This is the eighth full month with the solar being active.
Energy prices remained the same for this month, although there was 1 ‘Saver Session’ during the month.
December Electric:
The average daily consumption, including solar, for the month of December was 56.50kWh, solar production was pretty poor with a low of 0.95kWh and a high of 6.90kWh.
This in turn reflects quite visibly in the cost chart where we have a low of £4.42 and a high of £8.36 for peak electric usage.
Most days were overcast/wet as they have much larger dark blue sections than some previous months, the see-saw/sawtooth pattern for the Off-Peak is as usual due to whether or not the car was charged that night.
The average peak to off-peak percentage usage for the month was 45.99%, mainly because of the bad weather.
Average usage: off-peak 29.17kWh, peak 24.84kWh, total 54.01kWh
Average costs: off-peak £2.04, peak £6.64, total £9.17 (including standing charge of £0.4557)
December Gas:
The heating was on for the entire month, highest gas usage was 117.99kWh and the lowest 65.27kWh – £7.34 and £4.34 respectively (including the standing charge of £0.2747).
Average usage: 100.52kWh, average gas tariff was £0.0610.
Average cost: £6.41 (including standing charge of £0.2747)
Total daily energy average cost for November: £15.58 (including standing charges of £0.7304).
Total costs for December were £63.30 off-peak, £205.76 peak, £198.81 gas, £483.00 overall (including standing charge of £23.64).
December 2023 costs were £61.18 off-peak, £487.07 peak, £172.58 gas, £709.24 overall (including standing charge of £20.82).
This is a 32% saving compared to 2023!
December costs for 2024 using Dec 2023 E-ON tariffs £113.57 off-peak, £268.26 peak, £209.93 gas, £591.76 overall (including standing charge of £31.37).
So the practical saving was £108.97 vs staying on my old E-ON tariffs.
I also had my SEG tariff but did not export any electricity worth noting.
I will again use the same assumption as always of 14.5kWh of battery, there were no days where I carried some battery charge to the next day.
So for this month, I have 31 days of solar production which means 14.5kWh x 30 days = 449.0kWh for the batteries that need to ‘swap’ from off-peak to peak rate.
I then produced 92.58kWh of solar, none of which was given back to the grid.
This means that the additional savings for having solar and batteries are (449.0kWh * (£0.2672 – £0.070)) + ((92.58-0.00)kWh) * £0.2672), = (435.0kWh * £0.1972) + (92.58kWh * £0.2672) = £88.62+ £24.73 = £113.36
Which in effect means that I have saved £113.36 + £108.97 + £0.00 = £222.33 compared to my old E-ON tariff and no solar/batteries for the month of December.
These are the graphs of forecast vs actual production:
Not sure why I collected no forecast data for the 27th, this has happened a few times now
Month on month usage and cost graphs for 2024 (now including exports) for Electricity:
and the same for Gas:
As mentioned at the start of this post, there was a ‘saver session’ during the month, where you try and use as little electricity as possible, compared to your normal usage as viewed over the past 7-10 days during the hours in question, which this time was 18:00 – 19:00.
The session was on 11th of December, however I only noticed the email about an hour before the event was due to start.
The offer was 480 Octopoints (£0.60) per kW of power saved.
I immediately started charging the batteries, and then stopped as soon as the event started, I did not have enough charge to also perform a forced discharge.
I managed to save 1.467kW compared to my normal usage (about 1.7kW) which in turn equated to a saving of 704 Octopoints (£0.88).
Had I had more time to charge up, I would also have force discharged my batteries as I would potentially make £0.33 (£0.60 – £0.267) profit vs charging at peak rate for each kW exported.
Hopefully I will notice the email earlier and ave more time to charge up the batteries next time.