A Years Worth
Headlines:
- Cost - energy bills reduced by £160
- Cost reduction despite unit costs for electricity rising and despite keeping a gas supply with the associated standing charge.
- Home comfort - our temperature levels in the home during heating season were increased (compared to the previous year) to run the heat pump more efficiently (20 deg C during the day and 18 deg C overnight)
- Hot Water - as previously reported, this has been changed during the year and the system now ensures our preferred set point is reached giving hot water at the points we use it most.
Looking across the monthly usage, it becomes fairly obvious that any savings are focused on the higher usage months. I mention this in particular because as the heat pump is still used for hot water in summer, during these months in fact costs increased slightly compared to the equivalent months in the previous year. We have a busy household with 4 adults and so heating and hot water are important throughout the year.
Unit costs - I mentioned in the headlines that overall cost has reduced despite unit costs increasing. I do have a time of use (tou) tariff which gives 3 slots of off peak electricity each day and with the solar PV and home battery, this allows us to cover the peak (4-7pm) tariff slot with no grid usage at all.
- It is worth noting that our Solar PV and home battery system were installed for the full prior year and therefore their support does not modify the savings shown.
The previous year we had an average electricity unit cost of approximately 12p/kWh.
This year this has increased to approximately 15p/kWh.
Perhaps more importantly than all the data and statistics are the comments from family who all comment that the house is more comfortable due to a fairly consistently maintained temperature and while the hot water is no longer heated ‘on demand’, our hot water tank and heating gives hot water for all our needs and takes less time to deliver at temperature.
One other thing to mention perhaps is servicing - we have a service plan via our provider which costs £9 per month. This covers any call outs required during the year plus an annual service to keep the unit and system running at peak levels and covering the multi-year warranty.
I’ve chosen to look at actual costs as that impacts users more than anything else but some may want to look at a CoP (coefficient of performance) or specifically SCoP (seasonal CoP) which is recorded as 3.4 for this first year (Heating 3.7). That does have a bearing when comparing to other installations of course but ultimately it is energy cost which is a prime consideration.
You can see the previous update here where you can also see links to follow the story from install to a year in use.
