Solar thermal system harvests sunlight to generate heat.
Solar thermal panels, which are made up of solar thermal collectors, are (usually)
installed on the roof where they absorb energy from the sun. Rather than converting it into
electricity, as solar PV panels do, the energy is used to produce heat water stored in a cylinder.
There are two different types of solar panels used for this.
1. Flat-plate collectors and 2 Evacuated tube collectors
solar thermal energy systems have Higher Space-Efficiency, can harvest 70% of energy captured
Source - energy.gov
Solar Energy Companies List