First off solid state light detector diodes (whatever the band of light they are sensitive to) do not generate electricity they improve their conductivity (reduce
their voltage drop "losses" in rectification mode, their "base to collector" resistance lowers or "conductivity" improves) when their third virtual "emitter" (light exposure) is present. You must pass a current through them for them to "see", they are not photovoltaic "batteries".
A photovoltaic solar cell on the other hand converts light energy (or the heat that it produces) into electrical energy. Solar photovoltaic cells manufactured in broad, flat panels (or as surface coating layers) always have a much larger surface area than a single p/n junction, but a common lens (other than the Fresnel sort) only focusses a light source upon one single spot. A spherical lens is only efficient on one single axis and focal point of operation and a Fresnel is a much less efficient "wide diffuser" more than it is single, focal-area lens.
To use a spherical or Fresnel (onion-ringed) type of lens on a solar panel one must have some powered articulated means of automatically focussing and tracking the light source, lens and panel to it. In a solar application both the lens over a photovoltaic solar cell array and the array itself, and (to some extent) the distance between them must be continually adjusted to the sun.
Unfortunately using any sort of a lens with sunlight causes one a HUGE DESTRUCTIVE PROBLEM - "big, big heat" which is totally incompatible with most solid state semiconductors and most photovoltaic solar cells and even voltaic thermocouples.
Motorized parabolic or concentric mirrors focussed on circulated oil-type coolant tubing heat exchanger steam powerplants have already been built to use out in deserts to take advantage of such techniques. Unfortunately these methods don't work for stationary solar panels, or rooftop water tubes, because moving the things (with motors and controllers) causes power losses (generally) not made up for by the amount of power that smaller photovoltaics can produce, and serious reliability/maintenance issues in cold climates though there is an example of such an advanced single-axis only system at Nellis AFB out in the desert.
that uses no parabolic-lens mirrors nor "lenses"http://en.wikipedia.org/wiki/Solar_power_plants_in_the_Mojave_Desert