The following table shows the estimated consumption of electricity by the heat pump for each month in 2011 in units (kW.hours). There are separate columns for Domestic Hot Water (DHW) and Central Heating (CH which includes electric radiator, fan heater and electric towel rail), and the total of the two, followed by the number of units imported, the difference coming from the solar panels. The overall cost is based on a price of 13.17p per unit which was the price at the end of the year. This should be compared with the estimated cost of using oil of £2087, i.e. nearly halved. Some 827 units were generated by the solar panels, a saving of £108.91.
The same for 2012 based on a price of 14.36p per unit which was the price at the end of the year. This should be compared with the estimated cost of using oil of £2115, i.e. nearly halved. Some 873 units were generated by the solar panels, a saving of £125.36.
The same for 2013 based on a price of 14.36p per unit which was the price all year. This should be compared with the estimated cost of using oil of £2214.50, i.e. just over one third. Some 869 units were generated by the solar panels, a saving of £124.79. The exceptionally high amounts in November and December were due to a blockage in the heat pump which was identified and cleared in January 2014.
The same for 2014 based on a price of 12.39p per unit which was the price at the end of the year. This should be compared with the estimated cost of using oil of £2090, i.e. just about one third. Some 982 units were generated by the solar panels, a saving of £121.
The same for 2015 based on a price of 12.16p per unit which was the price at the end of the year. This should be compared with the estimated cost of using oil of £1566, i.e. just over one half (there has been a significant fall in the price of oil). Some 1154 units were generated by the solar panels, a saving of £140. On 11 April the income and savings from both the heat pump and solar panels invested in Funding Circle exceeded the installation and maintenance costs of the heat pump.
The same for 2016 based on a price of 12.16p per unit which was the price all year. Some 1003 units were generated by the solar panels, a saving of £122. In May the radiator in the hall was replaced by a modern efficient model and the single radiator in the lounge was replaced by two new radiators of the same size, but more efficient thus doubling the heat output. There was another blockage in the heat pump in late October but this was discoved early and cleared.
The same for 2017 based on a price of 14.03p per unit which was the price all year.
The same for 2018 based on a price of 16.88p per unit which was the price from 1 February (14.03p in January). The electricity has cost £8,157 to the end of the year instead of an estimated £14,863 for oil, saving £6,706.
The same for 2019 based on a price of 16.84p per unit which was the price from 1 March (16.88p till then).