All About Solar Thermal Collectors

All About Solar Thermal Collectors

What Is The Difference Between Flat Plates And Evacuated Tube Collectors?

What is the difference between Flat Plates and Evacuated Tube Collectors? While both types of collectors capture the suns energy and convert it to hot water each have there own advantages. Evacuated Tube Collectors are best used in northern climates where freezing can occur and can be utilized in areas where temperatures drop down to -60°F. Evacuated Tubes are are extremely efficient by virtue of the Tubes themselves. Each Evacuated Tube is hermetically sealed meaning it is highly insulated due to the fact that it is a sealed atmosphere nearly impervious to outside temperatures. Evacuated tubes can also be replaced if damaged, simply by plugging it in, no need to replace the whole unit. SunMaxx Flat Plate collectors use a highly efficient flat absorber material called Tinox which transfer heat to a series of copper tubes which circulate a 50% glycol/water mix. The collectors themselves are in essence a a sealed insulated box which captures the suns energy and transfers it via the Tinox, then through the pipes filled with glycol and into  the storage tanks.

MORE ABOUT EVACUATED TUBE COLLECTORS

Is it possible to melt snow off of my collectors?

Yes it is. Depending on your type of collector, you can program your controller to manually activate the circulator which will bring heat from your storage vessel and into the collectors, which will radiate that heat back out thus melting the snow. This method only works for FLAT PLATES however and will usually take as much energy as it makes. When the sun is out in full force, the rays passing through thge snow are typically enough to create substantial heat that in turn, melts the snow on flat plates. For Evacuated tubes however, there is very little you can do to melt the snow. If your collectors are sitting at a tilt off from the roof pitch, you should be okay because the snow will pass between the tubes onto the roof. But for flush mount EVT systems, snow can and will build up. However, in my experience, this will only affect the output for a day or two. Becuase if the sun is out enough to make any amount of BTU"S then there will be enough heat wasted at the roof/collector interface that begins to melt the snow alowing it to slide down from the top of the tubes. With only minimal exposure to the direct sunlight, the small amount of exposed tube will begin to yield significant amount of BTU's, even though they are mostly covered. So for tubes, dont sweat it, you are not going to lose much unless of course they get covered by a couple feet or so then perhaps you'll want to sweep them off if you can.

How do I decide between Flat plate and Evacuated tube?

This will be a debate well in to the future. For an more in-depth review please watch this Click here to watch this 1/2 hour webinar. Your decision should be based primarily on the following considerations:
  • 1- Temperature demand- What is you existing application? EVT's will outperform FP's at higher temp load.
  • 2- Climate location- In a general sense, flat plates have more value than evacuated tubes in warmer climates and EVT's will do better in cold, cloudy climates.
  • 3-Aesthetics appeal- This is where there is no "right" answer. Instead, each person has their own personal view. We recommend that you go with it. If they prefer flat plates for that reason then you install flat plates and if they prefer evacuated tubes for their aesthetic appeal, then by all means, you should install Evacuated tubes.
The point is, you really CANT GO WRONG. Each type will yield significant value and in the end, the differences will be negligible.