Nimesh Katariya LID (Light Induced Degradation) is the initial drop in power that crystalline silicon PV modules show during their first hours to weeks of sunlight, mainly from boron-oxygen defects in p-type cells. IEC 61215-2:2021 includes a stabilization procedure for it, and designers enter first-year LID as a loss in PVsyst.
Key Takeaways
- LID = initial PV module power loss under first light.
- PERC: 1.5-2.5%. TOPCon: <0.5%. HJT: <0.3%.
- Manufacturers spec year-1 power ≥ 98% to account for LID.
- TOPCon/HJT advantage in cumulative 25-year output.
How LID Plays Out in the Field
LID is a stabilization event, not an ongoing decline. A PERC module rated at, say, 540 W at the factory will typically settle to roughly 527-532 W within its first few weeks of outdoor exposure as the boron-oxygen defect reaction runs to completion, then hold that output going forward.
Because the effect is well characterized and repeatable across a given cell chemistry, manufacturers don’t treat it as a surprise, they set the year-1 power figure in the performance warranty to already reflect the post-LID, stabilized value, so every subsequent year of the 25-year warranty curve is measured against that lower baseline rather than the factory nameplate.
This is also why cell technology matters more here than most buyers expect. Since the boron-oxygen mechanism is specific to boron-doped p-type silicon, switching to an n-type cell architecture such as TOPCon or HJT removes most of the reaction rather than merely reducing it, which is the reason TOPCon and HJT modules are quoted with LID figures an order of magnitude below standard PERC.
Related Reading
LID is one of several first-year loss mechanisms that a bankable energy yield simulation has to account for before a lender will sign off on a project’s output forecast, alongside the slower, temperature-driven degradation covered in LeTID and the long-term annual degradation rate that governs years 2 through 25.
Because P50/P90/P99 yield reports are built on year-1 output as the baseline, understanding what’s already been absorbed into that number, versus what still needs modeling, is worth knowing before reading a report like the one described in P50, P90, P99 in Solar Yield Reports, A Lender’s-Eye View.
Module selection decisions that weigh PERC against n-type cells for LID exposure are typically made during the same Solar 3D Pre-Design stage where shading, layout, and yield simulation are worked out together.
Frequently Asked Questions
3 commonly searched questions about LID (Light Induced Degradation).
How much power do solar panels lose to LID?
How is LID modeled in PVsyst?
Is LID covered by the module warranty?
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