Ever since I've learned that cold solar panels are more efficient, I've dreamed about water-cooled PV that uses the heat for warm water supply. One thing I'm w

Ever since I've learned that cold solar panels are more efficient, I've dreamed about water-cooled PV that uses the heat for warm water supply. One thing I'm worried about in such an integrated solution is water leakage. It looks like you'll need quite a few of these elements to form your roof, and there's got to be a joint between each pair of elements, and each joint has the potential for leaks, for example due to thermal expansion and contraction. With traditional roof shingles (at least as they are done in central Europe), the tiles overlap, so that you don't need a perfect fit, and when the tiles expand at higher temperatures, the overlap still keeps water out. Doesn't seem like that simple mechanism could work if water flows through the solar tiles.