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Legacy Modernization for Energy & Supply: The Way to Agile Energy Transition

Legacy Modernization for Energy & Supply: The Way to Agile Energy Transition

Legacy-Modernisierung • 9 January 2026

By Björn Groenewold3 min read
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The energy and supply industry (EVU) is at a historic turning point. The **Energiewende**, driven by political requirements, technological progress and changing customer requirements, requires unprecedented agility and...

The real challenge in legacy modernization is not the code—it is keeping operations running without disruption.

Björn Groenewold, Managing Director, Groenewold IT Solutions

> Key Takeaway: IT system modernization in the energy sector targets replacing rigid mainframe solutions with flexible, cloud-capable platforms.

Goal: real-time control of decentralized generators, integration of smart grid data, and compliance with regulatory requirements (critical infrastructure, Energy Industry Act) while maintaining full operational continuity.


The energy and supply industry (EVU) is at a historic turning point. The Energiewende, driven by political requirements, technological progress and changing customer requirements, requires unprecedented agility and innovative capability. But this transformation is often slowed down by an invisible but powerful brake: Legacy systems.

These old systems, which have been the backbone of supply companies for decades, are more than ever an obstacle to the necessary digital evolution. The Legacy Moderation is therefore not only an option but a strategic necessity to ensure the future viability and competitiveness in a rapidly changing market.

In this comprehensive guide, we examine why the dissolution or modernization of these outdated IT infrastructures is crucial for energy suppliers and city works, which concrete advantages it offers and which applications release the greatest potential.

The challenge: Why legacy systems in the energy industry become a risk

Short: Legacy systems are usually monolithic applications written in outdated programming languages (such as COBOL or PL/I) and run on no longer contemporary hardware or operating system platforms.

Legacy systems are usually monolithic applications written in outdated programming languages (such as COBOL or PL/I) and run on no longer contemporary hardware or operating system platforms. In the context of energy and water supply, these systems lead to specific and critical problems.

High operating costs and inefficiency

The ** maintenance of Legacy-IT** is extremely costly. The Total Cost of Ownership (TCO) is steadily increasing as spare parts for the hardware are difficult to find and the licenses for the old systems are often expensive.

Added to this is the effort for manual troubleshooting and the complexity of the interfaces to modern systems. This inefficient IT infrastructure binds capital that is urgently needed for innovation.

Lack of scalability and flexibility

The dynamics of the energy market require rapid adjustments. New business models, such as decentralised production, Smart Metering and the integration of renewable energies, place enormous demands on IT. Legacy systems, however, are often not designed for processing large amounts of data (big data) or rapid scaling.

You can hardly or not support new regulatory requirements or the connection to modern cloud platforms, which massively impedes the digital transformation in the EVU.

Regulatory complexity and compliance

The energy industry is one of the most regulated industries. Changes in laws and regulations, such as the MaBiS requirements (market communication for accounting and accounting purposes) or the requirements of the ** Act on the digitization of the energy transition**, often require profound adjustments to the core systems.

In legacy systems, these adjustments are time-consuming, fe

References and further reading

Short: The following independent references complement the topics in this article:

The following independent references complement the topics in this article:

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About the author

Björn Groenewold
Björn Groenewold(Dipl.-Inf.)

Managing Director of Groenewold IT Solutions GmbH and Hyperspace GmbH

For over 15 years Björn Groenewold has been developing software solutions for the mid-market. He is Managing Director of Groenewold IT Solutions GmbH and Hyperspace GmbH. As founder of Groenewold IT Solutions he has successfully supported more than 250 projects – from legacy modernisation to AI integration.

Software ArchitectureAI IntegrationLegacy ModernisationProject Management

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