irex Consulting

Designing and Developing a gridfee Engine

After successfully starting a strategy & business consulting practice, irex Consulting diversified with a full-blown product development activity. We choose to develop and market software applications that:

  • Respond to an existing need at multiple clients and can easily integrate with their existing systems.
  • Are able to exist in a non-competitive fashion with our existing client portfolio
  • Can be developed iteratively, starting from proof-of-concept and growing into an integrated solution.

We have expertise across multiple platforms including mobile, desktop, server and web applications.

Business case

Energy suppliers are obliged to include distribution and transmission fees received from grid operators. These fees are calculated by complex formulas that combine the consumer’s measurements with a set of regulated tariffs that differ based on the region, the distribution grid operator (DGO) and the consumer’s physical set-up. Correct computation is fairly complicated as tariffs are updated multiple times a year and consumption periods can overlap with multiple tariff periods which requires correct data splitting. The sector-wide need for a calculation engine comes firstly from the time gap between the arrival of measurement data and the moment when the DGO sends the actual fee. This entails a delay between outgoing and incoming cash. Secondly, the received fees tend to contain errors which implies the need for checks to avoid incorrectly invoicing consumers. Finally (large) consumers are interested in predicting their invoices for budgeting purposes, investment decisions and impact analyses of legislative changes.


irex Consulting thought-out, designed, developed and tested a software product to calculate gridfees for all Belgian consumers. On top of checking invoices for errors, the tool is now used for simulating new locations and analyzing the impact on existing locations when tariffs, legislation or physical setups change. This capability is also used in developing business cases and searching for cost reductions. The integration into an invoicing application for sending settlement and prepayment invoices is underway. The problem has two general aspects: fee calculation and tariff updates. The calculation can be done manually using a Graphical User Interface or automated using well-documented services that can be integrated with existing application landscapes. The GUI includes batch importing and exporting, but also allows one-by-one calculations which are mostly used for simulation. Validation is supported by importing invoice data and the resulting errors can easily be navigated. One of the core issues of any calculation tool is handling change. We developed a separate tariff sheet parser, allowing swift updates of the underlying tariffs and achieving an application which is not only easy-to-use, but also easy-to-maintain. This helps us guarantee timely updates when tariffs change suddenly.


The project is under continuous development and goes through cycles consisting of three phases:

  1. Analyze requirements
  2. Design & Implement
  3. Test, Report and Finalize

A dedicated and multidisciplinary irex team takes care of these developments. Team roles include knowledge experts, project managers, analysts, IT architects, UI designers, developers and testers.

We delivered and actively maintain:

  1. A remote client to input, calculate and compare gridfees using web services with built-in security.
  2. A parser for DGO tariff sheets and a persistent back-end of parsed and tested tariffs.
  3. A local client to test & debug functional changes rapidly.
  4. A roadmap of improvements & expansions of the application.

“iDigital skilled team transformed grid fee expertise into a critical application, navigating seamlessly from concept to commercialization.”

irex Consulting gathered a team with in-depth knowledge regarding the structure, calculation and volatility of the Belgian gridfee. Experience in projects analyzing grid fee calculation error was combined with insights on how to create easy-to-maintain software applications using parsing, scalable data infrastructure and security. We successfully guided this application from an idea to a working application by delivering business requirements, a functional scope, a software architecture, a UI design and a working code-base. To complete this mission we leveraged skills in project management, data analytics, software engineering and database administration. irex Consulting is proud to own and commercialize this critical and highly demanded application.

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