All solar thermal collectors are incredibly efficient, but the highest efficiency collector is not necessarily the best collector for the job. SunEarth manufactures two of the most efficient solar thermal collectors on the market, each designed for different regions. While the most efficient collector can be a highly sought-after product, the most efficient collector if utilized with an application that does not require that level of efficiency can cause stagnation overheat, essentially damaging the system. In all cases, you want to go with a solar thermal collector that offers up the efficiency needed for the application.