In this document
We will introduce the importance of incorporating accurate, site-specific environmental factors in PV simulations, particularly focusing on ground albedo, which plays a significant role in influencing the amount of reflected irradiance.
Overview
Accurate albedo modeling is crucial for determining the total irradiance reaching PV modules, making it indispensable for reliable energy yield predictions. Seasonal variations in albedo are particularly significant, and the shift from using a single constant value to twelve monthly values in current industry standards provides a more detailed and precise representation for advanced PV modeling.
To validate Solargis' monthly albedo data, comparisons were conducted using ground-based measurements collected with albedometers. However, the availability of such measurements was limited to stations in North America.
Geographical scope | North America |
Data parameters | ALB (monthly values) |
Calculated indicators | Bias, MAD, RMSD |
Reference period | 2006 to 2015 |
Reference source | AMERIFLUX, SURFRAD |
ALB validation statistics
The growing adoption of bifacial modules has heightened the importance of accurate albedo data for design decisions, such as module height, tilt angle, and row spacing, to optimize the capture of reflected light. Therefore, the use of validated monthly albedo data has become increasingly vital for optimizing PV system performance. See results of the validation of Solargis albedo in the following table:
ALB | ||
---|---|---|
Number of validation sites | 8 | |
Mean bias for all sites | -0.01 |
The validation exercise demonstrated a very low mean bias of -0.01, indicating excellent agreement between Solargis albedo data and ground measurements.
Details of the ground measurements used for validation purposes are given in the map and table below.
Station name | Latitude, Longitude | Data source |
---|---|---|
Metolius Mature Pine | 44.452, -121.557 | AMERIFLUX |
Morgan Monroe State Forest | 39.323, -86.413 | AMERIFLUX |
Willow Creek | 45.806, -90.08 | AMERIFLUX |
Walnut Gulch Kendall Grasslands | 31.737, -109.942 | AMERIFLUX |
Fort Peck | 48.308, -105.102 | SURFRAD |
Desert Rock | 36.624, -116.019 | SURFRAD |
Table Mountain | 40.125, -105.237 | SURFRAD |
Bondville | 40.052, -88.373 | SURFRAD |
Conclusions
The validation results confirm the high accuracy of Solargis albedo data for PV simulations, even with limited ground-based measurements. Although this validation exercise is limited to a relatively small set of locations, they represent a reasonably broad climatic diversity.
The use of monthly albedo values, rather than constant values, aligns with current industry standards and provides a solid foundation for advanced PV modeling. This supports reliable energy yield predictions and optimized system design, particularly for bifacial systems and configurations sensitive to reflected light.
Differences between the field of view (FOV) of albedometers and the larger area covered by satellite imagery pixels can impact validation. Satellite imagery often captures non-homogeneous land cover surrounding albedometers, introducing some variability in the comparison of ground-based and satellite-derived albedo data.