| Work Detail |
Swedish scientists have developed a novel model to determine optimal photovoltaic installation angles in cold regions of high latitudes. The model uses meteorological big data and also takes into account the effect of transmittance change caused by snow, which is calculated taking into account the depth of the snow as well as its melting speed.
“Snow-induced loss could be a small proportion for low/mid latitudes,” the researchers say. “However, for high latitude areas, where winter seasons are usually long, snow effects play an important role, so their exclusion would significantly influence the reliability of the results.”
The new method combines an optimal PV installation angle model to maximize PV power generation with a simplified snow PV yield model (SPYM). The PV angle model is run with angles ranging from 0 to 90 degrees with intervals of 0.1 degrees, finding the optimal position based on the total global solar irradiation on the PV system, which is given by the sum of the direct irradiation , diffuse and by reflection.
The adjusted irradiance is obtained from the SPYM model, which is based on snow depth, air temperature and irradiance. While temperature can predict whether the snow on the panel melts or covers the module, the depth of the snow determines its transmittance.
“The calculation of this snow loss factor is based on the Perovich transmittance model,” the academics explain. “The transmittance drops sharply from 1 to 0.1 when the snow depth increases from 0 to 2 cm. The decrease is then smoothed out, and the value reaches 0.01 when the snow depth increases to 12 cm. When the snow depth is greater than 12 cm, the value is assumed to be 0”.
Following the development of the model, the scientists used historical Solcast meteorological data for the period 2012-2021 from the Swedish city of Hammarby Sjöstad as input. Optimal calculations were made for one year, five years and ten years. In their case study, they started from photovoltaic modules with an efficiency of 19.2% and a power of 430 MW.
They then compared and used their novel model for three scenarios. The first was a base case without snow conditions, considering only historical irradiance and temperature data. In the second scenario, the effects of snow were calculated assuming that it melts after 12 hours. In the last scenario, removal agents were assumed, which reduced the snow removal time to one hour. All results were compared to the commercial isolation angle of 15 degrees and the geometric angle for Sweden of 40.7 degrees.
“The photovoltaic system with the optimal annual angle exceeds that with the commercial angle, which represents an approximate increase of 4.8% in energy generation,” stated the research group. “The optimal photovoltaic installation angle decreases when snow conditions are considered, and the difference depends on the local weather conditions each year, reaching up to 7.8 degrees.”
Additionally, the scientific group found that snowy conditions reduce power generation conditions by 14.7%. They also found that the application of scavenging agents can improve photovoltaic performance by 0.1% to 2.3%.
Their conclusions were presented in “ A new optimal PV installation angle model in high-latitude cold regions based on historical weather big data ”, published in Applied Energy . The research was carried out by academics from Swedens KTH Royal Institute of Technology and the Swedish Meteorological and Hydrological Institute. |
