Lenses and Mirrors for Solar Energy

When the design simulation of the nonimaging Fresnel lens solar concentrator was completed, we thought of the lens as being a direct competitor to the compound parabolic concentrator (CPC), which is a mirror-based solar thermal concentrator. We still think this to be true, but we are also investigating the role of the Fresnel lens in photovoltaic (pv) applications. Two questions arise: first, why does 'refractive lens' sound like 'pv', and 'reflective mirror' like 'solar thermal'? And second, assuming the distinction to be merely historical, why are we considering and testing the nonimaging lens for use in the photovoltaic conversion of sunlight, and not only for solar thermal applications, as originally intended?