In late 2018 we moved into our 1970’s detached house in North Dorset. We chose the house because of the view across the Blackmore Vale, but it’s also south facing, perfect for solar panels. We found from the survey it had cavity wall insulation and thick loft insulation, so it was already cheaper to run than most houses of the same size.
However, it had an oil boiler which was polluting and high carbon, so we knew we had to reduce our carbon footprint. We’d wanted to do for this for years but in our previous home didn’t have the right aspect or roof space.
In January 2019, 15 solar panels were installed by H2Eco in Poole who also designed our configuration and guided us through the grants processes, These panels give us about 30kwh on a sunny day. A couple of months later we installed a Tesla Powerwall to store any excess energy. We just managed to qualify for the last of the FIT payments at the lowest rate of about 4.5p a unit, so estimate the solar would pay for itself in about 12-15 years.
Later in 2019, in November, the air-source heat pump was installed. This was a major upheaval for two or three days, and added cost. It required an increase of surface area of all the radiators because of the lower water temperature in a heat source system. After it was installed, we quickly learned its limitations and benefits because of the slower heat build-up of a heat pump, so we always keep the house temperature within a 3 or 4 degree temperature range. This is the most efficient way to run it, and you soon get used to thinking 4 or 5 hours ahead instead of 30 minutes with oil or gas central heating. A Nest smart thermostat also helps. With the RHI subsidy, we estimated we’d recoup about three quarters of our outlay in 7 years.
We started with Economy 7, but in 2021 our costs reduced further with the installation of a smart meter, as we could combine the Powerwall’s tech with more sophisticated tariffs. We then withdrew from the generation part of FIT payments so we could move to the Tesla Energy Plan, where your battery becomes a “virtual power station”. This lasted for two years, but was withdrawn in 2023. Since then we switch between Octopus Flux in the summer and Octopus Cosy in the winter, exporting stored energy at peak times at a much better rate than our FIT payments gave us.
By combining our equipment’s technology and switching energy tariffs, our energy costs in this all-electric house have been constantly low, less than £450pa. With various government grants, and compared to what we would have paid if we’d continued with oil and electricity, the whole investment of £25k in solar, battery and heat pump paid for itself in less than 7 years.
To make an appointment any time of the year, you can email me, bob.shirley.uk@gmail.com
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