All production, imbalance, and KÜPST figures are drawn from the EPİAŞ Real-Time Settlement (Gerçek Zamanlı Uzlaştırma / GZU) reports. Data is fetched at hourly resolution via the public EPIAS Transparency Platform REST API (eptr2) and aggregated to monthly plant-level summaries. The dataset covers all licensed solar (GES) or wind (RES) power plants that reported at least one hour of production in the analysis period.

The imbalance ratio measures how much a plant's hourly generation deviates from its day-ahead schedule, relative to what it actually produced. For each hour we take the absolute difference between the forecast (KÜDÜP) and the actual settlement quantity (UEVM), sum these over the month, and divide by total actual generation:Because the hourly differences are taken in absolute value, over-production hours and under-production hours do not cancel out — both count as imbalance. The metric therefore captures hourly forecasting volatility and is scale-independent, so plants of different sizes compare fairly. The separate net imbalance (signed sum, where surplus and deficit hours offset) is typically much smaller and is reported as a distinct figure.

Imbalance cost arises when a plant's actual hourly generation differs from its day-ahead schedule. Settlement is system-direction-dependent: positive imbalance (plant produced more than scheduled) is settled on min(MCP, SMP); negative imbalance (produced less) on max(MCP, SMP).

• Until Dec 2025 — flat 3% margin: positive at min(MCP, SMP) × 0.97, negative at max(MCP, SMP) × 1.03.
• From Jan 2026 (EPDK regulation, Official Gazette 29/12/2025) — the margin depends on whether the plant's deviation aggravates or relieves the system. A deviation in the same direction as the system imbalance is charged 6% (positive × 0.94, negative × 1.06); a deviation that helps the system keeps the 3% margin (positive × 0.97, negative × 1.03).

Figures use EPİAŞ's published hourly imbalance prices, which already embed the applicable system-direction coefficient. The reported monthly value is the net imbalance cost (TL) — the algebraic sum of positive and negative settlement differences over all hours.

KÜPST (Katılım Ücreti ve Perakende Satış Tarifesi Primi) is a penalty levied when a plant's monthly net imbalance exceeds a regulatory tolerance band:

• Solar (GES): 8% of monthly generation (10% before Jan 2026)
• Wind (RES): 15% of monthly generation (17% before Jan 2026)

The KÜPST unit price equals 3% of max(MCP, SMP, 750 TL/MWh) for the relevant hour. Only the portion of imbalance that exceeds the tolerance band attracts the penalty.

Unit cost = (Total Imbalance Cost + Total KÜPST Cost) ÷ Total Generation for the month, expressed in TL/MWh. It provides a scale-independent measure of settlement efficiency, allowing fair comparison across plants of different capacity.

Plants are ranked by their monthly imbalance percentage, defined as |Net Imbalance MWh| ÷ Generation MWh × 100. A lower value indicates better forecast accuracy. The bar chart shows the best and worst performers for the selected month; the full ranked list appears in the table below.

A plant is excluded from a given month's ranking — while remaining in the registry — in either of these cases:

• Zero activity: the plant reported zero generation and zero forecast for the whole month.
• Insufficient forecast coverage: the plant has both a forecast and an actual value for less than half of the month's hours — typically a unit commissioned or registered mid-month. Its imbalance ratio would not be comparable with a full-month plant, so it is listed rather than ranked.

Every excluded plant is listed below with its reason.

KARAPINAR YEKA-1 (approx. 1,365 MW) is excluded from the plant statistics due to its outsized scale. Its performance is reported separately.

Plants excluded this month

ELAZIĞ HİBRİT BES/GES	Zero production and zero forecast for the entire period
PAMUK GES	Zero production and zero forecast for the entire period
ALİAĞA-1 GES	Balancing Power Market (DGP) participant / commanded curtailment — not a forecast imbalance
ARTUKLU-1 GES	Balancing Power Market (DGP) participant / commanded curtailment — not a forecast imbalance
G4-VİRANŞEHİR-1 GES	Anomalously high imbalance — set aside as not representative of forecast performance
IĞDIR DGES	Balancing Power Market (DGP) participant / commanded curtailment — not a forecast imbalance
NEPSUN HADİM GES	Balancing Power Market (DGP) participant / commanded curtailment — not a forecast imbalance
OZE DEPOLAMALI GES	Balancing Power Market (DGP) participant / commanded curtailment — not a forecast imbalance