What is the best solar collector for a large scale operation of around 30,000 litres?

Question

What is the best solar collector for a large scale operation of around 30,000 litres?

Answer 1

If you are considering heating 30000litres of water/day from 20 deg to about 60 deg you will need 1.2 million kcals. The average solar collection south of Vindhyas in India is about 4800 kcals/day/sq.mtr collector area.

For your application this means about 250 sq.mtrs.

As a ball park estimate, it may cost about Rs.2 million.

There are many manufacturers, who can do this in India.

Answer 2

For a large system like that I would go with a collector with parabolic mirrors concentrating heat on pipes with  an oil mixture in them.  The oil mixture would then heat a secondary loop of whatever you wanted to heat I'm assuming water in your case.  With this system a sun tracker would make it more efficient.  If you didn't want to go with the expense of a sun tracker the flat black glass solar heater panels would probably do well as long as you don't need the higher heat the parabolic mirrors could give you.