amorphous silicon is WAY cheaper than monocrystalline silicon, but still WAY expensive to process. New polymer based technologies will hopefully bring costs down further.
I hope we all recognize that solar isn't terribly practical (regardless of cost) for a primary source of power due to the super-low energy density, but if it was affordable and widespread (EG, if solar panels replaced asphalt shingles), it could still make a few %dent in our energy consumption.
