Earth Notes: Saving Electricity and Gas (2018)

Meter readings and energy-saving comments for our dual fuel use at home in 2018.
2018 PV Output


See the daily PV generation logs for 2018 as .csv and .png chart.

2018/02: this is the coldest February here at 16WW while I've been monitoring. But we're nowhere near our highest gas use, thanks to insulation and to Radbot/OpenTRV!

2018/04/03: according to @Zapaman, ~26.8% of [16WW] household energy is from renewables, 8.1% from nuclear and hence a total 34.8% from low carbon energy.

2018/05/07: on the hottest day over the Early May Bank Holiday weekend (ie since 1978) it is ~27°C in our shaded porch. A snapshot of heating performance c/o Pilio shows R^2=0.94 and a slope of ~2kWh/HDD (at 15.5°C baseline).

heating performance

2018/06/10: ignoring the daytime PV flows showing up as consumption, the implication of my fine-grained Loop meter data is that overnight our vampire load is ~80--90W. Though that's likely not very accurate. It includes ~10W for the SmartThings monitoring that I use to cross-check OpenTRV devices. It probably excludes ~16W for the networking gear, since it's been mainly off-grid. Maybe ~40W is from the fridge, leaving ~40W for all other vampires. Still a little higher than I'd like, but not too shabby. (And possibly a figment of the Loop meter's imagination anyway!)

2018/07/10: I'm contempating grid-attached storage again. In principle something Tesla Powerwall 2 size should retain any generation for use in the house October to February inclusive, so no exports. Equally, such a beast should avoid any imports March to September. That relies on the storage system having both enough energy (kWh) and power (kW) capacity to absorb most/all generated PV and cover all loads. But a much smaller unit may get much of the same effect, maybe even as small as 1kWh/260W such as the Enphase AC Battery.

Notice how the 'excess' generation in June alone (a little under 500kWh) is about the same as the electricity deficit Oct to Feb inclusive... A mere 10t of containerised lithium battery could cover it. (Self-discharge of <3%/M helps.)

MonthConsumed kWh (/d)Generated -kWh (/d)Consumed kWh (/d) PeriodNotes
2018/01 214 (6.9/d) -62 (-2.0/d) 585 (19/d) 20171231-18:45-GMT to 20180131-19:19-GMT (31d) Meter readings: electricity generation 61.9kWh, export 35.3kWh, import 187.1kWh (thus net consumption (I+G-E) 213.5kWh); gas ~52.7m^3 (so 585kWh @ 11.1kWh/m^3).
"SmartThings" sensors to cross-calibrate OpenTRV devices draw ~10W, thus add ~0.25kWh/d to gross electricity consumption.
HDD12=166 vs 248 last January.
2018/02 186 (6.6/d) -104 (-3.7/d) 746 (28/d) 20180131-19:19-GMT to 20180228-18:32-GMT (28d) Meter readings: electricity generation 146.6kWh, export 104.4kWh, import 143.8kWh (thus net consumption (I+G-E) 186.0kWh); gas ~67.2m^3 (so 746kWh @ 11.1kWh/m^3).
This has been the coldest February (in terms of HDD) that I have observed at 16WW.
HDD12=237 vs 139 last February.
2018/03 190 (6.1/d) -216 (-7.0/d) 559 (18/d) 20180228-18:32-GMT to 20180331-17:10-GMT (31d) Meter readings: electricity generation 216.4kWh, export 167.3kWh, import 141.0kWh (thus net consumption (I+G-E) 190.1kWh); gas ~50.4m^3 (so 559kWh @ 11.1kWh/m^3).
A cold March, but not quite the coldest measured here!
HDD12=185 vs 77 last March.
2018/04 93 (3.1/d) -290 (-9.7/d) 137 (4.6/d) 20180331-17:10-GMT to 20180430-17:06-GMT (30d) Meter readings: electricity generation 290.4kWh, export 284.9kWh, import 87.6kWh (thus net consumption (I+G-E) 93.1kWh); gas ~12.3m^3 (so 137kWh @ 11.1kWh/m^3).
HDD12=64 vs 65 last April.
2018/05 160 (5.2/d) -647 (-21/d) 131 (4.2/d) 20180430-17:06-GMT to 20180531-19:30-GMT (31d) Meter readings: electricity generation 646.8kWh, export 553.0kWh, import 65.9kWh (thus net consumption (I+G-E) 159.7kWh); gas ~11.8m^3 (so 131kWh @ 11.1kWh/m^3).
HDD12=23 vs 23 last May.
2018/06 137 (4.6/d) -680 (-23/d) 103 (3.4/d) 20180531-19:30-GMT to 20180630-21:52-GMT (30d) Meter readings: electricity generation 689.2kWh, export 599.2kWh, import 56.0kWh (thus net consumption (I+G-E) 137.0kWh); gas ~9.25^3 (so 103kWh @ 11.1kWh/m^3).
Passed 8MWh generation on final (west-facing) PV segment. Tuning of off-grid PV storage control system is allowing ~0.5kWh/d load to be removed from grid consumption.
HDD12=2 vs 1 last June.