What’s the use of China PV junction Box in the diode of the use of three

 When test the China PV junction Box,it is generally positive and negative poles with a solar simulator to test their power and to confirm the value of its board, but it was suggested that the positive and negative poles of the junction box installed after the test, because in order to test the connection box on the feasibility of using three diode, my question is, if not three solar photovoltaic diode board, what will happen, or whether to use three or damaged diode their case will cause any damage that this board is not complete can not be used, or can also be used, but a little error it?

Add this thing is to prevent reverse charging the battery and to prevent damage to light a photocell circuit the battery pack can not use light