The charts to the right and below show the pressure drop test results of both metal collectors and
Sunreps' Geotextile 307 collector. The size of the
holes in the respective collector surfaces determine how fast air can pass through.
10 cfm per sq ft of air-flow through a transpired solar collector is scientifically noted as the optimum. Metal collectors max out at 7.6 cfm per sq ft.
Sunreps' 307 and 2307 collectors have an air-flow rate of 8.5 cfm per sq. ft. Overall this difference is rather small as it relates to a collector's efficiency but in the field of bragging, its huge.
Collector Test Results
There is basically one test required to understand the capabilities of a transpired solar collector and that is how fast air will pass through the collector surface at a specific static pressure level. .10 inch H2O of pressure is the baseline for a transpired solar collector. At .10 inches or above the wind will not pull the heat off the collector surface.
Below is the test result for the Sunreps 307 collector fabric. To be used in the commercial building sector all surfaces of a duct need to be fire resistant to a specified level. The test
results shown below meet those requirements.