WO2012038129A1 - Solar cell module and solar cell arrangement - Google Patents

Abstract

Solar cell module, particularly based on crystalline silicon, which is in thermal contact with a latent heat store which acts as a heat sink at elevated module temperature.

Description

 Description title

Solar cell module and solar cell assembly

The invention relates to a solar cell module, in particular based on crystalline silicon, and a solar cell arrangement constructed from such modules. State of the art

Solar cell modules heat up strongly under the influence of sunlight. On the one hand, the power increases with increasing irradiation, but the temperature of the module, which has a negative effect on the power output, also increases. Starting at 25 ° C, the power reduction is about 0.5% per degree of warming. This means that if a module can output 200 W at 25 ° C module temperature, the power at 75 ° C module temperature is reduced to 150 W (constant radiation). Fig. 1 illustrates these relationships with reference to a family of curves showing the module performance at different module temperatures and at constant irradiance of 1000 W / m ² . On the abscissa the module voltage U in V and on the ordinate the module power P in W is plotted. A denotes the so-called U _M pp region.

It is known to provide an active cooling, in particular by means of fans or blowers to avoid overheating of photovoltaic systems in strong sunlight and high outside temperatures. DE 20 2007 002 087 U1 proposes liquid cooling for photovoltaic systems, which comprises a low-temperature Stirling engine. A disadvantage of active cooling systems is the energy required for their operation, which inevitably leads to a reduction in the total energy yield of the photovoltaic system.

Disclosure of the invention

The present invention is a solar cell module, in particular based on crystalline silicon, which is in thermal contact with a latent heat storage acting as a heat sink at elevated module temperature. The invention further relates to a corresponding solar cell arrangement. In both variants of the invention, the latent heat storage is realized in particular as a component of the solar cell module or the solar cell array, but it can also be manufactured and delivered separately and brought into contact with the module or the arrangement only for use. The invention is based on the effect of latent heat storage, d. H. By a physical conversion process, a large amount of heat is stored without causing a temperature change. In the phase of direct sunlight, the module heats up with a time delay because the heat storage granules can absorb heat energy for a certain period of time without getting warm. In this sunny phase, the module can work with a higher efficiency (colder). In the subsequent clouding phase, the module temperature drops, and the granules can release their stored energy to the environment and thus build up heat storage capacity for the next sunshine phase. This solution is therefore particularly advantageous for cyclically changing clouding situation, as they are often found in northern Europe.

In one embodiment of the invention, the latent heat storage on a flat heat storage body, which is arranged in surface contact on a back side of the solar cell module, in particular a predominant part the back covered. This structure is structurally particularly simple and easy to handle during installation of a photovoltaic system, since the means for heat storage and prevention of the energy yield drastically reducing heating are integrated at the module level and do not significantly change the basic shape and handling of the modules.

According to an alternative embodiment of the invention, the heat storage body mentioned in surface contact with the rear side of the array of solar cells is assigned as a whole, so it is installed only during their assembly from the individual solar cell modules and thermally connected to the solar cells. This makes it possible to construct an arrangement according to the invention in principle essentially from modified commercial solar cell modules. On the other hand, then a certain additional effort is required on site. Also possible is an embodiment in which the latent heat storage of the solar cell assembly is assigned as a whole, but not in the form of a rear-mounted flat heat storage body, but in a different form and spatial allocation; see also below. In a further embodiment of the invention, the latent heat storage, in particular a heat storage granules, which is introduced into a heat storage body with a closed outer mold. A heat storage body in which the heat storage granules are introduced or embedded can have the flat shape already mentioned above adapted to the solar cell module. Such a heat storage body can also be manufactured and distributed as an accessory to conventional solar cell modules and optionally retrospectively installed in existing photovoltaic systems. Especially when the latent heat storage is created on the solar cell array level, but also the use of a loose bed of heat storage granules is possible, in which the solar cell array or essential parts thereof are embedded on the back. In a further embodiment of the invention is provided to establish the thermal contact between the solar cell module or the solar cell assembly and the latent heat storage a, in particular metallic, heat conduction. Such a heat conductor element can improve the thermal contact or comparative, even if there is a larger contact area between the solar cell and the latent heat storage anyway. Particularly advantageous is the use of an additional heat conductor element but in geometric configurations in which only a relatively small contact surface could be realized, so that the heat conductor element serves as a heat collecting device.

For the realization of the latent heat accumulator, various materials are known which have very different phase transition temperatures and whose sensible selection and combination makes it possible to realize a latent heat accumulator with parameters suitable for carrying out the invention. In a preferred embodiment from the present point of view, it is provided that a phase transition temperature of the latent heat store in the range between 20 ° C and 80 ° C is provided.

drawings

Further advantages and advantageous embodiments of the subject invention are illustrated by the drawings and explained in the following description. It should be noted that the drawings are only descriptive and are not intended to limit the invention in any way. Show it:

Fig. 1 is a graphical representation to illustrate the effect

 increased temperatures on the performance of solar cell modules,

Fig. 2 is a schematic representation of an embodiment of the

Invention, Fig. 3 is a further schematic representation of an embodiment of the invention and

Fig. 4 is a further schematic representation of an embodiment of the invention.

2 shows, in a sectional perspective view, a solar cell module 1 with a latent heat accumulator 3 integrally applied to the rear side, which is embodied here as a plastic plate cast on the solar cell module with a heat storage granulate filling 5. All technical details of the solar cell module, with the exception of a front cover glass la are omitted in this illustration.

FIG. 3 schematically shows a solar cell arrangement 7 of solar cell modules 1 arranged in matrix form one another. These rest on metal mounting strips 9 whose free ends in turn rest on a support 11 and the long side edges of the arrangement lying opposite on the support 11 into the cover surface of a heat storage body 13 pass, which is designed as a box and completely filled with a (not shown) heat storage granules. The metallic assembly bands 9 and the cover of the heat storage body 13 serve as heat-conducting elements for heat transfer between the backs of the solar cell modules 1 and the heat storage granules in the box 13. The lateral arrangement of the heat storage body can bring advantages for the assembly of the solar cell array or z. B. allow a shaded accommodation of the heat storage body and thus achieve a better effect.

FIG. 4 again shows, purely diagrammatically and omitting all details of the solar cell modules and arrangement not essential to the invention, a further solar cell arrangement 7 'of solar cell modules 1 as a further realization of the invention. In this case, the modules 1 are supported on carriers 11 along their longitudinal edges 'stored in a tub 15, the extends over the entire surface of the solar cell array and is filled with heat storage granules 5. The solar cells are thus embedded with their backs directly into the heat storage granules and have with this a contact surface which is almost equal to their (back) surface. The provision of additional heat conductor elements is dispensable in this arrangement.

Claims

claims 1. solar cell module, in particular based on crystalline silicon, which is in thermal contact with an acting at elevated module temperature as a heat sink latent heat storage. 2. Solar cell module according to claim 1,  wherein the latent heat accumulator has a flat heat storage body, which is arranged in surface contact on a rear side of the solar cell module and in particular covers a major part of the back. 3. Solar cell module according to claim 1 or 2,  wherein the latent heat storage comprises a heat storage granules, which is introduced into a heat storage body with a closed outer mold. 4. Solar cell module according to one of the preceding claims,  wherein for the mediation of the thermal contact between the solar cell module and the latent heat storage a, in particular metallic, heat conduction element is provided. 5. Solar cell module according to one of the preceding claims,  wherein a phase transition temperature of the latent heat storage is provided in the range between 20 ° C and 80 ° C. 6. Solar cell arrangement of a plurality of solar cell modules,  in particular based on crystalline silicon, wherein the solar cell assembly is in thermal contact with a latent heat storage acting as a heat sink. 7. Solar cell arrangement according to claim 1,  wherein the latent heat accumulator has a flat heat storage body, which is arranged in surface contact on a rear side of the solar cell array and in particular covers a major part of the back. 8. Solar cell arrangement according to claim 1 or 2,  wherein the latent heat accumulator has a heat storage granules, which is introduced in particular into a heat storage body with a closed outer mold. 9. Solar cell arrangement according to one of the preceding claims,  wherein for the mediation of the thermal contact between the solar cell array and the latent heat storage a, in particular metallic, heat conduction element, is provided. 10. Solar cell arrangement according to one of the preceding claims,  wherein a phase transition temperature of the latent heat storage is provided in the range between 20 ° C and 80 ° C.