Plunge pricing

Last night was the first time that I experienced being paid to use electricity since we finally changed to the smart tariff a week ago.

As a result of unusually high winds in some parts of the country there was an abnormal amount of electricity on the grid from wind turbines, causing the wholesale price to drop. Indeed the wholesale price dropped so low as to be negative.

My own electricity cost is linked to the wholesale cost, so my costs dropped very low and indeed negative at times. In those circumstances I remotely configured my car charging, battery storage and (for the first time) immersion heater to use the overnight power; and used the delay timers on the washing machine and dishwasher to start them during the negative cost period as their most intensive energy use is their initial water heating periods.
This snapshot shows the instantaneous consumption part way through that period with relatively high house loads and water heating.

My holiday project – building a Home Energy Management System (HEMS) – should automate the operation of the car charger and immersion heater around the periods where energy costs are lowest.

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One thought on “Plunge pricing

  1. Greening Me Post author

    Now that I have my monthly statement, I can see that I paid just 40p for 31.5 kWh of electricity in the early hours of December 8th, an average of 1.28 p/kWh. Electricity was also free for a few hours on Christmas Day, but that’s more about marketing than the actual market rates at that time.

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