The autumn months mean the solar generation from our 3.6kWp system starts to drop from the highs of the summer months.
Our Monthly Solar Performance
September 2024
Generation this month was 317kWh. It was 20% lower than September 2024's 399kWh, lower than the expected estimated monthly solar generation of 340kWh. Considering the weather this month it's not a surprise.
Due to the low solar generation and shorter days our self consumption of generation was 20%. This was actually 38% of our total home consumption (excludes EV consumption). This had dropped over the summer months when 50% of our home consumption was from solar self use. If we didn't charge the home battery overnight it would likely be much higher as there would be room in the home battery to store solar generation for us to use later.
We exported 254.54kWh (80%) of the 317kWh solar generation (317kWh). This produced an export payment of £38.18.
Generation per day over the month of September was a mixed bag. The middle of the month from 11th September to 18th September was great for 7 days as it produced 132.4kWh (41% of the total months solar generation)
There were 15 days over 10kWh and 7 days over 15kWh. Our highest daily generation was 14th September with 21.1kWh. There were 6 days under 5kWh. Our lowest was 2.4 kWh on 5th September.
By the end of September our solar panels had generated nearly 3438kWh since the start of last winter (1st December 2023). Thats 6% over the estimated generation so far of 3246kWh.
October 2024
October's solar generation was 235 kWh. That was 1kWh lower than the expected 236 kWh estimated generation.
Our self consumption this month of total electricity consumption was 10%.We exported 76% (179.5 kWh) of the overall solar generation of 235kWh
Our total imported electricity dropped to 533.1kWh as our EV went in for repair on 17th October.
Generation started off well in the first half of the month but started to decline towards the end of the month. Overall there were 9 days over 10kWh generation. There were 13 days with under 5kWh generation. The highest daily generation was 18.4kWh on 11th October.
We imported a total of 477.6kWh from the grid. 327kWh was for EV charging. Its quite obvious in the graph below that our imported electricity dropped off a cliff edge from 17th October. This was the date our EV failed and went away for repair on 17th October. It increased again on 31st October as we changed my wife's petrol car for an EV (and we fully charged it the night before a trip to the Lake District).
NOVEMBER 2024
November's generation took a nosedive due to the very poor start to November. High pressure over the UK gave us dry but very overcast conditions, no good fore solar generation! It took us 17 days to reach 50kWh. That was good considering it took 7 days to even reach double figures! The actual generation of 128kWh was lower than expected 162kWh.
The highest daily generation was 11.5kWh on 20th November. There were just 3 days over 10kWh generation. There were 18 days under 5kWh.
Our self use consumption was 12% as a percentage of total consumption. This was partly because our imported electricity use dropped because our high mileage EV was still away for repair. We had replaced our second car with an EV so we were still charging but at a much lower level.
Our daily electricity use still varied due to charging the EV. Its quite obvious when we charge the my wife's EV as our imported electricity consumption spikes! I expect we will charge my wife's EV once a week once I get mine back from repair.
Generation Performance
Solar generation in September (317kWh) was 7% below the estimated generation (340kWh). This wasn't surprising considering the rain.
Actual solar generation (235kWh) in October was just slightly below the estimated generation of 236kWh.
Solar generation in November was very low at 128kWh compared to the expected 162kWh. This was 21% under the estimated generation.
Overall autumn (680kWh) was 8% under the estimated generation of 738kWh.
For the year so far the actual generation (3801kWh) was still ahead of the estimated generation (3644kWh) by 157kWh. This was lower than the 4056kWh in 2023.
Savings
Unlike in 2023 we stayed on the same import tariff (Intelligent Octopus Go) and fixed export tariff (Outgoing Octopus) throughout the whole year. Due to the difference in import to export we charged the home storage battery overnight. We only charged the EV via the smart scheduling which ernabled EV charging to cost 7-7.5p/kWh. This made sure our EV charging costs were very low.
We exported 523.6kWh back to the national grid during the autumn months. Self use consumption accounted for 156.4kWh, all except 6.6kWh was consumed by our home. It doesn't make sense to charge the EV by solar as our daytime export is higher (15p per kWh) than the cost of overnight import (7p per kWh).
As expected savings from solar started to drop in autumn. Overall savings in autumn were £179.52. SEG export revenue was £78.54 from the 523.6kWh exported during autumn. Home unit rate import savings decreased in November because we were away for a week at the start of November.
SEG export revenue was lower than 2023 at £460.06 but extra revenue from the saving sessions and free electricity periods added £82.55, which made up for the lower export revenue from the fixed 15p/kWh export of Outgoing Octopus.
Overall the savings from Solar/home battery throughout 2024 were £963.35, which were slightly lower than 2023's £999.24. I'm quite impressed savings were nearly as higher as 2023 as the standard variable rate of electricity had dropped from 35p/kWh in 2023 to 23-25p/kWh during 2024.
Interestingly the overall savings followed a similar pattern to 2023 the difference between the seasons wasn't as great.
Over the year our home consumed 2002kWh of electricity, whilst the EV's consumed 6338kWh. This would have been higher if our high mileage EV was off the road from mid October and throughout November.
Whilst I expected overall savings to be higher in 2024 I hadn't factored in the decreased cost of electricity. Our overall unit rate averaged 7.9kWh in 2024. We exported 81% (3067kWh) of our solar generation in 2024, compared to 72% (2911kWh) in 2023. Thats quite good considering solar generation was
Summary
Key Statistics for Autumn:
* 680kWh generated.
* 523.6kWh exported.
* 156.4kWh (10% of overall consumption) self sufficiency from solar.
* £17952. saved.
* 21.1kWh (14th September 2024) highest daily generation in autumn.
Key Statistics for all four seasons
* 3801kWh generated
* 3067kWh exported
* 734Wh (9% of overall consumption) self sufficiency from solar
* £963.35 saved
* highest daily generation in 2024 - 26.1kWh (2nd June 2024)
2024 was much easier as we're getting used to having solar and home battery. Its been more stable as we've stayed on the same import and export tariffs throughout the whole year. I can't see us changing from Intelligent Octopus Go and Outgoing Octopus as it provides a good compromise between solar export and the cost of import to charge the EV for us.
The Octopriceuk.app website can give great a comparison of the costs of difference tariffs based on our use. At present the combination of Octopus Intelligent Go and Outgoing Fixed gives us the lowest cost difference of all tariffs. We could get more from our export but we would lose out on the cost of import.
This is a good explanation of why the best tariff for one person isn't necessarily the best for another person. Everyone's situation is different.