Tariff Compare

What is it?

The “Tariff Compare” tool originally came about several months ago. I’d bought an EV and myenergi zappi charger which along with the great work from twonk at https://github.com/twonk/MyEnergi-App-Api allowed me to query my usage for the first time. I’ve been waiting for a smart meter for several years and with the zappi, now I finally had real data available via an API. It was then I came across the Octopus API and the Agile and Go tariffs and I started modelling my usage on a spreadsheet.

Before long the spreadsheet became too complex and copy and pasting cumbersome. I needed something more automated. Dusting of my python books I started coding and several weeks later I’d create the first demo of the Tariff compare tool. There was a lot of hardcoding of my details but the comparison data and results made me think that other people could get benefits from using it too. I tried it on a few friends who also had Zappi’s and after a few tweaks and similar enlightening results I decided to push it out for Beta testing.

The tool looks at your usage (taken from your Zappi, Eddi or Harvi) by polling the MyEnergi API over a 7 day period. Then it takes your usage and calculates what you would have used over the same period on the Octopus Go and Agile tariffs. The Octopus Go and Agile data is available via the Octopus API too, so there are quite a few API calls flying around and then calculations and comparisons, culminating in a graph of your tariff against the Go and Agile tariffs along with an approximate calculation of savings over different periods in the year.

What Information do I need to use it?

Note that in order to use this tool, you must have a MyEnergi Zappi, Eddi or Harvi and the MyEnergi HUB installed.

MyEnergi Details

The HUB Serial Number and Password are used to query the MyEnergi API and retrieve your hourly usage statistics. Note: Your HUB Serial Number and password are NOT at any time stored on the site and are used in the API calls only.

Current Supplier Details:

Your current supplier is not used specifically in any of the calculations, but will be used in a future release to identify the exact tariff you are on and negating the need to request Unit Rate and Standing Charge.
Your Post Code is used to identify which Octopus Tariff you would be using. Octopus have different tariffs based on regions in the UK, so the calculations are more accurate when we know which region you are from. Again, no postcode data is stored on the site.
Unit Rate and Standing Charge are used to calculate your supplier costs for the respective 7 day period.

How does it work?


The hourly data is gathered from your MyEnergi device and used to calculate what the equivalent cost would be on the Octopus Go and Agile tariffs.

The bar graph shows individual day and the respective costs for each tariff.

The table shows the daily, weekly, monthly and yearly costs based on the 7 days you selected.

You can run the tool as many times as you wish throughout the year to see the comparison.

Note: Due to the shear amount of API calls and calculations required, it can take some time to compile the results. The 7 day window has been selected to give both a good view of your usage and also to reduce the amount of time taken to display the results.

Results will normally be displayed in less than 1 minute.

You can access the tool at the following link: