A method of controlling an electric system (5; 40) comprising a first control circuit and a plurality of modules (E i) arranged in series between first and second terminals (Phase, Neutral), each module (E i) comprising third and fourth terminals (B+, B-), at least one of the third and fourth terminals of each module being coupled to one of the third and fourth terminals of another module, each module comprising electric cells (C1, C2, C3, C4) and switches coupling the cells together and to the third and fourth terminals of the module and a second switch control circuit, the electric system further comprising at least one first data transmission bus (BUS; BUS0, BUS1) coupling the first control circuit to each second control circuit, characterized in that the first control circuit comprises a memory having, for each electric cell, an identifier of the electric cell and a priority level for the connection of the electric cell among priority levels stored therein, the method comprising the successive steps of: a) reception by the first control circuit of a new set point value; b) transmission, by the first control circuit to the second control circuits, of first control signals for the connection or the disconnection of at least one of the electric cells of the modules to follow said set point value; and c) transmission, by the first control circuit to the second control circuits, of second control signals for the connection of one of the electric cells and the disconnection of another electric cell among the electric cells, wherein the memory rows are arranged by increasing ranks and wherein step c) comprises the successive steps of: d) exchange of the first and second memory rows if the priority level of the electric cell at the first row is greater than the rank of the first row; and e) transmission, by the first control circuit to the second control circuits, of the second control signals for the connection of the electric cell having the identifier at the second row before the exchange and for the disconnection of the electric cell having the identifier at the first row before the exchange in the case where the electric cell having the identifier at the second row before the exchange is disconnected and the electric cell having the identifier at the first row before the exchange is connected. a) reception by the first control circuit of a new set point value; b) transmission, by the first control circuit to the second control circuits, of first control signals for the connection or the disconnection of at least one of the electric cells of the modules to follow said set point value; and c) transmission, by the first control circuit to the second control circuits, of second control signals for the connection of one of the electric cells and the disconnection of another electric cell among the electric cells, d) exchange of the first and second memory rows if the priority level of the electric cell at the first row is greater than the rank of the first row; and e) transmission, by the first control circuit to the second control circuits, of the second control signals for the connection of the electric cell having the identifier at the second row before the exchange and for the disconnection of the electric cell having the identifier at the first row before the exchange in the case where the electric cell having the identifier at the second row before the exchange is disconnected and the electric cell having the identifier at the first row before the exchange is connected.