Repowering of RES: what producers must complete by the end of 2026

Electricity producers from renewable energy sources that entered the extended feed-in premium support regime have, in most cases, only until 31 December 2026 to invest the approved economically justified costs. If they fail to fulfil this obligation or are unable to duly demonstrate the investments, they may face the risk of returning part of the funds to the support settlement entity. RONI repeatedly reminds producers of this obligation and has also announced inspections.

In practice, this is therefore not only a technical or accounting issue. It is a regulatory risk that may have a direct financial impact on RES producers.

What is repowering?

The mechanism referred to as repowering, or the prolongation of support, was introduced by an amendment to the Support Act [1], effective from 1 August 2021. Its essence is that the original 15-year feed-in premium support period was extended by an additional 5 years, while the Regulatory Office for Network Industries (RONI) simultaneously reduced the approved electricity price from which the feed-in premium is calculated.

The feed-in premium support therefore remained preserved, but was spread over a longer period and provided in a lower amount.

The calculation in the price proposal could also include expected investments in necessary repairs or technical modifications of the facility, intended to ensure the operability of the installation throughout the entire extended support period.

However, these investments are not merely a formal figure or a non-binding plan. The producer must actually carry them out and be able to demonstrate them.

By when?

In its notices, RONI states that the investments must be made no later than within the first five years following the year in which the electricity producer entered the extended support regime. In most cases, this is the period from 1 January 2022 to 31 December 2026.

For most producers, 2026 therefore becomes the final period in which they can fulfil the obligation to invest the approved economically justified costs.

Economically justified costs according to RONI

In 2024, RONI published a report entitled „ÚRSO informuje o nákladoch na opravu OZE pre účely predĺženej podpory“ (RONI informs about RES repair costs for the purposes of extended support). In this report, RONI for the first time dealt in greater detail with economically justified costs for RES repairs for the purposes of extended support.

In its latest notice of 23 January 2026, RONI published a procedure for demonstrating actually incurred economically justified costs for the necessary repair or modification of the technological part of the facility. According to this guidance, the costs are demonstrated by means of an expert opinion.

The expert opinion is to be prepared by an expert in the field of Electrical Engineering and Energy. The opinion is to determine the amount of the actually invested costs, compare them with the originally declared investments, assess their economic justification and determine the date of completion of the works.

It is therefore important for producers to have prepared in advance not only technical documentation, but also accounting, contractual and invoicing documents relating to the repairs or modifications carried out.

RONI announces inspections and repayment of funds

Already in its notice of 17 July 2025, RONI warned that, in the event of suspicion that the entire volume of funds has not been invested or that the funds have been used improperly, it may proceed with thorough inspections. Such inspections may lead to the return of the feed-in premium or part thereof to the support settlement entity and subsequently also to a reduction of the electricity price.

RONI returned to this issue again in its notice of 23 January 2026. If a producer does not invest the full amount of the approved economically justified costs, RONI may, during an inspection, determine the amount that the producer will be obliged to return to the support settlement entity. RONI states that, in determining this amount, it will proceed from the difference between the costs approved in the price decision and the actually incurred economically justified costs. The non-invested part is to be returned in full.

Put simply, if a producer is unable to demonstrate that it invested the approved economically justified costs to the required extent and in compliance with the conditions of the prolongation of support, it faces the risk of a financial correction.

The situation is legally sensitive

The legal framework governing the prolongation of support has been amended several times since 2021.

Producers entered the extended support regime under the original RONI Pricing Decree No. 18/2017 Coll., which was subsequently replaced by the new Pricing Decree No. 370/2023 Coll., and thereafter by the current Pricing Decree No. 154/2024 Coll.

This may in practice raise questions, in particular when assessing which costs may be regarded as economically justified, how to assess their factual connection with the technological part of the facility, and how to proceed in different periods covered by different legal regulations.

We note that it is precisely the current Pricing Decree No. 154/2024 Coll. which, in Section 45(5), introduced a procedure for demonstrating actually incurred costs by means of an expert opinion, which was absent from the original regulation.

What do we recommend?

We recommend that producers, before the end of 2026, verify not only the amount of the actually invested costs, but also the quality of the documentation, the economic justification of individual expenditures and their preparedness for an expert assessment.

If any doubts arise during this review, it is advisable to address them in a timely manner, before they become the subject of an inspection by RONI.

How can we help?

We can assist producers with the legal assessment of their position, analysis of the price decision and assessment of the conditions they must fulfil when investing the costs. We can also identify possible legal risks, prepare supporting documents for the expert and set up the next steps vis-à-vis RONI.

If there are doubts regarding the scope of invested costs, the completeness of the documentation or how to proceed when demonstrating investments, we recommend addressing the situation before the end of 2026.

Our firm has been dealing with the topic of repowering for a long time and with close attention (see our previous articles here (in English) and here (only in Slovak)).

[1]     Act No. 309/2009 Coll. on Support for Renewable Energy Sources and High-Efficiency Cogeneration and on Amendments to Certain Acts (“Support Act”).