For greenfield plants, it is assumed that the degradation rate is between 1% and 2.5%, for the first year of operation due to LID (Light Induced Degradation). This most affects p-Si module because thin film modules are not affected by this phenomenon.

The long-term degradation rate, (from operational year 2 to year 30-40), needs to be reliable to assess the most accurate LCOE, considered in the Business Plan.

Typically, several research papers [1] report that a consistent degradation rate for silicon technology (c-Si, p-Si) is 0.5%/year and for thin-film technologies (CdTE, CiGS) is 1%/year. This rate can be adapted according to the manufacturers of the solar panels, which have specific technology (back contact, PERC). For instance, a degradation rate of 0.35%/year can be assumed for mono-crystalline silicon modules, with back contacts cells technology.

For brownfield PV plants, (which are already in operation for several years), the degradation rate can be calculated according different methodology which consider the specificities of the site (influence of the environment, abnormal defects or not in the panels,etc). It should be estimated by a methodology based on annual energy production, based on Performance Ratio or based on laboratory study [2].

[1] Dirk C. Jordan and Sarah R. Kurtz, Photovoltaic Degradation Rates — An Analytical Review, Journal Article NREL/JA-5200-51664 June 2012

[2] Tetsuyuki Ishii & Atsushi Masuda, Annual degradation rates of recent crystalline silicon photovoltaic modules, 10 July 2017 in Wiley Online Library, https://onlinelibrary.wiley.com/doi/epdf/10.1002/pip.2903

David Roisse – Asset Manager