There are two popular kinds of solar collectors: Flat-Plate Collectors These are shallow rectangular boxes (typically 4 x 8) with tempered glass tops and insulated backs and sides. an absorber plate inside gathers solar heat and transfers it to a network of copper tubing through which the solar fluid flows. These work well in all climates have been used thelongest are efficient and competitively priced Shed snow and frost well Are very durable, but need secure mounting against high winds. |
Evacuated-tube collectors These are glass tubes (3 to 4 inches in diameter, 4-6 ft long) with a vacuum inside that avoids some heat loss. An absorber plate inside the tube gathers heat and transfers it to the solar fluid that runs across the top of the collector. These can be fragile because the glass is untempered. They can lose their vacuum over time Need a generously sized storage tank to avoid overheating. Work best when there's a consistent, year-round, daily load Are safer for windy areas because of spaces between the tubes in a collector. |
Integral Collector Storage Hot and Seasonal Climates Pros Proven design Low maintenance High efficiency Collectors mounted on roof or ground. Simplicity
Cons Collectors also store the water so they're very heavy Use only where freezing never occurs Loses heat because storage is outside | Presurized Closed-Loop Antifreeze Cold to hot climates
Proven design Low Maintenance High efficiency Usable in any climate, including extreme cold Most versatile collector mounting options No limit to pipe runs or piping configuration Can be sed for space heating
Antifreeze solution degrades when system is idle for extended periods Antifreeze must be replaced every 10 - 20 years.
| Drainback Moderate to hot climates
proven design Low Maintenance High efficiency Freeze protection in nearly all conditions Fluid drains when idle preventing degradation of solar fluid if antifreeze is used Can be used for space heating
Collectors must be mounted above drainback tank Installation requires care to ensure quick complete drainage Vulnerable to freezing in extreme cold
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