Polar axis type solar direct radiation spectrum measurement method and system

Abstract

The invention discloses a polar axis type solar direct radiation spectrum measurement method and system, belongs to the technical field of solar direct radiation spectrum measurement, and aims to solve the problems that an existing measurement system depends on complex double-axis tracking, has many errors, is high in maintenance cost and is insufficient in latitude adaptability. The system comprises a polar axis rotating reflector and a solar spectrum measurement system, the polar axis rotating reflector directly radiates and reflects the sun with the solar elevation angle of + / -23.5 degrees and the solar azimuth angle of + / -90 degrees to the measurement system, and measurement is achieved in combination with a spectrum reconstruction model. The spectral resolution is superior to 2 nm, the single-point error ranges from-6.83% to 6.61%, the area error ranges from-0.03% to 0.05%, the space-time uniformity is larger than or equal to 99.92%, the structure is simplified, all-year-round all-latitude high-precision measurement without moving tracking is achieved, and the method is suitable for the fields of solar energy development, climate change research and the like.

Description

Technical Field

[0001] This invention relates to the field of solar direct radiation spectral measurement technology, and in particular to a polar-axis solar direct radiation spectral measurement method and system. Background Technology

[0002] High-precision measurement of the direct solar radiation spectrum is of great significance for fields such as solar energy resource development, climate change research, and agricultural development. Current measurement systems all rely on complex mobile dual-axis tracking systems, which suffer from drawbacks such as multiple error propagation links, high maintenance costs, and insufficient latitude adaptability. These shortcomings severely restrict the stability and practicality of the measurement systems, resulting in the limited widespread application of direct solar radiation spectrum measurement devices.

[0003] Current solar tracking technologies primarily rely on motion tracking. While the STR series dual-axis motion tracking system developed by EKO in Japan in 2016 controlled the tracking error to within 0.01°, its mechanical complexity limited its large-scale application. In 2020, Nurzhigit Kutybay et al. demonstrated that single-axis motion tracking devices have lower installation and operating costs, but their tracking accuracy lags behind dual-axis devices. In 2021, Junying Wong et al. designed a 1.5-axis motion tracking scheme, but its performance was limited under certain conditions. Furthermore, polar-axis rotation tracking has not yet been effectively applied in the field of direct solar radiation spectroscopy measurement, making it impossible to achieve tracking-free direct solar radiation spectroscopy measurements. Summary of the Invention

[0004] The purpose of this invention is to provide a polar-axis solar direct radiation spectrum measurement method and system, which aims to solve the problems of existing solar direct radiation spectrum measurement systems that rely on complex dual-axis motion tracking devices, have many error transmission links, high maintenance costs, insufficient latitude adaptability, and the fact that polar-axis rotation tracking methods have not been effectively applied in this field, making it impossible to achieve tracking-free measurement.

[0005] This invention provides a polar-axis solar direct radiation spectrum measurement method, comprising the following steps: S1: Construct a polar-axis solar direct radiation spectrum measurement system, which consists of a polar-axis rotating mirror and a solar spectrum measurement system. The polar-axis rotating mirror adopts an XY polynomial freeform surface, and the solar spectrum measurement system adopts a cross-type Czerny-Turner optical path structure. S2: The polar axis rotating mirror, through its surface characteristics and rotation around the axis, reflects the direct solar radiation within a range of ±23.5° solar altitude angle and ±90° solar azimuth angle into the solar spectrum measurement system. S3: The solar spectral measurement system performs spectral measurements on the received direct solar radiation; S4: Using 13 equal-energy light sources at angles of -23.5°, -20°, -16°, -12°, -8°, -4°, 0°, 4°, 8°, 12°, 16°, 20°, and 23.5° as incident rays, a solar direct radiation spectrum reconstruction model was established, and the spectral curve measurement results and reconstruction coefficients of the equal-energy spectral light sources at each angle were obtained; S5: Replace the spectral curve of the light source with the AM0 or AM1.5G solar spectrum, and use the reconstruction coefficient to reconstruct the solar direct radiation spectrum to achieve the measurement of the solar direct radiation spectrum.

[0006] Furthermore, in step S3, the incident and diffraction angles of the grating are set to 30°. Based on the grating diffraction equation, the incident angle of the grating is calculated to be i = 18.4° and the diffraction angle of the grating is θ = 11.6°.

[0007] Furthermore, in step S5, to more accurately evaluate the accuracy of the reconstructed solar direct radiation spectrum measurement, a single-point error is selected. Detailed evaluation, area error An overall evaluation was conducted, and to assess the accuracy of the year-round measurement results, the spatiotemporal homogeneity RFUS was used for evaluation. The specific expression is as follows: In the formula For standard AM0 or AM1.5G solar spectra, These are the reconstructed measurements of the solar direct radiation spectrum; , X is 0 or 1.5G. and They are The maximum and minimum values.

[0008] This invention also provides a polar-axis solar direct radiation spectral measurement system, including a polar-axis rotating reflector and a solar spectral measurement system; the polar-axis rotating reflector adopts an XY polynomial freeform surface, used to reflect solar direct radiation within a range of ±23.5° solar altitude angle and ±90° solar azimuth angle to the solar spectral measurement system; the solar spectral measurement system adopts a cross-type Czerny-Turner optical path structure, used to perform spectral measurement on the received solar direct radiation.

[0009] Furthermore, the grating diffraction equation is: In the formula, d is the grating period. The incident wavelength, and These are the incident angle and the diffraction angle of the corresponding diffraction order m, respectively. It depends on whether the grating is reflective or transmissive; in this case, the grating's color resolution is... Set the incident diffraction angle of the grating Given an angle of 30°, the grating incident angle i = 18.4° and the grating diffraction angle θ = 11.6° are calculated based on the grating diffraction equation.

[0010] Furthermore, the solar spectrum measurement system includes a grating, a collimating mirror, a focusing mirror, and a 1-inch CCD device.

[0011] Furthermore, the number of grating line pairs is 400 lines / mm, the focal length of the collimating mirror is 185mm, and the focal length of the focusing mirror is 150mm.

[0012] Beneficial effects:

[0013] 1. This invention applies the polar-axis tracking method to the field of solar direct radiation spectrum measurement, constructs a corresponding measurement system, simplifies the structure of traditional measurement systems, realizes solar direct radiation spectrum measurement without the need for tracking throughout the year and across all latitudes, and improves the theoretical system of solar direct radiation spectrum measurement.

[0014] 2. The optimized optical system aims for a spectral resolution of 2nm for each field of view. The polar axis rotating mirror and the solar spectrum measurement system have good coupling effect, and the measurement spectral resolution is better than 2nm in the solar altitude angle range of -23.5° to +23.5°, providing a theoretical basis for the accurate measurement of the solar direct radiation spectrum.

[0015] 3. After reconstruction, the solar direct radiation spectrum distribution of each solar direct beam incident angle is basically consistent with the standard solar spectrum distribution. The single-point error distribution is between -6.83% and 6.61%, the area error distribution is between -0.03% and 0.05%, and the spatiotemporal uniformity is greater than or equal to 99.92%, indicating high measurement accuracy. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall architecture of the polar-axis solar direct radiation spectral measurement system of the present invention; Figure 2 This is a schematic diagram of the optical path of the polar-axis solar direct radiation spectral measurement optical system of the present invention; Figure 3 This is a schematic diagram of the spectral resolution at different wavelengths under an incident angle of 23.5° according to the present invention; Figure 4 This is a schematic diagram of the spectral resolution at different wavelengths under an incident angle of 16° according to the present invention; Figure 5 This is a schematic diagram of the spectral resolution at different wavelengths under an incident angle of 11.8° according to the present invention; Figure 6 This is a schematic diagram of the spectral resolution at different wavelengths under a 0° incident angle according to the present invention; Figure 7 This is a schematic diagram of the spectral resolution at different wavelengths under an incident angle of -11.8° according to the present invention; Figure 8 This is a schematic diagram of the spectral resolution at different wavelengths under an incident angle of -16° according to the present invention; Figure 9 This is a schematic diagram of the spectral resolution at different wavelengths under an incident angle of -23.5° according to the present invention; Figure 10 This is a schematic diagram of the polar-axis solar direct radiation spectral measurement system of the present invention; Figure 11 This is a schematic diagram of the direct solar radiation spectrum at various angles after AM0 reconstruction according to the present invention; Figure 12 For each incident angle of AM0 in this invention Distribution diagram; Figure 13 For each incident angle of AM0 in this invention Distribution diagram; Figure 14 This is a schematic diagram of the direct solar radiation spectrum at various angles after AM1.5G reconstruction according to the present invention; Figure 15 For each incident angle of AM1.5G in this invention Distribution diagram; Figure 16 For each incident angle of AM1.5G in this invention Distribution diagram; Figure 17 Schematic diagram of the angular response results of the polar-axis solar direct radiation spectral measurement system of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0018] I. System Composition and Parameter Settings The polar-axis solar direct radiation spectral measurement system of the present invention includes a polar-axis rotating reflector and a solar spectral measurement system. The specific structure and parameter settings of each part are as follows: 1.1 Polar axis rotating mirror The polar-axis rotating reflector employs an XY polynomial freeform surface design. Its surface equation is optimized using optical design software, enabling it to accommodate light incidence ranges of ±23.5° solar altitude angle and ±90° solar azimuth angle. The advantage of this surface lies in its ability to precisely reflect direct solar radiation at different angles to the incident port of the solar spectral measurement system through a combination of surface characteristics and rotational motion around the polar axis. This eliminates the need for a complex dual-axis tracking structure; solar radiation capture across the entire year and latitude range can be achieved solely through single-axis rotation.

[0019] 1.2 Solar Spectrum Measurement System The solar spectrum measurement system adopts a cross-type Czerny-Turner optical path structure, mainly composed of a grating, collimating mirror, focusing mirror, and a 1-inch CCD device. The parameters and selection criteria for each component are as follows: Grating: A reflective grating with a line pair count of 400 lines / mm is selected, with a period d = 1 / 400mm = 2500nm. This parameter is chosen based on the spectral resolution requirements: the line pair count is positively correlated with color resolution (color resolution R = mL, where m is the diffraction order and L is the grating width). 400 lines / mm can meet the requirement of spectral resolution better than 2nm while ensuring the measurement range.

[0020] Collimating mirror: The focal length is set to 185mm. It is used to parallelize the divergent solar radiation reflected by the polar axis rotating mirror, ensuring that the light enters the grating at a uniform angle.

[0021] Focusing mirror: The focal length is set to 150mm. It is used to focus different wavelengths of light after grating diffraction onto the photosensitive surface of the CCD device to achieve spatial separation of the spectrum.

[0022] CCD device: A 1-inch CCD detector with a pixel size of 3.45μm×3.45μm is selected, which can achieve high-sensitivity detection of the 380nm-780nm band spectrum and meet the measurement accuracy requirements of the solar direct radiation spectrum.

[0023] 1.3 Calculation of grating diffraction parameters Set the incident and diffraction angle of the grating (the sum of the incident angle i and the diffraction angle θ) to 30°, based on the grating diffraction equation: In the formula, d is the grating period. The incident wavelength, and These are the incident angle and the diffraction angle of the corresponding diffraction order m, respectively. It depends on whether the grating is reflective or transmissive; in this case, the grating's color resolution is... (Taking m=1; λ as the incident wavelength, with a center wavelength of 550nm), and combining i+θ=30°, we can simultaneously solve for: incident angle i=18.4°, diffraction angle θ=11.6°. These parameters ensure efficient diffraction and separation of the solar spectrum by the grating, further improving the accuracy of spectral measurements.

[0024] II. Specific Implementation Steps of the Measurement Method Step S1: System Construction Assemble the polar-axis solar direct radiation spectral measurement system according to the parameters in 1.1 and 1.2 above: install the polar-axis rotating mirror on the polar-axis rotating mechanism, ensuring that its rotation axis is parallel to the Earth's polar axis (suitable for installation at all latitudes); fix the solar spectral measurement system in place, aligning its incident port with the reflected optical axis of the polar-axis rotating mirror to ensure that the reflected light can stably enter the collimating mirror.

[0025] Step S2: Solar radiation reflection The polar-axis rotating reflector, by rotating around its polar axis (the rotation angle is adjusted in real time according to local latitude and time, automatically driven by the control system), combined with the surface characteristics of the XY polynomial freeform surface, reflects direct solar radiation at different times (solar altitude angle -23.5° to +23.5°, solar azimuth angle -90° to +90°) to the incident port of the solar spectral measurement system. The "-23.5° to +23.5° solar altitude angle" corresponds to the range of the sun's movement between the Tropic of Cancer and the Tropic of Capricorn, while the "-90° to +90° solar azimuth angle" covers the azimuthal changes of the sun throughout the day, ensuring that direct solar radiation is captured without any blind spots throughout the year.

[0026] Step S3: Spectral Measurement The solar spectral measurement system performs spectral measurements on the received reflected light. The specific process is as follows: A collimating mirror converts direct solar radiation into parallel light. Parallel light is incident on the grating at an incident angle of 18.4°. After diffraction by the grating, light of different wavelengths exits at a diffraction angle of 11.6°. The focusing mirror focuses the diffracted light of each wavelength onto the CCD detector. The CCD records the light intensity signal at different positions, forming the original spectral data (the correspondence between wavelength and CCD pixel position is determined through prior calibration).

[0027] Step S4: Establishing the Spectral Reconstruction Model Equal energy light source incident: Equal energy light sources (light sources with uniform light intensity of each wavelength) with a total of 13 angles of -23.5°, -20°, -16°, -12°, -8°, -4°, 0°, 4°, 8°, 12°, 16°, 20°, and 23.5° are selected to simulate incident light rays at different solar altitude angles and are respectively incident on the polar axis rotating mirror; Spectral measurement: Obtain the spectral curve of an equal-energy light source at each angle using a solar spectral measurement system; Reconstruction coefficient calculation: Based on the least squares method, the spectral curves at 13 angles are used as basis functions to solve for the reconstruction coefficients corresponding to each angle, and a spectral reconstruction model is established.

[0028] Step S5: Solar Spectrum Reconstruction and Accuracy Evaluation Spectral reconstruction: Replace the equal-energy light source spectral curve in step S4 with the standard AM0 and AM1.5G solar spectra, and use the obtained reconstruction coefficients to calculate the reconstructed solar direct radiation spectrum through linear superposition. Accuracy evaluation: Single point error Used for detailed evaluation, area error Used for overall evaluation, and simultaneously evaluated using the spatiotemporal homogeneity RFUS; used to evaluate the accuracy of measurements throughout the year, the calculation formula is as follows: In the formula For standard AM0 or AM1.5G solar spectra, These are the reconstructed measurements of the direct solar radiation spectrum. , X is 0 or 1.5G. and They are The maximum and minimum values.

[0029] (1) Evaluation of the accuracy of AM0 solar spectrum reconstruction measurement Using the AM0 solar spectrum as the incident spectrum curve, the reconstructed direct solar radiation spectra at various angles are obtained as follows: Figure 11 As shown.

[0030] Figure 11 The red line represents the standard AMO solar spectrum curve. The reconstructed direct solar radiation spectra at various angles show good consistency with the AMO spectrum curve, especially in the 380-540 nm range. However, the curve fluctuates more chaotically in the 540-780 nm range, but it remains largely within the standard AMO curve. The results are plotted as a violin graph (solid dots represent the mean, box plots represent the standard deviation, and colored areas represent the error distribution), as shown below. Figure 12 As shown, each incident angle Distribution as Figure 13 As shown.

[0031] Figure 12 It can be seen from various angles Between -9.05% and 13.35%, the average error is 0.03%, with the largest error of 13.35% occurring at 740nm of the 0° incident light, but this is the only point where the error exceeds 10%, and the largest standard deviation is 2.59% when the incident angle is 8°. Figure 13 It can be seen Between -0.04% and 0.09%, the maximum error of 0.09% occurs at an 8° incident light angle. At this point, the RFUS can be calculated to be 99.93%.

[0032] (2) Evaluation of the accuracy of AM1.5G solar spectrum reconstruction measurement Using the AM1.5G solar spectrum as the incident spectrum curve, the reconstructed direct solar radiation spectra at various angles are obtained as follows: Figure 14 As shown.

[0033] Figure 14 The red curve represents the standard AM1.5G solar spectrum. The reconstructed measurements at various angles are largely consistent with the AM1.5G curve, with characteristic peaks present, including a sharp peak at 610 nm, but these peaks are primarily distributed around the standard AM1.5G curve. The results are plotted as a violin graph (solid dots represent the mean, box plots represent the standard deviation, and colored areas represent the error distribution), as shown below. Figure 15 As shown, each incident angle Distribution as Figure 16 As shown.

[0034] Figure 15 It can be seen from various angles Between -9.19% and 13.66%, the average value is 0.02%, with the largest error of 13.66% occurring at 760nm of the -8° incident light, but only at this point does the error exceed 10%, and the standard deviation is the largest at 2.86% when the incident angle is 8°. Figure 16 It can be seen Between -0.03% and 0.11%, the maximum error occurs at an incident ray angle of 12°. At this point, the RFUS can be calculated to be 99.92%.

[0035] (3) Comparison of AM0 and AM1.5G solar spectral accuracy assessment AM0 and AM1.5G spectral reconstruction accuracy , And the RFUS comparison is shown in Table 1.

[0036]

[0037] Table 1 Comparison of Spectral Reconstruction Accuracy between AM0 and AM1.5G Comparative analysis of the AM0 and AM1.5G solar direct radiation spectral measurement results shows that the two are highly consistent in core accuracy indicators. The distributions are all close to normal, with average errors as low as 0.03%. However, the maximum... Both significantly exceeded 13%, with the AM0 spectrum reaching 13.35% at 0° incident angle and 740nm wavelength, and the AM1.5G spectrum reaching 13.66% at -8° incident angle and 760nm wavelength. This clearly reveals that the system has significant sensitivity in the long wavelength range (740–760nm). The extreme values ​​are all very small, with the AM0 spectrum reaching a maximum of 0.09% at an incident angle of 8° and the AM1.5G spectrum reaching a maximum of 0.11% at an incident angle of 12°. This confirms that the overall morphology of the measured spectra at each angle is highly similar to that of the standard spectrum. It is noteworthy that the AM0 and AM1.5G... Extreme values ​​occur at different incident angles, and The peak standard deviations of both spectra occurred at an incident angle of 8°, suggesting a slight influence of solar spectral conditions on the system's measurement results. Most importantly, the spatiotemporal homogeneity (RFUS) of both spectra was greater than or equal to 99.92%, strongly demonstrating the system's excellent adaptability (robustness) to incident angle variations within a range of ±23.5°, meeting the requirements for high-precision measurements across all latitudes and year-round.

[0038] III. Implementation Results Verification Through the above implementation steps, the system achieves the following technical effects: Simplified structure: The use of a polar-axis rotating reflector to replace the traditional dual-axis motion tracking system reduces mechanical transmission links, lowers maintenance costs, and enables solar direct radiation spectrum measurement without motion tracking throughout the year and across all latitudes, further improving the theoretical system of solar direct radiation spectrum measurement.

[0039] All-latitude adaptability: With its polar axis designed to be parallel to the Earth's polar axis, it can adapt to all latitude regions around the world without adjusting the installation angle; High-precision measurement: With a spectral resolution of less than 2 nm, the polar-axis rotating mirror and the solar spectral measurement system are jointly optimized to allow the solar beam reflected by the polar-axis rotating mirror to propagate freely within the system space to the solar spectral measurement system. Compared with aperture measurement, this reduces the constraint on the measured energy and improves the coupling effect of the optical system, providing a theoretical basis for the accurate measurement of the solar direct radiation spectrum. Single-point error, area error, and spatiotemporal uniformity indicators all show that the measurement accuracy meets the needs of solar energy development, climate change research, and other fields. A solar direct radiation spectrum reconstruction model was established, using 13 angle light sources (spectral distribution with iso-energy spectra) at -23.5°, -20°, -16°, -12°, -8°, -4°, 0°, 4°, 8°, 12°, 16°, 20°, and 23.5° to simulate the incident light of direct solar radiation. Experimental results and reconstruction coefficients for each angle were obtained. Taking AM0 and AM1.5G solar spectra as examples, the performance parameters of the system were verified by simulation. The results show that the reconstructed solar direct radiation incident light at each angle... The spectral distributions of direct solar radiation at the angle of incidence are basically consistent with those of AM0 and AM1.5G solar spectral distributions. The single-point errors are distributed between -9.05% and 13.35% and between -9.19% and 13.66%, respectively, but the average error is only 0.03% and 0.02%, respectively. This indicates that the error range is larger due to the influence of individual points. The area errors are distributed between -0.04% and 0.09% and between -0.03% and 0.11%, respectively. The overall spectral morphology is highly similar, and the spatiotemporal homogeneity is greater than or equal to 99.92%.

[0040] Future research aims to construct a high-precision solar direct radiation spectral measurement system adapted to extreme global environments. This will be achieved by optimizing weather-resistant hardware designs that are dustproof, waterproof, and corrosion-resistant, ensuring long-term stable operation of the equipment. Intelligent algorithms with dynamic environmental interference calibration and adaptive learning capabilities will be developed to synergistically improve measurement accuracy and system robustness. Furthermore, optical corrections will be made to the freeform surface mirrors based on the World Meteorological Organization's traceability standards to accurately compensate for spectral deviations at a 2.5° solar open angle. Ultimately, this will realize a closed-loop solar radiation monitoring technology that is climate-compatible and internationally traceable.

[0041] Those skilled in the art can fine-tune the surface parameters and number of grating line pairs of the polar axis rotating mirror according to the actual application scenario, but the core principles and implementation steps should all fall within the protection scope of this invention.

[0042] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship when the device or element is in normal use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation at any time, or be constructed and operated in a specific orientation, unless otherwise stated in the text.

[0043] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method of direct solar radiation spectral measurement with a polar axis, characterized in that, The method comprises the following steps: S1: constructing a polar-axis type solar direct radiation spectrum measurement system composed of a polar-axis rotating reflector and a solar spectrum measurement system, wherein the polar-axis rotating reflector adopts an XY polynomial free surface, and the solar spectrum measurement system adopts a cross-type Czerny-Turner optical path structure; S2: the polar-axis rotating reflector reflects solar direct radiation in a solar elevation angle range of ±23.5° and a solar azimuth angle range of ±90° into the solar spectrum measurement system through the surface characteristics and rotation thereof; S3: the solar spectrum measurement system performs spectrum measurement on the received solar direct radiation; S4: taking equal-energy light sources at 13 angles of -23.5°, -20°, -16°, -12°, -8°, -4°, 0°, 4°, 8°, 12°, 16°, 20° and 23.5° as incident light, a solar direct radiation spectrum reconstruction model is established, and spectrum curve measurement results and reconstruction coefficients of the equal-energy light sources at the angles are obtained; S5: the spectrum curve of the light source is replaced by an AM0 or AM1.5G solar spectrum, the reconstruction coefficients are used for solar direct radiation spectrum reconstruction, and measurement of the solar direct radiation spectrum is realized.

2. The method of claim 1, wherein, In step S3, the grating incident diffraction angle is set to 30°, the grating incident angle i is calculated to be 18.4° based on the grating diffraction equation, and the grating diffraction angle θ is calculated to be 11.6°.

3. The method of claim 1, wherein, Step S5 is to evaluate the accuracy of the reconstructed direct solar radiation spectrum measurement more accurately, and a single-point error is selected The area error is evaluated in detail The overall evaluation is carried out, and in order to evaluate the accuracy of the measurement results throughout the year, the space-time uniformity RFUS is used for evaluation, and the specific expression is , wherein AM0 or AM1.5G solar spectrum is the reconstructed direct solar radiation spectrum measurement value , X is 0 or 1.5G and are the maximum value and the minimum value of respectively.

4. A polarizing solar direct radiation spectral measurement system according to claim 1, wherein The polar-axis rotating reflector adopts an XY polynomial free surface and is used for reflecting solar direct radiation in a solar elevation angle range of ±23.5° and a solar azimuth angle range of ±90° into the solar spectrum measurement system; and the solar spectrum measurement system adopts a cross-type Czerny-Turner optical path structure and is used for performing spectrum measurement on the received solar direct radiation.

5. The system of claim 4, wherein, The grating diffraction equation is ; in the formula, d is a grating period, is an incident wavelength, and are an incident angle and a diffraction angle of a corresponding diffraction order m respectively; depends on a reflection or transmission grating; at this time, the grating color resolution capability is , the grating incident diffraction angle is set to 30°, based on the grating diffraction equation, the grating incident angle i = 18.4° and the grating diffraction angle θ = 11.6° are solved.

6. The system of claim 5, wherein, The solar spectrum measurement system comprises a grating, a collimating reflector, a focusing reflector and a 1-inch CCD device.

7. The system of claim 6, wherein, The grating has a line number of 400 line / mm, the collimating reflector has a focal length of 185 mm, and the focusing reflector has a focal length of 150 mm.

Images