Understanding the difference between solar thermal energy and solar electric energy is very important. Solar Electric is more commonly referred to as Photovoltaic (PV), in which energy from the sun is converted to electric power.
Solar Thermal energy, however, simply uses energy from the sun to heat water. Both PV and Solar Thermal technologies can be used together or separately.
While PV is used to power the electric needs of an entire home or building, Solar Thermal is the best choice for solar water heating. Solar Water Heaters have always been the first step when "going solar" due to low cost and high power density.