According to the actual power module work environment and user requirements for reliability, to select the input protection circuit to improve power system reliability, input protection circuit is made of fuse, reverse polarity protection diode, input capacitance, transient suppression diodes and other components , commonly used input protection circuit as shown:
1.Fuse
A fuse set in the Power Moduleinput side to provide security protection, the general specifications can be selected fuse 1.5-2 times the rated input current, if the dc dc converter module is operating in a fairly wide voltage range, the fuse should be chosen twice as large input currents. Whether selecting a fast fuse of fuse depends on the application. Generally speaking a common fuse to provide adequate protection, but in warm standby applications, we recommend the use of quick fuse to prevent the failure of the dc Solar PV power module input cable get circuit shorted.
2.Input capacitance
There should install one electrolytic capacitor at the input of the power module , the capacitor plays two roles: absorption dc power moduleinput voltage spikes instantaneous voltage drop occurs in the input timely, to maintain certain voltage for solar power module.
3.Reverse polarity protection
In order to prevent wrong polarity in the input dc power module, installing of diode at the input , this diode string in the input circuit, for low-voltage input power module can be connected in parallel input loop.