Monthly Archives: October 2016

Energy Unit Costs

We’ve just switched energy suppliers at the end of a fixed rate term.  Unit costs are as follows:

 Oct 2015
- Sep 2016
Oct 2016
- Dec 2016
Jan 2017
- date
Day-time electricity 11.71 p/kWh11.90 p/kWh11.48 p/kWh
Night-time electricity 7.57 p/kWh6.86 p/kWh7.87 p/kWh
PV electricity (when available if metered)4.85 - 4.91 p/kWh4.91 p/kWh4.91 p/kWh
Any-time gas3.01 p/kWh2.43 p/kWh2.35 p/kWh
PV electricity (when available if deemed like mine)0.00 p/kWh0.00 p/kWh0.00 p/kWh

In both cases electricity is on so-called ‘green’ plans where the supplier sources electricity to match my consumption from renewable sources such as wind turbines, solar farms, or hydroelectric.

I’ve included my export rates in the table as for some technologies this will make a difference to the cost-effectiveness of that technology.  My electricity company chooses to deem my export so it pays me assuming that 50% of my generated electricity is exported, rather than metering and paying for my actual export.  That results in the cost to me of using my own solar being zero, whereas if export was metered then using my own solar would cost me the export payment.  Thus for me it’s economically attractive to use excess solar to make hot water rather than using gas thus saving the cost of gas but, for someone with metered export, the lost export payment would outweigh the saving in gas.

Since the table rows are ranked by unit price (higher priced fuels are at the top) then another way to look at this is that it’s financially attractive to replace a fuel higher in the table with one lower in the table, but disadvantageous to replace a fuel lower in the table with one above.

Annual Energy costs

I was reading a newspaper article earlier which highlighted a 3 bed semi with annual energy consumption costs of £500.  Our net energy consumption costs for my early ’70s 4 bed detached in 2015/6 was £400.  That includes charging my electric car.


The house has:

  • A-rated gas boiler (Dec 2015),
  • A-rated double glazing throughout (prior owner),
  • C-rated hot water cylinder with bottom-entry immersion heater and all accessible hot pipes insulated (Dec 2015),
  • 7 day timer (prior owner) with Thermostatic Radiator Valves (TRVs)  throughout (except hall and 2 towel rails – Dec 2015),
  • Standard cavity fill and 4″ loft insulation (prior owner, now nearer 10″ but Oct 2016 installation outside 2015/6 data window),
  • Almost 100% low energy bulbs (mostly Sep 2015),
  • 4kWp solar panels (Sep 2015) with energy management system (Sep 2015) with remote monitoring (Mar 2016) directing surplus PV to car charger (Apr 2016) and/or hot water cylinder (Dec 2015), and
  • Economy 7 electricity (Oct 2015).

I spent £1,000 on gas and electric in 2015/6 which was partially offset by £600 revenue from my solar PV giving net costs of £400. Given that some of the above were introduced during the year, a full year’s use should reduce consumption further.