Finding DNO Tariffs

2025-10-18

In a pass-through electricity contract, one of the things that is often passed through are the Distribution Use of System (DUoS) charges from the Distribution Network Operators (DNOs. The DNOs publish their tariffs in an MS-Excel spreadsheet, which they put on their website. An example is SSE's charging statement for 24/25.

As a developer working on the Chellow bill validation system, I need to make sure that all the correct DNO tariffs are held in Chellow so that we can check that the DNO charges in each bill are correct. Here's a screenshot from Chellow showing a bill check for DUoS Green:

The table on the left shows that we've been overcharged by £14.28, and that the rate was correct, but the error was in the kWh. Chellow gets the virtual rate from its database of DUoS rates, which comes from the DNO's spreadsheets.

One brilliant thing about the DNO's spreadsheets is that even though they're produced by all the different DNOs, they're all in the same format, which makes parsing them a lot easier. A problem though, is that it's difficult to automate finding and downloading the spreadsheets, as they're scattered over the web. So what we've done is manually maintain a repository of DNO spreadsheets at:

https://github.com/WessexWater/chellow-rates

This is freely available for anyone to use. You click on the year you're interested in, then electricity -> duos -> and the DNO code, and then you should find the DNO spreadsheet, which you can download with the Download Raw File button. If the DNO you need isn't there, just let me know and I'll add it in.

While adding the DNO spreadsheets to the repository is a manual process, it only has to be done once, and then each instance of Chellow can automatically import the spreadsheets using the GitHub API. The API is free to use, so you're welcome to use it to automatically update your system's DNO rates.