The negative effect of the operating temperature on the functioning of photovoltaic panels has become a significant issue in the actual energetic context and has been studied intensively during the last decade. The very high operating temperatures of the photovoltaic panels, even for lower levels of solar radiation, determine a drop in the open-circuit voltage, with consequences over the electrical power generated and PV-conversion efficiency. The temperature effect over the efficiency of monocrystalline and polycrystalline photovoltaic panels by using a double-climatic chamber and a solar simulation device was studied experimentally for two photovoltaic panels, one monocrystalline and another polycrystalline, with the same nominal power of 30 Wp. The double-climatic chamber used is composed of two separate rooms, a cold and a hot one, while the PV panel is placed as a barrier between them. The study is focused on establishing the effect of raising the temperature of PV panels over electrical parameters: voltage, current, and power produced and for efficiency and fill factor to promote sustainable energy consumption. The findings highlight the positive impact of cooling on enhancing system efficiency, with the primary focus on quantifying its overall performance. The operating temperature is controlled by the flow of air on the backside of the PV panel inside the cold room. The level of radiation studied corresponds to a vertical integration of PV panels in building façades. The coefficient of the mean variation of the efficiency with the photovoltaic panels’ temperature was −0.52%/°C; for voltage, −0.48%/°C, and for current, +0.10%/°C.

The negative effect of the operating temperature over the functioning of photovoltaic panels has become a significant issue in actual energetic context, being studied intensively during last decade. The very high operating temperatures of the photovoltaic panels, even for lower levels of solar radiation, determines a drop of the open circuit voltage, with consequences over the electrical power generated and photovoltaic conversion efficiency. The aim of the study is to investigate experimentally the temperature effect over the efficiency of monocrystalline and polycrystalline photovoltaic panels by using a double climatic chamber and a solar simulation device. Within the experimental program were analyzed two photovoltaic panels, one monocrystalline and another polycrystalline, with the same nominal power of 30 Wp. The double climatic chamber used is composed of two separate rooms, the cold and hot one, while the PV panel is placed as a barrier between them. The study is focused on establishing the effect of raising the temperature of PV panel over electrical parameters: voltage, current and power produced and for efficiency and fill factor. The operating temperature is controlled by the flowing of air on the backside of the PV panel inside the cold room. The simulation of solar radiation was performed by using an equipment compatible with the dimensions and characteristics of the climatic chamber. The level of radiation studied corresponds to a vertical integration of PV panels in building facades. The coefficient of the mean variation of the efficiency with photovoltaic panels’ temperature was -0.52 %/°C, for voltage -0.48 %/°C and for current +0.10 %/°C.

This paper presents an analysis of the feasibility and sustainability of using local photovoltaic systems, ON-GRID central photovoltaic systems, and HYBRID systems for street lighting. By generating electricity from renewable sources (photovoltaic panels), solar energy contributes to environmental protection by avoiding the use of fossil fuels and nuclear fission energy, while also aligning with the European Union’s Energy Strategy commitments for the medium term (until 2030) and long term (toward 2050). The implementation of local/central photovoltaic systems for street lighting largely depends on the existing power supply infrastructure, the solar potential of the site, and a clear understanding of potential electricity and cost savings. This study compares local and central photovoltaic systems for street lighting to analyze their technical performance and economic feasibility. The main sustainable objective that this work aims to achieve is Sustainable Development Goal 7. The optimal solution for photovoltaic systems in street lighting was determined through this analysis. The estimated cost for implementing an ON-GRID photovoltaic power plant with a capacity of 153.90 kWp is approximately EUR 773,977.22, with a discounted Payback Time of about 9.33 years. The implementation of this solution results in an annual reduction in greenhouse gas emissions by approximately 58.52 tons of CO₂.

Energy is an essential element in the development of mankind and is the engine that has made possible all the discoveries and innovations of recent decades. It is found behind the comfort we have in everyday life, whether at home, at the office, or when traveling: an optimal temperature in the room, light at anytime, appliances to ease us and make our lives more beautiful. An energy system based on renewable energy has the ability to provide electricity in an economical, sustainable, long-term, non-polluting way and can serve the increasing population. One such example is represented by photovoltaic (PV) panels, which produces electricity from captured solar energy and is one of the solutions considered for reducing energy. The dimensioning of a photovoltaic system, from a technical and economic efficiency point of view, involves the analysis of input data, output data and hence the characteristics of an efficient system. The analysis can be done analytically, but also with the help of dedicated software, the result being, in the end, a safe system in terms of preventive operation and maintenance. In the article was made the dimensioning of a system, analytical and automatic – using software application – to determine if the result obtained – the photovoltaic system – is the same regardless of the method used.

Courtrooms are tall, densely occupied rooms in which cold glazing, radiator plumes and stratification shape winter comfort - effects that single-zone energy calculations miss. We combined infrared thermography with steady three-dimensional CFD simulations (OpenFOAM, Boussinesq approximation, k-epsilon model, cross-checked with Ansys Fluent) to assess how window replacement and external wall insulation change the heating demand and the thermal comfort in the occupied zone of three courtrooms in Iasi, Romania, at the design outdoor temperature of -18 C. Thermography identified the glazing as the weakest element of the recent building envelope. In all rooms and scenarios the radiators placed under the windows prevented downdraught in the occupied zone: the mean draught rate was 2-7%, the head-ankle temperature difference 0.9-1.8 K (an upper estimate) and the mean PMV between -0.10 and +0.02 (category A of ISO 7730). With radiators sized for the design transmission loss, the occupied-zone air reached 23-24 C, close to the values measured in winter 2025, which points to an oversupply of heat in milder weather. Window replacement cut the transmission loss by 13-21%, and its combination with wall insulation by 39-75%. After retrofit, the ventilation required by EN 16798-1 becomes the largest heat loss, so demand-controlled ventilation with enthalpy recovery should accompany the envelope measures.

This study presents an experimental investigation on the electrical performance, durability, and sustainability of different types of photovoltaic panels subjected to controlled climatic conditions and simulated solar radiation. Four photovoltaic technologies were analyzed, including monocrystalline, polycrystalline, and two semi-flexible panels, to evaluate their behavior under thermal stress. The experimental methodology consisted of repeated freeze–thaw cycles conducted in a double climatic chamber, with temperatures varying between −18 °C and +5 °C. Each panel was subjected to up to 500 cycles designed to reproduce repeated freeze–thaw environmental conditions representative of moderate cold-climate operation. At predefined intervals, the electrical characteristics of the panels were assessed using a solar radiation simulator based on high-pressure mercury vapor lamps, ensuring controlled and repeatable irradiation conditions. The results indicate that all tested panels exhibited relatively stable open-circuit voltage and output current values throughout the investigated thermal cycling interval, with only minor fluctuations observed during the experimental measurements. No visible macroscopic structural degradation and no major variations in the monitored electrical parameters were identified during the investigated testing conditions. Semi-flexible panels demonstrated comparable behavior to rigid panels, highlighting their potential for applications requiring mechanical adaptability. From a sustainability perspective, the observed durability and performance stability contribute to extending the operational lifetime of photovoltaic systems, reducing maintenance needs and material replacement rates. The findings provide comparative experimental observations regarding the evolution of selected electrical parameters under repeated moderate freeze–thaw exposure conditions.