Earth Notes: Saving Electricity and Gas (2017)
|Month||Consumed kWh (/d)||Generated -kWh (/d)||Consumed kWh (/d)|
|2017/01||207 (6.7/d)||-71 (-2.3/d)||867 (28/d)|
|2017/02||163 (5.8/d)||-109 (-3.9/d)||497 (18/d)|
|2017/03||166 (5.4/d)||-300 (-9.7/d)||357 (12/d)|
|2017/04||143 (4.8/d)||-482 (-16/d)||117 (3.9/d)|
|2017/05||149 (4.8/d)||-528 (-17/d)||142 (4.6/d)|
|2017/06||139 (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)|
|2017/07||147 (4.8/d)||-561 (-18/d)||105 (3.4/d)|
|2017/08||97 (2.9/d)||-519 (-16/d)||60 (1.8/d)|
|2017/09||143 (5.1/d)||-287 (-10/d)||113 (4.0/d)|
|2017/10||150 (4.8/d)||-180 (-5.8/d)||101 (3.3/d)|
|2017/11||179 (6.0/d)||-91 (-3.0/d)||344 (11/d)|
|2017/12||178 (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)|
|kgCO2||801kg (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.