Summer is when our solar system shines (pardon the pun). During the summer months it will produce its highest generation of the year.
Our Monthly Solar Performance
June 2024
Generation this month was huge, 558kWh, much higher tan the estimated monthly solar generation of 443kWh. It was just 4kWh short of June 2023's record highest ever month generation
The high generation meant our self consumption increased to nearly 53% for home use. Our self consumption has increased month on month since the start of the year as solar generation increased. Solar self use is still practically zero as we still aren't charging the EV using the excess solar as its better for use to export at 15p/kWh and charge the EV overnight at 7.5p/kWh.
As usual the bulk of our imported electricity is used to charge the EV (45.6kWh EV & 75.4kWh home use). As we are charging the EV and home battery at the same time 98% of our imported electricity is at the low rate (7.5p/kWh) lowering the cost of our energy bill.
466.63kWh of solar electricity was exported this month, producing a SEG export payment of £70. Revenue from SEG was 32% lower than in 2023 due to lower SEG rates. Last year we averaged 24p/kWh on Octopus Flux but this year we were paid 15p/kWh on Outgoing Octopus.
Where we are now saving is from imported electricity costs. June 2023 we paid £108.92 for 385kWh (average unit rate of 25p/kWh) on Octopus Flux. This year we paid £55.55 for 491kWh (average unit rate of 8p/kWh) on Intelligent Octopus Go. Being on an EV specific tariff is much better for us than a solar export orientated tariff.
In June our total energy bill (electricity and gas) was minus £4.95!
Generation per day over the month of June was very good, especially the second half of the month.
There were only two days below 10kWh and 12 days over 20kWh. Our highest daily generation was 2nd June with 26.1kWh. The lowest was 6.8kWh on 1st June. Talk about the tale of two very different days!
It should be noted the self use and energy exported figures from 7th June to 26th June in the graph above are wrong as their reporting was swapped around due to battery/EV charger installations experienced, which was resolved on 28th June.
By the end of June our solar panels had generated over 6MWh since installation in December 2022.
July 2024
July wasn't as good as June, which wasn't a surprise considering how brillant June was. July's generation of 483kWh was higher than the expected 452kWh.estimated generation. It was actually a take of two half's. By 16th July we had only generated 202kWh. 281kWh we generation in the final 15 days.
Our self consumption this month decreased to 11%, providing us with 79kWh of green electricity as we didn't charge the EV off the solar generation. We exported 404kWh of the solar generation to the national grid (84% of the overall solar generation). This is very different to easy July where we were charging the EV off the solar generation.
Just four days were under 10kWh, with nine days were over 20kWh. The highest being 24.1kWh on 29th July.
This month our EV solar charging was limited to just 0.3kWh due to changing the export margin to a level way above what our solar panels could produce. This allows the EV to remain plugged in early morning without charging from the early excess solar generation..
august 2024
August's generation was slightly below July's generation by only 5kWh. It was also much higher than the estimated generation of August (actual generation was 120% of the estimated 400kWh). That's quite impressive considering solar generation should start to drop after the expected peak generation of July.
The highest daily generation was 24kWh on 16th August. There were only 6 days under 10kWh generation, one of which was only 4.7kWh on 24th August.
Our self use consumption (10%) as a percentage of total consumption is still very low. This was mainly due to high EV consumption (650.9kWh) and very due to the fact we aren't charging the EV off solar generation. Due to the Octopus Outgoing fixed export rate (15p/kWh) being higher than the Intelligent Octopus low period rate (7p/kWh). Exporting the excess solar generation is worth more being exported than being diverted into the EV, which is charged much cheaper using low period imported electricity than solar generation. We also started every morning with a near full home battery as its charged overnight. This meant we were exporting solar generation earlier and not storing it in the home battery to use later.
Generation Performance
Generation performance in June was stunning, over performing the expected estimated generation by over 25% with a total of 558kWh.
July was 7% above the expected generation with 483kWh.
Solar generation was estimated to start to drop in August. In reality it was very slightly lower than July with 478kWh. This was 20% over the estimated generation.
Overall our actual generation has performed better than the estimated expected generation for our 3.6kW system. Actual generation (1519kWh) was 17% over the estimated generation (1295kWh).
For the year so far the actual generation is still ahead of the estimated generation by 215kWh.
Savings
We exported 1262kWh back to the national grid during the summer months. Self use consumption accounted for 256kWh.
Savings continued from spring into the summer month. Summer brought total savings of £291.49.
There was £189.39 revenue from the 1262kWh exported. Self use produced savings of £60.92. Home unit rate savings from charging the battery overnight gave savings of £39.80. Free electricity from Octopus' free electricity hours provided additional savings of £1.37.
Overall I'm impressive with a total savings so far of £783.82. If I included unit cost savings from electricity consumed by the EV overall savings would be around £1733.75 so far.
Summary
Key Statistics for summer:
* 1519kWh generated - slightly more than summer 2023's 1498kWh generated
* 1262kWh exported
* 256kWh (11.7% of overall consumption) self sufficiency from solar
* £291.49 saved
* 26.1kWh (2nd June 2023)
Summer savings 2024 compared to 2023
This summers savings of £291.49 were lower than summer 2023's £409.26 saving. This was mainly due to lower export revenue due to being on Intelligent Octopus Go tariff rather than Octopus Flux tariff. Lower electricity prices have also effected savings as standard variable tariff unit rates have dropped from 31p/kWh in 2023 to 23p/kWh in 2024.
The reason we have been on the Intelligent Octopus Go tariff rather than the Octopus Flux tariff is due to the lower cost of electricity to charge our EV. Due to our high EV electricity consumption were are much better off using the Intelligent Octopus import tariff than being on Octopus Flux for the slightly higher export revenue.
The import and export unit rates on Octopus Flux dropped in 2024 compared to 2023. Using 2023's consumption and export data the average export rate on Octopus Flux for us would be slightly above the export rate of Octopus Outgoing Fixed so there wouldn't be a big difference in export revenue this year.
When I looked at imported electricity it would have cost us more to be on Octopus Flux than Intelligent Octopus Go due to the higher import rate. Overall it would cost us £131.60 more on Octopus Flux than Intelligent Octopus this summer. We would have gained an extra £8.74 export on Octopus Flux but imported electricity would have costed £140.31 more than Intelligent Octopus Go.
If we looked at the overall bill cost, Octopus Flux would have meant we would have had to pay £89.30 this summer when export and import costs are considered. Intelligent Octopus Go import and export costs meant we would have been paid £42.30 as export revenue was higher than imported cost.
This is where comparison tools like www.octopriceuk.app are useful as at a glance its easy to see which import and export tariffs will work best for you.
