Solar radiation measuring system including a camera provided with a hemispherical objective and comprising a sensor adapted to receive light to generate an image, and a processor able to: - perform a geometric calibration of the camera in order to obtain the correspondence between the system of coordinates of pixels of the image and the system of coordinates of said camera, - calculate the solid angle subtended by each pixel (125, p) of said image, in order to weight the luminance value in the subsequent calculations, - perform a second calibration of the camera by comparing the theoretical position of the Sun and its position on the image, so as to obtain the correspondence between the system of coordinates of said camera and the cardinal points, - calculate the angle between each pixel and the zenith, the angle between each pixel and the azimuth, the angle between the Sun and the zenith and the angle between the Sun and the azimuth, then the angle between each pixel and the Sun, by the relation: cos = cos ⋅ cos +sin ⋅ sin ⋅ cos(|SAA-PAA|), - obtain a high dynamic range image of the sky, said high dynamic range image is obtained by the acquisition of several low dynamic range images taken with different exposure times then the combination of these images into a high dynamic range image, while maintaining the linearity of the camera sensor, characterized in that the processor is able to: - calculate the global horizontal irradiance index (σ GHI), the direct normal irradiance index (σ DNI) and the diffuse horizontal irradiance index (σ DHI), defined as the sum of the luminances measured by the pixels of said image belonging to a first region of interest (Λ 1), to a second region of interest (Λ 2) and to a third region of interest (Λ 3), respectively, where Ω p, L P and PZA are the solid angle subtended by a pixel p, the luminance measured by this pixel and the angle between this pixel and the zenith, respectively, and where said first region of interest (Λ 1) is the set of pixels of the image verifying PZA < 90° said second region of interest (Λ 2) is the set of pixels of the image verifying SPA < β, β being the angle defined as the limit between the circumsolar zone and the rest of the sky, and said third region of interest (Λ 3) is the set of pixels of the image verifying {SPA > β} ∩ {PZA < 90°}: σ GHI = ∑ p ∈ ∧ 1 L p Ω p cos PZA ∑ p ∈ ∧ 1 Ω p σ DNI = ∑ p ∈ Λ 2 L p Ω p ∑ p ∈ Λ 2 Ω p σ DHI = ∑ p ∈ Λ 3 L p Ω p cos PZA ∑ p ∈ Λ 3 Ω p - convert the global horizontal irradiance index (σ GHI), the direct normal irradiance index (σ DNI) and the diffuse horizontal irradiance index (σ DHI) into global horizontal irradiance, direct normal irradiance and diffuse horizontal irradiance, respectively. - perform a geometric calibration of the camera in order to obtain the correspondence between the system of coordinates of pixels of the image and the system of coordinates of said camera, - calculate the solid angle subtended by each pixel (125, p) of said image, in order to weight the luminance value in the subsequent calculations, - perform a second calibration of the camera by comparing the theoretical position of the Sun and its position on the image, so as to obtain the correspondence between the system of coordinates of said camera and the cardinal points, - calculate the angle between each pixel and the zenith, the angle between each pixel and the azimuth, the angle between the Sun and the zenith and the angle between the Sun and the azimuth, then the angle between each pixel and the Sun, by the relation: cos = cos ⋅ cos +sin ⋅ sin ⋅ cos(|SAA-PAA|), - obtain a high dynamic range image of the sky, said high dynamic range image is obtained by the acquisition of several low dynamic range images taken with different exposure times then the combination of these images into a high dynamic range image, while maintaining the linearity of the camera sensor, - calculate the global horizontal irradiance index (σ GHI), the direct normal irradiance index (σ DNI) and the diffuse horizontal irradiance index (σ DHI), defined as the sum of the luminances measured by the pixels of said image belonging to a first region of interest (Λ 1), to a second region of interest (Λ 2) and to a third region of interest (Λ 3), respectively, where Ω p, L P and PZA are the solid angle subtended by a pixel p, the luminance measured by this pixel and the angle between this pixel and the zenith, respectively, and where said first region of interest (Λ 1) is the set of pixels of the image verifying PZA < 90° said second region of interest (Λ 2) is the set of pixels of the image verifying SPA < β, β being the angle defined as the limit between the circumsolar zone and the rest of the sky, and said third region of interest (Λ 3) is the set of pixels of the image verifying {SPA > β} ∩ {PZA < 90°}: σ GHI = ∑ p ∈ ∧ 1 L p Ω p cos PZA ∑ p ∈ ∧ 1 Ω p σ DNI = ∑ p ∈ Λ 2 L p Ω p ∑ p ∈ Λ 2 Ω p σ DHI = ∑ p ∈ Λ 3 L p Ω p cos PZA ∑ p ∈ Λ 3 Ω p - convert the global horizontal irradiance index (σ GHI), the direct normal irradiance index (σ DNI) and the diffuse horizontal irradiance index (σ DHI) into global horizontal irradiance, direct normal irradiance and diffuse horizontal irradiance, respectively.