How can I tell a water heating panel from a solar electric module?
Solar electric modules are typically one to two inches (2.5 to 5 cm) thick with 32 or more three to four inch (7.5 to 10 cm) blue or black solar cells on the back of the cover glass. Solar water heating panels are generally much thicker and may have tubes connected to a flat black plate under the glass, or a black tank inside the collector panel.
