A Grade II listed building with 3 different wall structures and insulation levels that were built in 1860, 1990’s and early 2000. Planning permission was required for an air source heat pump, solar PV and a battery system. Exposed and within 2 miles from the sea. Traditional radiators with microbore pipe work.
With a heat loss from a comprehensive full design coming out at 10.9kW we needed to replace an 18 year old mains gas combi boiler that delivered heat and hot water to two wet showers and 4 bedrooms.
We wanted to maximize our roof space for solar and a battery to support the electric running costs of the air source heat pump. For this we had an East/West and limited space South roof option.
We went with a Stiebel Eltron WPL25 air source heat pump with a HSBC300
This solution delivered a 300L water cylinder and 100L buffer combined to maximize space for a small plant room area of 1.3msq. The heat pump can deliver 14kW but also has the added benefit of two boosters if required.
We went with a SolarEdge 6kW inverter with 24 x 400w panels giving a 9.6kW solar set up with a 10kW SolarEdge Home battery to store excess solar production. We also installed a SolariBoost which delivers any excess solar production to heat the water tank via the immersion.
We installed the system in November 2022 in the middle of the coldest winter (minus 8 degrees) for the last 20 years!! The heat pump worked fine and delivered plenty of heat and hot water when required.
The solar PV and battery supported on average between November and March (coldest months) 20% of our electric usage. Between April and July our self-consumption being covered by the solar and battery covered just over 90% of our electric usage.
The heat pump recorded just over 390% efficiency in the winter months and 510% efficiency between April and July.
On an Octopus Flux tariff we are also exporting solar PV at 0.22p per kWH off peak and 0.33p per kWH peak rate*
Overall we are really happy we moved to renewables and given the uncertainty of gas and oil prices over the last 18 months it was a good decision. Electricity prices have also increased so our predicted savings were not as high as expected, but the export tariff has also increased. We can see the electric pricing starting to come down in July 2023.
The Boiler Upgrade Scheme (BUS) also contributed £5,000 as a grant to replace our older gas boiler so this also supported our decision to switch to a cleaner energy.
