Photovoltaic Element Evaluation Using Pulsed Light for Capacitance Hysteresis

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Solution Overview

Problem

High-efficiency, high-capacitance photovoltaic elements present challenges in current-voltage measurements due to internal capacitance, leading to hysteresis effects and inconsistent results, particularly in standardised testing, which existing methods attempt to address but often result in time-consuming or costly solutions with potential for module heating or light uniformity issues.

Innovation Solution

A photovoltaic element evaluation method involving a time-controlled measurement system that includes a pulsable light emitting element, a measuring circuit with a voltmeter and ammeter, and a controllable impedance load, allowing for step-wise changes in electrical current, voltage, and impedance load during short flashes of light, sampling values to minimize reaction time and achieve accurate current-voltage characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If measurements are performed with very long pulse times (>100 ms) to minimize capacitance effects, then measurement accuracy is improved, but measurement time increases and module heating occurs

Engineering Contradiction:

Improvecurrent-voltage measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies periodic pulsed light action with optimized duration (1-100 ms) to excite the photovoltaic element repeatedly. By using multiple pulses with appropriate timing, the method captures transient current-voltage characteristics while minimizing total measurement time and avoiding excessive heating, thus resolving the contradiction between measurement accuracy and measurement time.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts measurement parameters including pulse duration, pulse repetition rate, and sweep time based on the specific capacitance characteristics of the photovoltaic element being tested. This dynamic optimization allows accurate capture of transient effects without requiring excessively long measurement times, thereby improving both precision and speed.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If sweep time is extended to more than 100 ms by segmenting current-voltage tracing, then measurement accuracy is improved, but measurement time increases and xenon lamp aging accelerates

Engineering Contradiction:

Improvecurrent-voltage characteristic accuracyVSAvoidxenon lamp service life

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

Instead of using a single long-duration pulse or sequentially segmented traces requiring extended lamp operation, the patent employs multiple periodic pulses within a shortened total time frame. This approach captures the necessary current-voltage characteristics through repeated excitation cycles, reducing overall lamp exposure time and extending service life while maintaining measurement accuracy.

Inventive Principle:

Principle #19Periodic action

3Productivity

If very short pulse multiflash methods are used with high repetition rates, then measurement speed is improved, but light uniformity and spectral mismatch issues worsen

Engineering Contradiction:

Improvemeasurement speedVSAvoidlight uniformity and spectral consistency

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent dynamically optimizes pulse duration and repetition rate based on the specific photovoltaic element characteristics and measurement requirements. By adjusting these parameters within an optimized range rather than using fixed very short pulses, the method achieves high measurement speed while maintaining adequate light uniformity and spectral consistency, thus resolving the contradiction between productivity and measurement precision.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method enables accurate, rapid, and cost-effective measurement of high-capacitance photovoltaic elements' current-voltage characteristics in a single flash of light, reducing measurement time and minimizing errors, while maintaining irradiance and spectral consistency, thus reproducing steady-state characteristics effectively.

Implementation Method 1

disposing said photovoltaic element to at least one short flash of light having a discrete lighting duration, said short flash of light being generated by a pulsable light emitting element

Methodology Applied

Scientific EffectLight emission: Luminescence

Implementation Method 2

A photovoltaic element evaluation method, comprising a time-controlled measurement of a current-voltage characteristic of a photovoltaic element

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentUS10305423B2Photovoltaic element evaluation method, measurement system configuration and process for using a measurement system configuration

Publication Date: 2019.05.28 TUV RHEINLAND SHANGHAI

AI summary

The invention is related to a photovoltaic element evaluation method, comprising a time-controlled measurement of a current-voltage characteristic of a photovoltaic element, said photovoltaic element being arranged in a measuring circuit for measuring at least an electrical current and/or an electrical voltage of said current-voltage characteristic.The invention relates furthermore to a measuring system configuration for performing time-controlled measurements of current-voltage characteristics of replaceable photovoltaic elements.