Solar spectral irradiance (SSI) measurements are important for solar collector / photovoltaic panel efficiency and solar energy resource assessment as well as being important for scientific meteorological/climate observations and material testing research. To date such measurements have exploited modified diffraction grating based scientific instruments which are bulky, expensive, and with low mechanical integrity for generalized deployment. A compact and cost-effective tool for accurately determining the global solar spectra as well as the global horizontal or tilted irradiances as part of on-site solar resource assessments and module performance characterization studies would be beneficial. An instrument with no moving parts for mechanical and environment stability in open field, non-controlled deployments could exploit software to resolve the global, direct and diffuse solar spectra from its measurements within the 280-4000 nm spectral range, in addition to major atmospheric processes, such as air mass, Rayleigh scattering, aerosol extinction, ozone and water vapour absorptions.