1st generation
By 1st Generation, I mean the typical Photovoltaic (PV) panels made through cutting fragile wafers and protecting them from the environment, outside of improving the efficiency of the cells over the years, in basic principle, nothing has changed with first generation PV panels - yes, Sharp is the one of the best, but the new emerging technology has gen 1 PV panels beat by a mile when it comes to efficiency and longevity.
A friend is involved in testing other solar applications, PV casting, string ribbons, there are solar windows in the infancy stages. For about 45 years now, we have been working with one style of solar panel, over the last 5 years, Solar technology has advanced by leaps and bounds making current technology obsolete. Much of it is currently not attainable by the general public (gen 3 and 4), second generation panels already are available, these panels are not as sensitive to environmental damage, their life span is over twice that of a 1st gen PV panel, efficiency is improved by close to 50% and the purchase cost is relative to the increase in efficiency. Install costs are lower, as a bonus, you require less area to produce the same amount of electricity.
There are other types of Solar collectors being developed - Copper Indium Gallium Selenide (CIGS) for example, although currently less efficient than PV, CIGS benefits from greatly reduced production costs, no solar degredation, and many other benefits such as a possible silicone shortage. CIGS will provide a much more affordable product on a per KWhr consumer cost, CIGS is the technology you've probably heard about as "Solar paint" - well, it doesn't stop there, it can be incorporated into just about anything, your entire building can incorporate CIGS to become a solar collector, the exterior shell of your car can be a solar collector, once efficiencies are improved, imagine driving forever, only to "charge up" on a rainy day! Anyways, this technology is still a little while away - say 3-5 years, but from the progress I've seen over the last 5 or so years, when it's time to re-shingle my roof (which isn't that far off), there will be some materials available that are going to blow a solar geeks mind, and at an affordable price point to boot.