What are
Solar Collectors?

• What are the types of solar collectors?


• What is the right size?


• What is the expected cost?

You need to buy a collector either when you buy a complete solar water heater system or when you need to replace a faulty one that you bought a long time ago.

What are Solar Hot Water Collectors?

The collector converts sun radiation to heat, using the “greenhouse effect”
Sun radiation in the visible range (what we humans see as colors and the blend of colors called white) penetrates through a transparent material (usually glass) and hits black absorbing material. The absorbing material radiates back heat waves in the infrared wavelength (what we humans sense as heat. Some animals like certain snakes have a specific sensing organ for infrared – very good for them as night hunters but bad luck for the pray)
Now comes the trick because glass is opaque to infrared.
In essence, we created a trap that converted light waves to heat
Next step – the heat is transferred to fluid, either water in mild areas or anti freeze liquid (like glycol) in areas where temperatures might drop bellow freezing point (32 degrees).

Bellow is a picture of a vacuum tube solar collector

The Two Types of Collectors

The one seen mostly has a planar construction. This type is usually called flat plate collector.

The evacuated tube collector is the one seen less, typical to the northern regions where sun radiation is not so abundant. It consists of circular shaped tubes

Cost and life expectancy of Solar Collectors

Flat plate collectors can cost around 700-900$ for 20 square feet size and 1100-1300$ for 40 square feet size (shipping cost and installation cost not included)

Evacuated tube can run way above 2000$. I saw lower prices from new comers. However, I usually recommend to go on a mature product line.

Federal energy tax credits as well as state level (in some of the states) are available

The life expectancy of collectors is long and 10 years is not unusuall. For open systems the maintenance is low, for closed system you might need to add glycol (same as in a car cooling liquid)