Solar Radiation Sensor Drift Estimation via Clear Sky Model
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Solution Overview
Problem
Solar radiation sensors used in solar energy production face challenges with measurement drift over time, requiring frequent recalibration, which is costly and complex, especially for distributed solar power plants, and existing methods are not suitable for on-site, continuous, and automatic calibration.
Innovation Solution
A method for estimating and calibrating solar radiation sensors using clear sky conditions to determine a correction coefficient, allowing for real-time calibration without external intervention or structural modifications, utilizing a digital processing circuit to compare measured radiation patterns with a theoretical clear sky model to adjust measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are sent back to the factory for recalibration, then measurement precision is restored, but device complexity and loss of time increase
Solution Approach 1:
The sensor performs self-calibration by comparing its measurements against a clear-sky radiation model. The system automatically detects clear sky periods, calculates the drift coefficient, and adjusts measurements without external intervention, eliminating the need for complex factory recalibration systems
Solution Approach 2:
A clear-sky radiation model serves as an intermediary reference standard. Instead of requiring physical contact with a calibration source or disassembly, the system uses atmospheric physics models to provide a reliable reference against which sensor drift can be measured and corrected
2Measurement precision
If sensors are sent back to the factory for recalibration, then measurement precision is restored, but loss of time increases
Solution Approach 1:
The system continuously accumulates measurement data during operation and identifies clear sky periods in advance. When sufficient clear sky data is available, calibration is performed proactively before significant drift affects measurement accuracy, rather than waiting for scheduled maintenance
Solution Approach 2:
Calibration is performed continuously during clear sky periods rather than through periodic interruptions. The system maintains uninterrupted monitoring by using available clear sky windows to update calibration coefficients, ensuring continuous measurement accuracy without stopping operation
3Measurement precision
If recalibration is performed frequently, then measurement precision is maintained, but cost increases
Solution Approach 1:
The autonomous self-calibration system eliminates the need for expensive external calibration services, technician travel, and facility overhead. By using freely available clear sky periods and open-source radiation models, the system achieves continuous calibration at minimal computational cost
Solution Approach 2:
The system dynamically adjusts calibration parameters based on environmental conditions. By monitoring meteorological parameters and clearing conditions, the system optimizes calibration timing and methodology to maintain accuracy while minimizing resource consumption
4Ease of operation
If solar radiation is used as a reference for calibration, then ease of operation improves, but measurement precision deteriorates due to atmospheric variability
Solution Approach 1:
A clear-sky radiation model acts as an intermediary that translates atmospheric conditions into expected radiation values. Instead of directly comparing with variable actual solar radiation, the system uses the model to account for atmospheric effects, providing a stable reference that maintains both ease of operation and measurement precision
Solution Approach 2:
The system dynamically adjusts the reference standard based on atmospheric parameters. By changing from a fixed reference to a variable clear-sky model that accounts for humidity, pressure, and aerosol conditions, the system maintains reference accuracy across varying environmental conditions while preserving operational simplicity
Data Source
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Figure 2A~4B
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AI summary
The invention relates to a method for estimating drift in a solar radiation sensor (2) and for calibrating such a sensor, in which the radiation (GMES) measured by this sensor under its conditions of use and a radiation model (51) are taken into account.