In continuation of previous entry on using solar energy efficiently, here is a suggestion for a simple, efficient design of solar thermal collectors.

1. See figure for a simple glass tubular structure for solar thermal heat collection using just air or water as medium.
2. The tubes can be held together with a mechanical frame and mounted exactly like the solar PV panels along east west direction at a tilt angle exactly as for a PV panel.
3. Note simple glass tubes made of toughened Borosil glass is suggested which has high transparency over entire solar spectrum. Quartz will be expensive.
4. 1.5 meter long tubes are available as standard could be used.
5. Same Borosil glass tubes could be bent as shown in Fig 2 to further improve solar energy collection to the maximum extent from Sunrise to Sun set. The panels are flat as silicon cells are flat, but glass tubes need not be flat.
6. The air or water transfer from one tube to another can be through dust proof silicone rubber tubes or a long two part molded part- to simplify assembly and molding design.
7. These panels will absorb maximum solar energy and will not cast any shadows below on the ground. Hence, land below can also be utilized for horticulture.
8. Compared to all other design configurations installed, this approach to capture solar energy will be maximum and efficient too- especially if semi-fixed tilt angle is adopted by manually changing the tilt angle every 15 days to a month.
9. Tilt angles for a solar panel for a latitude on the earth is available. Look up link for more details regarding tilt angle. But same does apply for solar thermal also.

http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-light-intensity