# Cost-Benefit Analysis of Small-Scale Rooftop PV Systems: The Case of Dragotin, Croatia
## 1 Introduction  
The use of renewable energy sources for electricity generation is in trend all over the world. However, this is not only on a large scale, with large companies for the production and distribution of electricity, but also on a small or consumer scale. In this sense, rooftop photovoltaic power plants (PVs) take a significant place. Environmental and climate change require action in all key sectors of the economy and strongly encourages the use of renewable energy sources. The European Building Fund currently emits approximately 36% of EU greenhouse gas emissions, and it is key to effectively decarbonizing the atmosphere. Emissions from the construction sector are still higher than in 2014, and the annual rate of energy renovation of buildings in the EU is only about 1%. The EU is trying to overcome these bottlenecks, and there is a new impetus towards rooftop solar installations, with a proven impact on achieving decarbonization and reducing energy demand from the electricity grid. If 90% of Europe's roof space is known to be unused, using it to install PV systems could make a significant contribution to Europe's energy transition. Under the moderate scenario, it is possible to install up to 570 GW roof photovoltaic capacity by 2030, which isa big step forward since installed 137 GW in 2020 [1]. Solar PV power plants on buildings in the EU could produce between 680 TWh and 1300 TWh. This represents a significant untapped potential for the growth of the solar energy market and job creation. In order to exploit this potential of solar roofs, EU Member States need to design support programs for citizens and businesses wishing to install solar energy [1]. Studies specifically focused on rooftop photovoltaic power plants claim that almost 25% of Europe's electricity consumption could be generated from these facilities. Of course, the results depend on various factors, such as investment costs, electricity tariffs, subsidies, and government policies. [2,3]. In 2019, Germany had the most installed PV capacity per capita in the EU (651 W/capita), followed by the Netherlands (539 W/capita) and Belgium (466 W/capita). Croatia has set a goal of reaching 300 MW of installed PV capacity by small consumers-producers of electricity by 2030 with a tax exemption for self-consumed electricity. Most of the capacity is planned for photovoltaic systems in buildings. This is only 198 W/capita, which is the lowest of all countries in the region and far lower than the EU average planned at 758 W/capita [1]. The cumulative installed capacity of solar power plants in 2020 in Croatia is 166 MW, so we estimate that the planned increase in capacity by 2030 is very modest, and this means a further lagging of Croatia behind neighboring countries. The decline in the cost of solar photovoltaic systems, combined with the increase in electricity costs, has increased the use of roof PV systems for their consumption in many parts of the world in recent years. Own consumption, which is a completely different system of production and consumption of electricity compared to the traditional system of production of electricity in large power plants, allows consumers to produce and consume their electricity. The main advantages of this system are increased energy autonomy and reduced energy costs. Production of electricity from renewable sources for own consumption creates immediate positive effects, such as a reduction of grid energy losses and reduced need for modernization of electricity infrastructure by integrating renewable distributed generation into the electricity system. Green energy, thanks to the growing success of its own consumption, plays a strategic role in the energy transition model aimed at combining technological innovation with health, environmental, and economic benefits as well as job creation [4].