Spring is the usually the start of higher solar generation as winter ends and the sun hopefully comes out for the warmer months.
Our Monthly Solar Performance
March 2024
Generation this month of 293kWh was just slightly lower than expected the estimated generation of 312kWh for our solar system. Although it was higher than March 2023 266kWh.
Our self consumption of solar generated electricity was just 20% with the other 80% exported to the grid.Part of the reason for the low self consumption is due to the home battery being charged overnight during the low rate window. We still aren't diverting any excess solar generation to the EV as we can still export solar at 15p/kWh and import it back at a lower 7.5p/kWh overnight using Intelligent Octopus Go smart charging.
Just like last year solar generation started slowly and picked up towards the end of the month. There were 4 days over 15kWh. The highest daily generation was 19.1kWh on 30th March.
April 2024
Solar generation has really started to pick up and has been much better than March. This month our generation was 420kWh. That was higher than the estimated generation of 403kWh. We exported 348.1kWh of this generation back to the national grid.
Whilst our home electricity consumption was nearly 175kWh our self consumption of solar increased from 6% in March to 11% in April. This was likely due to the longer daylight hours and better weather. Due to the favourable lower import rate of 7.5p compared to export rate of 15p we were still charging the home battery overnight to enable more solar generation to be exported rather than stored in the home battery.
In April only 7 days were under 10kWh. We also saw 3 days over 20kWh which means 20 days were between 10kWh to 20kWh. The highest being 21.7kWh on 30th April, which was only slightly higher than the 21.6kWh on 14th April.
On 17th April our solar panels had generated a total of 5MWh since installation in December 2022. That's an impressive amount of electricity generated directly from our relatively small house roof.
May 2023
The first few days of May started off quite poorly but we soon had a week of very good solar generation. It was a very mixed month.There were 10 days over 20kWh, but also 9 days under 10kWh. We ended the month with a total of 470kWh. That was higher than the estimated 443kWh expected, but lower than last May's 487kWh.
The highest daily generation was 24.3kWh on 9th May. the lowest was 2.8kWh on 3rd May.
Our self use consumption (14%) started to increase with less reliance on the home battery being charged overnight. Due to a couple of occasions where the Zappi carried on charging the EV outside of the Intelligent Octopus smart charge schedule we did charge the EV from solar.
Overall we exported 81% of the solar generated to the national grid. Our imported electricity was slightly down on other months as the EV only covered 1600 miles. Unlike other months we made a long trip so we had done some charging away from home too.
Generation Performance
A poor start to March meant that month was slightly lower than the estimated generation. April and May saw slightly above estimated generation in both months.
So far this year actual generation is ever so slightly behind the estimated generation.
Savings
Unlike last year we now have more saving revenues. The saving sessions we saw during winter stopped in April. We should see kWh unit rate saving from charging the home battery overnight - we're often at 98% low rate imported electricity use so its making a huge difference as our average unit rate is now around 8p/kWh each month.
It's interesting to see the longer and better solar days from the start of spring to the end of spring have decreased imported electricity for home use as the higher solar generation means we are using more solar generated power in our home.
The savings have started to pick up in spring, although not as rapidly as expected due to the loss of income from saving sessions. We actually had a higher saving in December 2023 than March 2024, April 2024 and May 2024 due to the income from the Savings Sessions.
Spring brought total savings of £264.19. £144.63 was from SEG export payments as we exported a total of 964.2kWh this season. Self consumption of 218.8Kwh saved £53.10. Unit rate kWh savings from importing electricity during the low rate saved £55.96.
We should see savings continue throughout the summer months. Unlike last year we shall stay on the same import and export tariffs as winter. Intelligent Octopus Go works well for us. It is the import and export tariff I was hoping for last spring when I wanted tariffs that work both for solar and EV owners.
We lose some export revenue due to a lower export rate on Outgoing fixed (15p/kWh) when compared to the higher export rates on Octopus Flux, but as Octopus Flux export rates have been reduced due to the recent decrease in electricity prices its not much difference to last years rates.
The Octopus Flux day time export rate is now 15.51p/kWh and the higher peak rate is 25.85p/kWh. Last spring these export rates were 22.9p/kWh and 36.2p respectively. As the export rates are now much lower the average export rate we would have achieved on Octopus Flux would have been much lower than last years 25p/kWh. I'd estimate our average spring export rate on Octopus Flux this year would have been circa 17p/kWh. That's only a little bit more than the 15p/kWh export rate on Outgoing Fixed.
We do gain more from the lower import rates of 7.5p/kWh on Intelligent Octopus Go compared to the low rate of 15.15p/kWh for just 3 hours each day on Octopus Flux. It's also much easier to charge the EV on Intelligent Octopus Go, which is important for us as we do such high mileage.
Summary
Key Statistics for spring
* 1183kWh generated
* 964.2kWh exported
* 10.8% self sufficiency from solar
* £264.19 saved
* Highest generation - 24.3kWh on 9th May
Changes in savings through winter to spring
The change from winter to spring nearly gave total savings of similar amounts. It's interesting to see how savings change from different sources from winter to spring.
Whilst the move to the long days of sunshine obviously means savings increase due to higher solar export (£47.49 in winter to £144.63 in spring) the interesting point is the change that occurs in unit rate savings and self use.
The longer solar days in spring means there is an increase in savings from solar self use from £28.67 in winter to £56.49 in spring.This in turn reduces our reliance on the home battery, which decreases the total savings from lower unit rate from £88.41 in winter down to £55.96 in spring.
The winter Saving Sessions finish in early spring which means there are little savings from the saving sessions in spring (£7.11) from £63.57 in winter.
Spring 2024 has shown the benefits and potential savings that are possible with solar and home battery storage. We should see similar savings throughout the summer months.
Savings in spring 2024 (£264.19) were actually lower than spring 2023 ( £315.71). This is likely due to the lower electricity prices in 2024 compared to 2023. This means export rates are now lower, but we are also on a lower fixed export rate as we have to be on Intelligent Octopus Go to keep the cost of charging the EV as low as we can.
When I compare Octopus Flux import and export tariffs to Intelligent Octopus Go and Octopus Outgoing fixed is clear we are better off losing £133 on export income compared to paying £927 more on imported electricity.
Overall we are £794 better off on Intelligent Octopus Go than Octopus Flux because we import so much to charge the EV. This isn't the case for everyone so tariff comparison tools on the likes of OctoPrice are worth checking to see your best tariff.