Law No. 15,269/2025 introduced what may appear to be a modest adjustment to the legal framework governing capacity reserve contracting in the Brazilian electricity sector. However, when examined through the lens of Law and Economics, the change carries potentially significant implications for the allocation of costs and incentives within the system. By adding paragraph 6 to Article 3-A of Law No. 10,848/2004, the legislator established that, in the case of energy storage systems in the form of batteries, the costs associated with capacity reserve contracting shall be allocated solely among electricity generators, in accordance with ANEEL’s regulation.
The amendment partially departs from the traditional logic underlying the socialization of system reliability costs in the Brazilian electricity sector. The caput of Article 3-A clearly reflects this historical rationale. The costs resulting from the contracting of capacity reserves—including administrative and financial expenses as well as tax charges—have long been treated as systemic costs, to be shared among all final users of electricity within the National Interconnected System (SIN). The economic justification is straightforward: the security and reliability of the power system benefit the market as a whole.
From a Law and Economics perspective, the legislative change deserves careful examination because it alters the allocation of costs associated with a service that is inherently systemic in nature. In complex infrastructures such as electricity systems, certain costs cannot be efficiently assigned to a single class of economic agents, since they arise from the fundamental need to ensure operational stability, reliability, and flexibility across the network. Energy storage—particularly battery storage—fits precisely within this category.
The economic function of storage extends beyond the individual activity of generation. Battery systems help smooth demand peaks, reduce volatility between periods of excess and scarcity of generation, avoid the dispatch of expensive thermal plants, and enhance supply reliability. In other words, storage produces diffuse benefits that extend across the entire structure of the electricity system. Consumers, traders, system operators, and the short-term electricity market all benefit from the operational flexibility that these technologies provide.
The legislative choice to assign exclusively to generators the costs of capacity reserve contracting associated with storage systems creates a misalignment between those who benefit from the service and those who bear its costs. In economic terms, the rule modifies the incentive structure of the market and may influence the behavior of investors and market participants in the coming years.
One immediate potential impact concerns the economic attractiveness of projects incorporating storage. Renewable generation projects with batteries already present higher cost structures than conventional solar or wind projects. The integration of storage systems requires substantial additional investment in equipment, engineering, technological integration, and operational management. By shifting further systemic costs onto generators that adopt storage technologies, the law may inadvertently reduce the internal rate of return of these projects.
The predictable economic consequence is a marginal disincentive to investment in solutions that increase the flexibility of the electricity system. An entrepreneur structuring a solar project may conclude that installing batteries—although technically beneficial for the system—becomes economically less rational under the new allocation of costs. The likely outcome is an increase in the number of projects operating without storage, leaving the electricity system itself to manage the variability inherent in renewable generation.
Another possible effect is the repricing of electricity in supply contracts. Additional costs borne by generators rarely remain confined to that stage of the production chain. In competitive markets, economic agents tend to incorporate new charges into the price formation of their products. Electricity markets follow the same logic. Projects that assume additional storage-related costs will likely reflect those expenses in long-term power purchase agreements within the Free Contracting Environment (ACL) or in contractual structures related to self-production arrangements.
The legislative change may also generate distortions in competition among technologies that provide system flexibility. Hydropower plants with reservoirs, dispatchable thermal plants, and demand response mechanisms all perform functions similar to battery storage in stabilizing the power system. If only one of these technologies becomes subject to specific costs related to capacity reserve contracting, battery storage may lose relative competitiveness. Paradoxically, the market could end up favoring technologies that are less aligned with the objectives of the energy transition.
The discussion becomes even more relevant when considering the rapid growth of new energy-intensive demands associated with the digital economy. Data centers, artificial intelligence processing hubs, and cloud computing infrastructure are among the fastest-growing sources of electricity consumption worldwide. These facilities present two characteristics that challenge traditional electricity system structures: continuous high-load consumption and an extremely high requirement for supply reliability.
In this context, projects that combine renewable generation with storage have become a strategic solution in several jurisdictions. Solar plants coupled with batteries allow energy generated during daylight hours to be shifted to periods of higher demand, thereby providing more stable supply conditions. Hybrid wind-plus-storage projects can also reduce generation volatility and offer more predictable energy output for large consumers.
If systemic storage costs are concentrated exclusively on generators, projects designed to supply large energy-intensive consumers—such as data centers—may face higher electricity costs. Generators required to internalize additional storage-related charges will likely adjust the prices offered in long-term energy supply contracts.
Consider, for example, a project in which a data center is located near a solar complex equipped with batteries intended to guarantee continuous renewable power supply. The economic viability of such arrangements depends on the ability to deliver firm energy at competitive prices. The imposition of additional charges on generators may alter the financial balance of these contractual structures, requiring price adjustments or a reassessment of the scale of the storage system.
Another possible scenario involves hybrid wind projects with batteries designed to stabilize production and reduce exposure to short-term market volatility. If systemic costs fall on the generators that invest in storage, some developers may opt to operate without batteries, accepting greater variability in generation and transferring operational challenges back to the electricity system.
Economic analysis suggests that regulatory efficiency depends on the coherence between three fundamental elements: the origin of a given cost, the agents who benefit from the service, and the ability of each agent to influence or mitigate that cost. In the case of energy storage, the benefits are broadly distributed across the electricity system. Improved grid reliability, reduced reliance on thermal dispatch, and greater integration of renewable sources generate gains that extend well beyond the individual activity of generation.
By concentrating the costs exclusively on generators, the legislator establishes an arrangement that may create incentive misalignments precisely at a moment when the Brazilian electricity sector faces structural challenges associated with the expansion of intermittent renewable sources and the growth of new energy-intensive loads. The role of ANEEL’s regulatory implementation will therefore be decisive in mitigating or amplifying these effects, particularly in defining the cost-allocation methodologies provided for in the law.
The evolution of this regulatory framework is likely to influence investment decisions in energy storage in Brazil, the pricing dynamics of electricity in the free market, and the competitiveness of new industrial and digital projects that depend on reliable and firm energy supply. In an electricity system that is becoming increasingly complex and digitalized, the way in which flexibility costs are distributed among market participants may determine not only the economic viability of certain technologies, but also the pace of Brazil’s broader energy transition.
