PV systems use silicon cells to create electricity from sunlight, while solar hot water panels use dark or selective surfaces to collect heat from the sun's radiation. Based on return on investment, solar hot water systems usually provide a stronger financial return than photo-voltaic (PV) systems. Part of that advantage is realized by the efficiency of the panels. Solar hot water collectors are roughly 66% efficient in harvesting the sun's energy, while most PV panels are still below 20% efficient. Many are below 15% efficient. If you choose higher efficiency PV panels, they cost more. The bottom line is that you need three to four times the surface area, to collect the same equivalent energy as a solar thermal system. PV systems cost considerably more than solar hot water systems, so you would need significantly more capital, to make such an improvement to your home or business. Certainly, PV systems do capture real energy, and I am of a you get what you get mentality, so yes, they do work and work well, they are, however, considerably more costly to install than a solar thermal system.