Method for detecting an electric arc in a photovoltaic installation, characterized in that it comprises the following steps: - Measurement (E6) of voltage values at at least one site of the electrical circuit of the photovoltaic installation; - Digitization (E8) of the measured voltage values so as to form voltage data; - Formation (E11) of a window of n recent digitized voltage data; - Computation (E12) of a test value associated with the said window of the n voltage data, this value resting upon the sole measurement of the voltage, characterized in that the step (E12) of computation comprises one of the following computations: - computation of the difference between the most recent datum and the oldest datum of the window or computation of the difference between the second most recent datum and the penultimate oldest datum of the window, or computation of any other difference between a more recent datum or a mean of a few more recent data of the window and an older datum or the mean of a few older data of the window; or - computation of the ratio between a more recent datum or a mean of more recent data of the window and an older datum or a mean of older data of the window ; the method comprising also the following steps : - Analysis (E13) of a test vector comprising m of said test values associated with m recent windows generating a quantity arising from this analysis representative of a risk of electric arc, this quantity resting upon the sole measurement of the voltage; - Comparison (E15) of this quantity arising with at least one threshold so as to deduce therefrom the presence or otherwise of an electric arc within the photovoltaic installation. - Measurement (E6) of voltage values at at least one site of the electrical circuit of the photovoltaic installation; - Digitization (E8) of the measured voltage values so as to form voltage data; - Formation (E11) of a window of n recent digitized voltage data; - Computation (E12) of a test value associated with the said window of the n voltage data, this value resting upon the sole measurement of the voltage, characterized in that the step (E12) of computation comprises one of the following computations: - computation of the difference between the most recent datum and the oldest datum of the window or computation of the difference between the second most recent datum and the penultimate oldest datum of the window, or computation of any other difference between a more recent datum or a mean of a few more recent data of the window and an older datum or the mean of a few older data of the window; or - computation of the ratio between a more recent datum or a mean of more recent data of the window and an older datum or a mean of older data of the window ; the method comprising also the following steps : - Analysis (E13) of a test vector comprising m of said test values associated with m recent windows generating a quantity arising from this analysis representative of a risk of electric arc, this quantity resting upon the sole measurement of the voltage; - Comparison (E15) of this quantity arising with at least one threshold so as to deduce therefrom the presence or otherwise of an electric arc within the photovoltaic installation. - Analysis (E13) of a test vector comprising m of said test values associated with m recent windows generating a quantity arising from this analysis representative of a risk of electric arc, this quantity resting upon the sole measurement of the voltage; - Comparison (E15) of this quantity arising with at least one threshold so as to deduce therefrom the presence or otherwise of an electric arc within the photovoltaic installation. <EOS>