Comparison of SunMaxx Heat Pipe Vs U-Pipe Evacuated Tube Solar Collectors:

Test Models:  SunMaxx-30 and SunMaxx-30U
Testing Report:  Solar Keymark Certification Testing

Model	SunMaxx-30U	SunMaxx-30
Collector Type	U-Pipe	Heat Pipe
Aperture Area	2.67 m2 (28.74 ft2)	2.79 m2 (30.03 ft2)
Conversion Factor (efficiency (no))	0.650	0.734
Heat Transfer Coefficient (a1)	1.585 W/(m2K)	1.529 W/(m2K)
Temperature Dependent Heat Transfer Coefficient (a2)	0.002 W/(m2K)	0.012 W/(m2K)
Typical Power Output/Collector
Tm – Ta (K)	@ 400 W/m2 @ 700 W/m2 @ 1000 W/m2	@ 400 W/m2 @ 700 W/m2 @ 1000 W/m2
10	649 1172 1693	772 1387 2001
30	562 1083 1510	650 1264 1879
50	469 990 1510	490 1105 1719
Power Output (W/m2 – Aperture Area) based on 1000W/m2 Irradiance	634 W/m2 of Aperture Area	717 W/m2 of Aperture Area
Power Output (BTU/h/m2 – Aperture Area) based on 1000W/m2 Irradiance	2163 BTU/h/m2 of Aperture Area 201 BTU/h/ft2 of Aperture Area	2446 BTU/h/m2 of Aperture Area 227 BTU/h/ft2 of Aperture Area
Total BTU/h	5923 BTU/h	6824 BTU/h
MSRP (collector)	$ 1243.75	$ 1748.75
BTU/h/$ Invested (Value of Collector)	BTU/h/$ 4.76	BTU/h/$ 3.90

It is clear from the results that the conversion efficiency of SunMaxx Heat Pipe Evacuated Tube Solar Collectors is superior to that of SunMaxx U-Pipe Evacuated Tube Solar Collectors. Despite this, U-Pipe Solar Collectors provide an extremely low-cost alternative to U-Pipe Solar Collectors, and their unique ability to be installed at 0 and 90 degreen angles (flat or vertical) make them a superb choice for commercial installations where space is often limited shading caused by multiple rows of solar collectors can be a problem for engineering and system design.

However, in pure dollar value – BTU/h/$ invested – SunMaxx U-Pipe Solar Evacuated Tube Solar Collectors deliver a higher energy value because of their extremely low price and high performance ratings.  If you are looking for the most value for your money, and the lowest possible initial investment, SunMaxx U-Pipe Evacuated Tube Solar Collectors are clearly the most viable choice.

In particular, U-Pipe Solar Collectors are the perfect for installations where the Solar Collectors will be mounted flush (flat) on a zero-pitch (flat) roof, or in a vertical orientation on the side wall of a building.