In order to legally be allowed to connect to the grid in each country, inverter 104,204 is preferably designed to comply with local electrical regulations. Electrical regulations typically dictate, among other things, the minimal and maximal voltages of the grid e.g. 220-260 root mean squares voltage V, and a range of permitted frequency, e.g. 45-55 Hz. Whenever the grid deviates from allowed values inverter 104,204 is required to disconnect from the grid. Disconnection from the grid is typically performed using software controlling inverter 104, 204 and control circuitry which constantly monitors grid parameters, e.g. voltage, frequency.

In system 10, solar panels 101 are directly connected (e.g. in series-parallel) to inverter 104. When an islanding condition is detected, inverter 104 is disconnected from the grid. Hence, inverter 104 stops drawing current and therefore panels 101 output a relatively high open circuit voltage typically 25% higher than the normal operating voltage. An open circuit voltage 25% higher than nominal working voltage is typically safe, (less than the allowed 600 VDC in the USA and 1000 VDC in Europe) which are typical ratings for inverters 104 designed to be able to handle the higher open circuit voltage.

In system 20, there are power converters 205 which “push” power to the output of converters 205. Under an islanding condition which has been detected by inverter 204, inverter 204 is shut down and current is not flowing between converters 205 and inverter 204. Consequently, in system 20, the open circuit voltage at the input to inverter 204, reaches dangerous voltages, higher than the open circuit maximum voltage ratings of inverters 104, 204.