Concentrator Photovoltaics (CPV) employs optical elements such as mirrors to focus solar flux to a small target area with a photovoltaic (PV) receiver. CPV system design is hindered by the fact that there is no standardised workhorse model to accurately evaluate CPV topologies. The spectral irradiance standards - the backbone of PV system analysis - could be used, but lose in validity the higher the concentration as the Sun is not a point source. The sunshape, a different model widely used in Concentrated Solar Power (CSP), considers the Sun as an extended source but does not consider spectral information. It follows that CPV system analysis requires a spectral radiance model of the Sun that contains both spectral and directional information. In this thesis, a model from the astronomical literature is combined with the spectral irradiance standards to establish the spectral sunshape, a spectral radiance model of the Sun. The spectral sunshape is proposed as a workhorse model of the Sun for CPV system analysis.