Photovoltaic Reference Module Field Calibration System
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Solution Overview
Problem
Existing methods for monitoring and calibrating photovoltaic (PV) reference modules in solar power plants face challenges such as degradation due to short-circuit conditions, inferior light intensity linearity, and high costs associated with laboratory-based calibration and handling of larger reference modules.
Innovation Solution
A system comprising reference device electronics units and a portable calibrator unit that allows for field measurement and calibration of PV reference modules, minimizing short-circuit induced degradation and facilitating calibration across a range of outdoor conditions, including light intensity and temperature, thereby reducing costs and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PV reference modules are used for monitoring, then spectral response matches PV modules well, but degradation occurs due to short-circuit conditions
Solution Approach 1:
The system dynamically adjusts the electrical operating conditions of the reference module away from fixed short-circuit conditions. By varying the bias voltage and operating point based on environmental conditions and measurement requirements, the system maintains measurement accuracy while reducing stress-induced degradation on the reference module cells.
Solution Approach 2:
The system changes multiple operating parameters simultaneously including bias voltage, load resistance, and measurement timing to optimize both measurement precision and module reliability. By adjusting these parameters, the reference module operates in less stressful conditions that reduce degradation while maintaining spectral response matching capability.
2Measurement precision
If laboratory-based calibration is used, then calibration accuracy is high, but costs and handling complexity increase
Solution Approach 1:
The system performs calibration functions autonomously in the field without requiring removal to laboratories. The reference module calibrates itself by comparing measurements against known reference values or using internal reference standards, eliminating complex handling and shipping while maintaining calibration accuracy through automated procedures.
Solution Approach 2:
The system introduces portable calibration equipment and software intermediaries that enable accurate calibration in field conditions. These intermediaries provide the necessary reference standards and control functions that would normally require laboratory infrastructure, allowing calibration to be performed on-site without increasing handling complexity.
3Measurement precision
If reference modules are used instead of reference cells, then spectral matching is improved, but linearity with light intensity deteriorates
Solution Approach 1:
The system implements feedback control that continuously monitors the reference module's output and compares it against expected linear relationships. When non-linearity is detected, the system adjusts operating conditions or applies correction algorithms to compensate for the non-linear response, maintaining measurement accuracy across varying light intensities while preserving spectral matching advantages.
4Measurement precision
If PV reference modules are deployed, then spectral sensitivity matches PV modules, but cost and handling difficulty increase
Solution Approach 1:
The system designs the reference module to serve multiple functions simultaneously: spectral measurement, light intensity monitoring, temperature sensing, and self-calibration. This multi-functionality reduces the need for separate equipment and simplifies deployment and operation, offsetting the inherent handling difficulties of PV modules while maintaining spectral sensitivity matching.
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
The system effectively converts any PV module into a reference module, reducing degradation and enabling accurate field calibration, thus improving the reliability and cost-effectiveness of PV reference module monitoring and calibration.
Implementation Method 1
Another widely used reference device is the PV reference cell. This device functions by measuring the short-circuit current from a single PV cell encapsulated in a package
Implementation Method 2
One of the most widely used reference devices is the thermopile pyranometer. This device measures the temperature rise of an absorbing disk exposed to the incident solar irradiance
Data Source
AI summary
A system for field measurement and calibration of photovoltaic reference devices, including a reference device electronics unit that measures the electrical output of a photovoltaic reference module and provides data to determine the solar irradiance received by the reference module as a function of its electrical output; and a calibrator unit that is used to routinely recalibrate the reference device electronics unit and the reference module, wherein the calibrator unit contains one or more calibrated photovoltaic reference cell(s).