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Old 02-13-12, 02:49 PM   #6
Apprentice EcoRenovator
Join Date: Nov 2008
Location: SW Montana
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Originally Posted by GaryGary View Post
If the collectors have been certified by the SRCC, you can go to the SRCC report for the collector and see the actual performance. Evac tubes vary widely in performance.

The SRCC report also gives the two efficiency curve parameters -- the intercept and the slope. You can copy those down and then use this calculator to compare the output of those collectors to other flat plate and evac tube collectors using the calculator: Solar Collector Efficiency Calculator
Just enter the weather and sun condition you want to look at and it will give you the heat out and efficiency.

Be sure to be realistic about the weather you put in. For temperatures put in realistic average daily high temps (since thats when you collect). Use Weather Spark of something like that to get realistic weather. Most people think its a lot colder where they are than it really is

I live in SW Montana -- a cold place, and we only have one month where the average daily high is below 32F.


This is the SRCC report for one of the SunMaxx Evac tube models:
Did not see the exact model that your link mentioned.

The intercept value for the efficiency curve on this model is 0.376. This means that the collectors highest efficiency under the best sun and weather conditions is 37.6% -- cold temps and part sun make it go down from that, but not very fast as the slope of the efficiency curve is 0.23, which is good.
Still, 37.6% as a maximum does not sound that good to me?
The intercept value for the Heliodyne Gobe (a good flat plate) is 0.752.

This is the link to all of the SRCC certified collectors:

If you just select "SunMaxx Solar" as the Company, you get all of their collectors.
The reports on each collector also give expected heat output for sunny, part sunny, and cloudy days and for services A through E where service C or D is usually used for domestic water heating. So, you can compare the output for the SunMaxx to flat plates and other evacs. If you want to compare two collectors of different sizes, you need to divide the heat output values by the area of the collector to get apples to apples.

GaryGary is offline   Reply With Quote