10 times compared to what? Installation cost? I can't make your post to make sense. Also, if it were generally true, why would solar heat systems be so popular?

10 times compared to what? Installation cost? I can't make your post to make sense. Also, if it were generally true, why would solar heat systems be so popular? I am thinking of vacuum tubes, the kind of installation which looks pretty much like a PV roof but it's only heat and water.