Fixed price or day-ahead market? A biogas plant in H1 2026

Only in a crisis. A biogas plant selling electricity at RDN prices, even with a double-membrane roof allowing it to operate in expensive hours, earned as much as under a fixed price only in half-years with a price shock (2021–2022); in I 2026 the result is PLN 619.5/MWh with 2× operation and PLN 670.7/MWh with 3× against PLN 828.4/MWh of FIT, i.e. 75% and 81%. An installation under FIP that additionally operates flexibly can, however, earn a similar amount: PLN 864.1/MWh (104% of FIT) with 2×. This is the last, twelfth analysis in the series. Below we summarise the whole period II 2020 – I 2026, and then discuss the latest half-year.

A reminder of the mechanism

The support rules (Articles 70a–70f of the Act on Renewable Energy Sources (ustawa o OZE)), the scenarios and the model assumptions are described in the first analysis of the series. You will find the results for the previous half-year in the previous analysis of the series (II 2025).

What twelve half-years showed

In the FIT column: 95% of the reference price for the "up to 500 kW" class. The model applies the regulations from 2020 (II 2020) and 2021 (I 2021 – I 2022), from 2022 (II 2022 – II 2023, also for II 2023, although from 10/11/2023 a higher price of PLN 828.4/MWh already applies to new declarations) and from 2023 (from I 2024). For 2024–2026 FIT is a reference point, because since 28/12/2024 it applies to installations below 200 kW. In the FIP + 2× column: the fixed price of 90% of the price for the 500 kW – 1 MW class, the market and the premium from the profile.

Conclusions from the table and chart. First, FIT in this series is not constant over time: it rises from PLN 617.5/MWh (declarations from 2020) to PLN 828.4/MWh (declarations after the regulation of 8 November 2023), and 2019 installations after indexation rose from PLN 631.7 to PLN 939.0/MWh. Second, the average RDN price exceeded FIT in only two half-years (I and II 2022), and 3× operation also in II 2021. Third, since II 2023 the RDN with 2× operation has been 53–75% of FIT. Fourth, FIP with 2× operation is equal to or higher than FIT in II 2021, in both half-years of 2022 and in II 2024, I 2025 and I 2026; in the other half-years since 2023 it falls within the range of 94–99% of FIT. Fifth, the premium for 2× operation rose from PLN 27.8/MWh (II 2020) to PLN 150.8/MWh (I 2026), with a maximum of PLN 184.8/MWh in II 2022, because the spread of prices within the day is growing.

The first half of 2026 in figures

The "2019 installation" price is 95% of the 2019 reference price (PLN 617.5/MWh) after cumulative indexation by the annual average CPI for 2019–2025 (Article 70e(3); GUS: 102.3; 103.4; 105.1; 114.4; 111.4; 103.6; 103.6).

The FIT in the table is 95% of the reference price for the "up to 500 kW" class. Since 28/12/2024 only installations smaller than 200 kW can use FIT, so for a 0.5 MW installation it is a reference point, and the support actually available remains FIP (the 200 kW – 1 MW class).

The cheapest hour is 13:00 (PLN 238.9/MWh), the most expensive 20:00 (PLN 731.3/MWh); a spread of PLN 492.4/MWh. There were 225 hours with a negative price, so excluding them raises RDN revenue from PLN 468.7 to PLN 501.3/MWh. The monthly averages fall from PLN 603.5/MWh in January to PLN 353.1/MWh in April, and then rise to PLN 487.5/MWh in June.

Is the roof enough and how much can be spent

With 2× operation the average biogas storage demand is 2,865 m³ (3,629 m³ at the 95th percentile), and with 3× it is 3,781 m³ (4,839 m³). One roof with a diameter of 26 m (about 2500 m³, an assumption based on DLG) covers 2× on 33% of days and 3× on 1% of days; two roofs (5000 m³) cover all of them. After annualisation, the surplus from operating in expensive hours allows spending PLN 4,076–5,015 thousand on an additional generating set and gas store for 2× and PLN 5,460–6,718 thousand for 3×, against assumed costs of PLN 1,106–1,830 thousand and PLN 2,260–3,826 thousand. The 2× variant pays back across the whole assumed cost range, and the 3× variant pays back across the whole assumed cost range. Remember, however, that increasing the installed capacity may change the class of the installation and the reference price — this is a matter to be clarified with the President of the Energy Regulatory Office (URE) before the investment.

The third option: an energy store

A 0.5 MW / 1 MWh store adds PLN 47.5/MWh to continuous operation (revenue PLN 516.2/MWh). The surplus allows spending PLN 1,034–1,265 thousand, i.e. PLN 1,034–1,265/kWh. The system costs (PLN 600–1,200/kWh) and the connection costs (PLN 50–400 thousand) are assumptions, not offers; after deducting the connection, the permissible cost is PLN 865–1,215/kWh and the store would pay back only in part of the range (a low connection cost, a low cost of capital, a cheaper offer). The calculation ignores distribution charges, the capacity charge and the balancing market. The twelve half-years show that the store adds from PLN 5 to PLN 50/MWh, and therefore usually less than 2× operation on its own biogas.

Legal status as of July 2026

FIT and FIP do not require agricultural biogas status — Article 70a(1) and (2) also covers landfill biogas, sewage treatment plant biogas and "other biogas", hydropower and biomass, with lower reference prices for biogas other than agricultural. Installations smaller than 200 kW use FIT (95% of the reference price), installations of 200 kW – 1 MW use FIP (90%). The support period is 15 years from the first sale, but no later than 30 June 2047 (Article 70f(1) in the consolidated text, Journal of Laws (Dz.U.) 2026, item 68). Article 93(11) requires a positive FIP balance to be offset against a future negative balance, and any amount not settled after the end of the period is returned to the renewable energy settlement operator (paragraph 12). Energy from every hour in which the RDN price is below zero is excluded from settlement (paragraph 4). The reference prices in the model come from the regulation of 8 November 2023 (Journal of Laws (Dz.U.) 2023, item 2440), which in the Sejm's ELI database remains the most recent regulation on this matter; we leave out investment aid, which may lower them. The consolidated text Journal of Laws (Dz.U.) 2026, item 68 also contains Articles 70g–70j (sales after the end of the support period for installations up to 1 MW), which according to the footnotes of the text enter into force on 30 June 2026; we did not extend the model to cover these provisions.

Planning flexible operation and VoltAlert

Operating in the 8 or 12 most expensive hours of the day requires knowing prices in advance. Day-ahead market prices are known once the auction has closed, so the generating set's operating schedule for the next day can be drawn up one day ahead. The VoltAlert app is helpful here — according to its website, it shows hourly energy prices (data from ENTSO-E, wholesale prices, not full bills) in 26 European countries, lets you set your own price threshold and receive an alert, and also browse an archive from 2015 with markings for negative and high prices. VoltAlert does not control the generating set and does not replace a model of the investment's profitability, but it can be used to plan the schedule and to track how often prices exceed the profitability threshold.

Conclusions for this half-year

• The RDN (PLN 468.7/MWh) and the RDN with 2× or 3× operation (PLN 619.5–670.7/MWh) are 57%–81% of FIT of PLN 828.4/MWh; the gap is PLN 157.7–208.9/MWh.
• FIP + 2× (PLN 864.1/MWh) and FIP + 3× (PLN 915.7/MWh) exceed FIT, but after spending on the generating set and gas store and with balance risk.
• Two roofs (5000 m³) cover all days, one — only 33% of days with 2×.
• An energy store does not change the calculation decisively: it adds PLN 47.5/MWh, and the costs in the model are ranges of assumptions.