Overview
IEC TR 63149:2018 - Land usage of photovoltaic (PV) farms – Mathematical models and calculation examples - is a Technical Report that provides mathematical models and practical calculation examples to estimate land requirements for PV farms. The document focuses on how to calculate distances between arrays to avoid shading while minimizing land use, and covers a broad set of array types and tracking strategies for flat and sloped sites.
Key Topics and Technical Content
- Scope and purpose: Models for determining no‑shading spacing and reasonably reducing land usage of PV farms.
- Coordinate systems and solar geometry: Ground Horizontal Coordinates (GHC), Equatorial Coordinates (EC), azimuth and hour angle definitions used consistently across models.
- Boundary conditions: Recommended setup parameters and no‑shading time windows (including winter solstice considerations) used as input to spacing models.
- Fixed array models: Calculation methods and worked examples for fixed-tilt PV arrays on flat and sloped land, and for non‑south orientations.
- Tracking systems: Land‑use calculations for multiple tracking configurations:
- Solar altitude tracking (manual adjustment)
- Horizontal E–W tracking (single-axis)
- Tilted E–W tracking (optimized S–N tilt)
- Pole‑axis tracking
- Double‑axis (equatorial and ground horizontal coordinates)
- Azimuth tracking
- Backtracking technology: Principles and examples showing how backtracking reduces inter-row shading and can lower required spacing.
- Practical aids: Numerous figures, tables and worked examples (e.g., S–N and E–W distance tables, array length/width ratios, winter solstice scenarios) to support design decisions.
Practical Applications
- PV project siting and layout optimization: Use the models to size array spacing, estimate land area per MW, and compare layouts (fixed vs. tracked).
- Feasibility studies and land acquisition: Produce defensible estimates of land needs under different shading constraints and tracking choices.
- Detailed engineering design: Integrate spacing data with electrical yield models and structural designs to balance energy yield and land cost.
- Policy, permitting and environmental assessment: Provide standardized calculations that support regulatory filings and land‑use planning.
- Research and modeling: Validate or benchmark PV farm layout algorithms and simulation tools against IEC TR examples.
Who would use this standard
- PV system designers, EPC contractors and layout engineers
- Project developers and land planners
- Consultants, asset owners and utilities
- Researchers and academic groups modeling PV farm performance
- Regulators and permitting authorities evaluating land-use claims
Related standards (context)
IEC TR 63149 complements other IEC publications and industry standards on PV modules, system performance and safety. It is intended to be used alongside technical standards and local regulations when planning and designing PV farms.
Keywords: IEC TR 63149:2018, land usage of photovoltaic farms, PV farm land use, array spacing, shading, mathematical models, tracking systems, backtracking, fixed PV arrays.