Poland’s power system sent two apparently conflicting signals in August. On August 4, transmission system operator Polskie Sieci Elektroenergetyczne (PSE) declared capacity-market system stress events from 17:00 to 19:00, activating obligations for contracted capacity providers. Two days later, another series of stress periods extended from 17:00 through 22:00. Yet later in the same month, PSE was doing something very different: on August 20, 22 and 23, it instructed both photovoltaic and wind installations to reduce generation through non-market redispatch. PSE capacity-market news
There is no contradiction once the system is viewed hour by hour rather than through annual generation totals. Renewable generators can be producing more electricity than the grid can accommodate under one set of conditions, while dependable capacity can become scarce under another. What Poland’s August events expose is a widening separation between the amount of electricity being produced and the value that electricity provides to the power system.
An additional megawatt-hour is not equally useful at every hour or every location. As Poland adds more variable renewable generation, the question is increasingly not only how much electricity can be generated, but whether that electricity can be absorbed, moved, stored or supplied when and where the system needs it.
A solar-heavy afternoon can still become a tight evening
August 4 provides an unusually clear example.
Modo Energy’s analysis shows Polish solar generation reaching around 12.8 GW at midday, pushing net load down to roughly 6.8 GW. By 20:00, net load had climbed back to about 12.2 GW as solar production declined. The evening also coincided with wind generation of only around 949 MW, while approximately 4.9 GW of coal and lignite capacity was unavailable for planned summer maintenance. High river temperatures further constrained some thermal generation because of cooling-water limits. Modo Energy analysis of the August 4 event
Solar did not cause the stress event. Several factors arrived together: thermal maintenance, heat-related restrictions, weak wind and the normal decline in solar output toward evening. The significance of the day lies instead in how quickly the resource mix changed.
At midday, solar was already large enough to reshape Poland’s residual demand. A few hours later, reliability depended on a very different combination of thermal generation, wind, imports, demand response and other flexible resources being available.
That distinction disappears easily in annual statistics. A country may add substantial renewable TWh while still facing tight conditions during individual hours. Likewise, 1 GW of renewable nameplate capacity does not automatically provide 1 GW of dependable capacity at 19:00.
During the August 4 event, Poland also did not yet have a battery fleet large enough to play a material role in that evening transition. Modo estimates that batteries supplied less than 0.2% of Polish demand during the called hours. The Polish system was already showing the characteristics of a solar-heavy daytime market before utility-scale batteries had become significant enough to reshape its evening operation.
Redispatch shows the other side of the market
Later in August, PSE instructed PV and wind installations to lower output on August 20, 22 and 23. The operator’s records also show repeated renewable redispatch earlier in the month, including PV on August 11–16 and wind on August 11, 15 and 16. PSE redispatch notice
It would be inaccurate to interpret every event simply as Poland “having too much solar.” Non-market redispatch can result from balancing requirements, network constraints and wider system-security conditions. PSE’s compensation notices establish that renewable generation was reduced; they do not establish one identical cause behind every instruction.
What they do show is that Poland experienced repeated periods this summer when available renewable generation could not be fully accommodated without intervention.
That matters because renewable growth can no longer be assessed only through installed GW or annual TWh. Another renewable MWh may still reduce fuel use and emissions over the year, but its immediate system value depends increasingly on when and where it appears and whether the network and wider power system can absorb it.
The redispatch events should not therefore be connected mechanically to the August capacity calls. They happened on different dates and under different system conditions. There is no evidence that the electricity curtailed during one event could simply have been stored and delivered during another.
The useful connection is broader: energy volume and system value are separating across time, location and controllability.
Redispatch reveals the cost of generation that cannot be fully accommodated when and where it appears. A capacity-market stress event reveals the value of dependable MW being available during specific hours. Poland is not simply switching between “too much electricity” and “too little electricity.” The same power system can value electricity very differently as conditions change.
Batteries are arriving as that gap becomes more visible
This is becoming more than a system-operations story because Poland is simultaneously moving toward a much larger battery fleet.
In December 2025, the National Fund for Environmental Protection and Water Management approved support for 174 storage projects across two programmes. Of these, 172 projects supported through the Modernisation Fund represent around 3.9 GW / 14.5 GWh of planned storage capacity and are due to be completed by the end of 2028. Separate support covers the large Żarnowiec and Ełk projects, which together represent 425 MW / 2,032 MWh. Polish Ministry of Climate and Environment · NFOŚiGW storage programme
Some of that capacity has already moved beyond announcements. PGE began construction of its Żarnowiec BESS in 2025. The project is designed for approximately 262 MW / 981 MWh, with commercial operation planned for the second quarter of 2027. PGE Żarnowiec project information
By April 2026, key DC-Link units had already begun arriving at the construction site for installation, providing a visible sign that the project had moved into physical delivery. LG Energy Solution project update
The timing is significant. Large batteries are beginning to move from auction results, connection queues and policy programmes into physical deployment just as the operational value of flexibility is becoming more visible.
But their role cannot be reduced to charging on surplus solar and discharging after sunset.
A battery can relieve a particular redispatch condition only if it is connected where its charging is useful, has sufficient charging headroom and is not restricted by the same network constraint. Providing dependable evening capacity creates another set of requirements: adequate duration, sufficient state of charge, market qualification and an operating strategy that preserves energy when it is needed.
The more important question for Poland is therefore not simply how much battery capacity will be built. It is what those batteries will be paid to do.
Poland’s BESS case is becoming a multi-market one
The capacity market has been an important part of the Polish BESS investment case because it provides a route to contracted availability revenue. The revenue contribution from that mechanism, however, has weakened substantially.
Modo Energy calculates that the BESS de-rating factor used in Poland’s capacity market fell from 95% to 13.4% over three years. At a 13.4% factor, a 100 MW battery receives capacity-market credit for only 13.4 MW. Modo estimates that effective capacity payments consequently declined by around 85%. Even so, approximately 5.1 GW of physical BESS capacity cleared the December 2025 auction according to its analysis. Modo Energy analysis of Poland’s BESS capacity market
That does not make the capacity market unimportant. It does mean that capacity revenue alone can no longer explain the scale of Poland’s BESS pipeline.
Balancing services and wholesale optimisation are becoming a larger part of the picture.
Modo’s annualised July 2026 benchmark for a modelled, unconstrained four-hour Polish battery was PLN 1.67 million/MW-year. In the simulation, aFRR capacity accounted for 67% of the revenue stack, day-ahead trading for 24% and FCR for 8%. Modo Energy July 2026 Polish BESS benchmark
Those figures are not reported earnings from an operating Polish battery. Poland does not publish asset-level utility-scale BESS revenue data, so Modo models a representative asset against actual market prices. The benchmark is useful for understanding market structure, not for predicting the revenue of an individual project.
What it does illustrate is that Poland’s emerging storage market cannot be understood as a simple midday-to-evening arbitrage opportunity. Capacity, balancing and wholesale markets are all part of the revenue stack.
As more batteries connect, those opportunities will change again. Competition can compress ancillary-service revenues, making duration, wholesale optimisation, grid location and dispatch strategy increasingly important. The batteries entering Poland will not merely participate in the market that exists today; at sufficient scale, they will help change it.
The next phase is about usable power
Poland’s August events are not evidence that the country simply has too much electricity at one moment and too little at another.
They show something more important.
Solar is already large enough to reshape daytime residual demand. Renewable generation has repeatedly required redispatch under certain system conditions. Yet dependable capacity can still become valuable only hours later when the generation mix changes and other resources are unavailable. At the same time, Poland’s utility-scale battery fleet is only beginning to move into physical deployment.
The next stage of the transition is therefore not simply about adding more renewable MWh. It is about converting increasingly variable electricity production into usable system value at the hours and locations where that value is needed.
Battery storage will be one part of that transition, alongside stronger networks, interconnection, demand-side flexibility and other dispatchable resources. Its role is more complicated than storing surplus renewable electricity—and potentially much more valuable.
Poland’s recent redispatch notices and capacity-market calls do not prove that batteries solve the problem. They show why the market is moving beyond electricity volume alone: as renewable penetration rises, value increasingly depends on when, where and how reliably power can be delivered.
