You've used £21.77 of Free Electricity so far
Here’s a breakdown of how you did:
On Sunday 18th August, you used 20.29kWh extra electricity, worth £4.85. You used 20.39kWh during the session and based on your meter data from the previous few weeks, you'd normally have used 0.1kWh at this time.
On Wednesday 21st August, you used 20.74kWh extra electricity, worth £4.96. You used 20.89kWh during the session and based on your meter data from the previous few weeks, you'd normally have used 0.15kWh at this time.
On Saturday 31st August, you used 19.35kWh extra electricity, worth £4.62. You used 19.52kWh during the session and based on your meter data from the previous few weeks, you'd normally have used 0.17kWh at this time.
Ok, so second and third not as low as I thought. Although this has shifted usage at 7p to reported day-time rate of 23.9p - so actual savings are more like a third of this - £7 - (0.07/0.239) + 10% for round-trip battery losses.