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Whole House Running Costs and Stats 2024

Whole House Running Costs and Stats 2024

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.

  • Regular 3 bedroom, 3 storey (with loft conversion) 1930’s semi detached in Sheffield.
  • 98sqm of floor space, EPC D rating at last inspection.
  • 2 adults, 2 teenagers, so definitely not scrimping on the hot water requirement.
  • Full electric house, no gas appliances.
  • 5.1kW of solar panels on a 3.68kW Solaredge Inverter
  • Lux AC 3600 inverter connected to 5 x 3.2kWh (16kWh total) of Hanchu batteries
  • 5kW Vaillant Arotherm air source heat pump (10 radiators)
  • 250L Mixergy water cylinder in a custom built plant room
  • Myenergi Eddi solar diverter
  • Myenergi Zappi EV charger (and solar diverter)
  • Heat pump tumble dryer
  • Induction Cooker
  • Octopus time of use tariffs (Intelligent Go used in 2024)

Most of these items have their own blog entry.

Table of Contents

  • Goodbye FIT 50% Deemed Export – an experiment
  • Yearly Solar Performance
  • Air Source Heat Pump Performance
  • Electricity Usage and Cost Breakdown
  • Breakdown of Energy Usage Device
  • Air Source Heat Pump Running Costs
  • Monitoring Equipment
  • Summary and Round-up

Goodbye FIT 50% Deemed Export – an experiment

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

Octopus Outgoing Yorkshire

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

My Solar Generation History

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.

Yearly Solar Performance

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

5 years with Solar PV

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!!

Air Source Heat Pump Performance

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

Second Winter With Our Vaillant ASHP

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.

  • 11,559 kWh of heat divided by 2735 kWh of electricity = 4.23 COP (or SCOP, seasonal coefficient of performance)

The split between heating and hot water looked like this

  • Heating: 7877 kWh (68% of usage) – Heat only SCOP: 4.45
  • Hot Water: 3682 kWh (32% of usage) – Hot Water only SCOP: 3.84

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:

My 5kW Vaillant Arotherm Heat Pump

You can also explore month by month performance of the heat pump in more detail here

Electricity Usage and Cost Breakdown

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

  • Filling the batteries every night as part of ditching the FIT exports experiment
  • Not discharging to the batteries during the off peak period (always importing at cheaper rate)
  • Running one of the two heat pump hot water runs overnight
  • Letting Intelligent Octopus Go schedule EV charging in off peak slots

On Octopus Intelligent Go the peak / off-peak breakdown is as follows

  • Off-Peak: 23:30 to 05:30
  • Peak: 05:30 to 23:30

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

  • January to end June: 7.5p
  • June to end December: 7.0p

Peak

  • January to end March: 29.6p
  • April to end June: 25.8p
  • July to end September: 22.3p
  • October to end December: 24.7p

Read more about Octopus Intelligent Go here

Intelligent Go Yorkshire

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

  • 24p price cap pricing (10,113 kWh): £2,427.12 (average £202 per month)
  • 24p price cap pricing (7,677 kWh): £1842.48 (average £154 per month)
  • 9.69p blended rate (7,677 kWh): 744.00 (average £62 per month)

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)?

Breakdown of Energy Usage Device

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.

Are Heat Pump Tumble Dryers cheaper to run?

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.

Goodbye Gas Meter

Air Source Heat Pump Running Costs

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

  • Solar / Battery / Time of use Tariff : £125.50
  • Excluding solar contribution: £267.83
  • 24p Price cap electricity: £663.36
  • 6p Price cap gas (85% efficient boiler): £816

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.

Monitoring Equipment

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.

Summary and Round-Up

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.

  • EV versus Petrol – £688
  • Solar Generation – £854
  • Solar Exports – £169
  • Difference between 10,113 kWh at 24p price cap versus my 9.69p imports – £1851
  • Heat pump using all the above versus 6p gas using a boiler – £691
  • No gas standing charge – £100

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.

Referral information and free credit offer

If you find the content of this website useful and are thinking of joining Octopus Energy, please consider using my referral code or ‘buy me a coffee’ to help support running costs of the website (hosting fees / cloud servers etc).

Using this referral code will gift you £50 of free Octopus Energy credit after signup: https://share.octopus.energy/linen-pearl-869

If you would like to ‘buy me a coffee’ to show support, please use this link: http://buymeacoffee.com/SVHgIbUYM

If you’re considering owning part of a wind farm through Ripple Energy, get £25 of free credit (if investing more than £1000) using my Ripple referral link.

Energy Stats can also be found on Twitter / X.  Please follow us @energystatsuk for daily tariff pricing graphs and summaries.

We have also started posting the same graphs over on Mastodon.  You can find us here: https://mastodonapp.uk/@energystatsuk

And now over on Bluesky too.  Find us here: https://bsky.app/profile/energystatsuk.bsky.social

And we are even trying to get the info out via Instagram.  Find us here: https://www.instagram.com/energystatsuk/

Note: The current and past performance of energy pricing is not necessarily a guide to the future.

Zarch