April Solar Generation and Export Numbers
Here is the overview for April 2025. Cosy Octopus had a small price rise in April as a new price cap came into effect. The three price times are still the same, 4am-7am, 1pm-4pm and 10pm until Midnight. The rate at those times is 14.14 per kWh. The price cap is 27.33p. There is a peak rate of 43.24p between 4pm and 7pm. All other times it is 28.83p. The batteries cover the two higher rates.
April set new records for solar production. We have never produced over 500 kWh in April in the previous two years. This month we generated 599.90 kWh and exported 19 out of 30 days. I count an exporting day as a day when we export more than 10p.
This year I am using a different approach to charging the batteries. As the Cosy rate is almost equal to the export rate, there is no point charging the batteries to try and export earlier in the day. When we were on Agile the price difference between import and export was larger. This year, I only charge the batteries if they are below 50% at 3.55am. This means we are exporting less as it takes longer for the batteries to fully charge. Saying that, we are only being charged around 60p a day from the grid. The majority of that is the standing charge. This means we only need to export 4 kWh to break even. This means we are greener, but making less profit.
This year we have had days 20 where we generated more solar than we consumed, and 38 days more solar was generated than we imported from the grid. In April, 29 days the solar generated more than we imported, and of those 18 days more than we consumed.
We also had One Octopus Saving Sessions that earned us 240 Octopoints, £0.30.
Below is the cost difference between heat pump and gas for April 2024 and 2025.
Heat Pump v Gas
| Month | Difference | Gas (2024) | Electricity (2024) | Gas (2025) | Electricity (2025) | |
|---|---|---|---|---|---|---|
| April | -15.81 | £38.61 | £33.46 | £11.06 | £45.20 |
According to the Octo-Aid app this was the breakdown of our usage per rate.
Grid Usage by Rate (High, Mid and Low)
You can see the heat pump statistics here.
The worst generation day was the 15th with only 7.00 kWh. The best was the 29th when 28.50 kWh was generated.
The best export day was the 5th with 12.60 kWh.
As solar panels output declines over the years I have added the 2023 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
Octopus Watch Tariff Comparison Report. This does not include exporting
Best Solar Generation
| 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 |
Solar Generation April 2025
| Date | kWh | |
|---|---|---|
| Best generation | 29th | 28.50 |
| Best front generation | 29th | 17.00 |
| Best back generation | 29th | 11.50 |
| Worst generation | 15th | 7.00 |
| Worst front generation | 15th | 3.40 |
| Worst back generation | 15th | 3.60 |
Best Solar Export and Profit
| 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 |
Solar/Battery Export and Profit April 2025
| Date | kWh | Income/Cost | |
|---|---|---|---|
| Best kWh export - Battery & Solar | 5th | 12.60 | |
| Best kWh export - Solar Only | 5th | 12.60 | |
| Best export profit | 5th | 12.60 | £1.89 (15p kWh) |
| Cheapest Day | 30th | £-0.76 |
The graph below shows the generation for both front and back panels
Solar generation for both front and back panels
The graph below shows generation, battery discharge, battery charging, export, import to use and consumption for 2025
Showing generation, battery discharge, battery charging, export, import to use and consumption for 2025
Generation
Overview for April
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
Front panel generation for for 2025
Back panel generation for 2025
Octopus Cosy
The costs shown here do include the standing charge. Any comparisons are compared to the unit cost if we were not on Cosy Octopus, which is 27.33p per kWh. The standing charge was 50.84p
April Grid Information
| Standard Tariff | 27.33p | ||
| Standing Charge | 50.84 | ||
| Cost from the grid | £30.39 (Cosy) | £55.34 (Standard) | |
| Savings including export | £41.81 | ||
| Exported | 112.40 kWh | £16.86 @ 15p kWh | |
| Charging slots used | 55 | ||
| Agile plunge slots used | 0 | ||
| Average unit slot price | 15.00p | ||
| Cheapest slot | 14.14p | ||
| Most expensive slot | 28.83p | ||
| House consumed | 582.10 kWh | ||
| Solar generated 2025/2024 | 599.90 kWh | 489.50 kWh | |
| Percentage generated by solar | 103% | ||
| Self Sustained Days 2025 (More solar than consumed) | 20 | ||
| Self Sustained Days 2025 (More solar than we imported) | 38 | ||
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.