This page considers the merits of the two most common types of solar collectors: flat plate and evacuated tube. At Creative Solar, we believe that each has its place for either domestic or commercial use depending on the application.
But...
...there is a very important caveat that affects ALL installations: that being the quality and efficiency of the total system.
There is much more to a system than just the collectors!
Any of the following will and often does affect the performance of a system (performance resulting in the amount of heat actually available for transfer to the utility)
♦ Distance from the collectors to the utility location ♦ Insulation quality of the line set travelling between the collectors and heat exchanger ♦ Inside or outside location of the line set ♦ Sizing: enough collector area to meet user demand, but not oversized ♦ Correct or best orientation and angle of the collectors ♦ Size and efficiency of the storage tank(s) ♦ Effectiveness of the heat transfer system (internal vs external heat exchangers) ♦ Best pump(s) and controls to deal with fluid volumes and heat loads
If there are miscalculations or issues with any of these factors, the install may not perform as intended, regardless of the type of collector.
FLAT PLATE COLLECTOR: Can be mounted in portrait or landscape depending on the space available and the manufacturer.
EVACUATED TUBE COLLECTOR: Most often seen in multiples of 20, although 10, 15, and 30 are also available.
COLLECTORS COMPARED
With both evacutated tube and flat plate collectors readily available, considerable verbage is being generated as to which system has an advantage for any given installation. The truth is, they both work well and they both capture solar energy for many years - in fact, most systems today are expected to last 20 years as a minimum and are likely going to last up 30 yrs or more with a maintenance program.
At Creative Solar, we will recommend either type of collector, from selected, quality manufacturers, depending on the installation and application.
Check out some of the differences below - all of which are well documented. Get in touch with us if you have specific questions or comments about these systems and we'll do our best to help you along, ...and, welcome to the discussion!
FLAT PLATE
♦ Less expensive = lower cost BTU/$ ♦ Robust construction: aluminum frames, tempered glass ♦ Flush mount will often be less noticeable ♦ Some heat loss through glass surface ♦ Proven, long term reliability (since at least 1890) ♦ Snow will accumulate on low slope installs (heat loss will influence melting) ♦ Lower performance on cloudy days ♦ Performance ratings decline on coldest days ♦ Better suited to design integration with most buildings ♦ Space requirements will dictate placement options
EVACUATED TUBE
♦ Well suited to multiple heat demands (in-floor & DHW combined) ♦ Easier to install w/lighweight components ♦ Wind load about 25% that of flat plate ♦ Require more care in handling and assembly ♦ Appearance may influence placement location ♦ Zero heat loss thru vacuum tubes ♦ Will operate at higher efficiency at very low temperatures ♦ ~ 10% more expensive than flat plate, but price dropping ♦ Tubes have been known to fail but easy to replace ♦ Higher output temps require greater care w/installation ♦ Take up less space and can be installed in 'difficult' locations
FURTHER READING
This article from Home Power magazine goes into considerable detail as to the merits and considerations when evaluating flat plate and evacuated tube collectors.
TUBE SYSTEM - FOUR PERSON HOUSEHOLD (Rear of Home)
This system, installed in a Dartmouth, NS, home, was still producing heat after this picture was taken at 4:30 pm in late January. At that time the 'smart', Apricus controller had slowed the system's pump to allow for maximum heat capture which continued until 4:45 on this SW roof face.
Apricus, 40 Tube System
Creative Solar 63 McQuade Lake Crescent, Halifax, Nova Scotia B3S 1C4 Tel. 902-446-8161, Fax. 902-455-1522 E. info@creativesolar.ca
