Multi-layer thin film solar collector

A solar collector, comprising:

• a front sheet formed from a polymer film;
• a middle sheet formed from a polymer film;
• and
• a back sheet formed from a polymer film, wherein the front, middle, and back sheets are welded together by a plurality of longitudinal welds, with the middle sheet being between the front and back sheets, wherein some of the longitudinal welds are only between the front sheet and the middle sheet to form the front layer of channels between the front and middle sheets and other of the longitudinal welds are only between the middle sheet and the back sheet to form the back layer of channels between the middle and back sheets, wherein each layer of fluid flow channels comprises a plurality of fluid flow channels that extend substantially longitudinally along the solar collector, and wherein the first layer of fluid flow channels provides a flow path therethrough in a first direction and the second layer of fluid flow channels provides a flow path therethrough in a second direction, wherein the first and second directions are opposite directions.

A solar collector system comprising:

• a front sheet formed from a polymer film;
• a middle sheet formed from a polymer film;
• and
• a back sheet formed from a polymer film, the back sheet having a substantially same length as the front sheet and the middle sheet being shorter than the front and back sheets wherein the front, middle and back sheets are welded together by a plurality of longitudinal welds to define first and second layers of substantially parallel fluid flow channels that extend longitudinally along the collector, the longitudinal welds on the middle sheet alternate between a weld to the front sheet and a weld to the back sheet, wherein the first layer is between the front sheet and the middle sheet and the second layer is between the middle sheet and the back sheet, and wherein the first layer of fluid flow channels provides a hot thermosiphonic flow path therethrough in a first direction and the second layer of fluid flow channels provides a cold flow path therethrough in a second direction, wherein the first and second directions are opposite directions.