Application of vertical photovoltaic installation
It is assumed that the optimal angle of inclination for photovoltaic modules is approximately 30 degrees.
However, research carried out by Dutch scientists from the independent group TNO has shown that radically positioning the modules vertically can bring greater benefits. Does this arrangement make sense in European latitudes? The lack of complications with snow removal in winter is certainly an advantage, but is that the only thing?
The TNO research team focused on the impact of mounting modules vertically on energy yield. It was already known that this moderately favorable arrangement, in terms of absorbing sunlight, brings greater profits than horizontal arrangements. Additionally, vertical installation means that the temperature of the cells during operation remains lower than in the case of horizontal systems, maintained in the same operating conditions and full sunlight exposure of the module.
The researchers were motivated by the lack of specific studies analyzing this anomaly, even though the aspect of cell temperature is crucial for the final energy yield. According to the analyses, an increase in sunlight results in an increase in generation in a logarithmic manner, but increasing cell temperature leads to a decrease in voltage, typically by 0.3-0.4% per degree Celsius.
The TNO team found that the generation gains associated with high solar radiation are lost due to the increase in cell temperature. For standard installations, systems perpendicular to the ground are characterized by a smaller increase in cell temperature, and voltage changes on the modules are not significant.
In order to analyze various table arrangements, researchers used the so-called digital twins that allow installation conditions to be accurately simulated using software, eliminating the need for physical changes to the installation layout. Thanks to this, each module system was analyzed under the same environmental conditions.
The tests were carried out on an installation in Petten, the Netherlands, where the panels were arranged vertically, east-west. The system consisted of 9 rows of photovoltaic panels, 8 each. The modules used were of the bifacial type with a power of 315 W.
The research also took into account the coefficient of heat transfer from the environment to the module, determining that for vertical installations the heat transfer was almost twice as high as for modules mounted horizontally. According to TNO, this translates into 2.5% higher energy generation per year. Additionally, the lower operating temperature of cells slows down the degradation process of modules, which, according to scientists, is particularly important at higher ambient temperatures and intense sunlight.
Will this influence investors' decisions about this type of installation? We'll probably find out over time. And for now, photovoltaic telemarketers will have good arguments for a customer living in a block of flats with a balcony ;-)
Sources:
Globenergia
TNO Research, pv-magazine