Now of coarse we understand that every company tries to sell their product as “the best”,
but lets analyse the both collectors so you can come up with your educated judgement.
The Flat panel collector
As you can see above, fluid enters the copper pipe, from which the pipe is bonded to an absorber.
This absorber plate/copper pipe is put inside an aluminium frame with fibre-glass insulation backing and hardened glass top.
The sun heats up the absorber plate and transfer’s the heat to the copper pipe which in turn heats the water.
This design works well in hotter climates as ambient temperature will affect how hot the copper pipe will get.
In reverse condition, if it can go to near zero degree’s at night time, the water can freeze, expand and split the piping.
In a hot, sunny climates these collectors can work nearly as well as evacuated tube collectors, though over time
they loose their efficiency with calcification in the piping and lime scale build up in the inside of the glass panel,
which in-turn restricts the amount on sunlight that passes through the glass and onto the absorber plate.
Simple as that!
The evacuated tube collector
1. Inner glass tube
2. Selective absorbing coating
3. Vacuum gap
4. Outer glass tube
5. Supporting component
6. Gas absorbent
7. Absorbing film
There are two glass tubes, ours have a 47mm outer tube and 35mm inner tube. These glass tubes are bonded
together and sealed with a vacuum between them.
On the outside of the inner tube, there are special selective coatings, ours have a coating of copper, stainless steel and the aluminium nitrate with a final anti-glare coating.
Inside the inner tube is a copper heat pipe surrounded by an aluminium shim that conducts as shown in the top picture.
The sunlight goes into the glass tube, the heat is trapped inside the vacuum. Because the heat is inside a vaccum, the easiest way for the heat to escape is through the selective coatings, onto the aluminium shim, transferred to the copper heat pipe which heats up a manifold and then in-turn heats the water in the manifold.
(For more information refer to “How does our collector work?”)
This is an infa-red heat sensing picture, with a flat panel collector on the left and an evacuated tube on the right.
Heat / energy has to go somewhere!..... on the flat panel collector there is a lot of heat reflecting back to the atmosphere, where as in the evacuated tube collector the majority of the collected heat is transferred to the water, thus the evacuated tube collector being 50% more efficient!
Flat panel vs evacuated tube...... with the facts of how they are made, now you can decide what you would like on your home!