The panels used by KW Solar are vacuum tube solar panels of the newest generation with Heat Pipe.

How does this work, which other solar panel types are on the market and why did we decide for this type of solar panel?

Today on the market we can find two different types of solar collectors. The flat collector (which looks like a black window or a flat plate) and the vacuum tube collector (the one with the tubes).

A flat-plate collector basically consists of an insulated box, covered with a glass and a dark-coloured absorber plate connected to the tubes, where the solar fluid passes through. Solar radiation is absorbed by the absorber plate and transferred to the fluid.

The vacuum tube collector consists of parallel rows of glass tubes connected to a header pipe. Each tube has the air removed from it to eliminate heat loss through convection and radiation. These collectors fall into two main groups:

• Direct-flow vacuum tube collectors, where the solar fluid passes directly through a pipe inside the glass vacuum tube.
• Vacuum tube collectors with heat pipe technology, where a so called heat pipe is mounted inside the vacuum tube and transfers the heat from the glass tube to the solar fluid in the absorber, mounted on top of the tubes.

The solar "experts" around the world are divided with their opinions about which type of collector is better. The flat collector was commonly used in Europe in the past. It is less expensive but especially in the wintertime it is less efficient as well (because it reflects more of the radiation and its insulation is not very good and it looses a lot of heat.).

The vacuum tube collector is getting used more and more in the last years due its very high efficiency when it is cold or windy outside. It is a more expensive system, but due to the vacuum tubes (the vacuum is an almost perfect isolation) its efficiency in the winter times is much better than the efficiency of the flat collectors.

In summer there is not much difference between both types of collectors. So if you want to use the house principally in summer, the flat collectors are a good alternative, because they are cheaper. If you are using the installation all year long, we would recommend vacuum tube collectors.
We normally use vacuum tube collectors with heat pipe technology. This type of collectors are very efficient and easy to install. They have no maintenance and as the connection between the heat pipe and the absorber is "dry", the individual tubes can be exchanged without emptying the entire system of its fluid.