P50 Profile Modeling Approach

Overview

This document explains how our system creates P50 (50th percentile) solar generation profiles for any site in Europe using an ensemble approach that combines multiple trusted data sources.

What is a P50 PV Generation Profile?

A P50 generation profile represents the expected energy output where there is a 50% probability that actual generation will exceed or fall below this estimate. It serves as the median expected generation under typical meteorological conditions, making it the standard reference for energy yield assessments and financial models.

Our Ensemble Approach

We use a multi-source ensemble methodology that:

  1. Collects data from two leading solar resource databases
  2. Models PV generation for each dataset separately
  3. Combines the results using a median approach to reduce bias
  4. Normalizes the output as capacity factors (0-1 range)

Data Sources

PVGIS (European Commission)

The Photovoltaic Geographical Information System provides high-resolution solar radiation data specific to European conditions.

PVGIS API Documentation

NSRDB (NREL)

The National Solar Radiation Database offers comprehensive solar resource data with global coverage.

NSRDB API Documentation

Modeling Process

1. Location-Specific Parameters

For any given site coordinates, we:

  • Identify the nearest country in our database
  • Apply appropriate tilt and azimuth angles for fixed-mount systems
  • Set expected irradiance ranges for validation

2. Data Validation and Processing

For each data source, we:

  • Validate irradiance components (GHI, DNI, DHI) against expected ranges
  • Apply physical corrections to ensure consistency
  • Adjust data for nighttime, clear-sky limits, and overcast conditions

3. PV System Modeling

We use industry-standard methods to model:

  • Plane-of-array irradiance using the Pérez model
  • Cell temperature effects on panel efficiency
  • Inverter performance characteristics
  • DC to AC conversion with appropriate losses

The model assumes:

  • Fixed-tilt mounting with country-specific angles
  • DC/AC ratio of 1.2-1.3 (slightly oversized DC capacity)
  • Modern module and inverter technology

4. Ensemble Creation

Rather than relying on a single source, we:

  • Calculate generation profiles from each data source
  • Take the median value at each timestamp
  • This approach reduces biases in individual datasets

5. Standardization and Time Handling

The output is standardized to:

  • A reference year (2024)
  • UTC timezone
  • 15-minute resolution
  • Normalized capacity factors (0-1 range)

Using the Generation Profiles

The generation profiles can be:

  • Scaled to any system capacity
  • Mapped to any date range while maintaining time-of-day and seasonal patterns
  • Used for Re-Twin PV modeling setup e.g. PV+BESS setup

Performance Indicators

The system calculates expected capacity factors for each location, providing a quick reference for annual energy yield as a percentage of nameplate capacity.

Advantages of Our Approach

  • Robust: Less sensitive to biases in any single dataset
  • Geographically optimized: Uses parameters specific to each European country
  • Physically sound: Ensures adherence to solar physics principles
  • Flexible: Normalized output can be scaled to any system size
  • High resolution: Captures intra-hour variability important for grid studies

References and Resources

Table of Contents