DE3744829C2 - Solar plant with plane surface absorbers or solar cells - Google Patents

Abstract

The absorber surfaces and/or solar cells are arranged rigidly on the roof of a building or on supporting elements (14), whilst the mirror surfaces are fixed in a plane running inclined to the absorber plane stretching northwards or southwards, and the mirror surfaces free of shadows extending out sideways over the absorber surfaces.The mirror surfaces, with their associated supporting elements arranged on one of the planes extending to the north or south, are subdivided into at least two plane mirror surfaces (17a,17b, 17c,17d), the inclination of which (gamma 1-4) increases with larger distance from the absorber (2) w.r.t. the horizontal. A distance (d) is set between at least two of the mirror surfaces (17c,17d), into which a spacer (27) is fitted

Description

The invention relates to a solar system according to the Oberbe handle of claim 1.

It is known to design the mirrors as flat surfaces tracking the and the sun in two axes. This results in but a lot of effort and a considerable Ver susceptibility to wear and malfunction. In one embodiment you also have several elongated ones at an angle to the horizon talen lying mirrors below a fuel pipe at a distance arranged to each other. This distance results in the disadvantage that a mutual influence of the one individual flat mirror surfaces is not possible. Furthermore the fuel tube casts shadows on the mirrors, so that these are not effective in this regard (DE-OS 27 39 254).

In another solar system, the mirrors are on the side away from the sun at a distance from the absorber arranged so that the reflection radiation to the greatest part from the north. For this is the floor area needs greatly enlarged because the distance between the Ab sorber and the mirror surface about a third of the absorbers width should be. At midday this caused the absorber cast strong shadows on the mirror surfaces north of the absorber, so that they cannot be used in this respect. In one trap is an angling the east and west extending mirrors provided by the sun thrown onto the collector in the morning and evening should. If the bend is omitted, will decrease the total amount of solar energy that can be collected (DE-OS 25 57 843).  

In addition, there is a salt heat storage with rigid spie are known that one end wall in the east and one in the west has, which can consist of transparent mirror film. These is however very complex and has to go through numerous ver fortifications are held in place, the shadows throw on the surface to be heated (US 43 26 498). Finally, there is also a pivoting solar system flat mirror surfaces only on the south edge of the Ab known sorber. The pivotability is not used here Sun tracking, but at night the mirror pivoted over the absorber surface to protect it from rain, Protect snow, hail, etc. This plant shows how Many others have the disadvantage that the mirrors are early in the morning and are not effective late at night because the mirror surfaces only have the width of the absorber surfaces (JP-OS 58/2 13 158).

By the not previously published deut cal patent (DE-PS 36 00 881) already solves the problem Solar system with mirror and absorber surfaces and / or Equip solar cells where not only those directly on solar radiation is used, but also the early morning and late evening sun rays, without any sun tracking of the mirrors or the absorber surfaces must be provided.

This is achieved in that the mirror surfaces are with regard to the absorbers, shading-free laterally expand the absorber surfaces. In this way gets extra sun especially in the morning and evening radiation used without the effect of the mirror at noon or at other times by some kind of shading  is hindered. Furthermore, the floor space requirement or other space requirements thereby only increase insignificantly eats.

They were facing north and south mirrors arranged in a single plane.

Here was particularly the south-facing mirror area in its effective size by the following Circumstances limited:

The angle to the horizontal should be as small as possible, hence the low solar radiation on the absorbers can be directed. But you come across the Size of the mirrors soon to a limit. The bigger the game gel, the greater the angle must be be horizontal to most of the radiation still reflect on the absorber.

The invention has for its object one with mirrors as well as absorber surfaces and / or solar cells equipped Sun. Lar system for which no sun tracking of the mirrors or the absorber surfaces is provided, thereby in their lei Stability to improve that the same size of Absorber or solar cell module surface for the mirrors unchanged space is used more effectively.

To solve this problem, the characteristic features of claim 1 provided. This is the total radiation directed more towards the absorbers than before, and also some additional concentration through interaction the mirror enters.

In this way, there is the surprising effect that the mirror surfaces can be enlarged as desired that correspondingly high temperatures with little effort can be achieved relatively quickly.

Further advantages and details of the invention result itself from the following description of some execution examples with reference to the drawing. In this shows

Figure 1 is a schematic side view of a first embodiment.

Fig. 2 is a view like Figure 1 with another embodiment.

Fig. 3 is a view like Figure 1 on a further embodiment.

Fig. 4 is a side view as before, but on a larger system and

Fig. 5 is a schematic side view of a further embodiment.

Fig. 1 shows on the right an absorber 2 , which is arranged by the floor support 14 and the floor bar 13 in a known manner on a flat roof or the floor 28 at an inclination angle α to the floor 28 , which in this case is 45 °.

This need not be explained in more detail because it is well known to the expert. The absorber 2 can be known to be integrated into a memory which is provided with transparent thermal insulation materials, as is just known.

Right is north and left is south. To the south, the absorber 2 is followed by the mirror surface 17 a, the inclination of which towards the bottom 28 is zero. The mirror surface 17 a is thus together with its associated support element on the floor 28 or the flat roof.

At the mirror surface 17 a connects to the left to the south, the mirror surface 17 b, which is here ge according to the invention. Therefore, the associated support element is supported by the supports 18 at the south end.

The bend of the mirror surface 17 b is smaller in the vicinity of the absorber 2 or solar cell module and becomes larger with increasing distance from the absorber.

Especially when metal or plastic surfaces are provided as a support for the mirror surfaces the effort is relatively low, these support elements to shape accordingly with the mirror surfaces. This is especially the case when it comes to ent talking of large numbers.

The gradual transition will of course also a slightly stronger concentration compared to levels Mirror surfaces reached.

As a result of this design, in the case of FIG. 1, a construction line 26 of 10 ° is shown in broken lines.

This means that every sun coming from exactly south radiation that is higher than 10 ° through the mirror surfaces is also thrown onto the absorber.

Some different radiation levels acting on the mirrors are now shown. The solar radiation arriving directly at the absorber 2 is not shown for the sake of clarity.

First you see the 25 ° beam on the left, which arrives at the central point 25 a of the mirror surface 17 b and from there is reflected on the point 7 of the mirror surface 17 a. From there it is reflected on the absorber 2 .

As a result of the different inclinations, the low sun rays are not reflected directly from the mirror surfaces 17 b, but are only reflected by them onto the mirror surfaces 17 a and only then from there onto the absorber 2 .

It is different with the higher sun rays. The 35 ° beam also arrives at point 25 a and is reflected directly from there onto the absorber 2 . It is the same with the even higher sun rays 1 (40 °, 45 °, 55 °, 60 °). The 60 ° beam is also largely reflected on the absorber 2 .

In addition, these higher sun rays also reach the mirror surface 17 a directly and are directed from there to the absorber 2 .

As can be seen in FIG. 1, these beams intersect at different points, so that this results in an amplification which, with only a single continuous plane mirror surface, would not occur without the subdivision with the different inclinations.

In addition, there is the advantage that the mirror surfaces 17 a and 17 b of the two mirrors taken together can be larger than in the case of a uniform mirror, because this would largely deflect the high solar radiation upwards to a much greater extent.

In the present case, this is only the case with respect to one mirror surface 17 a. The other mirror surface 17 b also directs the high solar radiation up to 60 ° for the most part onto the absorber 2 .

There is also the possibility of attaching additional mirrors to the upper north edge and also providing the subdivision of the mirror surface with different angles as in FIG. 1. Of course, the effort here is much greater than that on the south side, because the elevation on the north side is more complex.

However, this is a question of the space available. On many flat roofs, as with the outdoor facilities, there is enough space to the south, so that the facility according to FIG. 1 will certainly be preferred.

Fig. 2 shows an angle of inclination α of the absorber 2 of 60 °, as is favorable in winter and in the transition periods. At the absorber 2 below three mirror surfaces 17 a, 17 b, 17 c join, again the mirror surfaces 17 a, 17 b, 17 c are bent, the increasing angle of inclination γ ₁, γ ₂ between them and a horizontal floor , γ ₃ and γ ₄ have. This can again be a flat roof or a horizontal outdoor installation.

As a result, the building line 26 is again in the range of only 10 ° for the reason mentioned above.

A fourth inclined mirror surface 17 d is arranged at a distance d. As a result of the distance d, which is ensured by a spacer 27 , this mirror 17 d also remains within the aforementioned construction lines 26 of only 10 °. The support elements for the mirror surfaces mentioned, which are not shown here in detail, are still supported by the supports 18 a, 18 b, 18 c, 18 d and 18 e.

Similar to before, some sun rays with different heights are drawn here again. They hit the center 25, 25 a, 25 b and 25 c of the mirror surfaces 17 a, 17 b, 17 c and 17 d and are reflected from there, as shown, onto the absorber surface 2 .

Even the 55 ° radiation that strikes the mirror surface 17 d still reaches the upper part of the surface of the absorber 2 . The 30 ° radiation that hits the same point 25 c also largely reaches absorber 2 . However, there is a slight shading from the mirror surface 17 c. This could be greatly reduced by increasing the distance d and at the same time also increasing the bend somewhat. Using a computer calculation, it is possible to optimize the distance d and the bend depending on the local irradiation conditions so that there is almost no mutual shadowing by the other mirror surfaces. Of course, this also includes the size of the mirror surface 17 d. The smaller this is chosen, the lower the risk of shading from the mirror surface 17 c. In the meantime, a certain amount of shading can be accepted if the high solar radiation can thereby be used to a considerable extent, as is the case according to FIG. 2.

This makes it practically possible to arrange any number of additional mirror surfaces 17 in the manner according to the invention, whereby a very high concentration with correspondingly high temperatures can be achieved if sufficient floor space is available. Under these circumstances, the arrangement of the northern mirror surfaces can be completely dispensed with for the reason mentioned.

The invention now offers the possibility of using the same collectors economically much higher tem to generate temperatures in a much shorter time. Thereby you can keep the absorber area much smaller than so far.  

This also applies to the use with solar cell modules. As a result of the higher temperatures, the effect decreases is known to decrease somewhat. Recently there however, solar cell modules sprinkled with water constant cooling, where this disadvantage is not a should occur, so that the advantage mentioned by the Invention also fully affects here.

It is the very large cost difference is crucial between the absorber surfaces or solar cell modules on the one hand and the mirror surfaces on the other hand, which are given at least 10: 1 can.

For example, the collector field on the sloping roof of a building or in this roof can be integrated in a known manner so that the mirror surfaces 17 are arranged on an adjacent flat roof. This means that the roof and the roof structure of a building are designed in this way. In this case too, the mirror surfaces 17 can form the roof skin itself. As is known, there are mirror tiles for this, which can be installed rain tight on the roof. But there are also plastic mirror plates or a reflective roof skin.

For this purpose, it was already shown in Fig. 1 that the mirror gel area 17 a is arranged on the horizontal flat roof. In deviation from this, the roof can also be slightly inclined from south to north, for example at an angle of only 10 °, which is also favorable so that the rainwater can run off in this direction. A rain gutter will then be arranged between the collector field and the mirror field. This is easily understandable for the expert on the Bausek gate, even if this is not shown in the drawing. There is also the possibility that the collector array is inte grated into a known storage container, which is seen with transparent thermal insulation material. In this case, there is the possibility to arrange additional additional mirror surfaces 17 at a greater angle to the floor, north of the collector field. It must be accepted that when the sun is low, shading of these northern mirror surfaces occurs through the collector field. However, these northern mirrors are effective when the sun is higher. The thereby deflected solar radiation penetrates the transparent thermal insulation material and heats the storage tank, which is effective as a kind of collector in this way. This is also understandable to the person skilled in the art without being shown in the drawing.

Finally, there is also the possibility of arranging the mirror arrangement according to the invention between the collector rows arranged at a distance from south to north. Although with this arrangement mutual shading of the individual rows of collectors is unavoidable when the sun is low, a very large number of such solar systems are already permanently installed all over the world, for example outdoors. Here, however, the distance has been chosen to be relatively large in order to reduce this shading. Therefore, there is the possibility of arranging the mirror surfaces 17 in this intermediate space with considerable economic benefit.

The above-mentioned arrangement of the mirror surfaces north the absorber is of course also for tube collectors preferred if this with a larger angle of inclination are set up.

Fig. 3 shows a side view of a frame with egg ner common rigid rectilinear support 35 which is fastened by means of a joint 33 to the support 18 on which the solar modules or absorbers 2, 2 a, 2 b at intervals a from below above and left to right, ie from south to north. This distance a must not exceed 200 mm so that the diffuse radiation can also be fully used. The invention is based on the knowledge that the diffuse radiation can be reflected, at least over a short distance.

At this distance a, both types of mirrors, namely the north mirror surfaces 1, 1 a, 1 b, 1 c, 1 d, 1 e and the south mirror surfaces 17 a, 17 b, 17 c, 17 d, are arranged, their supporting elements support each other.

One can first see the mirror surface 1 on the north edge of the absorber 2 , to which the mirror surface 1 a adjoins at the top. This is connected to the mirror surface 17 b, to which the mirror surface 17 a connects to the right and thus to the south. These two mirror surfaces 17 a, 17 b thus form the lower south mirror for the absorber 2 a. At the north edge of the same, the mirror surfaces 1 b, 1 c at a distance b and 17 d, 17 c follow as before. These thus form the southern lower mirror for the absorber 2 b, to which the mirror surfaces 1 d and 1 e also connect at a distance b, which are held by the horizon tal support 12 for receiving the wind load. In the upper area, the floor support 14 is fastened to the support 35 by means of the joint 34 . Bottom support 14 is attached to support 18 c in points 30 . In order to change the angle of inclination of the support 35 , it is possible to connect the bottom support 14 at the bottom either with the support 18 b at points 31 or the support 18 d at points 32 , the supports 18 being arranged at a distance c from one another.

This adjustment is seasonal. So you have different positions for spring, summer, autumn and winter conditions of the angle of inclination of the support 35 , which automatically changes the position of all absorbers or solar modules, but also all mirrors with respect to the horizontal.

It is understandable to the expert that there is still a great deal larger number of collectors or solar modules with it proper mirrors can be provided if there is should be a correspondingly large plant.

Fig. 4 makes it clear that there are no limits to the size of the system, despite the relatively small dimension a. You do not need the frame with the supports 14, 35 to be excessively large, but you can arrange as many rows of such frames in the north-south direction.

First of all, the frame consists of the supports 18 a, 35 , 14, 18 b, with the absorbers or solar modules and the mirror surfaces 1, 17 in between, as before, and therefore does not need to be described again. In this case, the adjustability can be omitted by the different supports, so that only one support 18 b for the floor support 14 is provided here.

To the left of it towards the south you can now see two large mirror surfaces 17 f, 17 g, which are held on the left by an additional support 18 , while on the right the support 18 a also serves as a support for the large mirror surface 17 g.

This mirror arrangement with the large mirrors enables an additional concentration according to the same inventive scheme as before. The mode of action therefore does not have to be explained again. It is readily understandable that, in addition to the small mirror gels on the supports 35, now also the large mirror surfaces 17 f, 17 g are additionally effective, so that a repeated concentration, partly via the small mirror and partly also directly on the absorber takes place.

Further to the right on the north side, a further additional large mirror surface 17 is mounted on the bottom support 14 h, for which purpose the bottom support has been arranged in the gewünsch th angle 14 of course. Through this mirror surface 17 h there is therefore no additional shading for the white ter lying north with the support 35 .

At the large mirror surface 17 h continues to the right, the large mirror surface 17 i, which is supported again on the support 18 a. It is the same frame as previously described. For the sake of simplicity, the mirror surfaces 1, 17 are drawn straight. They are bent as in Fig. 3.

Now there is the possibility of any number of additional frames to expand the facility to the south or north organize. But there is also the possibility the frames to the east and west extend.

Fig. 5 shows schematically a vacuum tube collector with the tubes 36-41 , in which the absorbers 2-2 e are arranged in a known manner, which therefore need not be explained in more detail. It is also known to incline the absorbers in these tubes to the left south, similar to what is done with the much larger absorbers.

According to the invention is now again the distance a, as previously provided between the absorbers in which the southern mirror surfaces 17 a- 17 j between the lower edge of the northern absorber for a game is 2 a, and the upper edge of the southern absorber, for example 2 , as before, are arranged. According to the prior art, the distance in this case is still much less, without the south mirror being arranged in between. The invention also has the advantage, inter alia, that the mutual shading occurs less in this case due to the somewhat larger distance a than in the prior art. It is crucial, however, that not only the direct solar radiation is additionally used by the mirror surfaces 17 over the short distance, but the diffuse radiation in the cloudy sky is also amplified by the measure according to the invention, as has been proven by tests.

In this case, as in all the others, it is preferred to choose this distance a not greater than 120 mm, in which case the mirror surfaces 17 can be formed by white color.

Experiments have shown that the diffuse Radiation at such a short distance through white color be reflected as well as by a reflective one Metal foil or other industrial mirror surface.

According to FIG. 5, the distance should of course not be too small, and not only from the aforementioned reason, namely, the mutual shading of the absorber as completely as possible to prevent, but also to ensure that the levels in between find enough space. This lower limit depends on the diameter of the tubes 36-41 . In the trade there are for example collector tubes with a diameter of 100 mm, but also those with a much smaller diameter. The smaller the diameter of the tubes, the smaller the distance a can of course be, which is favorable for the reflection of the diffuse radiation.

As is known, the proportion of diffuse radiation is in Central Europe around 50% overall. This means that too in clear weather, the proportion of diffuse radiation, for example Is 20%.

From this it can be seen that the subject of the invention by no means only benefits in bad weather.  

It is also preferred that the upper edge of the mirror surfaces 17 in the areas that extend laterally beyond the absorber surfaces is directed downwards in the sense that the width of the mirror surfaces with their associated support elements in this lower area, the barrel adapted to the sun, decreases. As is well known, the sun is lower in the morning and evening than at noon. By this measure, there is thus an adaptation to the course of the sun, so that the mirror surfaces with the associated inclination angle, which in some cases cannot be effective in the morning and evening anyway, clear the way for the other mirror surfaces with the lower inclination angle. But it can also be provided a gradual adjustment.

Claims (12)

1. Solar system with flat absorbers and / or solar cells in a collector field, on the edges of which at least partially one or more mirror surfaces are arranged at an angle to the absorbers and / or solar cells, the solar radiation striking the mirror surfaces at least partially From the absorber and / or solar cells falls and the mirror surfaces and the absorber surfaces and / or solar cells are rigidly arranged on the roof of a building or on support elements, the mirror surfaces in a plane extending to the north and / or south and inclined to the absorber Are attached level and the mirror surfaces with respect to the absorber shading stretch laterally beyond the absorber surfaces, characterized in that the mirror surfaces ( 17 ) with their associated support elements are bent in the side view, with a gradual transition from a smaller angle of inclination ( γ ₁) too large en inclination angles ( γ ₂, γ ₃) between the mirror surfaces ( 17 a, 17 b, 17 c) and a horizontal bottom ( 28 ). 2. Solar system according to claim 1, characterized in that a distance (d) is arranged at least between two such mirror surfaces ( 17 c, 17 d). 3. Solar system according to claim 2, characterized in that a spacer ( 27 ) between the two mirror surfaces ( 17 c, 17 d) is arranged. 4. Solar system according to claim 1, characterized in that the collector array is arranged on a support ( 35 ) on the roof of a building or is integrated in the roof or the roof skin of the same, and that the mirror surfaces ( 17 ) on the adjacent Arranged flat roof or are integrated into this roof or form the roof skin. 5. Solar system according to claim 1, characterized in that the mirror surfaces ( 17 g, 17 h) are arranged between the south to north spaced rows of a collector field or solar cell module field. 6. Solar system according to claim 5, characterized in that the distance (a) between the rows of absorbers ( 2, 2 a, 2 b) or solar cell modules in which the mirror surfaces ( 1, 17 ) are arranged with their associated support elements, the Amount of a = 200 mm does not exceed. 7. Solar system according to claim 5, characterized in that the absorbers ( 2, 2 a, 2 b) or rows of solar cells with their associated support elements are arranged on a common rigid support ( 35 ), the angle of inclination of which is arranged at the bottom at a distance (c) Supports ( 18 b, 18 c, 18 d), is adjustable. 8. Solar system according to claim 7, characterized in that on an inclined floor support ( 14 ) on the north side, an additional mirror ( 17 h) is arranged for arrangement on the common support behind ( 35 ). 9. Solar system according to claim 1, characterized in that the distance (a) between the tubes ( 36-41 ) of a vacuum tube collector system is provided, the absorber ber ( 2-2 e) in the tubes ( 36-41 ) are slanted. 10. Solar system according to claim 1, characterized in that the distance (a) between the rows of absorbers ( 2, 2 a, 2 b) or solar cell modules is not greater than a = 120 mm, and that the mirror surfaces ( 17 ) are formed by white color. 11. Solar system according to claim 1, characterized in that the upper edge of the mirror surface ( 17 ) in the areas that extend laterally beyond the absorber surfaces, directed downwards in the sense that the width of the mirror surfaces ( 17 ) with their associated support elements in this lower area, adapted to the course of the sun, decreases. 12. Solar system according to claim 1, characterized in that the south to the absorber ( 2 ) adjoining ß mirror surface ( 17 a) has an inclination to the bottom ( 28 ) equal to zero and thus as a flat mirror gel surface on the floor or Flat roof rests.