Bifacial modules are expected to have a 60% share in the PV market, which require spectral irradiance data incident on both sides to optimize the design. Sensors that provide spectrally resolved data are expensive and thus a cost-effective spectrally resolved albedometer was designed in two previous PVMD Master Theses. This albedometer measures irradiance in three wavelength bands. The focus of this research is on developing a model that reconstructs the spectral irradiance incident on the top part of the albedometer.

The spectral simulation program SMARTS was converted to MATLAB, after which a Particle Swarm Opimization Algorithm was added to determine values for unknown parameters. The model was first tested against spectra generated by SMARTS. After which both the original model and an model with additional modification coefficients was tested with clear-sky measurements from the albedometer and validated against an EKO spectroradiometer.

The original model proved to fail in the first wavelength band, which caused the other wavelength bands to be reconstructed poorly as well. The adjusted model performed close to the performance of the EKO for clear-sky irradiances above 400 J/Z2 in the total albedometer region, 320-1100 nm.