Earth Notes: Saving Electricity and Gas (2023)

Updated 2024-02-26.
Meter readings at home. #4kWhDHWClub
2023 PV Output
Meter readings and analysis of our electricity and gas carbon footprint at home in 2023. Aggressive use of the heat battery, a mild November/December, and a boiler failure all pushed down gas use well beyond the target 2MWh to a new low of 1.3MWh, a 7x reduction since 2007.


See the daily PV generation logs for 2023 as .csv and .png chart.

2023-05-24: Clock Skew

Note the following snippet from E2023.csv, in particular the 24th to the 26th.


At some point the SunnyBeam clock was maybe 12h out so I had to manually reset it (on the 26th). I suspect that this is the result. This was probably caused by the RPi power-supply failure on the 12th.

2023-12-21: Bath and Shower DHW Use

The boiler was (briefly) resuscitated today after well over a week asleep. In passing, using the Eddi reports of energy into the Thermino currently supplying all our DHW, it is more or less confirmed that a bath is ~4kWh and a shower ~2kWh, in most cases.

2023 Fuel Consumption Data
MonthConsumed kWh (/d)Generated -kWh (/d)Consumed kWh (/d) PeriodNotes
2023-01 312 (10.1/d) -71 (-2.3/d) 451 (14.5/d) 20221231T18:04Z to 20230131T18:26Z (31d) Meter readings: electricity generation 70.5kWh, export 1.0kWh, import 242.6kWh (thus net consumption (I+G-E) 312.1kWh, self consumption ((N-I)/N) 22%); gas ~40.6m^3 (so 451kWh @ 11.1kWh/m^3).
Lots of wind power on the grid and thus low-carbon-intensity top-up to the heat battery has covered very roughly half (~2kWh/d) our DHW.
Generation from the first solar PV sub-array passed 41MWh.
Bathroom MHRV running well.
The Enphase emailed monthly report for January (triggered 2023-07-01) says: produced (generated) 71.0kWh (max 4.5kWh on the 30th), consumed 298.6kWh (max 24.9kWh on the 29th), grid energy imported 243.3kWh and exported 0.3kWh, grid dependence 81% (min 51% on the 20th).
HDD12=194 vs 204 last January.
2023-02 274 (9.8/d) -124 (-4.4/d) 346 (12.4/d) 20230131T18:26Z to 20230228T17:00Z (28d) Meter readings: electricity generation 124.3kWh, export 4.4kWh, import 154.2kWh (thus net consumption (I+G-E) 274.1kWh, self consumption ((N-I)/N) 44%); gas ~31.2m^3 (so 346kWh @ 11.1kWh/m^3).
The Enphase emailed monthly report for February (triggered 2023-07-01) says: produced (generated) 124.6kWh (max 7.3kWh on the 15th), consumed 253.0kWh (max 15.1kWh on the 24th), grid energy imported 150.4kWh and exported 3.4kWh, grid dependence 59% (min 15% on the 7th).
HDD12=145 vs 116 last February.
2023-03 314 (10.1/d) -217 (-7.0/d) 230 (7.4/d) 20230228T17:00Z to 20230331T17:15Z (31d) Meter readings: electricity generation 217.0kWh, export 25.2kWh, import 122.6kWh (thus net consumption (I+G-E) 314.4kWh, self consumption ((N-I)/N) 61%); gas ~20.7m^3 (so 230kWh @ 11.1kWh/m^3).
2023-03-15: the weather and forecast warmed to the point (~12°C during the day) where I turned the heating off (~21:00Z) to save gas/money/carbon.
The Enphase emailed monthly report for March (received 2023-04-12) says: produced (generated) 215.4kWh (max 14.9kWh on the 27th), consumed 290.5kWh (max 14.5kWh on the 23rd), grid energy imported 122.4kWh and exported 22.6kWh, grid dependence 42% (min 14% on the 27th).
HDD12=129 vs 113 last March.
2023-04 287 (9.4/d) -426 (-14.2/d) 15 (0.5/d) 20230331T17:15Z to 20230430T19:04Z (30d) Meter readings: electricity generation 426.0kWh, export 179.3kWh, import 34.2kWh (thus net consumption (I+G-E) 286.9kWh, self consumption ((N-I)/N) 88%); gas ~1.4m^3 (so 15kWh @ 11.1kWh/m^3).
Exports passed 39MWh.
Most of the family was away two weekends in April, which reduced consumption!
The Enphase emailed monthly report for April (received 2023-05-11) says: produced (generated) 428.2kWh (max 21.7kWh on the 4th), consumed 257.5kWh (max 14.2kWh on the 23rd), grid energy imported 28.4kWh and exported 176.3kWh, grid dependence 11% (min 1% on the 15th).
HDD12=87 vs 75 last April.
2023-05 331 (10.7/d) -573 (-18.5/d) 17 (0.6/d) 20230430T19:04Z to 20230531T17:22Z (31d) Meter readings: electricity generation 573.2kWh, export 267.4kWh, import 24.7kWh (thus net consumption (I+G-E) 330.5kWh, self consumption ((N-I)/N) 93%); gas ~1.5m^3 (so 17kWh @ 11.1kWh/m^3).
Generation from the first PV array passed 42MWh.
The Enphase emailed monthly report for May (received 2023-06-11) says: produced (generated) 576.9kWh (max 28.6kWh on the 27th), consumed 313.1kWh (max 16.2kWh on the 14th), grid energy imported 20.6kWh and exported 264.3kWh, grid dependence 7% (min 1% on the 27th).
HDD12=20 vs 14 last May.
2023-06 285 (9.5/d) -656 (-21.9/d) 3 (0.1/d) 20230531T17:22Z to 20230630T17:20Z (30d) Meter readings: electricity generation 656.1kWh, export 382.1kWh, import 10.6kWh (thus net consumption (I+G-E) 284.6kWh, self consumption ((N-I)/N) 96%); gas ~0.3m^3 (so 3kWh @ 11.1kWh/m^3).
Gas boiler turned off entirely since 10th as an experiment: no problems. (As insurance, the Thermino has been set to a minimum 30% level fill!)
The Enphase emailed monthly report for June (triggered 2023-07-01) says: produced (generated) 659.3kWh (max 29.2kWh on the 4th), consumed 271.0kWh (max 14.1kWh on the 10th), grid energy imported 7.7kWh and exported 378.8kWh, grid dependence 3% (min 1% on the 2nd).
HDD12=3 vs 3 last June.
2023-07 275 (8.9/d) -527 (-17.0/d) 0 (0/d) 20230630T17:20Z to 20230731T17:16Z (31d) Meter readings: electricity generation 526.6kWh, export 274.7kWh, import 22.6kWh (thus net consumption (I+G-E) 284.6kWh, self consumption ((N-I)/N) 92%); gas ~0m^3 (so 0kWh @ 11.1kWh/m^3).
A few days' holiday reduced demand a little.
Exports passed 40MWh.
Gas boiler still turned off, thus zero gas consumption (hurrah)! Made small tweaks to Thermino control code (given the 30% 'insurance') so as to reduce spurious top-ups from mains during fast run-off, ie typically baths.
The Enphase emailed monthly report for July (triggered 2023-08-01) says: produced (generated) 529.6kWh (max 28.4kWh on the 7th), consumed 258.9kWh (max 15.2kWh on the 15th), grid energy imported 18.2kWh and exported 270.5kWh, grid dependence 7% (min 1% on the 25th).
HDD12=0 vs 0 last July.
2023-08 214 (6.5/d) -521 (-15.7/d) 0 (0/d) 20230731T17:16Z to 20230902T21:43Z (33d) Meter readings: electricity generation 520.5kWh, export 316.4kWh, import 10.2kWh (thus net consumption (I+G-E) 214.3kWh, self consumption ((N-I)/N) 95%); gas ~0m^3 (so 0kWh @ 11.1kWh/m^3).
Holiday reduced demand a little, and delayed the end-of-month reading.
Gas boiler still turned off, thus zero gas consumption (hurrah)!
Ecotricity is projecting ~1.1MWh/year electricity import, and ~1.8MWh/year gas.
The Enphase emailed monthly report for August (triggered 2023-09-01) says: produced (generated) 498.6kWh (max 24.6kWh on the 9th), consumed 190.8kWh (max 14.5kWh on the 16th), grid energy imported 7.8kWh and exported 297.3kWh, grid dependence 4% (min 1% on the 29th).
HDD12=1 vs 0 last August.
2023-09 276 (9.9/d) -340 (-12.1/d) 10 (0.4/d) 20230902T21:43Z to 20230930T10:44Z (28d) Meter readings: electricity generation 339.5kWh, export 108.5kWh, import 44.9kWh (thus net consumption (I+G-E) 275.9kWh, self consumption ((N-I)/N) 84%); gas ~0.9m^3 (so 9.9kWh @ 11.1kWh/m^3).
Gas boiler back on for DHW (fallback) on 11th; consumption back to ~0.5kWh/d.
The Enphase emailed monthly report for September (triggered 2023-10-01) says: produced (generated) 371.5kWh (max 19.7kWh on the 3rd), consumed 266.1kWh (max 13.1kWh on the 14th), grid energy imported 41.1kWh and exported 124.6kWh, grid dependence 15% (min 0% on the 30th).
HDD12=1 vs 13 last September.
2023-10 290 (9.4/d) -208 (-6.7/d) 7 (0.2/d) 20230930T10:44Z to 20231031T17:00Z (31d) Meter readings: electricity generation 207.5kWh, export 35.9kWh, import 118.3kWh (thus net consumption (I+G-E) 289.9kWh, self consumption ((N-I)/N) 59%); gas ~0.6m^3 (so 6.7kWh @ 11.1kWh/m^3).
The Enphase emailed monthly report for October (triggered 2023-11-01) says: produced (generated) 201.6kWh (max 11.4kWh on the 8th), consumed 273.2kWh (max 17.0kWh on the 13th), grid energy imported 120.2kWh and exported 29.3kWh, grid dependence 44% (min 6% on the 1st).
HDD12=28 vs 17 last October.
2023-11 328 (10.9/d) -77 (-2.6/d) 35 (1.2/d) 20231031T17:00Z to 20231130T17:56Z (30d) Meter readings: electricity generation 77.2kWh, export 1.5kWh, import 252.7kWh (thus net consumption (I+G-E) 328.4kWh, self consumption ((N-I)/N) 23%); gas ~3.1m^3 (so 34.5kWh @ 11.1kWh/m^3).
The heating stayed off this month, though at the end external temperatures were around freezing and internal ~14°C.
Ecotricity is projecting ~1.2MWh/year electricity import, and ~1.7MWh/year gas, circa £860, as of the bill covering November. This bill >£100.
The Enphase emailed monthly report for November (triggered 2023-12-01) says: produced (generated) 78.1kWh (max 4.6kWh on the 1st), consumed 311.5kWh (max 23.1kWh on the 18th), grid energy imported 250.1kWh and exported 0.8kWh, grid dependence 80% (min 62% on the 29th).
HDD12=114 vs 65 last November.
2023-12 362 (11.7/d) -37 (-1.2/d) 161 (5.2/d) 20231130T17:56Z to 20231231T16:13Z (31d) Meter readings: electricity generation 36.5kWh, export 0.3kWh, import 325.1kWh (thus net consumption (I+G-E) 362.3kWh, self consumption ((N-I)/N) 10%); gas ~14.5m^3 (so 161.4kWh @ 11.1kWh/m^3).
The heating ran from 1st Dec and then failed about a fortnight in. December was the second mildest since/including 2007: we did not freeze. All our DHW since was delivered via the Thermino (with my driver script in "primary DHW" mode); grid intensity was generally low.
Ecotricity is projecting ~1.4MWh/year electricity import, and ~1.3MWh/year gas, circa £870, as of the bill covering December. This bill >£150.
The Enphase emailed monthly report for December (triggered 2024-01-01) says: produced (generated) 36.7kWh (max 2.3kWh on the 6th), consumed 351.1kWh (max 19.8kWh on the 30th), grid energy imported 327.7kWh and exported 0.1kWh, grid dependence 93% (min 63% on the 26th).
HDD12=113 vs 219 last December.
2023 total (Jan--Dec) 3335 (9.14/d) -3658 (-10.0/d) 1275 (3.49/d) 20221231T18:04Z to 20231231T16:13Z (365d) HDD of 836 (vs 839 for 2021), below the 2008 to 2020 mean of 984.
Gas consumption down to 1275kWh, lowest ever, reduced via the eddi/Thermino and a December boiler failure! PV generation of 3658 slightly down on last year (3925kWh). Gross electricity consumption (minus heat, conexDHW) high ~2203kWh, close to 2020 lockdown record of 2365kWh, but gross including DHW is 3335 because of more aggressive top-up algorithm. Imports at at 1364kWh are up from last year (832kWh) with heat-battery grid top-ups (709kWh up from previous 201kWh, vs 636kWh cf previous 642kWh diverted). Exports at 1597kWh are the lowest since 2010, because of aggressive behind-the-meter storage. Self-consumption calculated as (N-Imp)/N was 59%, down from 72%. Total grid flows (import+export) at 2959kWh.
kgCO2 1434kg (3.9/d) -1573kg (-4.3/d) 242kg (0.7/d) ~0.103tCO2 [though see below] (~0.28kgCO2/d) gas/electricity emissions total for 4 people, based on fixed (outdated but used for consistency with previous calculations) 0.43kgCO2/kWh for electricity (netted) and 0.19kgCO2/kWh for gas, ie slightly carbon positive.
We did not fly this year and still do not own a car.
With the heat battery gas use has been cut by an over-target ~2MWh/y, partly by being careful when electricity is used for DHW instead of gas.
With data from the Enphase metering and the FUELINST log I compute a potentially more accurate CO2 electricity balance, noting the relatively low carbon grid intensity when exporting summer PV and high intensity when importing in winter. (There is still the argument that any balancing at the moment may be done by a gas turbine in practice.) See below for the computations — the estimated figure is now a slightly positive 0.212tCO2 (-0.030(e) + 0.242(g)) overall for gas and electricity.

2023-12-31: Grid Intensity Updates

As of the system had in place the following FUELINST kgCO2/kWh generation fuel year-2023 intensities (other fuels/sources are ignored): BIOMASS=0.12 CCGT=0.394 COAL=0.937 INTELEC=0.053 INTEW=0.458 INTFR=0.053 INTIFA2=0.053 INTIRL=0.458 INTNED=0.474 INTNEM=0.179 INTNSL=0.016 INTVKL=0.126 NPSHYD=0.0 NUCLEAR=0.0 OCGT=0.651 OIL=0.935 OTHER=0.3 WIND=0.0.

As of year-2024 intensities (other fuels/sources are ignored): BIOMASS=0.12 CCGT=0.394 COAL=0.937 INTELEC=0.062 INTEW=0.288 INTFR=0.062 INTIFA2=0.062 INTIRL=0.288 INTNED=0.262 INTNEM=0.123 INTNSL=0.012 INTVKL=0.126 NPSHYD=0.0 NUCLEAR=0.0 OCGT=0.651 OIL=0.935 OTHER=0.3 WIND=0.0.

2023: ToD Carbon Calculation

% sh script/analytic/ 2023
Created/updated out/yearly/Enphase-1h-2023.csv.gz
Created/updated out/yearly/FUELINST-1h-2023.csv.gz
Unique hours in data: 8673
Created/updated out/yearly/Enphase-join-FUELINST-1h-2023.csv.gz
Unique hours in joined data: 8582
Scale factor to allow for missing data: 1.02074
Raw 16WW electricity CO2 kg for 2023: -28.9679
Adjusted 16WW electricity CO2 kg for 2023: -29.5687

On an "extra demand just runs some gas turbines up a bit" basis footprint (with a fixed assumed intensity for import and export between CCGT and OCGT) was ~100kgCO2 for the whole house/family for 2023. On a dynamic hourly intensity basis (using the instantaneous intensity of transmission-connected generation) about twice that, including opportunity cost of diverted PV for example. The absolute difference in implied CO2 emissions is low.