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


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

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)
2017/11179 (6.0/d)-91 (-3.0/d)344 (11/d)
2017/12178 (5.7/d)-46 (-1.5/d)619 (20/d)
2017 total (Jan--Dec)1862 (5.10/d)-3794 (-10.4/d)3423 (9.38/d)
kgCO2801kg (2.2/d)-1632kg (-4.5/d)650kg (1.8/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.)

2018/01/01 18:23Z: total solar PV generation from the grid-tied PV to date, as reported via the inverters and the SunnyBeam, is 33,666.4kWh.