Hemispherical Camera System for Solar Radiation Measurement
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Solution Overview
Problem
Current methods for measuring components of solar radiation, such as direct normal irradiance (DNI), horizontal diffuse irradiance (DHI), and global horizontal irradiance (GHI), are costly and require frequent maintenance, with instruments like pyrheliometers and pyranometers being expensive and complex to operate.
Innovation Solution
A system utilizing a camera with a hemispherical lens and a processor to capture images of the sky, perform geometric calibration, calculate solid angles, and estimate radiation components using HDR imaging, eliminating the need for multiple instruments and reducing maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple specialized instruments (pyrheliometers, pyranometers, SAM instruments) are used to measure solar radiation components, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines multiple specialized measurement instruments (pyrheliometer, pyranometer, and solar profile measurement device) into a single integrated camera system with hemispherical lens. This single device captures the entire sky hemisphere and processes images to extract all solar radiation components (DNI, DHI, GHI) and solar profile data, thereby reducing device complexity while maintaining measurement capabilities
Solution Approach 2:
The camera system with hemispherical lens serves multiple functions simultaneously: it measures direct normal irradiance, diffuse horizontal irradiance, global horizontal irradiance, and solar profile characteristics. The single device replaces multiple specialized instruments, achieving multi-functionality that reduces the overall system complexity
2Measurement precision
If multiple specialized instruments are deployed for comprehensive solar radiation measurement, then measurement precision is improved, but maintenance requirements and costs increase
Solution Approach 1:
By merging multiple instruments into a single camera-based system, the patent reduces the number of components that require maintenance. Instead of maintaining separate pyrheliometers, pyranometers, and solar profile instruments, the system only requires maintenance of the camera, hemispherical lens, and processing unit, significantly easing repair and maintenance operations
3Measurement precision
If traditional measurement instruments with masks and mechanical tracking are used, then measurement precision is improved, but ease of operation deteriorates due to frequent maintenance and complex operation
Solution Approach 1:
The patent replaces mechanical sun-tracking systems and movable masks with a stationary camera system that uses computational methods. The hemispherical lens captures the entire sky field of view simultaneously, and image processing algorithms identify the sun's position and calculate radiation components without any mechanical movement, greatly simplifying operation
Solution Approach 2:
The system performs automatic image processing and calculation of solar radiation components without requiring operator intervention for mask positioning or tracking adjustments. The processing unit automatically extracts DNI, DHI, GHI, and solar profile data from the captured images, making the system self-operating and easier to use
4Measurement precision
If expensive specialized instruments are used for solar radiation measurement, then measurement precision is improved, but cost increases significantly
Solution Approach 1:
The patent replaces expensive, specialized scientific instruments with a relatively inexpensive camera and hemispherical lens combination. The camera, which is a common commercial component, captures the necessary radiation data, and computational algorithms process the images to extract precise measurements, dramatically reducing the cost of the measurement system while maintaining accuracy
Solution Approach 2:
The patent substitutes expensive mechanical measurement instruments with an optical-imaging-based system using a camera and hemispherical lens. This substitution leverages computational photography and image processing to achieve precise solar radiation measurements at a fraction of the cost of traditional specialized instruments
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
Enables cost-effective and efficient measurement of solar radiation components with a single camera, providing reliable values for DNI, DHI, and GHI without the need for masks or mechanical sun tracking, and allows for precise solar profile analysis.
Implementation Method 1
a camera (10) provided with a hemispherical lens (20) and comprising a sensor (12) capable of capturing light to generate an image
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a system for measuring solar radiation. The system comprises a camera (10) equipped with a hemispherical objective (20) and comprising a sensor (12) able to sense light in order to generate an image, and a processor (30) able to: perform a geometric calibration of the camera (10) in order to obtain the correspondence between the coordinate system of the pixels (125) of the image and the coordinate system of the camera (10); calculate the solid angle occupied by each pixel (125) of the image; perform a second calibration of the camera (10) by comparing the theoretical position of the sun and its position in the image, so as to obtain the correspondence between the coordinate system of said camera (10) and the cardinal points; calculate the angle between each pixel (125) and the zenith (PZA), the angle between each pixel (125) and the azimuth (PAA), the angle between the sun and the zenith (SZA) and the angle between the sun and the azimuth (SAA) then the angle between each pixel (125) and the sun (SPA); obtain a high-dynamic-range image (HDR) of the sky; calculate the global horizontal irradiance (σGHI), the direct normal irradiance (σDNI) and the diffuse horizontal irradiance (σDHI), which are defined as the sum of the luminances measured by the pixels (125) of the image belonging to a first region of interest (Λ1), to a second region of interest (Λ2) and to a third region of interest (Λ3), respectively, the sums being weighted by the solid angle of the region of interest in question; and convert σGHI, σD N I and σDHI into global horizontal luminance (GHI), direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI), respectively.