Update 11: Not yet net zero, but the costs are!
Update 11: Interim Report – The Results so Far
We set out to see if Net Zero was possible in a domestic house. We have come a long way and it's certainly more complex than we envisaged; while the lock-down has put a pause on the project, it has given us the opportunity to take stock and see where we are.
In the half year to June 30, we have generated an average of 39 kWh/day (with a peak day of 87 kWh on June 23rd). With greater light levels since the spring equinox, we have been able to bring down the “grid supplied energy” to an average of 29 kWh/day but in the same period we exported an average of 22.5 kWh/day back to the Grid. Therefore, if we could have used all the power we generated, we would be much closer to Net Zero.
So why was this ?
Moving to a three phase supply was a necessity for an all electric house with capacity for EV charging, but it has brought a complexity we hadn’t considered: essentially it split our “house grid” into three separate generation, storage and consumption systems. Getting all three into balance across the day, the week and the seasons, largely stands between us and achieving our goal. It's an intriguing problem to solve.
The lock-down data research has come up with five new initiatives to get to zero:
1. Sub-metering control to identify which loads to switch across the phases and better manage usage across the day.
2. Installing Voltage Optimisation to drop the voltage from 250 to 225v, to save 10% consumption.
3. Complete the original external wall insulation plan (which the lock-down and council incompetence delayed).
4. Beta testing a new product between Octopus and GivEnergy to move consumption to the lowest half hourly tariffs.
5. Investigating a “Vehicle to Home” solution to utilize an EV car battery as flexible house energy storage.
All five are exciting and some are truly ground breaking and with the potential to take us into net zero territory for long periods of the year.
However we are much closer to achieving net zero from a financial view point. Despite increasing the house size by 60% and filling it with power hungry kit, the daily cost of electricity in the second quarter has fallen by an astonishing 88%, to just £ 0.40/day, with an average cost of 5.9 pence per kWh (little difference now to Gas prices).
For just under half the month of June, the daily cost has been negative: it's the Agile Tariff that has been the game changer !