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With the depletion of traditional fossil fuels, their disastrous impact on the environment and rising costs, renewable energy sources such as photovoltaic (PV) energy are rapidly emerging as sustainable and clean sources of power generation. The performance of photovoltaic systems is based on different factors such as the type of photovoltaic modules, irradiation potential and geographic location. In this research, PVsyst simulation software is used to design and simulate a hybrid photovoltaic system used to operate energy-efficient street lightning system. The simulation is performed to analyze the monthly/annual energy generated (kWh) by the hybrid system and specific power production (kWh/KWp). Additionally, various PV system losses are also investigated. The hybrid PV system has 4 parallel strings, and each string has 13 series-connected (mono crystalline 400 W Canadian Solar) PV modules. The energy storage system consists of 16 Narada (AcmeG 12 V 200) batteries with a nominal capacity of 1600 Ah. The simulation results show that the total annual energy production and specific energy production, were calculated to be 26.68 MWh/year and 1283 kWh/kWp/year, respectively. Simulation results also show the maximum energy injected into the utility grid in the month of June (1.814 MWh) and the minimum energy injected into the utility grid in the month of January (0.848 MWh). The battery cycle state of wear is 84.8%, and the static state of wear is 91.7%. Performance ratio (PR) analysis shows that the highest performance ratio of the hybrid system was 68.2% in December, the lowest performance ratio was 62.7% in May and the annual average performance ratio of a hybrid PV system is 65.57%. After identifying the major source of energy losses, the detailed losses for the whole year were computed and shown by the loss diagrams. To evaluate the cost effectiveness of the proposed system, a simple payback period calculation was performed. Full article

In April 2020, due to the coronavirus pandemic and the tourism decrease in Cracow (Poland), the Road Authority of the City of Cracow, followed by the authorities of several neighbouring municipalities, decided to turn off street lighting at night. It is worth noting that this is the first time that street lighting has been turned off in such a large area on a longer time frame at this scale, including one of the most populated cities in Poland, which made it possible to make unique observations. During this period, with the help of small night-sky radiance meters (Sky Quality Meters (SQM)), many ground-based measurements were made, both within the city and in its vicinity. For this purpose, the existing light pollution monitoring stations in Cracow and neighbouring cities were used. It was found that after switching off street lighting, the zenith surface brightness of the cloudless sky decreased by 15–39%, and this value was proportional to the city’s population. The night-time light satellite data (VIIRS/DNB) on radiance from Cracow and neighbouring communes were also analysed, both their daily values as well as monthly and annual averages. It was found that in the case of a large city such as Cracow, turning off all street lighting reduces the amount of light energy radiated into the sky by about 50%, which is a relatively small decrease in radiance, while reducing the surface brightness of the night sky by about 40%, regardless of the state of the atmosphere. The effect of a significant decrease in radiance as a result of switching off street lighting was found in each of the analysed communes, especially the urbanised ones. Full article