Chellow is an open source web application for checking the UK electricity and gas bills of large organisations. It's been used in production since early 2006, and the code is hosted at GitHub.
Chellow is suitable for organisations for which one or more of the following is true:
Supplier bills are imported into Chellow, and then they are checked by comparing them to virtual bills that are created by Chellow. Any differences are due to either the actual bill being incorrect or the virtual bill being incorrect. Once errors in the virtual bill have been corrected, any remaining differences can be queried with the supplier. The idea is that at the end of the process, the organisation can be sure that it's paying the correct amount for its electricity and gas.
Some of the features of Chellow are:
As a result of the bill checking process, Chellow ends up with a good dataset of electricity that has been used by the organisation. This can then be used for monthly reports for finance, purchasing and operations departments. Chellow also ends up with a good model of electricity costs, which can be run under different scenarios to answer questions such as: how much money would be saved if a solar panel were to be installed?