New publication from the SUNLAB: IEEE Journal of Photovoltaics

How do photovoltaic (PV) system irradiance models hold up for vertical and high latitude PV? The SUNLAB’s latest paper, first-authored by recent PhD graduate Erin Tonita, shares results from validating five PV system irradiance models: PVSyst, bifacial_radiance, the System Advisor Model, bifacialVF, and DUET, with a year of vertical reference cell data in Fairbanks, Alaska (65°N) and half a year of data in Golden, Colorado (40°N).

The paper shows:

• The impact of low irradiance timestamps, snowy ground conditions, cloudy conditions, and operations and maintenance practices on model accuracy.

• That deviations between model-predicted annual insolation tend to be 2 to 3 times higher for vertical PV systems than south-facing fixed-tilt systems.

• The importance of temporal resolution for vertical PV and PV systems in snowy locations.

Click here for the full article.

E. Tonita, S. Ovaitt, H. Toal, K. Hinzer, C. Pike, and C. Deline, Vertical bifacial photovoltaic system model validation: Study with field data, various orientations, and latitudes, IEEE J. Photovolt., Early Access (2025). DOI: 10.1109/JPHOTOV.2025.3561395