Transmission grid fees in Belgium could increase by 92% for battery energy storage systems (BESS) and by 150% for offshore wind projects by 2035, according to a study by Aurora Energy Research examining the evolution of network tariffs and their economic implications for energy projects.

The report, titled Transmission Grid Fees in Belgium: Outlook & Impact Assessment, was commissioned by Adaptogen Capital, BayWa r.e., Norther, Otary and Storm, amid regulatory changes affecting the costs of accessing and using Belgium's electricity transmission infrastructure.

The analysis follows the publication of the tariff methodology for the 2028–2031 regulatory period by Belgium's energy regulator, CREG, ahead of transmission system operator Elia's expected publication of updated grid tariffs in 2027.

Grid fees for batteries could reach €112/kW by 2035

One of the main changes examined in the study is the planned phase-out of the 10-year grid fee exemption for battery energy storage systems, a mechanism that has helped limit network costs for eligible storage projects.

According to Aurora's central scenario, the combined effect of removing this exemption and rising overall network costs could result in a 92% increase in the total grid fee burden for a typical battery, reaching €112/kW by 2035.

The study estimates that, without mitigation measures, average annual margins for battery storage projects could fall to €47/kW.

Björn Hofman, Senior Associate, Advisory, at Aurora Energy Research, warned that rising grid fees could place additional pressure on the economics of battery storage projects and other grid-connected assets in Belgium.

He noted that discount mechanisms are available, including incentives to avoid charging during peak hours and the potential introduction of voluntary flexible connection agreements. However, these measures are unlikely to fully offset the projected increase in network costs.

Offshore wind faces a potential 150% increase

The second major regulatory change identified by Aurora is the introduction of a capacity-based feed-in fee for electricity injected into the grid, which would add another cost component for renewable electricity generators.

According to the analysis, Belgium's projected feed-in fees could reach €11/kW, exceeding the levels expected in neighbouring markets.

Germany is preparing similar charges in the range of €4–7/kW, while Belgium has yet to announce comparable protections for existing projects or developments that have already committed investment.

Aurora notes that Germany has announced a 20-year exemption for assets that reach a final investment decision (FID) before the new fee enters into force. The Netherlands is also expected to introduce an equivalent exemption to maintain comparable investment conditions across European markets.

Belgium, by contrast, has not yet made a similar commitment to protect projects from changes to the tariff framework after investment decisions have been taken.

This regulatory difference could affect the competitiveness of Belgian renewable energy projects relative to those in neighbouring countries.

Industry representatives call for protection of existing investments

Mathias Verkest, CEO of Otary, warned that allocating grid costs between electricity consumers and producers could have implications for final electricity prices and the financing conditions of new projects.

He explained that developers may seek to pass additional costs on to consumers. Where this is not possible, higher network charges could instead translate into increased risk premiums, potentially raising the cost of financing new developments.

Verkest therefore supported the introduction of grandfathering provisions to protect existing and upcoming projects, following the approach adopted in Germany and the Netherlands.

Similarly, Christophe De Schryver, Executive Manager at Norther, stressed that investment in renewable electricity generation depends on a stable and predictable regulatory framework over long periods.

He warned that introducing substantial new injection charges without protecting previously committed investments could undermine investor confidence and weaken Belgium's attractiveness for future energy investment.

Aurora identifies measures to limit rising network costs

The study outlines several measures that could help contain the increase in transmission charges, including alternative financing arrangements for part of the required grid investment, stimulating electricity demand to expand the tariff billing base, and stricter cost controls.

For the remaining costs, Aurora recommends implementing grandfathering exemptions for existing and upcoming projects, maintaining discounts for avoiding consumption during peak periods, and extending flexible connection discounts to both voluntary and imposed agreements.

The consultancy warns that, without regulatory action, higher network charges could delay investment decisions in storage and renewable electricity generation while increasing costs for electricity consumers.

The report therefore identifies the evolution of transmission tariffs as a factor that could influence the profitability of BESS and offshore wind projects, financing conditions and the deployment of renewable energy capacity in Belgium over the coming decade.