The effect of capacitance on high-efficiency photovoltaic modules: a review of testing methods and related uncertainties

Abstract

The effect of solar cell capacitance in the electrical characterization of photovoltaic (PV) modules at Standard Test Conditions (STC) is known since the 1990s. With the efficiency of solar modules increasing in the years, the corresponding measurement artefact has been generally resolved with long pulse simulators, from few milliseconds in the 2000 s and up to hundred milliseconds nowadays. With the last improvements in module technology, with the growing interest in n-type silicon and silicon heterojunction, and with the increasing wafer and cell sizes, it is demonstrated that even 100 ms simulators are no longer enough for accurate direct I–V measurements. The need for continuous simulators is therefore becoming more frequent even for accurate measurement of commercial size modules. This work summarizes the basic physics behind the effect of capacitance on the electrical characterization of silicon PV modules, with the simplest approach of a single diode capacitive model and with examples from high efficiency modules commercially available. It reviews eight measurement methods to mitigate the effect for accurate electrical characterization at STC; finally, it presents a novel and comprehensive analysis of the uncertainty contribution to the maximum power and open-circuit voltage determination of these measurement methods. The paper is a review of the best practices in advanced testing laboratories of silicon PV modules nowadays, and it represents a contribution addressed to metrologists, researchers and module manufacturers.

Onymous early‐life performance degradation analysis of recent photovoltaic module technologies

“… * Although the absolute measured values differ from one sweep direction to another, 17,18 this study reports on relative changes over time. As such, the IV curve sweep direction should have a negligible effect as long as each laboratory is consistent over time.…”

Bandwidth Characterization of c-Si Solar Cells as VLC Receiver under Colored LEDs

“…At low bias voltage, the junction capacitance, which slightly changes in such a voltage range, dominates. At higher bias voltages instead, the diffusion capacitance, which changes exponentially with the bias voltage, becomes dominant [10]. This result indicates that higher power output is achieved at the expense of communication bandwidth.…”

Development of an electronic interface for diagnostics of photovoltaic strings

“…It is worth noting that the short-circuit current is primarily affected by solar irradiance and temperature, with minimal influence from the electrical parameters of the photovoltaic string, such as series resistance, shunt resistance, and electrical mismatch. Additionally, the internal capacitance of PV modules can have a substantial impact on the measurement accuracy of current-voltage characteristic points if the scan time is too short, especially in the case of recent high efficiency PV modules [15].…”