AN3432 Datasheet, PDF (19/24 Pages) STMicroelectronics – How to choose a bypass diode for a silicon panel junction box

AN3432
Application constraints
3.2.2
200 cycles
This test is requested for the crystalline silicon terrestrial photovoltaic modules design
qualification. It is described in the standard EN61215 paragraph 10.11.
The bypass diode is polarized in reverse when the module temperature is above 25 °C.
Figure 15 illustrates the test conditions.
Figure 15. 200 cycles test conditions
V_R
Ipeak
Maximum cycle time
100 °C/h max.
+85
Minimum
time 10 min.
+25
Minimum
time 10 min.
-40
Time h
1
2
3
4
5
6
As the diode is in reverse, the junction temperature is very close to the ambient temperature
due to low reverse losses. So there is no risk to exceed maximum junction temperature. The
critical parameter in this test is the value of voltage when T_amb = 25 °C. Actually, the reverse
voltage of a diode decreases with the temperature and then the diode V_RRM (25 °C) is the
higher value and needs to meet the following requirement:
VRRM(25 °C) > VR(25 °C)
For an ST Schottky diode, the V_RRM is guaranteed at 25 °C.
Doc ID 019041 Rev 1
19/24