Dear PVsyst Team,
I am working with an N-type Module that has 0% LID (as technology says) loss and would like clarification on how to properly apply the degradation values for simulation. The module datasheet specifies the following:
1st Year Degradation: 1%
Annual Degradation (2nd year to 30 years): 0.4%
However, I noticed that PVsyst assumes half of the annual degradation applies in the first year. This leads to some confusion regarding how to properly simulate the degradation over the 30-year period.
To clarify, I am trying to split the LID and annual degradation using the following methods:
1. Case 1 (as per PVsyst):
LID = (1st Year Degradation) - (Annual Degradation / 2)
i.e., LID = 1% - (0.4% / 2) = 0.8%
As per case 1, I can set the Input in PVsyst like, LID - 0.8% and annual degradation - 0.4%
As per these results, PVsyst considers: 1st year - 1.0% (0.8% + (0.4 / 2)%), 2nd Year - 1.4% (1.0% + 0.4%), 3rd Year - 1.8% (1.4% + 0.4%) ,..........
2. Case 2 (General Practice Approach):
LID = (1st Year Degradation) - (Annual Degradation)
i.e., LID = 1% - 0.4% = 0.6%
As per case 2, I can set the Input in PVsyst like, LID - 0.6% and annual degradation - 0.4%
As per these results, PVsyst considers: 1st year - 0.8% (0.6% + (0.4 / 2)%), 2nd Year - 1.2% (0.8% + 0.4%), 3rd Year - 1.6% (1.2% + 0.4%) ,..........
When using Case 2, the total first-year degradation will be 0.8%, which is lower than the module datasheet value of 1%. On the other hand, if I want to match the datasheet values accurately, I would need to use Case 1, which results in the actual degradation values throughout the 30years of entire simulation (both for the first year and for the following years).
Also, Kindly clarify why PVsyst considers only half of the annual degradation for the first year? If the PV module vendor provides the LID value, how can we adjust the degradation losses in PVsyst to align with the datasheet values for the first year?
Could you please provide clarification on how to simulate the full 30-year degradation, taking into account these considerations? I want to ensure the simulation should aligns with both the datasheet values and PVsyst’s recommended degradation approach.
Thank you for your assistance.