Earth Notes: Saving Electricity and Gas (2017)

Meter readings and energy-saving comments for our dual fuel use in 2017.
Oct2007 bill graph savings2017 PV Output

2017

See the daily PV generation logs for 2017 as .csv and .png chart.

2017ElectricityGas
MonthConsumed kWh (/d)Generated -kWh (/d)Consumed kWh (/d)
2017/01207 (6.7/d)-71 (-2.3/d)867 (28/d)
2017/02163 (5.8/d)-109 (-3.9/d)497 (18/d)
2017/03166 (5.4/d)-300 (-9.7/d)357 (12/d)
2017/04143 (4.8/d)-482 (-16/d)117 (3.9/d)
2017/05149 (4.8/d)-528 (-17/d)142 (4.6/d)
2017/06139 (4.6/d)-622 (-21/d)109 (3.6/d)
2017 running total (Jan--Jun)967 (5.3/d)-2112 (-12/d)2079 (11/d)
2017/07147 (4.8/d)-561 (-18/d)105 (3.4/d)
2017/0897 (2.9/d)-519 (-16/d)60 (1.8/d)
2017/09143 (5.1/d)-287 (-10/d)113 (4.0/d)
2017/10150 (4.8/d)-180 (-5.8/d)101 (3.3/d)

2017/05: Ecotricity sent our annual summaries for electricity and gas, stating that we had used just over 1.3MWh of electricity (~£270) and a ~4.2MWh of gas (~£262).

The gas figure is higher than usual, given that it was a cold winter, and ~3.5MWh would be more typical (maybe ~£250).

Given that we don't yet have a heat-pump, but that resistance heating is beginning to approach the carbon intensity of gas on the GB grid (currently ~300gCO2/kWh vs ~190gCO2/kWh), what would be the effect of moving from gas to electricity for all heat including water (DHW)?

At ~17p/kWh for electricity that 3.5MWh would be ~£600, but getting rid of gas and its standing charge and an annual gas boiler inspection/service would leave us 'just' net ~£250 per year worse off. IE we might expect a £900/year electricity bill, rather than a £550 dual-fuel total (+~£100 maintenance).

Moving all our DWH consumption to solar PV that we'd otherwise export (eg with the help of a resistance-driven Sunamp store) would be roughly cost neutral, since the gas per-kWh cost is similar to what we are paid for electricity exports.

Even in the depths of winter, we export in electricity ~10% of what we consume in gas; a heat-pump and store could double that to ~20%, still requiring us to import the remaining 80%. In the shoulder months with a suitable Sunamp-like store we could probably cover all space heating. Without a heat-pump the effect on utility bills of using our own power locally is roughly neutral, though kind to the grid in avoiding shipping that energy back and forth.

2017/09/22: I just had to fork out ~£250 for a boiler repair, most of which was the cost of a new diverter valve. (And it took several attempts to find someone available, which absorbed a lot of time.)