June Solar Generation and Export Numbers
This was our worst June to date, as it marked the first time we produced less than 700kWh of solar energy. We faced some particularly challenging days, including eight separate days where production dipped below 20 kWh, with the 11th of June producing a mere 8 kWh. This was largely due to a very wet and overcast start to the month following a brief heatwave at the end of May and the start of June. Because of that lingering heat, we actually had to run the air conditioning on four different nights. We extended our 'force discharge' windows during three Octopus Saving sessions that fell outside our usual routine of force discharging window of 4pm to 7pm, proving how adaptable our system can be when conditions change.
Below, we are breaking down our energy usage to see how we fared during June, tracking everything from solar generation to specific appliance use like the heat pump and immersion heater. This level of granular tracking is what allowed us to stay on top of our energy consumption even when the sun wasn't shining as much as we'd like! It really highlights how robust our solar investment has become, especially as we continue to manage without a gas standing charge. In the this post we talk about performance, but bear in mind this is in relation to it being June and not the performance of the system overall.
Note: These metrics reflect this June's specific output. As June is typically our strongest production month, these figures represent a lower-than-average result for this period alone and not any system related issues.
Solar Generation
Looking at the raw numbers, we generated 672.50 kWh this month, which is a decrease of 75.40 kWh compared to the same period last year. Despite this being a lower-performing month for our panels, we still managed to cover a remarkable 97.14% of our house consumption. We had 13 days where our solar output exceeded our household usage and 22 days where it exceeded what we imported from the grid. This shows that even during a 'bad' month, our system remains incredibly reliable at providing significant self-sufficiency.
Battery Performance
We continued our battery management strategy of charing overnight at the cheap 8p kWH rate. This means we export at 12p kWh for most the day. We utilised 225 charging slots (each 30 minutes in length) to achieve this. Additionally, we used 135 suspended slots where the battery stopped charging because it was more cost-effective to use the grid at those specific times. This strategic approach ensured we weren't wasting energy on unnecessary cycles, allowing us to maintain high operational health while keeping costs down during a period of lower production.
We charged the battery a total of 417.60 kWh and discharged 413.20 kWh this month. The ability to pivot our strategy specifically by extending force discharge windows to accommodate extra Octopus Saving sessions allowed us to make extra savings.
Grid Usage
We imported a total of 637.70 kWh from the grid this month, but thanks to the Intelligent Octopus Go (IOG) tariff, the costs remained impressively low. Our total imported electricity bill on IOG was only £67.66, which is massive compared to what we would have paid on a Standard Tariff of £170.79 for the same consumption. This highlights just how much our choice of tariff is insulating us from high energy prices.
Our average unit cost for the year has settled at an incredible 13.37p, which sits well below the current price cap of 24.67p and the yearly average cap of 26.18p. We had a brilliant day on the 19/06/2026 when our electricity cost us only -63p!
Cost Savings Summary
The data from this month proves that even when the weather isn't on our side, proactive management keeps the costs down. We achieved massive savings compared to what we would have paid using imported kWh at the price cap (a saving of £155.53). More importantly, our savings compared to the house consumption cost on a standard tariff amounted to £169.00.
Furthermore, our exported excess power reached 443.10 kWh, providing us with Exported Savings of £53.17 this month. This meant our bill from Octopus was £14.49.
While June was a disappointing month compared to previous June’s for our solar panels, the combination of our IOG tariff and smart battery management ensured that we still achieved an incredibly efficient result. Stay tuned for our July generation report!
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.
Octopus Energy bill
Octo-Aid Tariff Comparison
| 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 | 19 June 2026 | 31.80 |
| Best front generation | 29 June 2026 | 19.10 |
| Best back generation | 13 June 2026 | 13.50 |
| Worst generation | 11 June 2026 | 8.30 |
| Worst front generation | 11 June 2026 | 4.80 |
| Worst back generation | 11 June 2026 | 3.50 |
| Metric | Date | kWh | Profit |
|---|---|---|---|
| Best kWh export day (Battery) | N/A | N/A | |
| Best Battery and Solar Export Profit | 19 June 2026 | 21.70 | |
| Best kWh export day (Solar) | N/A | N/A | |
| Best export profit | 19 June 2026 | 21.70 | £2.60 |
| Cheapest Day | 19 June 2026 | -0.63p |
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
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 | 24.67p | |
| Standing Charge | 52.19p |
| Cost from the grid | £67.66 IOG | £157.32 Std |
| Savings including export | £142.83 | |
| Monthly bill including export | £14.49 | |
| Exported (@12p kWh) | 443.10 kWh | £53.17 |
| Charging slots used | 225 | |
| Battery Suspended Slots | 135 | |
| Average unit slot price | 10.61p | |
| Cheapest slot | 8.00p | |
| Most expensive slot | 33.32p |
| House consumed | 692.30 kWh | |
| Car charger | 58.40 kWh | |
| Heat pump | 52.60 kWh | |
| Immersion | 8.40 kWh |
| Solar generated | 672.50 kWh 2026 | 747.90 kWh 2025 |
| Battery Charged / Discharged | 417.60 kWh | 413.20 kWh |
| Percentage generated by solar | 97.14% | |
| Self-sustained days (solar > consumed) | 13 | |
| Self-sustained days (solar > imported) | 22 |
Here is the Octopus Watch report summary
Octopus Watch summary
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.