Renewable energy sources are critical to the global effort to achieve carbon neutrality. Alongside hydropower, wind and nuclear plants, the photovoltaic (PV) systems developed greatly, with new PV technologies emerging in recent years. Although the conversion efficiencies are improving and the materials used have a lower impact on the environment, the feasibility of these technologies is required to be assessed. This paper proposes a levelized cost of energy (LCOE) model to assess the feasibility of five PV technologies: high-efficiency silicon heterojunction cells (HJT), N-type monocrystalline silicon cells (N-type), P-type passivated emitter and rear contact cells (PERC), N-type tunnel oxide passivated contact cells (TOPCon) and bifacial TOPCon. The LCOE considers capital investment, government incentives, operation and maintenance costs, residual value of PV modules and total energy output during the PV system’s life span. To determine the influence of PV system’s capacity over the LCOE values, three systems are analyzed for each technology: 3 kW, 5 kW and 7 kW. The results show that the largest PV systems have the lowest LCOE values, ranging from 2.39 c€/kWh (TOPCon) to 2.92 c€/kWh (HJT) when incentives are accessed, and ranging from 6.05 c€/kWh (TOPCon) to 6.51 c€/kWh (HJT) without subsidies. The 3 kW and 5 kW PV systems have higher LCOE values due to lower energy output during lifetime.

Nowadays, as the technology behind solar photovoltaic systems has been significantly improved, along with a significant decrease in costs, grid-connected photovoltaic systems are becoming an important option to reach a low-carbon energy transition. The high cost of electricity consumed at the Technical University of Cluj-Napoca represented a good reason for the university to increase its energy efficiency by adopting and increasing energy consumption from renewable energy sources. This paper assesses the technical, economic, and environmental feasibility of deploying four photovoltaic systems at the aforementioned university situated in the Northwestern part of Romania, according to the Romanian renewable energy legislation. PVSOL software has been used to estimate the performance of photovoltaic installations. The results indicated that the most viable distributed generation system is the one with a capacity of 100 kW, meeting approximately 23 percent of university electricity needs, and at the same time, reducing carbon dioxide emissions by approximately 460 tons. A sensitivity analysis has been performed to evaluate the effect of several critical parameters on the PV system’s economic feasibility. The results provide valuable decision-making information regarding the buildings’ solar potential for other universities, supporting the transition to solar energy.

This article analyses data on general government expenditure, at the level of the European Union (EU 28) according to the Classification of the Functions of Government – COFOG over the 2008-2017 period. Data shows that the expenditures increased at the beginning of the economic crisis in all EU countries, being followed by a slowdown in expenditures growth. All countries have adopted policies in order to reduce government expenditures towards the end of the period, aiming to increase their efficiency. Usually in high-income countries, compared with low-income countries, government expenditures are much larger as percent of gross domestic product (GDP), but the relations are not very strong though.

The transition to a circular economy (CE) represents a complex socio-technical evolution, requiring synchronized policy frameworks and strategic capital reallocation. Adopting a systems-thinking lens, this study combines bibliometric network mapping with exploratory econometric modelling, to examine the associations between five core policy instruments and tangible circular investments (INV_CE) across the EU-27. Bibliometric analysis identifies the “firm” and “supply chain” as central functional hubs within the CE knowledge system, acting as primary mediators for capital flows. Econometric results indicate that Tradable Permits (TPOs) and an integrated Policy Integration Index (PII), comprising subsidies and energy-based taxes, show the strongest statistical association with circular investment patterns (p ≤ 0.001). However, patterns of structural disparity emerge between OECD and non-OECD Member States (p = 0.014), where the latter often exhibit a more rigid, tax-centric approach. Spearman correlations point toward institutional maturity, specifically government effectiveness (r_s = 0.48) and eco-innovation capacity, as a potential systemic gateway for investment absorption. Furthermore, a structural decoupling appears between voluntary approaches (VAs) and governance capacity in emerging systems, suggesting that such instruments may be less effective without “institutional readiness.” The findings suggest that circular transition is path-dependent and congruent with the co-evolution of policy and institutional regimes. To bridge the investment gap, the study highlights the need for systemic interventions that move beyond “one-size-fits-all” regulations toward targeted strategies that strengthen the institutional and data reporting infrastructures of circular systems.

Grid-connected residential rooftop photovoltaic systems with battery energy storage systems are being progressively utilized across the globe to enhance grid stability and provide sustainable electricity supplies. Battery energy storage systems are regarded as a promising solution for overcoming solar energy intermittency and, simultaneously, may reduce energy expenditure by minimizing grid exports or maximizing solar electricity self-consumption by households. This chapter aims to assess the feasibility of six lithium-ion and lead-acid batteries with different capacities connected to a grid-connected rooftop solar photovoltaic system for a dwelling situated in the north-western part of Romania. The results pointed out that the most viable option is the photovoltaic system combined with the 16.8 kWh lead-acid battery, generating an additional value of almost $18,000 USD over the investment’s lifetime. The results provide important decision-making information as regards the viability of grid-connected photovoltaic systems combined with different battery energy storage system technologies.