The effect of uncertainty in modeling coefficients used to predict energy production using the Sandia Array Performance Model

Abstract

Predicting photovoltaic array performance is an important part of system design and monitoring, so it's important to quantify the uncertainty associated with the predictions. The Sandia Array Performance Model [1] is one of many tools used to predict annual energy production, but the effect of the uncertainty in model coefficients has not been fully investigated. This paper quantifies the relative importance of voltage and current temperature coefficients, as well as the coefficients relating voltage and current to solar irradiance, for crystalline silicon modules. Using the coefficient variation observed in the Sandia module database and computer simulation, the effect of the uncertainty was quantified in terms of the range in predicted annual energy production relative to actual energy production by three small grid-connected PV systems. The relative importance of each coefficient by month of the year was also determined in order to understand the seasonal behavior of the performance model.

Successful transfer of Sandia National Laboratories' outdoor test technology to TÜV Rheinland Photovoltaic Testing Laboratory

“…Although these differences appear large, they are actually differences in very small numbers and are statistically insignificant. The calculated values for αIsc and αImp from both labs fall within the historical range of calculated values for more than 50 measured crystalline silicon modules [4]. The voltage temperature coefficient plays the primary role in power changes with temperature, and uncertainty in βVmp has a greater impact on energy predictions than does αImp by nearly a factor of two [4].…”

Relative efficiency revealed: Equations for k<inf>1</inf>&#x2013;k<inf>6</inf> of the PVGIS model

“…The ideality factors of c-Si PV modules can vary between about 1.1 and 1.5 [6], [17]. However, values above 1.3 may be overestimates due to imperfect algorithms, high contact resistance in the cells or current-dependent R S0 [6], [18].…”

The wind chill temperature effect on a large‐scale PV plant—an exergy approach

“…Project developers usually do not take into consideration what happens in areas with greater wind speed than 1 m/s. Sandia National Laboratories have implemented some research on the specific topic and have proposed an empirical relationship (which presents acceptable simulation results for wind speeds up to 18 m/s) that correlates panel and air temperature, solar irradiance, and wind speed . Matsukawa et al .…”