Abstract The photovoltaic solar energy has been growing in installed capacity worldwide year by year, and Brazil has also been investing in this renewable source of energy generation. The conversion of light into electrical energy occurs in the photovoltaic cells, which are sensitive to the increase of the temperature. A considerable amount of the energy incident on the module is transformed into heat, rising its temperature and decreasing its efficiency. This study aims to estimate the temperature in photovoltaic cells (Tc) for polycrystalline silicon modules from a grid-connected photovoltaic systems through several equations proposed over the last decades by researchers. This estimation will occur in the municipality of Curitiba, using data from INMET's automatic station, located in the same city. The estimation was calculated hourly, throughout the day for one year. The validation of the estimated results was performed by measuring the cell temperature of a photovoltaic system installed in Curitiba, where it was observed that the equation proposed by Duffie and Beckman (2013) was the one that most approached to the measured value.