Photovoltaic fleet degradation insights

Abstract

In the PV Fleet Performance Data Initiative, high‐frequency data from commercial and utility‐scale photovoltaic (PV) systems have been collected to examine performance loss rates (PLRs) at a fleet scale. To date, performance data from more than 7.2‐gigawatt (GW) capacity, 1700 sites and 19,000 inverters—approximately equivalent to 6% to 7% of the entire US PV market—have been collected. An overall PLR of −0.75%/year was found, which is in line with historical and recent findings. Tracked silicon (Si) and cadmium telluride (CdTe) performed comparably with all fixed‐tilt systems. Higher PLRs were found for hotter temperature zones; cooler climates exhibit a median −0.48%/year loss, which increases to −0.88%/year in hotter climates. High‐efficiency module technologies showed median PLRs in line with conventional Si technologies but demonstrated markedly different PLR behavior when filtered only for low‐light conditions <600 W/m2. Causes for this technology‐dependent behavior are under investigation.

Reducing Uncertainty of Fielded Photovoltaic Performance (Final Technical Report)

“…Data from 16 partners has been collected as of 2021, and 10 custom partner reports have been issued, along with multiple public presentations and reports. [33] PV Fleet Performance Index Analysis PV system performance is often quantified as a comparison between realized system energy production and an expected or modeled energy production called a performance index (PI) rather than a performance ratio. Here we calculate expected performance at 30-minute time periods based on a PVLib-Python PVWatts energy model, including site metadata information and NSRDB satellite resource data (Eq.…”

“…The median and zero PLR are shown as guide to the eye as horizontal and vertical dashed grey lines, respectively. [33] Climate was found to provide an important differentiation in system long-term performance.…”

“…[4,7,16] • System owners can identify local underperformance and inform operation and maintenance decisions. [9,32,33,36] • A new cloud data interface will reduce barriers to data sharing, leverage existing DuraMAT infrastructure, and enable scalable analysis for industry partners. [30] • The energy output of a broad swathe of PV systems in the United States will be accurately evaluated and published, identifying regional performance differences, and providing future developers and analysts evidence of high system quality and performance.…”

“…[30] • The energy output of a broad swathe of PV systems in the United States will be accurately evaluated and published, identifying regional performance differences, and providing future developers and analysts evidence of high system quality and performance. [4,15,17,33] 7. Project Results and Discussion: (includes project milestones and details on completion)…”

“…Our scalable cloud-based time series database contains over 30 billion rows (20TB) of PV time series data, representing over 1700 commercial and utility-scale systems, and over 7.2 GW of DC capacity (Fig 1). Initial field performance results have been distributed in several public reports [32,33] captured by the overall degradation rate distribution in Fig 2 . Because our fleet composition and data quality methods are continually improving, annual updates to these results are published to our PV Fleet webpage [34] and DuraMAT data hub [35]. Another existing dissemination channel used for observed soiling losses is a map we maintain for soiling losses.…”