KR20100078011A - Solar array caring apparatus moving on track with reciprocation - Google Patents

Abstract

PURPOSE: A solar powered array management device for reciprocating on an orbit and emitting water is provided to perform simultaneously washing a solar powered array and cooling. CONSTITUTION: A solar powered array management device for reciprocating on an orbit and emitting water comprises a rail(30), a water jet injection nozzle(20) and a solar power generation module(10). The orbit is installed in the solar power generation array. The water jet injection nozzle moves along an orbit and generates an impinging jet to the solar power generation module surface.

Description

Solar array caring apparatus moving on track with reciprocation

The present invention is characterized in that a nozzle for spraying a water jet toward a photovoltaic array for cleaning and cooling or snow removal of the photovoltaic array {array} reciprocates over an orbit placed parallel to the photovoltaic array. It provides a structure.

Photovoltaic power generation refers to a form of power generation in which solar light is directly converted into electricity in a solar cell. The photovoltaic module is an assembly of solar cells connected in series and is a substantial basic power generation unit of photovoltaic power generation. Such a photovoltaic module assembly is called a photovoltaic array. The principle of solar cell power generation is based on the photovoltaic effect. When solar light is irradiated to a pn-junction solar cell with n-type doping on a silicon crystal, electromotive force generated by electron-holes is generated by light energy. This is called the photovoltaic effect. For example, when light is incident on the photovoltaic module from outside, electrons in the conduction band of the p-type semiconductor are excited to a valence band by the incident light energy. Is an electron-hole pair (EHP) in the p-type semiconductor, and the electrons in the electron-hole pair generated are n-type semiconductors by an electric field existing between pn junctions. It passes to and supplies current to the outside.

Currently commercialized solar cells are mainly silicon-based solar cells. Although silicon is not an optimal material for solar cells, it can be easily mass-produced by the conventional semiconductor process, and thus, has been established as the main force of solar cells after 30-40 years of research and development and demonstration. Currently, the power generation efficiency of polycrystalline silicon solar cells is 16-18%, and the power generation efficiency of single crystal silicon solar cells is about 22 ~ 24%.

Unlike conventional energy sources based on fossil raw materials, photovoltaic power generation is a clean energy source that does not cause the risks of greenhouse gas emissions, noise, and environmental degradation that cause global warming, and is depleted because it is based on infinite solar power. There is no worry. The availability of solar energy is 2,890 times the global annual energy requirement as of 2005, and its location is unconstrained, unlike other wind and sea power. As carbon emissions cause climate change and international cooperation under the Kyoto Convention, etc., photovoltaic power generation is attracting attention as an alternative to sustainable green growth. Although the cost of photovoltaic power generation has fallen by more than one-third in 2008 compared to the early 1990s due to cost reduction and efficiency improvement due to technological innovation, the cost of photovoltaic power generation compared to fossil fuels is still 7-8 times higher. Therefore, the most important issue of the current photovoltaic technology is the reduction of the unit cost through the improvement of power generation efficiency.

Silicon P-N junction diodes are characterized in that the photovoltaic power decreases with increasing temperature. In the 1960s, several researchers have already confirmed this temperature, starting with the work of Joseph J. Wysocki and Paul Rappaport of Princeton University. The decrease in the electromotive force {O.C.V (open circuit voltage)} due to the temperature rise means that the output of the solar cell according to the temperature rise of the photovoltaic module. Therefore, in order to maintain high power generation efficiency under high insolation conditions such as summer season, cooling of the photovoltaic module helps to improve output. Joseph J.W., Paul R. Effect of Temperature on Photovoltaic Solar Energy Conversion, 1959, J. of Applied Physics Vol. 31,571-578.

PV output fluctuates with changes in seasonal concentration and average temperature. Rather than summer, when the maximum concentration is recorded, the photovoltaic output shows the maximum value in spring and autumn, which is due to the decrease in output caused by overheating of the photovoltaic module due to excessive solar radiation in summer.

As another factor that lowers the output of photovoltaic power generation, a decrease in light transmittance due to surface contamination may be suggested. In general, a large area photovoltaic array is exposed to the external environment for a long time, the surface transparency is reduced by contaminants such as yellow dust, scattering dust, bird dirt. The resulting reduction in power generation efficiency averages about 10%. 2 H. Haeberlin and J.D. Graf, Gradual Reduction of PV Generator Yield due to Pollution, 1998, 2nd World Conference on Photovoltaic Solar Energy Conversion, Vienna, Austria

In winter, the solar altitude is low and the solar power output is reduced. In addition, snowfall caused by winter snowfall drastically reduces the solar PV output in winter. However, removing snow from manpower in cold weather is expensive, risks of surface glass breakage of photovoltaic modules, and snow removal of photovoltaic arrays installed on roofs or rooftops is dangerous.

In order to cope with these problems, photovoltaic module management techniques related to cooling and cleaning of the photovoltaic module have been proposed. These technologies can be roughly classified into three categories: first, focusing on cooling of the photovoltaic module, second, enabling simultaneous cooling and cleaning of the photovoltaic module, and finally cleaning of the photovoltaic module. It is divided into technologies that focus on. The above schemes are described in more detail as follows.

First, the technology focused only on the cooling of the photovoltaic module is equipped with a fin tube through which refrigerant flows on the back of the photovoltaic module, and the refrigerant is put on the back of the photovoltaic module and repeated evaporation and condensation according to the temperature change. And there is a way to cool the photovoltaic module. [Document 3] JP 1998321890, (HITACHI CHEM CO LTD) 1998.12.4, [Document 4] JP 1989148037, (HITACHI LTD), 1989.6.9. Second, a technology that can simultaneously cool and wash the photovoltaic module is a method of flowing water from the top of the photovoltaic module. Document 5 DE10028093 (MUELLER FRIEDRICH UDO) 2001.12.13. [Document 6] JP59150484 (TOKYO SHIBAURA ELECTRIC CO) 1984.8.28, [Document 7] KR20-2007-0001305 (Kim Kyung-sook, Kim In-chan) 2007.12.20. Through visual confirmation or by using a sensor to detect the pollution level of the photovoltaic module, electric signals are generated and water is sprayed onto the surface of the photovoltaic module and flowed down using gravity. At this time, the water sprinkled on the surface of the photovoltaic module can obtain an additional cooling effect.

Third, the technology focusing on the cleaning of the photovoltaic module is a method of physically removing contaminants using a cleaning tool such as a brush or a rubber wiper. Document 8 WO 2008014760 A2 (HETTINGER, GERD), 2008.02.07, Document 9 JP2002273351 (HINO JUSHI KK), Document 10 DE202006003697U (SCHULZ EBERHARD), 2006.5.4, Document 11 DE102005007200 (BAUMGARTNER HANS) 2006.8.17, 12. WO2004091816 (INST JUFT UND KAELTETECHNIK GG) 2004.10.28.

When the shadow is cast on the photovoltaic module, not only the output drop occurs as much as the shadowed area, but also the back electromotive force is generated, and the output is drastically lowered. This phenomenon is called hot spot effect, and a bypass diode is installed to alleviate the hot spot phenomenon. Therefore, it is desirable to maintain a high output so that at least part of the photovoltaic module does not cast shadows.

The present invention provides a water impinging jet as a method that can perform the cleaning and cooling or snow removal of the photovoltaic module surface. Impingement jets have excellent heat and mass transfer effects from the fluid to the impingement surface. For this reason, it is widely used for tempering of glass plates, annealing of metal plates, drying of textile products, cooling of heating parts in gas turbine engines and freezing of ice in aircraft systems. Document 13 INCROPERA, FUNDAMENTALS OF HEAT AND MASS TRANSFER

Conventional photovoltaic modules or photovoltaic arrays have just been left exposed to outside air for a long time. Therefore, a phenomenon in which the power generation output decreases due to factors such as overheating or pollution and snowfall has occurred. As the spread and diffusion of photovoltaic power generation is accelerated, the output improvement of photovoltaic power generation is considered to be a significant issue. Conventional photovoltaic module cooling technologies are ineffective in cleaning and snow removal of photovoltaic modules, and present additional risks of environmental pollution when refrigerants other than water are used. Existing technologies that can simultaneously cool and wash solar power modules are primarily focused on cleaning.However, by simply flushing water with low water pressure from the top, it is impossible to expect a cleaning effect beyond natural precipitation. According to the installation angle of the power generation module and the surface distribution position of the contaminants, it is difficult to evenly wash and cool the entire surface. In addition, in the case of the existing technology in which water is distributed from one pipe through several nozzles, it is difficult to uniformly distribute water to each nozzle, so that even washing and cooling efficiency of the entire area of the photovoltaic array including a plurality of photovoltaic modules This decreases. In terms of heat transfer, the cooling effect due to simple evaporation of water is less effective in that the water flowing in the direction of gravity cannot stay on the surface of the solar cell for a long time. do.

Lastly, existing technologies focused mainly on cleaning the solar power module have been performed by cleaning tools such as brushes and rubbers that continuously perform physical movements, especially reciprocating rotation, on the surface of the solar power module. It may scratch the surface glass. In addition, it is inevitable to replace the cleaning tool after additional time due to wear and contamination due to repeated operation, deterioration of durability due to overheating in summer, freezing of winter season, etc. In particular, when a large area of a photovoltaic array in which a photovoltaic module is collected needs to be processed, a disadvantage occurs in that the peripheral equipment is heavy enough to give a burden to the photovoltaic module frame.

In order to improve the cooling, cleaning, and snow removing problems of the photovoltaic module 10 which is directly connected to the above-mentioned photovoltaic output improvement, the present invention provides a nozzle 20 for spraying water toward a photovoltaic array. It provides a structure characterized in that the reciprocating movement over the track (30) installed in parallel or in the same direction as the power generation array. Water jet is injected toward the photovoltaic array from the nozzle reciprocating on the orbit 30, and the water jet is generated after cooling, cleaning, and snow removal of the photovoltaic array composed of a plurality of photovoltaic modules. This stops and the orbital nozzle stops at one end of the photovoltaic array.

The water jet spray nozzle 20 sprays water toward the photovoltaic array while reciprocating along the track 30 between both ends of the photovoltaic array.

When the temperature of the photovoltaic module 10 rises and cooling is required, the cooling water is sprayed toward the photovoltaic module 10 through the water injection nozzle 20 reciprocating on the track 30. When the temperature measurement of the photovoltaic module 10 rises above the set value, the water jet spray nozzle 20 sprays the coolant to perform a cooling operation on the photovoltaic array. At this time, the water jet sprayed through the water jet spray nozzle 20 is stopped when the water jet time elapses or when the temperature measurement value of the photovoltaic module 10 reaches a set value. . In addition, after spraying water through the water jet spray nozzle 20, water injection is stopped until a predetermined time elapses, thereby preventing malfunction and waste of water due to frequent driving.

If the surface of the photovoltaic module 10 is contaminated and the light transmittance is judged by the naked eye or a sensor, the photovoltaic module in the water jet spray nozzle 20 reciprocating along the track 30 is moved. It generates a water impinging jet (impinging jet) directed directly to the photovoltaic array surface consisting of (10).

The present invention generates a water impinging jet (impinging jet) having a relatively excellent heat transfer effect and momentum transfer effect on the surface of the photovoltaic module (10) compared to the simple watering can perform the cleaning and cooling smoothly compared to the prior art Can be. In addition, the momentum transfer effect generated in the water collision jet may enable snow removal on the surface of the solar module. Since there is no physical contact of the cleaning tool, there is no problem such as wear or replacement of the cleaning tool or scratches on the surface of the solar module, which is advantageous in terms of durability and maintenance cost.

The apparatus of the present invention treats a relatively large area photovoltaic array with a small number of nozzles by spraying the water jet 22 with a water jet spray nozzle 20 reciprocating on an orbit parallel to the photovoltaic array. This is advantageous compared to the prior art. In general, when a constant hydraulic pressure is supplied, as the number of nozzles increases, the water jet pressure decreases in inverse proportion. When the water jet water pressure decreases, there is a disadvantage in that the heat transfer and momentum transfer effects on the surface of the photovoltaic module are lowered. The structure provided by the present invention is relatively advantageous in maintaining a high water jet jet pressure due to the small number of nozzles. Do.

Photovoltaic power generation requires a large area for power generation. Therefore, in urban areas, it is often installed on the roof or roof of buildings that are difficult to access. In order to clean, cool, and remove snow from large-area photovoltaic arrays, a large amount of costs and risks are required. The structure provided by the present apparatus can automate such operations efficiently and unattended. It is advantageous for cost reduction and is expected to contribute to spread and diffusion by improving profitability of photovoltaic power generation.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The photovoltaic array management apparatus and the photovoltaic array which are reciprocated on a track according to an embodiment of the present invention are shown in FIGS. 1 and 2. 1 and 2 is a conceptual diagram according to a preferred embodiment of the present invention. 1 and 2, the nozzle 20 spraying the water jet 22 toward the surface of the photovoltaic array moves along the trajectory 30. The water jet 22 is sprayed at a distance of a few meters with a constant water pressure and impinges on the surface tempered glass of the photovoltaic module 10 constituting the photovoltaic array. The water jet 22 generating a flow having momentum performs cooling, cleaning, and snow removal on the surface of the photovoltaic module 10. In general, jet flows have two to three times more heat transfer and momentum transfer effects than normal flows. The nozzle 20 for spraying the water jet moves along the track 30 to secure an injection area for the entire area of the photovoltaic array. The water jet spray nozzle 20 that reaches the end of the track 30 while moving along the track 30 is moved in the opposite direction by a switch signal of the control device 31. The water jet spray nozzle 20 moving in the opposite direction likewise reaches the end of the opposite orbit 30 while spraying the water jet 22 toward the photovoltaic array. The water jet spray nozzle 20 which reaches the end of the track 30 moves on the track again in the opposite direction by the signal of the control device 31, and is reciprocated due to the repetition of the operation. Through this reciprocating movement it is relatively easy to spray the water jet 22 having a constant water pressure over a large area of the photovoltaic array.

If the jet of water jet 22 is stopped due to a lapse of time or the surface temperature measurement signal of the photovoltaic module, etc., the jet of water jet nozzle 20 moves to the end of the track 30 and then the jet of water jet ( 22) The spraying stops. This prevents shadows from being cast on the photovoltaic array, thereby preventing a hot spot effect that dramatically reduces the electromotive force of the photovoltaic module 10.

3 is a view showing a case where the present invention is installed with a plurality of photovoltaic array. Referring to FIG. 3, the apparatus of the present invention installed in the space between the photovoltaic arrays installed at a distance apart from each other in which shadows are not cast on each other is merely a plurality of photovoltaic arrays. Water jet spraying to the module can be easily performed.

1 is a perspective view showing the present invention and the photovoltaic array together.

2 is a side view showing the present invention and the photovoltaic array together.

3 is a schematic view showing a plurality of the present invention devices and a plurality of photovoltaic arrays together.

<Explanation of symbols for the main parts of the drawings>

10: solar power module

11: support {support}

20: water jet nozzle

21: reciprocating motion drive

22: water jet

30: Orbit {track}

31: controller

Claims (6)

Orbits 30 installed parallel to or in the same direction as the photovoltaic array. Photovoltaic array management apparatus characterized in that the water jet jet nozzle (20) moving along the track (30) to generate a water impinging jet (impinging jet) directly directed to the surface of the photovoltaic module (10). The method of claim 1, Photovoltaic array management apparatus characterized in that the water jet spray nozzle 20 sprays water toward the photovoltaic module 10 while reciprocating along the orbit 30 between both ends of the photovoltaic array. . The method of claim 1, Photovoltaic array management device, characterized in that for spraying the cooling water toward the photovoltaic array through the water jet spray nozzle (20) when the temperature measurement of the photovoltaic module (10) rises above the set value. The method of claim 3, wherein The water sprayed through the water jet spray nozzle 20 is characterized in that the water injection is stopped when a certain water spray time elapses or when the temperature measurement value of the photovoltaic module 10 reaches a set value Photovoltaic Array Management Device. The method of claim 3, wherein Photovoltaic array management device, characterized in that the water jet is stopped until a predetermined time elapses after the water is jetted through the water jet spray nozzle (2). The method of claim 1, When it is determined that the surface of the photovoltaic module 10 is contaminated by the naked eye or a sensor and the light transmittance is deteriorated, the photovoltaic module (from the water jet spray nozzle 20 moving along the orbit 30) 10) A photovoltaic array management device characterized in that a structure for generating a water impinging jet (jetting) direct toward the surface.

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