WO2008067808A2

WO2008067808A2 - Electrothermal solar module

Info

Publication number: WO2008067808A2
Application number: PCT/DE2007/002217
Authority: WO
Inventors: Hans Joachim Stengert
Original assignee: Aton Aktiengesellschaft
Priority date: 2006-12-08
Filing date: 2007-12-10
Publication date: 2008-06-12
Also published as: DE112007003327A5; DE202006018592U1; WO2008067808A9; WO2008067808A3

Abstract

The invention relates to an electrothermal solar module consisting of a base plate, photovoltaic elements being arranged on the side of the base plate facing the sun and a frame being attached to the edge of the base plate. The frame is a U-shaped profiled element which is covered with a transparent plate, the open side of said profiled element facing the sun. At least one hollow profiled element through which a liquid flows extends through the inner part of the frame.

Description

Electrothermal solar module

The invention relates to an electrothermal solar module, consisting of a base plate, on the sun-facing side te photovoltaic elements are arranged and at the edge of a

Frame is attached.

The use of solar energy has a centuries-old tradition. According to the current state of the art, there are numerous methods for the direct production of thermal energy, solar thermal energy, and for the generation of electrical energy, the photovoltaic. For the solar thermal energy conversion, it is common in the Mediterranean countries to arrange a dark-painted water tank on the house roof, which heats the hot water in the noon hours close to the boiling point. A principal disadvantage of this arrangement is that of the collected radiation energy of the sun a very large part is lost by radiated heat again.

Therefore, it has become customary to surround a liquid-carrying hollow body with a thermally insulating housing, which consists of the sun side of a translucent material. Used are plates made of glass or plastic, which leave most of the short-wave sun rays through, which then heat the fluid-carrying hollow body in the interior of the housing. With increasing temperature, it radiates a portion of the previously recorded energy again as long-wave heat radiation, which is only partially transmitted through the transparent cover, which is why the principle of operation of the solar collector is often referred to as "heat trap" or "greenhouse effect". So that as little heat as possible is lost through the remaining walls of the housing, it is advisable to insulate them, for which in the simplest case insulating material is used which has numerous air inclusions up to insulating layers which are a vacuum.

With solar collectors efficiencies of 60% to 75% can be achieved. Their disadvantage is that the energy is available only in the form of a heated liquid. When transporting further, thermally insulating lines are therefore required as well as possible, which should be as short as possible in order to ensure that they are of no significant value on the transport route

To suffer energy losses.

It follows that the solar collector must be arranged as close as possible to the consumer and the energy should primarily be used unchanged in the same form, so preferably to be used for heating domestic hot water and for heating indoor spaces. Suitable energy converters are heat exchangers in which the liquid flows out of the solar collector through a coil which is arranged in a large storage tank for hot water and heats it in this way. Even easier are flowed through by the liquid radiator for heating of interiors.

According to the current state of the art, large, thermally insulated water reservoirs in or beneath buildings are commonplace for storing heat energy that is not currently required, which are so well insulated that they do not cool down too much for months.

Thanks to the high efficiencies of 60 - 75%, the use of solar thermal energy by solar collectors is always very efficient. if the energy gained can be used directly as thermal energy.

For conversion to other forms of energy, such. B. mechanical see or even electrical energy, although there are numerous methods that require such a high cost that, especially for very small investments, the cost of the investment in a disproportion to the consumption costs are.

For the conversion of solar energy into electrical energy, therefore, photovoltaics is an economically viable alternative. In plates of semiconducting material - z. For example, silicon - incident photons generate electrons and "holes" that are separated in the electric field of the space charge zone of the P-n junction When the two electrodes of such a solar cell via an electrical

The electrons flow back into the "holes", a direct current has formed and, according to the current state of the art, a direct current can generate an alternating current via an "inverter" which can be fed into the electrical supply network and in this way can be easily transported to distant points of consumption.

A principal advantage of electrical energy is that it can be transported with great efficiency over long distances and processed with equally high efficiency. One disadvantage is that it can only be stored directly with great effort. However, since numerous devices of daily life are electrically constructed, the supply of electrical energy is one of the basic needs of everyday life. From the above consideration it follows that both thermal energy and electrical energy is needed at the same time, for. For example, for the supply of residential and working buildings and that for their extraction from solar energy currently also different, efficient processes are known. A major disadvantage of all previously known energy converters, however, is that they generate either electrical or thermal energy.

Against this background, the invention has set itself the task of developing a solar module that emits both thermal and electrical energy and works with the highest possible efficiency, but is still very simple and can rely on existing and proven components. Parts of the solar module should be usable for photovoltaic as well as for solar thermal energy.

As a solution, the invention proposes an electrothermal solar module, in which the frame is a U-shaped profile, the open side facing the sun and which is covered with a translucent transparenzenzplatte and through the interior of which at least one hollow profile extends, which of a liquid can be flowed through.

The photovoltaic part of a solar module according to the invention consists of standard solar cells produced on the

Base plate are applied flat. Such an arrangement has been known in principle since the 1950s and is produced and applied on a large scale in the current state of the art. Solar cell modules based on this principle are predominantly mounted on rooftops, where they can withstand the stresses caused by

Storm, rain and snow load must defy. That's a solid one Frame common, which includes the plate with the solar cells, their attachment to rooftops or other structures allows to produce sufficient mechanical stability that absorbs the forces of storm and snow load and dissipates into the roof.

It is the core idea of this invention to use such a structure additionally for solar thermal energy generation. In the first approach, the frame required for the mechanical stability of the photovoltaic structure is anyway used, by designing the frame as a sun-open, U-shaped profile whose open side is covered by a transparent transparency plate. In the resulting interior at least one hollow profile, which is flowed through by a liquid runs.

This structure corresponds to the current state of the art for solar collectors: The short-wave radiation of the sun penetrates the transparency plate and heats the hollow profile with the liquid contained therein. As a result of the heating, the hollow profile radiates heat which, however, due to its long waves, is for the most part prevented by the transparency plate from escaping out of the interior again. A thermal insulation of the remaining walls improves the efficiency.

For the improvement of the other properties of this flat collector, which is integrated in the solar module, various variants are proposed. The liquid-flow hollow profile is in the simplest case a tube or a hose. To increase its surface, rib profiles on the outer surface are advantageous. In a further improvement stage, flow channels are formed in the inner wall, which enlarge the effective inner surface. Of the The next step in a meaningful improvement is to make the flow channels spiral, so that the liquid gets a twist, which forms turbulence, which significantly improves the heat transfer.

Since the heat transfer between donor and receiving body is better, the greater the temperature difference, it is proposed to connect the hollow profiles in the U-shaped profile so that the liquid flows in opposite directions, whereby a relatively cool hollow profile always a relatively cool, further

Hollow profile is adjacent. The less heated liquid is heated with very good efficiency, surplus thermal energy from the adjacent, already strongly heated hollow profile can be delivered to the cooler hollow profile, whereby overheating is avoided and an approximately uniform temperature level is achieved along the frame.

Further variants of the electrothermal solar module according to the invention result from the fact that the efficiency of the photovoltaic elements on the base plate in accordance with the current state of the art

Technology is below 20%, so 80% of the incidental solar energy remains unused according to the current state of technology. This effect manifests itself in the fact that the base plate on which the photovoltaic elements are attached is heated.

To use this heat, the invention proposes various embodiments. In the simplest option, the contact surface between the frame and base plate is dimensioned larger than is necessary for purely mechanical fastening of the base plate and the discharge of the loads. As a result, the area for forwarding the thermal energy from the base plate into the frame is removed. greater! To improve the heat transfer, the contact surface can be acted upon with a thermal paste, so that forms a perfect, thermal transition even when not completely touching contact surface and base plate. This configuration makes sense if the temperature of the base plate is higher than the temperature of the frame.

Another interesting option is to provide the baseplate with additional piping through which the liquid flows. It is possible to form these pipelines within the base plate or to apply them on an outer surface. Since the sun-facing side should be reasonably reserved for the photovoltaic elements, the invention prefers the attachment of these additional pipes on the back. Welding, gluing, soldering, clamping or grooving are suggested for the connection between piping and base plate. Other, thermally well conductive compounds are also suitable.

At the current level of energy prices, it has proven to be economically viable to make the effective surface area of the photovoltaic elements about as large as the effective surface area of the solar collectors for thermal energy.

In the following, further details and features of the invention will be explained in more detail by way of examples. However, these are not intended to limit the invention, but only to explain.

It shows in a schematic representation: Figure 1 electrothermal solar module, with a broken corner shown

Figure 2 Cross-section through the frame and the base plate The figures show in detail:

In Figure 1, a solar module is drawn, which consists of numerous, juxtaposed photovoltaic elements 2, which are mounted on the base plate 1. At the edge of this base plate is circumferentially fixed to the frame 3, which z. B. on the outside integrally formed fastening eyes 32 for screwing the complete solar module on the roof. In the corner of the solar module shown cut, it can be seen that the frame 3 is a U-shaped profile whose open side is covered by the transparency plate 4. In the interior of this profile run in the drawing two hollow sections. 5

In Figure 1, the additional embodiment is shown with pipes 7 on the back of the base plate 1. The pipes 7, like the hollow profiles 5, are flowed through by a liquid which serves to remove the solar thermal energy.

FIG. 2 shows the cross section through the frame profile and the base plate 1 fastened thereto. The profile of the frame 3 has on its outer side fastening eyes 32, by means of which the solar module can be attached, for. B. can be screwed onto a roof surface. On the opposite side of the frame, the contact surface 31 can be seen on softer the base plate 1 rests and z. B. is secured by a screw. In Figure 2 it can be seen that the profile of the frame 3 is designed approximately U-shaped and is closed at the top by the transparency plate 4. This creates a closed interior, in which run in this example, two hollow sections 5. These hollow profiles have on their outer side the rib profile 51 in order to increase the effective surface and thereby improve the heat transfer. In its interior, the flow channels 52 are formed in the inner wall. If these flow channels 52 are spirally wound around the longitudinal axis of the hollow profile, a spin arises in the liquid 6, which leads to turbulences, which mix the liquid 6, so that all particles of the liquid come into direct contact with the wall of the hollow profile 5 and to be heated better.

In Figure 2 is not shown that the liquid 6 in the one

Hollow section 5 should have a direction opposite to the adjacent hollow profile 5 flow direction.

It can clearly be seen, however, that the base plate 1 rests on the contact surface 31 of the frame 3. It is well understood in Figure 2 that thermal paste between these two elements noticeably improves the heat transfer.

As a further embodiment, a pipe 7 is shown in Figure 2, which rests on the underside of the base plate 1 and is held there with the clamp 71. The pipeline 71 has such a profile that it contacts the base plate 1 over the entire area with a large proportion of its outer surface, so that a good heat transfer between the base plate 1 and the pipeline 7 is ensured. In Figure 2 it is understood that a thermally even better connection is achieved by the integration of the pipe 7 directly into the material of the base plate 1.

LIST OF REFERENCE NUMBERS

1 base plate, carries photovoltaic elements 2

2 photovoltaic elements, on base plate 2 3 frames, made of U-profile, supports base plate 1

31 contact surface of the frame 3 to the base plate. 1

32 fixing eyes on the frame 3

4 transparency plate covers frame 3 upwards

5 Hollow section, through which liquid flows, in frame 3 on the inside

51 Rib profile on the outside of hollow profile 5

52 flow channel on the inner wall of hollow section 5

6 liquid flows in the hollow section 5 and pipe 7

7 Pipeline, under or in base plate 1 71 clamps, for fixing the pipe 7 under the base plate 1

Claims

claims

1. electrothermal solar module consisting of a base plate 1, on the sun-facing side of photovoltaic elements 2 are arranged and at the edge of a frame 3 is fixed, characterized in that the frame 3 is a U-shaped profile

- The open side facing the sun and - that is covered with a translucent transparency plate 4

- And through the interior of which at least one hollow profile 5 extends, which is traversed by a liquid 6.

2. Electrothermal solar module according to claim 1, characterized in that the hollow profile 5 has a rib profile 51 on the outside.

3. Electrothermal solar module according to one of the preceding claims, characterized in that 5 flow channels 52 are formed in the inner wall of the hollow profile.

4. An electrothermal solar module according to claim 3, characterized in that the intricate flow channels 52 spirally wound around the longitudinal axis of the hollow section 5.

5. An electrothermal solar module according to one of the preceding claims, characterized in that the frame 3 contains at least two hollow profiles 5, which are in opposite directions of the liquid 6 can flow.

6. An electrothermal solar module according to any one of the preceding claims, characterized in that the contact surface 31 between the frame 3 and the base plate 1 is dimensioned larger than it for purely mechanical attachment of

Base plate 1 and the discharge of the loads is required.

7. An electrothermal solar module according to one of the preceding claims, characterized in that the contact surface 31 between the frame 3 and the base plate 1 is acted upon by a thermal paste.

8. An electrothermal solar module according to one of the preceding claims, characterized in that the base plate 1 is provided with additional, can be traversed by the liquid 6 pipes 7.

9. An electrothermal solar module according to claim 8, characterized in that the pipes 7 are applied on the side facing away from the sun.

10. An electrothermal solar module according to claim 9, characterized in that the pipes 7 through

- welding and / or

- gluing and / or - soldering and / or

- Terminals 71 and / or

- Pressing in grooves or

- Are connected in another thermally conductive manner with the base plate.

11. An electrothermal solar module according to one of the preceding claims, characterized in that about the same, effective surface portion by photovoltaic and solar thermal energy is available.