This web app collects the data automatically each day from Octopus Energy using its public API. It then uses that data to perform calculations based on the data you add to the form. Rubbish in, rubbish out.
Tracker data for this script is now collected automatically from Octopus. And should be updated each day before 7am. I have also started collecting the data for the Gas Tracker tariff, also exceptional value. I will publish graphs and calculators for gas tracker when I find some time.
Or see the calculations using Octopus Energy data for Tracker tariff: Octopus Tracker tariff calculator
Thanks to those who have already used this link to switch.