This post looks to detail all the running costs of our electrified house during 2024. That includes heat pump for heating and hot water, EV, cooking and everything else.
How much does it cost to run a fully electrified 3 bed semi in Sheffield with solar, batteries, heat pump and EV using time of use tariffs?
A quick reminder of our house and what equipment forms part of our renewable journey that started in 2018.
Most of these items have their own blog entry.
Table of Contents
Since my solar was installed in late 2018 I’d stuck with guaranteed deemed export payments as part of the Feed in Tariff.
Which meant that for every kWh I generated I was automatically paid around 6p per kWh for 50% of that generation. Known as ‘deemed export’.
You can read about export tariffs here
You can see here over the past 6 full years how much I generated, consumed, imported and exported.
Year | Gen | Avg Gen | Cons | Avg Cons | Import | Avg Import | Export | Avg Export | Export % of Gen |
2019 | 4244 | 11.6 | 3406 | 9.3 | 2044 | 5.6 | 2881 | 7.9 | 68% |
2020 | 4324 | 11.8 | 5298 | 14.5 | 2494 | 6.8 | 1517 | 4.1 | 35% |
2021 | 4151 | 11.4 | 6719 | 18.4 | 3088 | 8.5 | 518 | 1.4 | 12% |
2022 | 4419 | 12.1 | 10293 | 28.2 | 6361 | 17.4 | 483 | 1.3 | 11% |
2023 | 4065 | 11.1 | 10297 | 28.2 | 6541 | 17.9 | 310 | 0.8 | 8% |
2024 | 3561 | 9.7 | 10123 | 27.7 | 7687 | 21.0 | 1125 | 3.1 | 32% |
The above figures were taken from the following post
So in 2023 having generated 4,065 kWh, I was paid 2,032 kWh (half of 4,065) x 6.79p = £138 under deemed export terms.
Even though I only exported 310 kWh back to the grid.
For 2024 I decided to move from FIT deemed exports to Actual Exports and the Octopus Outgoing Fixed tariff where I would be paid 15p for every kWh that I did send back to the grid.
No 50% guessing now, I would be paid for what I was actually sending back to the grid as recorded by the smart meter.
Note: I left my generation payments on the Feed in Tariff and will continue to receive those for the life of the FIT contract.
I wanted to see how much I could send back to the grid.
Because I’m on Octopus Intelligent Go and I have batteries, I decided that every day I’d fill the batteries at 7.5p (7p later in the year). Yes, every day regardless. And also not discharge the batteries during the off-peak period.
I would then try and get through the day on a combination of solar and batteries and if there was any surplus solar it would go back to the grid and I’d get 15p for each kWh I’d send back.
So to break even on the experiment and match the 2023 deemed export payment I’d need to send back around 880kWh throughout the year.
Here is a breakdown of how things went.
Solar Gen (kWh) | Exported (kWh) | Unit Rate (p) | Earned |
115 | 5 | 15 | £0.75 |
145 | 10 | 15 | £1.50 |
263 | 34 | 15 | £5.10 |
388 | 94 | 15 | £14.10 |
449 | 180 | 15 | £27.00 |
531 | 249 | 15 | £37.35 |
509 | 232 | 15 | £34.80 |
457 | 189 | 15 | £28.35 |
257 | 70 | 15 | £10.50 |
243 | 47 | 15 | £7.05 |
121 | 10 | 15 | £1.50 |
83 | 6 | 15 | £0.90 |
3561 | 1126 | £168.90 |
By the end of the year we had exported 1126 kWh.
So at 15p per kWh, that earned us £168.90, an increase of around £30 compared to the £138 deemed export of 2023.
Whilst not a massive improvement, moving from deemed export to actual export meant that we could also take part in demand flexibility events (DFS) and get rewarded sending back to the grid during those times too.
Something that isn’t possible if you stay on old FIT deemed exports as you need your exports to go through your smart meter, which they do on ‘actual exports’.
Whilst I didn’t make a note of what I received during those saving sessions, I did recall some of the events paying up to £3.50 per kWh. So they could be pretty lucrative.
I think being on actual exports seems the best option moving forward, although with Octopus and other suppliers possibly reducing the export rate from 15p it does seem one to watch.
Whilst right now, importing at 7p overnight and exporting at 15p is a no brainer. If the export rate reduces, perhaps it won’t be? Perhaps the myenergi Eddi and Zappi solar diverters come back into play?
Maybe you’d look to import less into the battery overnight and make more use of the generated solar in the house rather than send it back to the grid?
I just think you need to keep your options open and ensure the technology you buy has the flexibility moving forward to adapt to market swings.
For example, don’t buy ‘dumb’ batteries with poor controls. Look at battery systems that have the potential to talk to smart tariffs.
Let’s take a look at the whole year of solar PV generation with a month by month breakdown.
Month & Year | Gen | Avg Gen | Cons | Avg Cons | Import | Avg Import | Export | Avg Export | Export % of Gen |
Jan-2024 | 115 | 3.7 | 1205 | 38.9 | 1095 | 35.3 | 5 | 0.2 | 4% |
Feb-2024 | 145 | 5.0 | 1009 | 34.8 | 873 | 30.1 | 10 | 0.3 | 7% |
Mar-2024 | 263 | 8.5 | 1080 | 34.8 | 850 | 27.4 | 34 | 1.1 | 13% |
Apr-2024 | 388 | 12.9 | 858 | 28.6 | 564 | 18.8 | 93 | 3.1 | 24% |
May-2024 | 449 | 14.5 | 592 | 19.1 | 323 | 10.4 | 180 | 5.8 | 40% |
Jun-2024 | 531 | 17.7 | 573 | 19.1 | 293 | 9.8 | 249 | 8.3 | 47% |
Jul-2024 | 509 | 16.4 | 665 | 21.5 | 387 | 12.5 | 232 | 7.5 | 46% |
Aug-2024 | 457 | 14.7 | 633 | 20.4 | 365 | 11.8 | 189 | 6.1 | 41% |
Sep-2024 | 257 | 8.6 | 727 | 24.2 | 541 | 18.0 | 70 | 2.3 | 27% |
Oct-2024 | 243 | 7.8 | 706 | 22.8 | 509 | 16.4 | 47 | 1.5 | 19% |
Nov-2024 | 121 | 4.0 | 921 | 30.7 | 810 | 27.0 | 10 | 0.3 | 8% |
Dec-2024 | 83 | 2.7 | 1154 | 37.2 | 1077 | 34.7 | 6 | 0.2 | 7% |
Total | 3561 | 9.7 | 10123 | 27.7 | 7687 | 21.0 | 1125 | 3.1 | 32% |
Around March time I noticed that one of my panels was not generating any power. Further investigations found that the optimiser under the panel was dead and that panel had not been generating any power since January. The others were all okay.
SolarEdge exchanged the faulty optimizer for free under warranty (their products have a 25 year warranty), but they don’t pay any labour charges to get the unit swapped.
Because of where it was located on the roof I needed to get scaffold erected to safely get it swapped.
The original installer of my system is no longer trading so I found a local installer to come and help.
Homeco Energy (https://www.homecoenergy.co.uk/) had been recommended to me by a friend, so I went with them and they did a great job for me. I would recommend them if you’re in the Sheffield, Yorkshire or Derbyshire area.
But this meant I was a whole panel down in generation from January up until I was able to get the work completed in September.
You can see this when we look back at historical yearly generation. There is a marked reduction in 2024 compared to previous years.
It’s crazy that one 300 watt south facing panel could contribute so much!
Year | Gen | Avg Daily Gen |
2019 | 4244 | 11.6 |
2020 | 4324 | 11.8 |
2021 | 4151 | 11.4 |
2022 | 4419 | 12.1 |
2023 | 4065 | 11.1 |
2024 | 3561 | 9.7 |
But even generating just 3,561 kWh, you could put a street value of £854 on it when you price this at 24p per kWh price cap energy.
My solar install has already paid for itself in the first 6 years as detailed in this article
I continue to absolutely adore my solar install. Best thing I ever did.
It started this whole renewable journey for me. Definitely the gateway drug!!
2024 was the second full year (January to December) with our 5kW Vaillant Arotherm heat pump having been installed in October 2022.
Month / Year | Electric Input kWh | Heat Output kWh | SCOP |
2023 | 2856 | 10718 | 3.75 |
2024 | 2735 | 11559 | 4.23 |
That first full year was definitely a big learning curve for us, working out how best to use it.
I feel that in the second full year we had a better handle on how to tweak the system and get more efficiency out of it.
You can see this in the direct year to year comparison.
Despite needing more heat output in 2024 we actually used less electricity because of the efficiency gains.
Read about some changes and thoughts in this article after last winter
The heat pump produced 11,559 kWh of heat output to heat the house and provide all the hot water, using just 2,735 kWh of electricity to do that.
Which is where the COP (coefficient of performance) of 4.23 comes from.
The split between heating and hot water looked like this
Looking around at other heat pumps on https://heatpumpmonitor.org/ I know we are high users of hot water compared to many.
But we are a family of four with 2 teenagers!! Who seem to love just standing in the shower!!!
Let’s look at a monthly breakdown of stats in more detail.
Month / Year | Electric Input kWh | Heat Output kWh | COP | Outside Low | Outside Avg | Outside High | Avg Room | Heating % | DHW % |
Jan-2024 | 503 | 1956 | 3.89 | -5.3 | 4.3 | 13.1 | 19.6 | 81 | 19 |
Feb-2024 | 332 | 1409 | 4.24 | -0.8 | 7.1 | 15.7 | 19.7 | 78 | 22 |
Mar-2024 | 318 | 1380 | 4.34 | -1.1 | 7.3 | 14.9 | 19.9 | 76 | 24 |
Apr-2024 | 238 | 1011 | 4.25 | 0.3 | 9.2 | 18.9 | 20.1 | 69 | 31 |
May-2024 | 103 | 421 | 4.09 | 6.2 | 14.4 | 23.9 | 20.9 | 32 | 68 |
Jun-2024 | 101 | 412 | 4.08 | 4.9 | 15.0 | 27.0 | 21.3 | 35 | 65 |
Jul-2024 | 79 | 326 | 4.13 | 7.1 | 16.7 | 27.8 | 21.8 | 16 | 84 |
Aug-2024 | 65 | 247 | 3.80 | 7.1 | 16.5 | 25.5 | 21.9 | 13 | 87 |
Sep-2024 | 117 | 509 | 4.35 | 2.8 | 12.7 | 22.8 | 20.6 | 40 | 60 |
Oct-2024 | 180 | 837 | 4.65 | 1.2 | 10.2 | 16.2 | 19.9 | 58 | 42 |
Nov-2024 | 343 | 1434 | 4.18 | -4.5 | 6.6 | 13.8 | 19.7 | 74 | 26 |
Dec-2024 | 356 | 1617 | 4.54 | -0.6 | 6.4 | 12.8 | 19.8 | 75 | 25 |
Total | 2735 | 11559 | 4.23 |
I’m really happy heading into 2025 with the heat pump.
You can see the performance gains (COP) later in the year in October, November and December versus January, February and March, showing even more efficiency to come this next year.
I will be publishing a “third winter with our heat pump” article at the end of the winter heating season where we can summarise what changed etc.
But it won’t be much above what i’ve already shared in previous articles; open loop, no zoning/valves, use weather compensation, low and slow heating, low compressor mode hot water etc.
You can read more about the heat pump installation here:
You can also explore month by month performance of the heat pump in more detail here
In 2024 the whole house (and EV) consumed 10,113 kWh of electricity.
At 24p price cap pricing, this would have cost £2,427.12 (average £202 per month).
The solar array generated 3,561 kWh which left 7,677 kWh that we had to import (10,113 kWh minus 3,561 kWh).
This would have been £1842.48 at 24p price cap pricing (average £154 per month).
Of that 7,677kWh, 940 kWh was imported at peak rates (12%) and 6,742 kWh was imported off peak (88%).
You can see in this graph from Smarthound Octopus Watch the average spread over my imports throughout the year across the 48 x 30 min daily slots. With a heavy weighting towards overnight and off-peak.
This high off peak percentage was due to a combination of factors
On Octopus Intelligent Go the peak / off-peak breakdown is as follows
Note: you can sometimes get ‘extra’ slots when the grid is green or your car has a big battery that needs filling, but we primarily stuck to the normal slots.
The off-peak and peak pricing looked like this throughout the year.
Off peak
Peak
Read more about Octopus Intelligent Go here
Here is a breakdown showing the amount of off-peak and peak electricity imported each month.
In the final two columns you can see the average unit rate paid and the total amount paid for each month.
Month | Imported (kWh) | Import Peak (kWh) | Peak % | Import Off Peak (kWh) | Off-Peak % | Avg Unit Price (p) | Monthly Cost |
January | 1107 | 244 | 22 | 863 | 78 | 12.44 | £137.71 |
February | 885 | 124 | 14 | 761 | 86 | 10.68 | £94.52 |
March | 860 | 95 | 11 | 765 | 89 | 9.94 | £85.48 |
April | 576 | 23 | 4 | 553 | 96 | 8.18 | £47.12 |
May | 337 | 17 | 5 | 320 | 95 | 8.36 | £28.17 |
June | 303 | 15 | 5 | 288 | 95 | 8.41 | £25.48 |
July | 398 | 12 | 3 | 386 | 97 | 7.52 | £29.93 |
August | 274 | 25 | 9 | 249 | 91 | 8.35 | £22.88 |
September | 541 | 54 | 10 | 492 | 91 | 8.49 | £45.93 |
October | 509 | 31 | 6 | 478 | 94 | 8.01 | £40.77 |
November | 810 | 130 | 16 | 680 | 84 | 9.88 | £80.03 |
December | 1077 | 172 | 16 | 905 | 84 | 9.84 | £105.98 |
Total | 7677 | 940 | 12% | 6742 | 88% | 9.69 | £744.00 |
Across the whole 12 months, our fully electrified house (including EV) cost us £744 in imported energy (excluding standing charges). So an average of £62 per month.
With the average import cost per unit across the whole year being 9.69p per kWh. We can call this the ‘blended rate’. Ie, the average unit rate paid across the whole year.
For comparison
Remember from earlier, we also earnt £168 by exporting 1126 kWh back to the grid.
Bringing the total spend down to £576 (£744 – £168 = £576). Average £48 per month.
None of the above includes the 3,561 kWh of electricity solar generated in 2024 that we put at an estimated value of £854 (3,561 kWh x 24p price cap energy).
So you could say the value of electricity we generated from the solar array (£854) was more than our import costs for the year (£576)?
Using Open Energy Monitor to track usage of big items using CT clamps and using Localbytes smart plugs for the smaller appliances I can provide month by month usage for lots of devices in the house as well as yearly totals.
Solar Generation | EV | ASHP | To Battery | Washing Machine | Tumble Drier | Induction Cooker | Dishwasher | |
January | 115 | 141 | 512 | 554 | 26 | 20 | 24 | 19 |
February | 145 | 142 | 330 | 492 | 35 | 22 | 32 | 32 |
March | 263 | 189 | 339 | 488 | 40 | 23 | 36 | 36 |
April | 388 | 147 | 241 | 351 | 29 | 13 | 37 | 37 |
May | 449 | 45 | 103 | 225 | 30 | 9 | 31 | 30 |
June | 531 | 46 | 101 | 179 | 31 | 8 | 30 | 30 |
July | 509 | 88 | 78 | 232 | 22 | 10 | 31 | 31 |
August | 457 | 95 | 64 | 222 | 15 | 8 | 25 | 25 |
September | 257 | 161 | 117 | 322 | 22 | 10 | 30 | 30 |
October | 243 | 93 | 180 | 363 | 19 | 13 | 23 | 23 |
November | 121 | 110 | 343 | 470 | 25 | 18 | 29 | 20 |
December | 83 | 291 | 356 | 515 | 30 | 15 | 34 | 23 |
Total | 3561 | 1548 | 2764 | 4413 | 324 | 169 | 362 | 336 |
The EV used 1,548 kWh and if we assume 4 miles per kWh, which is fair for our Hyundai Kona, that’s around 6,192 miles.
And knowing that all the EV electricity was purchased off peak at either 7.5p (January to June) and 7.0p (July to December), let’s say an average of 7.25p for simplicity.
1,548 kWh x 7.25p = £112 for 6,192 miles.
That’s madness, right?
What would 6,000 miles cost in petrol?
Assume £1.35 per litre (Jan 2025 prices) and 45 miles per gallon
That would be £800 in fuel using this calculator
https://www.fleetnews.co.uk/costs/fuel-cost-calculator
An astonishing difference.
If you can charge at home and you’re okay with any range limitations your driving circumstances may present, then you could save a lot of money moving to an EV.
And EV are so much nicer to drive in our opinion. My wife has said she’d never go back to a petrol car now.
That means the EV used £112 of the £576 yearly import total, leaving the rest of the house at just £464 (heating, hot water, cooking, living etc). Average £39 per month.
It was fun putting the smart plugs on the smaller devices and seeing the monthly and yearly totals on things like the washing machine, tumble dryer and dishwasher etc.
Note: we have a heat pump tumble dryer which has proved way more efficient than our old condenser model.
It was also our first year with an induction cooker. We had always been on gas since forever.
We bought a 600mm wide standard induction cooker the first week in January and it’s been amazing. We’d never go back to a gas cooker now.
Ditching the last gas appliance meant we could have the gas meter removed which has saved us around £100 this year in standing charges.
This table shows a monthly breakdown of the amount of electricity used by the heat pump in providing all our heat and hot water throughout the year.
Heat Pump Usage (kWh) | Solar Gen (kWh) | Shortfall (kWh) | Avg Unit Price (p) | Import Cost | |
January | 512 | 115 | 397 | 12.44 | £49.39 |
February | 330 | 145 | 185 | 10.68 | £19.76 |
March | 339 | 263 | 76 | 9.94 | £7.55 |
April | 241 | 388 | 8.18 | ||
May | 103 | 449 | 8.36 | ||
June | 101 | 531 | 8.41 | ||
July | 78 | 509 | 7.52 | ||
August | 64 | 457 | 8.35 | ||
September | 117 | 257 | 8.49 | ||
October | 180 | 243 | 8.01 | ||
November | 343 | 121 | 222 | 9.88 | £21.93 |
December | 356 | 83 | 273 | 9.84 | £26.86 |
Total | 2764 | 3561 | 1153 | £125.50 |
The table also shows how much solar we generated each month.
You can see that for 7 months of the year (April to October) we generated more electricity from the solar array than the heat pump used.
And even in the other months (November to March), the solar array still contributed at least a quarter of what the heat pump needed.
This table really highlights that if you have solar (and battery) getting a heat pump is a bit of a no brainer!
Having made the assumption that the energy generated by the solar (and stored in the batteries) covered the heat pump from April through to October, the running costs are therefore nil for those months as there are no import costs.
For the other months I’ve calculated the shortfall (heat pump used minus solar) and then used the average unit rate of import we paid to calculate the monthly cost of what remains.
The import shortfall for the whole year was £125.50.
But what If we exclude the solar contribution, just take the whole of what the heat pump used (2,764 kWh) and use the average 9.69p unit price across the whole year.
2,764 kWh x 9.69p = £267.83
What about at 24p price cap rates?
2,764 kWh x 24p = £663.36
Finally, what about comparing the heat pump to an 85% efficient gas boiler using 6p price cap gas rates?
The heat pump outputted 11,559 kWh of heat.
On an 85% efficient boiler you’d need to buy 13,600 kWh of gas to get that amount of heat.
13,600 kWh gas x 85% = 11,560 kWh heat output.
13,600 kWh gas x 6p price cap = £816
Note: I won’t include the electricity required by the boiler for running the electronics and the pumps as that would be too pedantic. LOL
Heat pump running costs comparison
One of the main reasons the heat pump running costs are low is because the heating system has been designed to be efficient and achieve a whole year SCOP of over 4.
Which goes to show that design is king when looking at a heat pump. Ensure you get someone who knows their stuff, like a Heat Geek.
I wrote an article where I try to help demystify the relationship between heat pump COP/SCOP and the amount you would pay for your heating and hot water.
The smaller appliances in the house are monitored using smart plugs from Localbytes.
I’ve configured them to pass the data through into Home Assistant for easy aggregation.
The larger electrical items in the house are monitoring by using CT clamps attached to Open Energy Monitor electrical kit. So I monitor the solar, EV, batteries, induction cooker etc using CT clamps.
All heat pump monitoring is also done by Open Energy Monitor, but using their billing grade approved heat pump equipment. Both heating and electrical.
My heat pump is then tracked alongside many others as part of https://heatpumpmonitor.org/
You can track mine individually via https://emoncms.org/energystatsuk
For electricity pricing data I use Octopus Watch by Smarthound (https://octopus.smarthound.uk/)
It has some great reports and shows breakdown of peak and off-peak usage etc.
Solar, Batteries and Heat Pump and well are truly the Holy Trinity.
If you then add Time of Use tariffs and an EV you’ve got an amazing complete package that is capable of slashing your electricity import costs.
If you already have solar and batteries then an EV could open up more tariffs for you like Intelligent Go.
Which then makes getting a heat pump almost a no brainer as the numbers here have shown.
You could make the case that I’ve saved literally thousands of pounds in 2024 making use of all the technology.
Granted, some of those are counting twice in some ways, but you get the idea.
Yes, there is an initial outlay with all the equipment and it’s up to you whether you think that outlay is worth it over the long haul. I can only provide real world figures here from our house for you to make your own mind up.
The above savings are just for one year of course, but all the investments will continue to reap rewards for years to come, just as they have already done in the past.
I hope you’ve found this information useful.
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Energy Stats can also be found on Twitter / X. Please follow us @energystatsuk for daily tariff pricing graphs and summaries.
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Note: The current and past performance of energy pricing is not necessarily a guide to the future.
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