Summer should be when our 3.6kWp system produces its highest generation of the year.
Our Monthly Solar Performance
June 2023
Generation this month was huge, 562kWh. It was 27% higher than the expected estimated monthly solar generation of 443kWh. That's an average of 18.7kWh per day.
The high generation meant our self consumption decreased to 27%. of total consumption. Even though this was lower than previous months it was actually our highest self consumption figure by kWh's so far. Even though the EV has caused our overall consumption figure the high self consumption figure was partly due to charging the EV using the granny charger to transfer some of the excess solar to the EV, and also due to adding a home battery. Due to installation issues the battery was switched off for most of the month, but the longer June days allowed the solar generation to cover more of our evening consumption.
419.9kWh of solar electricity was exported this month, producing a SEG export payment of £103.72.
Generation per day over the month of June was very good. There were only two days below 10kWh and 16 days over 20kWh. Our highest daily generation was 4th June with a huge 27kWh, which is beat the previous highest ever daily generation record set in May 2023.
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 2MWh since installation (actual generation sp far was 2260kWh).
July 2023
July wasn't as good as June, which wasn't a surprise considering how brillant June was. July's generation of 464kWh was still slightly higher than the expected 452kWh.estimated generation.
Our self consumption this month increased to 35%, providing us with 254.1kWh of green electricity. This meant our exported solar generation dropped to just 209.9kWh (just 45% of the overall solar generation).
Five days were under 10kWh, with just four days were over 20kWh. The highest being 26kWh on 7th July
The high self use was achieved by having a working home battery (145.9kWh of self use electricity), and also because the Myenergi Zappi EV charger allowed just the excess solar generation to be sent to the EV. This enabled the EV to be charged with 108kWh of green electricity from our own solar panels. That was enough electricity to drive 355 miles, or around 3/4 of a petrol tank in our previous Toyota Prius.
august 2023
August generation was slightly above July's generation, and also much higher than the expected 400kWh. Its quite impressive considering solar generation should start to drop after the expected peak generation of July.
The highest daily generation was 24kWh on 9th August. There were only 5 days under 10kWh generation.
Our self use consumption (27%) as a percentage of total consumption was lower than July. This was mainly due to the EV using less excess solar than it had the previous month. This was due to the EV often being out in the daytime. Once the EV was home the excess solar was being exported in the peak period between 1600-1900. Exporting the excess solar generation is worth more being exported than being diverted into the EV, which can be charged much cheaper using low period imported electricity.
The EV means our daily electricity use can vary greatly. We also had a home battery installed at the end of May. Since it’s been installed our home has hardly imported any electricity outside of the low period scheduled EV charge.
Generation Performance
Generation performance in June was stunning, over performing the expected estimated generation by over 25%. June was actually the hottest ever June on record in the UK which could explain the 562kWh solar generation.
July was just slightly above the expected generation but still good. Considering July was the hottest month ever recorded for global temperatures it wasn't so good in the UK due to a 'blocked weather pattern'.
Solar generation was estimated to start to drop in August. In reality it was slightly better than July with 472kWh.This was 18% over the estimated generation.
Overall our actual generation has closely matched the estimated expected generation for our 3.6kW system, the exception of course being June which was much higher than expected.
For the year so far the actual generation is still ahead of the estimated generation by 328kWh.
Savings
During the summer due to the longer evenings into the peak periods the Octopus Flux SEG payment averaged 23p per kWh. We exported 918kWh back to the national grid during the summer. Self use consumption accounted for 579kWh, the majority (365kWh) being consumed by the home due to the longer days of sunshine covering from 5am to 10pm. the home storage battery also helped increase self consumption and reduce imported energy to less than 35kWh by the house.
Savings continued from spring into the summer month. Summer brought total savings of £409.26. There was a £211.05 SEG revenue from the 914.7kWh exported. The export solar energy in the summer was lower than the 986kWh exported in the spring. Even though solar generation was higher in the summer exports dropped because self consumption increased to 583kWh from 225kWh in the spring. This self consumption increase was because the home storage battery was working from later June. The Zappi EV charger also helped to send only the excess solar to the EV during the day time too.
Overall I'm impressive with a total savings so far of £771.83. If I were to add in unit cost savings from electricity consumed by the EV overall savings would be around £905 so far.
The SEG export revenue will likely drop over autumn months due to the lower solar generation. The home battery shall likely store most of the lower solar generation rather than exporting it. Due to the the lower exports I'm looking to change from the Octopus Flux tariff to the Octopus Go EV tariff. Whilst SEG export will drop from 23p per kWh to just 4.1p per kWh I'm currently importing an average of 450kWh per month at an average 19p per kWh. The Octopus Go tariff will drop the unit cost down to 9.5p per kWh. That would cut the import cost from around £85 per month to around £42 per month. I will also start charging the battery in the low cost period each morning as solar generation can be quite sporadic in winter. Whilst this will result in more imported energy the overall unit rate of the imported electricity will be lower.
It will be interesting to see how autumn alters how solar performance.
Summary
Key Statistics for summer:
* 1498kWh generated
* 918kWh exported
* 579kWh (30% of overall consumption) self sufficiency from solar
* £409.26 saved
* 27kWh (4th June 2023) - highest ever daily generation
Our summer results show the benefits and potential savings that are possible with solar. The installation of a home storage battery means we have become less reliant on imports from the national grid for home use during the summer months. We do import around 1kWh per day from the grid. It is mainly because the home battery has to be 'switched off' to enable schedule charging of the EV during the low cost period. Even with this home import our overall imported electricity has been within the low cost cost for 98% of our 464kWh consumption in August. This is one of the benefits of smart tariffs as we've lowered overall unit rate from the standard flexible single rate tariff of 31p per kWh to just 19p per kWh. That's nearly a 40% saving on unit rate for imported electricity on the Octopus Flux tariff compared to the standard variable tariff.
Breakdown of unit rate period of August electricity consumption
It will be interesting to see how changing to an EV tariff will alter how we manage imported electricity, and also how it changes how we use our solar panels over the autumn and winter.