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  • Jon Bumstead

Update 7: Timing is Everything


Despite one of the wettest Februarys on record, solar generation increased to over 15 kWh/day, comfortably doubling January’s average, with a peak day of 36 kWh. Now spring has arrived and the average has moved up again to 24 kWh/day in the first week. On this basis, I have increased the projected yearly yield up by 15-20%.

This good news is timely as our total demand-led consumption has soared to an eye-watering 118 kWh/day, as a result of all the new electrical loads now being up and running (swimming pool heating etc). This is slightly lower than my design estimate of 125 kWh but nothing to celebrate! Now the hard work on heating optimization is underway with thermostatic control and external wall insulation to come and the early signs are encouraging (will report in the next blog as this could be very significant).

The next piece of good news is that I have now been able to move onto the Octopus Agile tariff, as from early 2020 they have opened this to three-phase users like us. I feared this would be difficult with new smart meters, but no, Octopus managed to make my meter smart remotely and I was up and running in minutes.

The Octopus Agile tariff brings Half-Hourly electrical wholesale rates to the domestic user and those rates vary significantly across the day/week (e.g. I have seen highs of 35p/kWh down to a low of 0.44 p/kWh in my first week) and I am told that at times they will pay you to take power (i.e. negative rates).

The early signs are good, matching my un-optimized raw demand profile over the day has lowered the cost per day by 15% already, reducing the average unit cost per unit from 14.8p to 12.58p; match that Auto-Sergei !!!

But the real deal is the potential of shifting demand around in the day, using the 19 kWh of batteries we have in the loft. The Agile tariff spikes between 4-7pm (actually 7.30pm) and today this represents 22% of our daily consumption, but now 48% of the daily cost !...if we could use only battery power during this time from the daily solar generation, we could halve our electricity bill !!! …even on cloudy dark days, we have the option to import power over-night at rates between 2-7p we will still be quids in (still got to get this to work properly though)

Octopus are bringing out another beta product out called “Octopus Outgoing” allowing time of day tariffs for exporting energy back to the rest of the grid too and we’ll be signing up. Timing really has become everything.

All this has left my head spinning with the endless possible “what-if” scenarios and boring the rest of the house-hold to death. Now if we can get the heating under control, we really will be in business !

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