There is described a plant (1) for converting solar energy into electrical energy, comprising a photovoltaic generator (2a) including at least one string (2) of photovoltaic modules (M), a pulse generator (31) able to send electrical pulses to the input of the string (2), a signal detector (OP) arranged at the output of the string (2) and able to detect, at the output of the string (2), the presence of a signal which is a function of the electrical pulses at the input, and alarm means connected to the signal detector (OP) and able to generate an alarm in the event that there is no signal at the output of the string (2).