Solar power

The most common types of thermal solar power

1. The most uncomplicated type of solar panel is the swimming pool solar panel, often manufactured in black plastic or rubber. Without insulation or glass panel over the solar panel this gives a very limited thermal power but it can function relatively well for a pool given the low temperatures in the pool.

2. Another model is the flat model. It has typically got an insulated underside over which there is an absorbing surface covered by glass. This model is still very common and much more efficient than the swimming pool solar panel. Some of the very best flat solar panels can almost compare with the vacuum solar panel when it comes to the total energy produced per year in terms of kWh/m². The flat model can produce more energy during the summer than the vacuum tube type but considerably less during cold half of the year.

3. The vacuum tube solar panel is the most sophisticated type. It consists of vacuum tubes assembled to modules. The vacuum tube solar panel is characterised by its high power and small heat losses. The vacuum tube solar panel is sometimes referred to high-temperature solar panels. The vacuum layer creates a “thermos bottle”. Just like a thermos bottle works well both of the beach and in the ski slope the thermal solar panel.

The two main types of vacuum tubes are:

A) Full vacuum tube with a total vacuum inside a glass tube/vacuum tube with only one layer of glass. With this type of vacuum tube it is unavoidable that the glass tube needs to be sealed against the metal at the top of the tube in order to enclose the vacuum where the tube is passing from the inside of the vacuum tube to the collecting tube. This is a significant problem since the glass and the metal moves differently when heated causing loss of vacuum. Another disadvantage with this type is that the absorbing unit is usually flat making it less effective when the sun hits it from an angle.

B) The thermos type consists of one inner and one outer glass tube seals together in the bottom and at the top. This gives a seamless enclosure of the vacuum layer, in principal like a traditional thermos bottle. This construction makes it possible to keep the vacuum intact over time. This type has furthermore a round absorbing surface (360°) making it very effective when the sun is coming from the side.

The two types of interior configuration in the vacuum tube are:

A) The U-tube type. A tube goes down and turns up in an absorbing sheet normally made of aluminium. With this model it is more difficult to change a faulty vacuum tube. Sometimes the glycol mix has to be emptied from the system. Another disadvantage is a significant pressure fall when the liquid shall pass through all narrow tubes. There is a risk that the circulation will not reach all tubes if an air pocket/bubble appears in one of the tubes in the module. More connection points in the collecting tube gives a higher risk for leakage.

B) Heat Pipe, a copper tube surrounded by heat-conducting flanges usually made of aluminium. The heat pipe contains a small amount of liquid which is evaporated when heated. The gas rises up to the heat exchanging top of the heat pipe where it is heat exchanged to a glycol mix that is transported down to the heating storage, most of the time in the former buffer tank. When the heat exchange occurs in the collecting tube of the solar panel the gas is condensed to liquid form runs down and starts the same process all over again. This is the same principal function as a heat pump but in the heat pump this process is achieved through a compressor while it is achieved by the sun in the case of the vacuum tube. Even a day with overcast skies Intelli-heat can produce more or less heating depending on how thick the clouds are. The main part of the UV-radiation is blocked by the clouds but the bulk of the IR-radiation can pass and is received in the vacuum tube. The Heat Pipe has a so called “dry-connection” (heat transfer). This makes it very easy to replace faulty tube without turning off or emptying the solar panel. This is one of the advantages with this type. Intelli-heat vacuum tubes consist of the “thermos bottle” type and the interior configuration is of the heat pump type.

Intelli-heat

We focus on some main factors: High efficiency (best in the market as mentioned by the official Swedish test institute), quality and reliable system solutions. We are actively working with product development and lead the development of system solutions for different combinations with thermal solar panels. Since we are buying big volumes of components and have good agreements with manufacturers and logistic partners we can offer competitive prices that our clients can benefit from. Our ambition is to make good technology available for eve¬ryone. Installation of solar energy in Europe hit a record level last year and is expected to increase