some reason it was a complex Octopus billing month so I have added all three
Octopus Energy bill
Octopus Energy Bill
Octopus Energy Bill
| Date | kWh | |
|---|---|---|
| Generation | 26th May 2023 | 32.90 |
| Front generation | 14th June 2023 | 19.80 |
| Back generation | 7th June 2023 | 14.70 |
| Worst generation | 12th December 2022 | 0.20 |
| Date | kWh | Profit | |
|---|---|---|---|
| Exported kWh | 15th June 2024 | 22.20 | |
| Exported profit | 15th June 2024 | 22.20 | £3.15 (15p kWh) |
| Profit day | 14th April 2024 | 18.20 | £2.67 |
| Metric | Date | kWh |
|---|---|---|
| Best Generation | 2 October 2026 | 14.30 |
| Best front generation (pv2) | 8 October 2026 | 9.80 |
| Best back generation (pv1) | 4 October 2026 | 5.20 |
| Worst generation | 20 October 2026 | 1.20 |
| Worst front generation (pv2) | 20 October 2026 | 0.60 |
| Worst back generation (pv1) | 20 October 2026 | 0.60 |
| Metric | Date | kWh | Profit |
|---|---|---|---|
| Best Battery and Solar Export Profit | 4 October 2026 | 9.90 | |
| Best export profit | 4 October 2026 | £2.19 | |
| Cheapest Day | 2 October 2026 | -6p |
| Metric | Date | Time | Exported | Rate |
|---|---|---|---|---|
| Best Export Slot | 6 October 2026 | 18:30–19:00 | 0.93 kWh | 35.76p |
| Worst Export Slot | 10 October 2026 | 11:00–11:30 | 0.51 kWh | 1.02p |
The graph below shows the generation for both front and back panels
Total Solar Generation
The graph below shows generation, battery discharge, battery charging, export, import to use and consumption for 2026
Showing generation, battery discharge, battery charging, export, import to use and consumption for 2026
Energy Breakdown
One of the best features of my Home Assistant setup is this level of visibility. This chart breaks down our entire home's power profile, from high-draw circuits like the immersion heater and car charger to specific devices like the TV and office UPS systems. It’s a powerful way to monitor our daily habits and see how different parts of the house contribute to our overall energy footprint.
Home Assistant Individual Device Usage and Energy Flow
The graph below shows the generation for each day
Graph showing production for the month
The graphs below show the generation split between the front and back panels
Graph showing production for the front facing panels
Graph showing production for the back facing panels
The graphs below show the yearly generation split across both the back and front panels
Total Front Solar Generation
Total Back panel generation
Intelligent Octopus Go
The costs shown here do include the standing charge. Any comparisons are compared to the unit cost if we were not on IOG. There are two comparisons. One is the cost of what we imported from the grid for battery charging. The other is, the cost of the energy used by the house, house consumption.
| Standard Tariff | 26.32p | |
| Standing Charge | 51.67p |
| Cost from the grid | £65.80 IOG | £185.42 Std |
| Savings including export | £139.15 | |
| Monthly bill including export | £46.27 | |
| Exported (Agile Outgoing Octopus) | 150.60 kWh | £35.03 |
| Charging slots used | 275 | |
| Battery Suspended Slots | 121 | |
| Average unit slot price | 9.34 | |
| Cheapest slot | 6.60p | |
| Most expensive slot | 35.89p |
| House consumed | 676.90 kWh | |
| Car charger | 64.79 kWh | |
| Heat pump | 83.73 kWh | |
| Immersion | 5.72 kWh | |
| Air conditioner | 0.00 kWh |
| Solar generated | 235.20 kWh 2026 | 185.10 kWh 2025 |
| Solar vs last year | +50.10 kWh | |
| Battery Charged / Discharged | 496.40 kWh | 520.50 kWh |
| Percentage generated by solar | 34.75% | |
| Self-sustained days (solar > consumed) | 0 | |
| Self-sustained days (solar > imported) | 0 |
Here is the Octopus Watch report summary
Octopus Watch does not report smart charging costs at the cheap rate. It uses the full unit cost.
Octopus Watch Billing Month Review
Featured posts
Solar panel performance declines over the years. I thought it might be interesting to see how mine compares. Of course weather comes into it, but hopefully this will be a useful guide.