Solar panels that come as ink, and can be printed onto foil using printing-press technology, seem a little far-fetched- or maybe too good to be true. Believe it, though: the technology, called thin-film photovoltaic (PV), was actually invented in the mid-1970s and over the past couple of years has been resurrected. The British Columbia Institute of Technology, shown here, has a building covered with enough thin-film solar panels to provide all of its own lighting (and let's face it, British Columbia doesn't get a lot of sun!). Typically, thin-film PV cells are used to coat sheets of metal foil, and can transform energy from the sun directly into DC power for your home. Some companies are now making shingles with thin-film incorporated into them or, as shown in this video, metal roofing sheets coated with the stuff. No one is sure when the technology will take off. Although it has the potential to be much less expensive than more typical solar panels, and thus more accessible to the wider population, thin-film is still pretty hard to mass produce in a cost-effective way. Sure is a good idea though.