The Ministry of Mines and Energy (MME) has moved to overhaul how solar and wind power plants calculate their physical guarantees. Formalized under Portaria SNTEP/MME nº 3.257, signed October 28, 2026, and published November 4, 2026, the proposal seeks to curb the volatility of energy estimates and stabilize revision cycles for renewable assets.
Shifting to the P90 Standard
At the heart of the MME’s proposal is a pivot from the P50 to the P90 criterion for solar projects. The ministry intends to curb the frequency and scale of downward revisions, a common point of friction for developers. Historical data underscores the necessity of this shift: between 47% and 54% of analyzed solar plants saw their physical guarantees slashed during annual reviews.
To further refine these estimates, the MME plans to incorporate energy losses resulting from constrained-off events. By integrating these specific operational realities, the ministry aims to tailor calculation procedures to the unique technical requirements of each generation source.
Government Establishes Minimum Verified Generation Periods
The current regulatory framework relies on shorter timeframes, a mechanism the MME identifies as a primary driver of instability in guarantee amounts. Under the new proposal, the government establishes a minimum period of verified generation to be considered in reviews: 48 months for solar plants and 60 months for wind plants.
Reliability standards are also being hardened. The methodology introduces a maximum tolerance of six minutes for data transmission failures within any 30-minute interval. Any outage exceeding this threshold will be excluded entirely from generation estimates.
These proposals are the product of technical evaluations by the Energy Research Office (EPE) and the MME, backed by a Regulatory Impact Assessment (AIR). National Secretary of Energy Transition and Planning Mariana de Assis Espécie signed the document, exercising authority delegated by Portaria MME nº 692 of 2022, alongside provisions under Decree nº 5.163/2004 and Process nº 48360.000333/2024-51.
The physical guarantee remains a critical pillar for the National Interconnected System, dictating the structural balance between long-term supply and demand and setting the ceiling for energy trading contracts. Between July and September 2026, the MME issued new or revised guarantees for 3 wind farms, 35 photovoltaic plants, and 151 thermoelectric plants.
Public Consultation Deadline
The public consultation period is now active. The MME will accept contributions for 45 days, closing on December 18, 2026. Interested parties can submit feedback via the MME Public Consultations page or the Brasil Participativo platform. For direct inquiries, the MME Special Social Communication Advisory is available at (61) 2032-5759 or via email at imprensa@mme.gov.br.