Although the evacuated tube solar water heaters are slightly more efficient in the winter and look cutting-edge modern, many people think the flat plate solar water heaters are esthetically more pleasing.

In fact, a 4 square meter flat plate solar water heater is equivalent in heat production to a 3 square meter evacuated tube solar water heater.

The flat plate solar water heaters tend to be a little less expensive, making them, dollar per dollar, about equal to the evacuated tube solar water heaters from an investment standpoint.

Quoting Intelligent Energy Solutions:

An independent study by the DTI compared a number of different types of system and the panel that produced the most hot water was of the flat plate variety.