Using renewable energies is one of the alternatives to mitigate climate change. Among them, photovoltaic energy has shown a relevant growth of participation in the electric sector. In the backdrop of such growth, in countries such as Brazil, photovoltaic energy has surpassed the generation of electricity by petroleum derivatives since 2019. The significant growth in photovoltaic generation around the world can be attributed to several key factors, including abundant sunlight, supportive government policies, falling solar panel costs, environmental concerns, energy diversification goals, investor interest, job creation, and local manufacturing. However, photovoltaic system performance is heavily tied to weather variability. Different models are used to account for this meteorological dependence; however, there is a gap regarding the differences in the outputs of these models. The study presented here investigates the variability and sensitivity of the models used to estimate photovoltaic production ($P_{pv}$). Six models were compared by percentage difference analysis. Statistical analyses from the perspective of variability revealed that the difference between the $P_{pv}$ estimated by these models reaches a 12.89% absolute power difference. Considering that temperature and solar irradiance are the meteorological variables that most influence $P_{pv}$, the sensitivity analysis focused on these. Regarding sensitivity, in the context of temperature changes, the average relative difference in $P_{pv}$ between models can reach up to 5.32% for a 10 °C change, while in the context of changes in solar irradiance, the average relative difference can reach up to 19.05% for a change of 41.67 W/m². The consideration of the variability and sensitivity of the main sets of equations used to estimate the potential of photovoltaic energy production can help refine methodologies and assumptions in future research in this area. There are variations and sensitivities, as observed, of such magnitude that, depending on the set of equations adopted in the study, they can alter the conclusion about photovoltaic energy production in a given region. Accurate estimations are pivotal not only for feasibility analyses but also for gauging economic and socio-environmental impacts. These divergences can, in turn, reformulate feasibility analyses and compromise the reliability of photovoltaic energy systems, thus leading to different economic and socio-environmental consequences.

The state of Paraíba, located in the northeastern region of Brazil, comprises 223 municipalities and covers an area of 56,469 km². Paraíba is divided into four major mesoregions: Zona da Mata, Agreste, Borborema and Sertão Paraibano. For this study, the Sertão Paraibano mesoregion, a semiarid area, was chosen to understand vulnerability to climate change, taking into account the region’s economic importance for water and energy supply. The Mann-Kendall non-parametric test was applied to evaluate trends in the historical series of monthly, trimestrial, biannual and annual precipitation data. The series utilized corresponded to the period 1912-2012 and were built from data generated by five meteorological stations distributed throughout the mesoregion. These stations are maintained by the Executive Agency for Water Management (AESA) and National Department of Works Against Drought (DNOCS). The results indicated increasing precipitation trends for the Sertão Paraibano mesoregion, especially in the annual evaluation, for the first semester of the year (January to June), for the trimester December-January-February and the month of January, with slopes between 2.67 mm/year and 5.45 mm/year. The results evidenced the need to deepen studies on the influence of climate change in the area, to promote prompt adaptation measures.

Resumo Estudos indicam a intensificação das mudanças climáticas, com aumento da temperatura do ar, alterações no padrão das chuvas e maior variabilidade para outros elementos climáticos. O setor energético renovável pode contribuir com a redução dos impactos na atmosfera. Todavia, as fontes renováveis dependem do clima e o aumento da demanda por energia exige um planejamento coerente com as novas condições. Este estudo teve como objetivo apresentar os resultados relacionados à radiação solar incidente na superfície e à nebulosidade para o Nordeste brasileiro. Utilizou-se um conjunto de modelos climáticos globais (BESM, HadGEM2-ES e CanESM2) associados ao regional Eta, para projetar dados futuros para os períodos de 2041-2069 e 2070-2099, comparando-os ao período histórico de 1961-1990, considerando os cenários RCP4.5 e RCP8.5 aplicados pelo Painel Intergovernamental sobre Mudanças Climáticas. Os resultados evidenciaram o aumento predominante da radiação solar incidente (média de 1,7% pelo HadGEM2-ES e 2,5% pelo CanESM2), exceto para o BESM (-3,5%) e redução para a nebulosidade, com valores médios entre -1,1% (BESM) e -53,4% (CanESM2). Esses resultados podem favorecer a produção de energia solar fotovoltaica nesta região, sendo assim, tem-se elevada expectativa quanto à diversificação da matriz energética brasileira, redução da dependência de combustíveis fósseis e aumento da segurança energética.