When making a solar water heater has anyone used a Fresnel Len as the glass to increase heating?

Question

When making a solar water heater has anyone used a Fresnel Len as the glass to increase heating?

Answer 1

They do use them, but not configured as you say.

Just using the glass won't change the amount of energy.

The proper way to use it is to put a big (much bigger than the collector) lens well in front of the collector, with the focal length chosen to concentrate the energy onto the collector.

Answer 2

Yes, of course.  Because a fresnel lens, these days, is made of thin plastic, a properly constructed lens can be made that is long and narrow and come to a focus when it is mounted flat or when it is arched.  In either case, the lens collects light from a wide area and focuses it on a line where there should be a pipe ideally with a treated surface to absorb as much energy as possible