How spectral effects impact capacity testing — a case study
· Keith McIntosh · SunSolve Yield Videos
This is an extended version of the presentation given by Dr Keith McIntosh (PV Lighthouse) at the 2026 PVPMC workshop. It details how spectral effects can easily introduce errors exceeding 1% in solar capacity tests, and different modeling approaches can lead to highly variable results.
When capacity test models ignore spectral variation:
- They assume a fixed reference spectrum (AM1.5G) that doesn’t match real-world conditions
- Atmospheric parameters like aerosols, precipitable water vapor, and air mass create significant spectral variations
- Two commonly used correction methods (First Solar model vs. reference module measurements) produced results differing by 2.5%