Photovoltaic roof and atmospheric water generator

Abstract

A roof (4) which is covered with a photovoltaic surface (2) delimits a space (3) in which a large volume of an adsorbent / desorbent (9) for water vapour is dispersed. In this space (2) a circulation of ambient air (5N) at night (N) is cool and said adsorbent (9) becomes laden with moisture, then a circulation of ambient air (5J) by day (J) is heated on contact with the lower part of the photovoltaic surface (2) which is exposed to the solar radiation (12) and becomes laden with moisture (14) on contact with the adsorbent / desorbent (9). An atmospheric water generator (10) condenses the water vapour out of the outgoing air flow (7J) that has been humidified by passing through the space (3) formed by the roof (4) and the photovoltaic surface (2), and produces a volume of water that is increased relative to the usual operation thereof without this humidifying device (1).

Description

PHOTOVOLTAIC ROOF AND ATMOSPHERIC WATER GENERATOR Technical field of the invention

[0001] The invention relates to photovoltaic roofs and atmospheric water generators. Technical background

[0002] Photovoltaic roofs are roofs on which photovoltaic solar panels have been installed. The panels then take on a slope and orientation that are those of the roof. In general, the photovoltaic panels are slightly spaced from each other to allow a flow of ambient air under the panels, which helps reduce the temperature rise of the panels. Indeed, the panels are generally black in color, which has the effect of absorbing part of the solar radiation and transforming it into thermal energy; the rise in the temperature of the cells would then reduce their performance.

[0003] When solar panels are placed on the ground, it is known and advisable to orient and tilt the photovoltaic panels in a certain way relative to the horizontal in order to produce on average over a year a maximum of kWh of electricity; this electrical production being proportional to the useful surface area of ​​said panels. To do this, it is necessary to space the panels from each other sufficiently so that they do not cast shadows on each other regardless of the position of the sun during the year and whatever the time of day. The useful surface area of ​​the solar panels is then less than the total surface area of ​​the land on which the panels are installed, but they individually produce a maximum of electrical energy depending on the latitude and climatic characteristics of the location. This observation is also valid for the installation of solar panels on flat and horizontal roofs.A choice must then be made between a maximum of photovoltaic surfaces installed horizontally or a smaller useful surface area of ​​solar panels but well oriented. The difference in production between these two choices can be up to 60% more production for panels installed horizontally and over the entire available surface. This surplus production is at the expense of the cost price of the kilowatt-hour (kWh) produced, since this surplus production will have required a surplus of poorly oriented (horizontal) photovoltaic surfaces and therefore less efficient. Choosing the option of maximum electricity production with regard to the available installation surface and with a higher cost price per kWh produced (such as for example the total surface area of ​​a flat and horizontal roof with solar panels positioned horizontally), is generally done when the need for electricity is a priority to the detriment of its cost.This is particularly the case for electrical applications in isolated sites, therefore outside a public distribution network, and when the surface area for installing the panels is small, particularly when this is the roof of a building or industrial premises. When this need for electricity takes priority over its production cost, it is because at least one application is powered by solar panels and this application itself is a priority, whether in an economic, health or ecological context. Presentation of the invention

[0004] The aim of the invention is to describe a photovoltaic roof which supplies electricity to an atmospheric water generator and which increases the water production performance of said generator. To increase the performance of said photovoltaic water generator, it is therefore wise to choose a total photovoltaic surface on the roof rather than choosing an arrangement of solar panels which are inclined and separated from each other.

[0005] Indeed, the production of atmospheric and photovoltaic water can be a priority necessity which requires a maximum of solar electricity production (therefore a maximum useful surface of solar panels). The invention then describes a means of increasing the performance of said atmospheric water generator.

[0006] In its basic version, the device ( : 1) which is the subject of the invention is a photovoltaic roof ( : 4) ( : 2), horizontal or at any angle of inclination, which generates atmospheric water ( : 11) and which comprises:

[0007] - a roof ( : 4) of a building, house, hangar, or more generally any type of covering covering a construction ( : 14) supported by a frame.

[0008] - photovoltaic solar panels ( : 2) positioned above said roof ( : 4) and arranged so as to form an airtight photovoltaic surface ( : 2); the photovoltaic surface ( : 2) being able to cover all or part of said roof ( : 4).

[0009] - a space ( : 3) formed between said roof ( : 4) and said photovoltaic surface ( : 2), this space ( : 3) being capable of being crossed by an air flow ( : 14) coming from the outside ( : 5N at night and 5J during the day) by means of incoming openings ( : 15), outgoing openings ( : 13) and fans ( : 6 and 8).

[0010] - an atmospheric water generator (10) which sucks in the outgoing air flow ( : 7N at night or 7J during the day) from said space ( : 3) and which extracts (at least in part) its water ( : 11),

[0011] characterized in that said space ( : 3) contains an adsorbent / desorbent ( : 9) effective for retaining atmospheric water vapor at ambient temperature and restoring it at a higher temperature, so that at night ( : N) an incoming fresh air flow ( : 5N) passes through said space ( : 3) and charges the adsorbent ( : 9) with moisture, and that during the day (J) an incoming outside air flow ( : 5J), less cool than that at night, passes through said space (3) and is heated in contact with the lower part of the photovoltaic surface ( : 2) which is heated by solar radiation ( : 12), so that said heated air flow ( : 14) is charged with the moisture from the adsorbent / desorbent ( : 9) then exits ( : 7J) through the outgoing opening ( : 13) and supplies said atmospheric water generator ( : 10).

[0012] The advantage of this device ( : 1) of roof ( : 4) photovoltaic ( : 2) and atmospheric water generator ( : 11) is that it allows both:

[0013] - to produce a maximum of solar electricity due to a large photovoltaic surface ( : 2) compared to the surface of said roof ( : 4); said roof ( : 4) can be covered ( : 2) in its entirety.

[0014] - the photovoltaic surface ( : 2) being airtight, it allows on the one hand significant resistance to strong winds and on the other hand easy recovery of rainwater.

[0015] - the ventilation ( : 6 and 8) of the space ( : 3) between the roof ( : 4) and the photovoltaic surface ( : 2) creates a cooling of said roof ( : 4) during periods of high heat; this cooling having a positive impact on the cooling of the interior of the building ( : 14).

[0016] - the adsorbent ( : 9) plays a role in regulating the temperature of said roof ( : 4). Indeed, said adsorbent can be in itself a good thermal insulator like silica gel which has the same insulating properties as glass. And on the other hand, said adsorbent ( : 9) on the one hand sees its temperature increase during its adsorption phase, that is to say during periods of low outside air temperature ( : 5N and mainly at night N) and on the other hand sees its temperature decrease during its desorption phase, that is to say during periods of high outside air temperature ( : 5J and mainly on day J).

[0017] - the atmospheric water generator ( : 10) receives air ( : 7J) during the day which has been humidified in contact with the adsorbent ( : 9), which allows said generator ( : 10) to condense more water ( : 11) with the same expenditure of electrical energy. The average water production can thus be doubled.

[0018] - the local production of atmospheric water ( : 11), at the construction level ( : 14), allows easy watering of vegetated surfaces arranged on the facades or on part of the roof ( : 4).

[0019] - the adsorbent ( : 9) which plays a major role in the effectiveness of the device ( : 1) can have a relatively low purchase cost when purchased in large quantities. Indeed, in the example of silica gel (silica oxide) used in the form of beads 2 to 5 mm in diameter, placing a layer one centimeter thick on the surface of said roof ( : 4) would only require a weight of approximately 8 kg of silica gel per square meter of surface, i.e. a cost of less than 10 euros.

[0020] In additional embodiments, said roofing device (: 1) (: 4) comprises a photovoltaic surface (: 2) which is flat, curved or contains inclined planes, transparent or semi-transparent parts, or rainwater recovery devices. Indeed, as the photovoltaic surface (: 2) is airtight, it is also watertight; which allows rain to flow towards storage tanks

[0021] In an improved embodiment, said roofing device (: 1) (: 4) according to the invention uses as adsorbent / desorbent (: 9) of water vapor effective materials chosen from the following list: organometallic frameworks, covalent organic frameworks, zeolitic imidazole frameworks, metal catecholates, metal azolates, zeolites, carbon, charcoal, porous rocks, silica, silica oxide, porous polymers, porous organic polymers, microporous polymers, polymers, crosslinked polymers, salts, metal oxides, porous cages, clathrates, monoliths, organic molecules, lamellae, metals, metalloids, or combinations thereof,

[0022] In another improved embodiment, said roofing device (: 1) (: 4) according to the invention, the adsorbent / desorbent (: 9) is distributed in a thin layer on the surface of the roofing (: 4) or arranged on drying supports of all types and shapes so as to facilitate contact between the flow of air passing through (: 14) and said adsorbent / desorbent (: 9).

[0023] In a more efficient embodiment, said roof device (: 1) (: 4) according to the invention comprises at the roof outlet (: 4) a device which cools the outgoing air flow (: 7J), for example by means of a plate heat exchanger (for example of the air / air type), because in fact the outgoing air (: 7J) has been heated in contact with the solar panels (: 2) and the atmospheric water generators (: 10) operate better when the air temperature is lower; moreover it may be advantageous to have an air flow rate (: 7J) which is variable depending on the air temperature (: 5N and 5J), the power of the solar irradiation (: 12) and the electrical power consumed by the atmospheric water generator (: 10).

[0024] In another interesting embodiment, said roof device (: 1) (: 4) according to the invention produces water (: 11) which is made drinkable by means, for example, of filtration, ultraviolet irradiation, and the addition of nutrients.

[0025] In another particular embodiment, said device: (1) of roof (: 4) according to the invention comprises fans (: 6 and 8) and an atmospheric water generator (: 10) which are supplied with electricity by at least part of the electrical power of the photovoltaic solar panels (: 2). This electrical power supply may also comprise intelligent management of the electrical production, batteries and other devices for storing electricity and thermal energy, so as to supply the fans (: 6 and 8) and the water generator (: 10) during periods of low light or during at least part of the night (: N)

[0026] In another particular embodiment, said roofing device (: 1) (: 4) according to the invention, comprises at least part of the roofing (: 4), possibly located under said photovoltaic surface (: 2), or at least part of the vertical walls of the construction (: 14), which is planted. Detailed description of the invention

[0027] The invention is now described more precisely using the attached figure which represents in sectional view the basic diagram of a roof (: 4) covered with photovoltaic solar panels (: 2) which supply electricity to an atmospheric water generator (: 10) whose performance has been increased.

[0028] A construction ( : 14) of the "building" type has a flat roof ( : 4); but said roof ( : 4) can also have any type of shape and inclination. The roof ( : 4) is covered with an airtight photovoltaic surface ( : 2). This photovoltaic surface ( : 2) can be composed of photovoltaic solar panels juxtaposed with each other, possibly with a seal between them. The space ( : 3) between the roof ( : 4) and the photovoltaic surface ( : 2) comprises an adsorbent / desorbent ( : 9) capable of absorbing and desorbing water vapor depending on its temperature, and is arranged in a thin layer on the surface of said roof ( : 4). Said adsorbent / desorbent is for example composed of silica gel beads. At least two openings ( : 15 and 13) allow, thanks to fans ( : 6 and 8), to circulate a flow of air ( : 14) from outside on either side of this space ( : 3).At night ( : N) (represented by the lunar symbol) ambient outside air ( : 5N) is introduced into the space ( : 3) so that it humidifies the adsorbent ( : 9), then it comes out ( : 7N) with lower humidity. During the day ( : J) (represented by the sun symbol) a flow of ambient outside air ( : 5J) is introduced into the space ( : 3) so that it is humidified in contact with said adsorbent ( : 9), then comes out ( : 7J) with increased humidity. Indeed, generally speaking, said adsorbent / desorbent adsorbs more humidity when its temperature is low; and desorbs more humidity when its temperature is high. The incoming air flow ( : 5J), during the day, is therefore heated by contact with the interior surfaces of said photovoltaic surface (2) which receives and absorbs the solar radiation ( : 12), then comes out ( : 7J) and is directed towards an atmospheric water generator ( : 10) which condenses the water vapor ( : 11) of said air flow ( : 7J).As the relative humidity of said outgoing air flow ( : 7J) is higher than the relative humidity of the ambient air ( : 5J), said water generator ( : 10) will therefore produce more water ( : 11) than if it had only treated the non-humidified ambient air ( : 5J). The performance (in terms of water production as a function of the electrical energy consumed) of the atmospheric water generator ( : 10) has therefore been increased due to the use of an adsorbent ( : 9) (here as an example silica gel beads) which has been spread over the entire surface of the roof ( : 4). The gain in water production can then reach twice, when the temperature and humidity conditions of the ambient air are ideal. In addition, thanks to the photovoltaic surface ( : 2) which shades the roof ( : 4) and thanks to the layer of silica gel ( : 9) which lowers the air temperature when it is in the desorption phase (during the day), the roof ( : 4) is better insulated against external heat. Examples

[0029] An example of an implementation includes an industrial building with a flat, horizontal roof ( : 4) made of concrete and measuring 10 m x 20 m on each side, or 200 square meters in area. As concrete is a significant heat accumulator, it was necessary to thermally insulate the building using environmentally friendly materials. For this purpose, the vertical walls of the building were planted to provide thermal insulation, an aesthetic appearance, and action against the production of greenhouse gases. The roof was covered, at an average height of approximately 60 cm, with a surface area of ​​220 m2 of photovoltaic solar panels for a maximum peak power of 44 kWp. The panels are juxtaposed to each other to produce an airtight surface ( : 2). A row of x5 fans, each with a power of 100W, are arranged on each of the two 10 m long sides.The fans on one side will suck the ambient air into the roof and the fans on the other side will suck the air from below ( : 3) the photovoltaic surface ( : 2) to redirect it to a small technical room of 20 m3 which contains three atmospheric water generators ( : 10) with an electrical power of 6 kW each, for a total power of 18 kW. On the surface of said roof ( : 4) is placed a layer of silica gel ( : 9) 1 cm thick. The total weight of the silica gel is approximately 2 tons and it can on average adsorb / desorb up to 5% of its weight in water during a temperature variation of 10°C, which commonly happens during the day / night cycles, and which therefore corresponds to 2000 kg x 0.05 = 100 liters of water.The said generators ( : 10) are capable of producing a maximum of 450 liters of water per 24 hours when the relative humidity is around 40% and the average temperature is 25°C, or 150 liters of water during the 8 hours of operation during the day. But with the roof device ( : 1) which contains the 2 tons of silica gel, the volume of water ( : 11) which is produced on average is then around 250 liters; which corresponds to an increase in water production of 66%. ADVANTAGES OF THE INVENTION

[0030] Ultimately, this invention, which uses a photovoltaic surface ( : 2) positioned above a roof (4) and the presence, in good quantity, of a cheap adsorbent / desorbent ( : 9), makes it possible to increase the production of water ( : 11) from atmospheric water generators ( : 10). The water thus produced could, for example, be used to water the plants positioned on the facade of the building ( : 14)

Claims

- Device (1) for a photovoltaic (2) roof (4), horizontal or at any angle of inclination, and generating atmospheric water (11) comprising: a cover (4) covering a construction (14) supported by a frame and forming a roof (4), photovoltaic solar panels (2) positioned above said roof (4) and arranged so as to form an airtight photovoltaic surface (2); the surface of this photovoltaic surface (2) being able to cover all or part of the roof (4), a space (3) formed between said roof (4) and said photovoltaic surface (2), this space (3) being able to be crossed by an air flow (14) coming from the outside (5N at night and 5J during the day) by means of incoming openings (15), outgoing openings (13) and fans (6 and 8), an atmospheric water generator (10) which sucks in the outgoing air flow (7N at night or 7J during the day) from said space (3) and which extracts (at least in part) its water (11),characterized in that said space (3) contains an adsorbent / desorbent (9) effective for retaining atmospheric water vapor at ambient temperature and restoring it at a higher temperature, so that at night (N) an incoming fresh air flow (5N) passes through said space (3) and charges the adsorbent (9) with humidity, and that during the day (J) an incoming outside air flow (5J), less cool than that of the night, passes through said space (3) and is heated in contact with the lower part of the photovoltaic surface (Figure 1: 2) which is heated by solar radiation (12), so that said heated air flow (14) is charged with the humidity of the adsorbent / desorbent (9) then exits (7J) through the outgoing opening (13) and feeds said atmospheric water generator (10)., – Device (1) for roofing (4) according to the preceding claim 1, characterized in that the photovoltaic surface (2) is flat, curved or contains inclined planes, comprises transparent or semi-transparent parts, or rainwater recovery devices. – Device (1) for roofing (4) according to one of the preceding claims, characterized in that the adsorbent / desorbent (9) of water vapor is chosen from a group comprising, as desired: organometallic frameworks, covalent organic frameworks, zeolitic imidazole frameworks, metal catecholates, metal azolates, zeolites, carbon, charcoal, porous rocks, silica, silica oxide, porous polymers, porous organic polymers, microporous polymers, polymers, crosslinked polymers, salts, metal oxides, porous cages, clathrates, monoliths, organic molecules, lamellae, metals, metalloids, or combinations thereof, – Device (1) for a roof (4) according to one of the preceding claims, characterized in that the adsorbent / desorbent (9) is distributed in a thin layer on the surface of the roof (4) or arranged on drying supports of all types and shapes so as to facilitate contact between the flow of passing air (14) and said adsorbent / desorbent (9). - Device (1) for roofing (4) according to one of the preceding claims, characterized in that the air flow (7J) leaving the roof (4) is cooled, for example by means of an air / air plate heat exchanger, that its air flow (7J) is variable depending on the air temperature (5N and 5J), the power of the solar irradiation (12) and the electrical power consumed by the atmospheric water generator (10). - Device (1) for a roof (4) according to one of the preceding claims, characterized in that the water (11) produced by the atmospheric water generator (10) is made potable by means, for example, of filtration, ultraviolet irradiation, and the addition of nutrients. - Device (1) for roofing (4) according to one of the preceding claims, characterized in that the fans (6 and 8) and the atmospheric water generator (10) are supplied with electricity by at least part of the electrical power of the photovoltaic solar panels (2). - Device (1) for a roof (4) according to one of the preceding claims, characterized in that at least part of the roof (4) (possibly located under said photovoltaic surface) or at least part of the vertical walls of the construction (14) is planted.

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