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How to insert First year module loss?


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This depends on the technology.

With crystalline modules, this is the LID (Light Induced Degradation) and may be specified as such in the "Detailed losees" dialog. This loss arises usually during the first hours or days of exposition to the sum.

With amorphous, the initial degradation (some months) is not taken into account in the simulation: the STC specified values are supposed to be the stabilized values.

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  • 8 months later...
Using version 6 this aspect of including LID as its own entity is great. I do have a request however. LID rates for crystalline often are completed after a specific amount of time (30 days or 45 days etc.). Right now my understanding of how the LID is implemented is that is a straight loss over the entire year. I would like to request an input for a specified amount of time as well as the starting point in the year when this LID would come into effect. This input would be similar to how the grid availability is input. This would help with LID implementation during different times of the year. As we know LID exposure occuring in the fall months versus winter months versus summer could yield different results overall for the year. Hopefully the request is understood.
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As for the initial degradation of amorphous modules, the initial state without LID is neglected for the simulation.

The simulation results are usually meant as a "normal year" yield, and often assumed as a result valid over several years (by sometimes applying an annual degradation on the results for the next years). This would not make sense to take a transitory effect into account in the general simulation evaluation.

By the way the LID loss -and its evolution/durability - is never well known (may depend on the crystal quality, the production batch, etc). The little gain we could observe by treating this initial degradation is probably completely negligible, far below the uncertainties of the rest of the simulation. The important thing is to determine the absolute value of the LID loss (by respect to the specified STC performance), as it will affect the yield during the whole life of the power plant.

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  • 2 years later...


I apologize for replying to an old thread, but it covers a subject I'm wondering about. I would appreciate your perspective on LID losses in PVsyst.

- Let's assume crystalline modules.

- Recently module manufacturer's have been providing test reports on measured LID for their modules, ranging from 0.5-1.5%. I usually assume this is the minimum possible module degradation in the first year.

- Module manufacturer's also have warranty language that specifies the module degradation in the first year, ranging from 2-3%. I usually assume this is the maximum possible module degradation in the first year.

- Given that there are factors other than LID that might contribute to degradation in the first year, I'm usually inclined to use the LID PVsyst input to account for them all, picking a number between the module manufacturer's specified LID and the warranty language. Is this a reasonable approach, or would you recommend simply using the LID number provide by the module manufacturer?

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