I’ve been on my dynamic smart tariff for some months now, so I thought it would be a good time to see what I’m actually saving. My actual tariff rate changes each half hour, but for the purposes the supplier calculates the weighted average of what I’ve actually paid for the invoice. In principal that should be monthly, but I’ve had some bills combined over more than one month.
Month  Year 2018/19  Year 2019/20  Year 2020/1  Year 2021/2  Year 2022/3 

November  14.27 p/kWh  8.96 p/kWh  6.69 p/kWh  7.37 p/kWh  12.75 p/kWh 
December  10.17 p/kWh  6.51 p/kWh  9.61 p/kWh  7.66 p/kWh  14.26 p/kWh 
January  6.86 p/kWh  9.74 p/kWh  8.32 p/kWh  15.36 p/kWh  
February  5.59 p/kWh  11.18 p/kWh  6.93 p/kWh  11.36 p/kWh  
March  5.02 p/kWh  8.85 p/kWh  6.88 p/kWh  10.14 p/kWh  
April  8.35 p/kWh  8.74 p/kWh  7.36 p/kWh  9.33 p/kWh  
May  4.48 p/kWh  11.50 p/kWh  6.36 p/kWh  8.59 p/kWh  
June  7.03 p/kWh  3.49 p/kWh  12.52 p/kWh  9.48 p/kWh (part old Go at 7.5 p/kWh) 11.28 p/kWh (part new Go at 9.5 p/kWh) 

July  8.20 p/kWh  4.40 p/kWh  15.60 p/kWh (part) End Agile / Start Go 5.92 p/kWh (part)  10.09 p/kWh (new Go with 7.5 p/kWh overnight)  10.62 p/kWh (to 30/6) 10.39 p/kWh (from 01/07) 
August  6.29 p/kWh (part) 5.99 p/kWh (balance)  6.15 p/kWh  6.19 p/kWh  11.82 p/kWh  11.63 p/kWh 
September  5.63 p/kWh  7.62 p/kWh  6.30 p/kWh  11.07 p/kWh  13.41 p/kWh (to 15/09) 12.66 p/kWh (from 16/06) 
October  6.86 p/kWh  6.97 p/kWh  6.83 p/kWh  13.76 p/kWh  13.66 p/kWh 
Over the course of the last few months my electricity price has reduced very significantly. I suspect that this is down to a combination of several factors including:
 With the development of my HEMS (including its control of the battery storage) I’m getting slicker at optimising my purchase price
 As we move into the summer the energy price is dropping with reduced demand and more renewable power available.
For reference the Energy Saving Trust reckons that the average UK price for electricity is 15.75 p/kWh on a flat rate tariff, or 19.0 on days and 9.1 p/kWh on nights for Economy 7. Thus my average electricity price in a month always beats their day rate and often beats their night rate. Of course the EST figures are the average market rates, so both better and worse deals will exist with different suppliers.
The 7.03 p/kWh for June 2019 seems to have been received with incredulity elsewhere so here’s the relevant part of the bill..
I’ve never felt so engaged with my electricity supply, and am very pleased to have made the move from the dualrate Economy 7 tariffs that I’ve used for around 30 years.
You can switch to Octopus yourself and earn the current referral bonus. https://share.octopus.energy/ochrebeach637
Updated with July 2019 data. I suspect that the increase in my average unit rate versus June reflects reduced mileage in my electric car due to school vacation and thus fewer kWhs purchased at the lowest prices.
Later in June 2021 I switched to another Octopus tariff as wholesale electricity prices rose https://greening.me.uk/2021/06/26/farewellagilehellogo/