Updates and GreenTech News

We have now assembled the 2023 full year data for energy performance, cash savings, and emissions reduction at our home, resulting from our use of electricity for all our driving, heating, lighting, and all other domestic uses. The results, summarised in this infographic are strongly positive, and have improved cash and carbon savings by around 10% Year on Year, even compared to the very good results achieved in 2022.

In short, we eliminated 27.916 tonnes of CO₂ emissions and saved £21,118 in cash

Our savings of 27.916 tonnes of CO₂ emissions and £21,118 in cash, are calculated compared to an ‘OldTech’ baseline as follows:

• Driving 25,817 miles (41,548 km) in EVs, rather than petrol cars of equivalent size, saved us over £7,000 in cash and eliminated around 5 tonnes of CO₂ emissions.
• Using an Air Source Heat Pump (ASHP), rather than an oil boiler, for central heating and domestic hot water, saved us nearly £4,000 in cash and eliminated around 14.5 tonnes of CO₂ emissions.
• Maximising the use of our on-site batteries to import cheap off-peak grid power, and to store the surplus energy from our 7.5MWh of on-site solar generation, saved us well over £11,000 in cash compared to the UK regulated ‘Price Cap’ rate per kWh. Using an officially-certified 100% renewable electricity tariff also eliminated around 8.5 tonnes of CO₂ emissions compared to the UK grid average for all suppliers.
• We also received around £2,400 in Government incentive payments, which pay out gradually over time to offset some of the upfront costs we incurred for installing some of the solar array (Feed In Tariff – FIT) and the ASHP (Renewable Heat Initiative – RHI). 
• A small part of the incentives received, just over £100, was paid by our energy supplier for our participation in the National Grid Demand Flexibility Service during November and December 2023. DFS pays consumers not to use electricity at times of grid stress, which typically occur when renewable generation is low and demand is high in the evening peaks. Not using electricity in these periods reduces the need to switch on polluting coal and gas fired power stations. Because we have 39 kWh of battery storage available, we are able reduce our grid consumption to absolute zero during the DFS ‘Savings Sessions’.

The ‘hard cash’ economics worked out as set out below.

• Our total energy cost for 2023 was was £3,612 paid to our grid electricity supplier. This one cost covers all the energy we used to power and heat our home, and to power the 25,817 miles (41,548 km) we drove in our cars.
• Offsetting this cost, we saved a total of £22,347 by not buying petrol for the cars, by not buying heating oil for a boiler, and by leveraging our batteries to access a Smart Energy grid supply tariff and therefore not buying energy at the OFGEM ‘price cap’ rate for standard rate electricity.
• Further offsetting the cost, we also received a total of £2,384 in FIT, RHI and DFS incentive payments.
• The 2023 full year Net Financial Benefit to us was £21,119. (£22,347 + £2,384 – £3,612)
• Our total net cost of energy for the full year 2023 was only £1,228, covering all home and motoring consumption. This result is produced by subtracting the £2,384 incentive payments we received from the £3,612 bill we paid to our grid electricity supplier.
• Therefore, our total energy cost was only £3.36 per day, which is less than the typical £4.05 price of a Grande Cappuccino at a well-known coffee chain.
• The net price we paid for electricity after incentives was only 3.28p per kWh, averaged over the year. This takes into account our mix of 19.8% solar, 56.1% off-peak grid, and 24.1% peak grid usage.  This compares with the OFGEM ‘price cap’ rate, which varied between 26.58p/kWh and 33.66p/kWh during 2023, in our grid region (Northern England).
• We achieved these savings using the Intelligent Octopus Go Faster tariff for our grid energy. This excellent package works really well for us, providing a minimum of 6 hours cheap overnight electricity at around 25% of the peak-hours cost, but it’s only available to customers who have an electric vehicle. Here’s a link if you’d like to know more. If you sign up to Octopus via the link you will receive £50 off your first bill. For full disclosure, we will receive a £50 referral bonus.

During 2023 the difference in cost between off-peak and peak electricity prices widened significantly as a result of the Ukraine war. This prompted us to invest in one further Tesla Powerwall battery, additional to the two already installed, primarily to increase our capacity to import very cheap overnight off-peak electricity, which now costs around four times less than peak-time power.

The additional battery increased the total capital we have invested to nearly £146,000, but bear in mind that this figure includes two EV cars (a Tesla Model X and a Nissan Leaf), in addition to a 32 panel solar array, and the 3 Tesla Powerwall batteries installed in phases over approximately a decade from 2014 onwards, and a complex ASHP system added in late-2021. 

Despite the heavy up-front capex, the system is performing ahead of projections, and is on course to fully pay back the £146,000 investment cost in a total of 6 years 11 months. Taking into account the lower savings we achieved as parts of the system were gradually installed over the seven year period 2014 to 2021, plus the £19,000 we saved in 2022, plus the £21,000 saved this year, we’re accounting the system as 75% paid-off at 31 December 2023. Depending on the amount of sunshine and the price of grid energy, we expect the system to have fully paid for itself by around mid-2025, fully including the cost of both cars. From that point onwards, it’s ‘pure upside’.

Comprehensive data is available in the 2023 Final Report here. It’s a 15 page PDF which presents the information summarised here in full. It can also be accessed by clicking the image at the end of this post.

For comparison, you can view the 2022 Final Report here. In that year, we saved over £19,089 in energy costs, and eliminated 25.5 tonnes of CO₂ emissions.

Some thoughts on policy & Net Zero finance

We recognise that we are dealing with a large house here, and that (because we have worked hard and taken risks in our careers) we are in the fortunate position of being able to invest capital up front, in order to save operating costs over time. We fully acknowledge that only a minority of people are in such a position.

In part, we are publishing this data to show what can be achieved if a means is found to enable every household to afford the up-front cost of installing the technologies that will get us collectively to Net Zero.

In this broader context, the data we are publishing provides hard evidence, for policymakers as well as individual citizens, of the financial benefits which flow over time to households making an upfront capital investment in Net Zero technologies. 

Although the GreenTech investment in the average home is likely to be smaller (and therefore cheaper), it is self-evident from the results that the substantial financial benefits accruing to any household making such an investment will provide a sustained and predictable stream of income and/or savings. It is precisely this long-term financial predictability which unlocks the possibility of mortgage lenders or social housing finance providers advancing the necessary up-front capital, to be repaid over time from a contractually-guaranteed slice of the savings. 

Such an arrangement could perhaps be underwritten by some form of Government ‘backstop of last resort’ if required. Governments frequently provide such ‘backstops’, to underpin the long term finances of centralised projects, such as multi-decade programmes to build nuclear power stations which produce electricity, for example. 

Far more rapid results will be achieved by decentralising the investment over the tens of millions of households which consume electricity, most notably by decarbonising domestic heating, by substituting ASHPs for gas boilers, and by installing ‘edge of grid’ energy storage in every home and business premises. Such storage essentially ‘parks’ surplus renewable energy, distributed gradually in off-peak hours, where it’s actually needed. This is a far more rational, and massively cheaper, alternative to agglomerating surplus renewables only in multi-billion pound centralised storage, which then requires multi-billion pound grid upgrades, to allow for ‘distressed distribution’ to tens of millions of points of use, during peak peaks, which will inevitably occur when the wind isn’t blowing in the North Sea and/or the sun isn’t shining on the solar fields around the country.

And here’s the no-brainer. Using a Government guarantee to underwrite a single multi-billion pound project has, by definition, a 1-in-1 exposure to the risk of that project failing and the ‘banker of last resort’ having to pay up, or otherwise bail out the project. Micro-slicing that same type of guarantee into a national programme to equip the UK’s millions of households with Net Zero technology, on the other hand, massively spreads the risk. Reduced to its basics, a 1-in-30,000,000 million risk exposure beats 1-in-1 hands down!

Plans for 2024

No further upgrades or expansions of our GreenTech systems at home are currently planned for 2024. We anticipate simply continuing to operate the system, and continuing eliminate many tonnes of CO₂ and save tens of thousands of pounds.

However, we will be completing a very significant new project in the year ahead. We’re taking everything we’ve learned from transforming the energy performance of our home, and are now applying it to the conversion of a redundant 1875 church building into one of the UK’s most energy efficient homes. We believe it to be the first church-to-domestic conversion in the world to Passivhaus standards for ultra-low energy consumption, super-insulation, and airtightness. These standards will massively reduce the Primary Energy Requirement of the building compared to standard home construction.

And the even better news? We’ll be opening Warksburn Old Church as a luxury holiday rental property in late-Summer 2024. We look forward to welcoming you! More information is here, along with the extraordinary history of the Net Zero visionary who funded the original building 149 years ago.

If you are interested in booking a stay, or just want to make an enquiry, please email us on

info@warksburnoldchurch.com

01 January 2024

Finally reached Month 12 of detailed data collection. So now we’ve got a full year’s worth of information on:

• Consumption: total kWh slurped down by the house and Anne’s electron-munching pottery kiln.
• Consumption: total kWh ‘fuelled’ into the two EVs.
• Self-generation: total kWh generated by the 7.5 kWp solar panel installation on the roof.
• Grid imports: total kWh imported from National Grid, using the 100% renewable Octopus Go smart tariff which provides dirt cheap electricity between 00:30 and 04:30 every night and a slightly below-average cost at all other times.
• Storage input: total kWh charged into the domestic storage battery, using a mix of only solar generation and off-peak grid electricity.
• Storage output: total kWh discharged from the domestic storage battery at peak times, avoiding grid imports.
• Total financial savings from smart electricity generation, storage and discharge over the year’s domestic and pottery kiln consumption.
• Total mileage charged into EVs, using solar and off-peak electricity.
• Total financial savings from use of EVs charged on this electricity mix, versus the cost of petrol which would have been required to cover the same mileage in Internal Combustion Engine (ICE) cars.
• Total tonnes emissions avoided from domestic energy optimisation.
• Total tonnes emissions avoided by EV use.

You can see or download a PDF summary of the whole year’s data (14MB) by clicking the image below.

Below is the final performance report for the data collection year, September 2020.

It was not a bad month weather-wise, with the Met Office reporting a decent 151 hours of sunshine in our area. The key results are tabulated below.

Item	Result
Solar production	524 kWh
Off-peak grid energy imported	725 kWh
Peak grid energy imported	169 kWh
Peak grid imports avoided by using stored energy from Powerwall battery	484 kWh
Total energy consumed (domestic consumption and EV charging)	1,418 kWh
Net cost of grid energy, incl standing charge, net of Govt payments for solar	£39.88
Cost of 1,162 kWh at UK ‘Big 6’ average rate per kWh	£219.75
Saving on 1,162.6 kWh vs UK Big 6 average rate	£179.87
Total range charged to EVs, from solar and off-peak grid imports	1,194 miles
Actual cost of solar + off-peak grid energy to charge 1,185 miles	£15.14
Fuel costs to drive an ICE car 1,185 miles using @35mpg & £1.32/litre	£252.55
Saving on 1,185 miles vs cost of motor fuel for same mileage	£237.41
Electricity and motor fuel savings in month	£417.28
CO2 savings on domestic energy by using solar & 100% renewable grid energy	255.2 kg
CO2 savings on 1,185 emissions-free miles versus ICE @ 125.1 g/km	240.4 kg
Total CO2 emissions avoided in month	495.6 kg

The usual monthly calcographic is available for download here or by clicking the image below.

August 2020 was pretty dull. Coronavirus was still doing its (dull and boring) thing. And the sun only bothered to shine for 136.3 hours in the North East of England. So that meant, inevitably, a pretty dull and underproductive month for our solar micro-generation. However, the Tesla Powerwall domestic battery enabled substantial savings by ‘peak-shifting’. Additionally, the gradual easing of lockdown meant we drove more miles in the EVs. The table below summarises the data.

Item	Result
Solar production	564 kWh
Off-peak grid energy imported	509 kWh
Peak grid energy imported	89 kWh
Peak grid imports avoided by using stored energy from Powerwall battery	423 kWh
Total energy consumed (domestic consumption and EV charging)	1,162 kWh
Net cost of grid energy, incl standing charge, net of Govt payments for solar	£17.26
Cost of 1,162 kWh at UK ‘Big 6’ average rate per kWh	£180.21
Saving on 1,162.6 kWh vs UK Big 6 average rate	£162.95
Total range charged to EVs, from solar and off-peak grid imports	1,185 miles
Actual cost of solar + off-peak grid energy to charge 1,185 miles	£13.65
Fuel costs to drive an ICE car 1,185 miles using @35mpg & £1.32/litre	£248.97
Saving on 1,185 miles vs cost of motor fuel for same mileage	£235.07
Electricity and motor fuel savings in month	£398.02
CO2 savings on domestic energy by using solar & 100% renewable grid energy	209.3 kg
CO2 savings on 1,185 emissions-free miles versus ICE @ 125.1 g/km	238.7 kg
Total CO2 emissions avoided in month	448.0 kg

Here’s the link for detailed monthly performance report in PDF format. You can also get the report by clicking the calcographic below.

Follow this link to view the in-month and cumulative impact of August 2020 on payback of the capital costs of our solar, battery and EV charging installation

July was a pretty good summer month, by North East England standards. Key results are as follows:

• 1,215 kWh total energy consumption.
• 816 kWh solar
• 314 kWh off-peak grid (100% renewable supplier)
• 86 kWh peak grid (100% renewable supplier).

Taking into account the minor Government subsidy we receive for solar generation, we once again had a negative net cost of energy, paying minus £5.36 for the month’s electricity.

We fuelled our two EVs (and a Renault Zoe we had on test for the first half of the month) for a total of 758 miles in the month. The ‘fuel mix’ going into the EV batteries was 360 kWh solar and 97 kWh off-peak electricity. This blend produced a total electricity cost for 792 miles of EV motoring of £4.84, or 0.6 pence per mile. Using our normal comparison with a 35mpg OldTech car fuelled at the long-term average of £1.32 per litre, we saved £262 fuel costs in month.

The total net financial benefit in July was £384.93, made up of these £262.08 fuel savings and the £122.86 difference between the price we would have paid for 758 kWh of domestic energy at ‘Big 6’ utility company rates (£117.50) and the net minus £5.36 we actually paid.

Emissions avoided in the month by the combination of solar generation, 100% renewably sourced grid supply, and 792 miles of zero emissions driving totalled 378 kg.

Click the graphic below to download the full report in PDF format.

Other than the ongoing mass death virus thingy and associated economic implosion, June 2020 was an exceptionally pleasant month in the UK. As anyone with solar panels will tell you, it was very, very sunny indeed towards the end of the month, although the MetOffice recorded only about 165 hours of bright sunshine in June in our region, compared to the positively Arabian 269 hours which had beaten down on us in May.

Whatever the Bracknell stats geeks say, we ended up with enough sunshine to produce another month with negative cost of energy. As the calcographic below shows, although we consumed nearly a megawatt of electricity for domestic use and charging EVs during this (still a bit lockdowny) month, we actually ended up £12.19 better off in net terms at the end of the period.

The £36.12 Government payment for 740 kWh of solar generation was more than the £23.93 cost of importing the meagre 225 kWh of grid electricity we did not generate ourselves in the month, which includes £7.50 of ‘standing charge’ fixed fee for grid connection at £0.25/day.

Our two EVs were charged roughly 70% with solar (195kW), plus 30% (82kWh) with zero carbon off-peak energy supplied at only 5p/kWh on the Octopus Go tariff overnight rate. Coronavirus ensured that June 2020 was still a very travel-restricted period, so we only covered 593 miles. However, even over this relatively small mileage, that still added up to fuel savings versus petrol/diesel ICE cars of £160.40. The electric ‘fuel’ for the EVs cost us just £4.10 in the month, which works out at only 0.7 pence per mile! It would have cost us £164.49 to travel the same distance in ICE cars, using our standard mpg calculations.

We also won big-time on our 719 kWh domestic consumption. 76% (545 kWh) was solar, including 374 kWh which was stored in the Powerwall stationery battery during the sunshine hours and used in the evenings. The remaining 24% (173 kWh) was zero carbon source grid electricity from Octopus. And over half of the grid imports were stored during the super-cheapo off-peak hours into the Powerwall and discharged at zero additional cost to us during the peak period.

Taking into account the solar generation payment we received from Government, our 719 kWh of domestic energy cost us minus 1.7 pence per kWh, making minus £12.19 net. If we had bought those kWh at UK ‘Big 6’ average rates, we would have paid £111.37. So that’s a net financial benefit of £123.56 for domestic energy consumption.

Putting domestic energy savings and motor fuel savings together, net financial benefit was £283.96 in the month of June. And the planet was 298.6 kg of CO2 emissions better off too.

Please click the image below for a downloadable PDF of the detailed monthly report. The impact of this month on financial payback of system costs is here.