Sandra Pšeničny, mag., Faculty of Administration, University of Ljubljana

The photovoltaic solar power plant of the Faculty of Administration works diligently. In a study on the installation of a solar power plant on the roof of the Faculty of Administration in Ljubljana, prepared by dr. Kristijan Brecl and prof. dr. Marko Topič from the Laboratory of Photovoltaics and Optoelectronics at the Faculty of Electrical Engineering, University of Ljubljana, the authors predicted an annual output of almost 70 MWh. By 13 May 2020, our power plant had produced 313.94 kWh / kWp. Considering that solar radiation is lower in this part of the year compared to the summer months, the values ​​we are achieving are very encouraging. Namely, when 1027 kWh / kWp (predicted in the study) is divided by 12 and multiplied by three and a half months of operation, we get the value of 299.54 kWh / kWp.

The return of megawatt hours of electricity produced is also within the expected limits. By 13 May, our power plant had produced 22,446.79 kWh, and expectations according to the study were 69.40 MWh per year. Such results can certainly be attributed to an above-average number of sunny days this spring.

At the same time, the environmental aspect is not negligible, as the projected annual savings in CO2 emissions for our solar power plant amount to 503 kg CO2-eq / kW or a total of almost 34 t CO2-eq / year. The carbon footprint that would be generated by the equivalent production of electricity in Slovenia will therefore be smaller.

The reasons for setting up a solar power plant on the roof of the Faculty of Administration were namely not only financial but also ecological. The solar radiation of the Earth is the cleanest and least used source of energy. The sun sends as much energy to Earth every hour as humanity consumes in one year. The potential of the sun thus significantly exceeds the total energy needs of humanity. According to the authors of the study, solar radiation is also “a permanent, inexhaustible and ecologically sound source of energy, which nature has been using since the very beginning. The conversion of solar energy occurs when solar radiation enters the receiver. Plants use photosynthesis to convert solar energy into chemical (biomass), solar collectors into heat, and solar cells convert solar energy directly into electricity.”

And how did it all start? The proposal for the installation of a solar power plant on the roof of the Faculty of Administration was made by the Innovation and Development Institute of the University of Ljubljana as part of the energy audit of university buildings. Then the installation of a solar photovoltaic power plant was discussed at a session of the Faculty of Administration, which proposed a feasibility study thenprepared by experts from the Laboratory of Photovoltaics and Optoelectrics of the Faculty of Electrical Engineering, University of Ljubljana, dr. Kristijan Brecl and prof. dr. Marko Topič. The Management Board of the Faculty of Administration was acquainted with the feasibility study for the installation of a photovoltaic solar power plant and informed the Management Board of the University of Ljubljana about the purpose of the installation, which provided feedback. This was followed by the beginning of the public procurement procedure, in the framework of which the company Esotech d.d. was selected as the contractor, which set up the solar power plant and will maintain it as the selected contractor for another 7 years. We have 260 modules and 3 inverters on the roof of the Faculty of Administration. The power of each module is 275 Wp, so that the total power of the power plant is 71.5 kW. We expect to use all the electricity produced for our own needs, as we have the highest electricity consumption in the summer, when production will also be highest.