Search

US-12620930-B2 - Multi-tier, foldable photovoltaic roof and method

US12620930B2US 12620930 B2US12620930 B2US 12620930B2US-12620930-B2

Abstract

A multi-tier, foldable roof includes photovoltaic (PV) cells for transforming solar energy into electrical energy. The roof includes a climate layer configured to close an opening of a structure and also configured to control temperature and humidity of an interior of the structure, a PV screen having plural PV panels, each PV panel configured to include plural PV cells, and an outer layer configured to protect the PV screen from soiling. The climate layer, the PV screen and the outer layer are spaced apart from each other with a given distance (H), and each of the climate layer, the PV screen and the outer layer is configured to change from a retracted state to an expanded state.

Inventors

  • Thomas Gerald ALLEN
  • Ahmed Hesham BALAWI
  • Michele De Bastiani
  • Niclas HEESCHER
  • Michael Filipe SALVADOR
  • Emmanuel P. VAN KERSCHAVER

Assignees

  • KING ABDULLAH UNIVERSITY OF SCIENCE AND TECHNOLOGY

Dates

Publication Date
20260505
Application Date
20230607

Claims (18)

  1. 1 . A multi-tier, foldable roof including photovoltaic (PV) cells for transforming solar energy into electrical energy, the roof comprising: a climate layer configured to close an opening of a structure and also configured to control temperature and humidity of an interior of the structure; a PV screen having plural PV panels, each PV panel configured to include plural PV cells; and an outer layer configured to protect the PV screen from soiling, wherein the climate layer, the PV screen and the outer layer are spaced apart from each other with a given distance (H), and wherein each of the climate layer, the PV screen and the outer layer is configured to independently change from a retracted state to an expanded state.
  2. 2 . The roof of claim 1 , further comprising: plural connecting mechanisms configured to suspend each of the climate layer, the PV screen and the outer layer from a corresponding hanging wire.
  3. 3 . The roof of claim 2 , further comprising: an electrical connection mechanism configured to electrically connect a first PV panel of the PV screen to a second PV panel of the PV screen.
  4. 4 . The roof of claim 3 , wherein the electrical connection mechanism includes an electrical cable having first and second end pads, the first pad being configured to electrically connect to the first PV panel and the second pad being configured to electrically connect to the second PV panel.
  5. 5 . The roof of claim 4 , wherein a connecting mechanism, of the plural connecting mechanisms, that mechanically connects the first PV panel to the second PV panel includes a bracket, and first and second fabric layers, the first fabric layer connects with a first end to the bracket and with a second end to the first PV panel, and the second fabric layer connects with a first end to the bracket and with a second end to the second PV panel.
  6. 6 . The roof of claim 5 , wherein the electrical cable extends from the first PV panel to the second PV panel through holes made in the first and second fabric layers.
  7. 7 . The roof of claim 2 , wherein a connecting mechanism, of the plural connecting mechanisms, that mechanically connects the first PV panel to the second PV panel includes a bracket, and first and second fabric layers, the first fabric layer connects with a first end to the bracket and with a second end to the first PV panel, and the second fabric layer connects with a first end to the bracket and with a second end to the second PV panel.
  8. 8 . The roof of claim 1 , wherein in the retracted state, the PV panels are substantially parallel to each other and in the expanded state, the PV panels extend substantially in a single plane.
  9. 9 . The roof of claim 1 , wherein the PV screen is located between the outer layer and the climate layer.
  10. 10 . The roof of claim 1 , wherein the PV screen is partially transparent to light with a transparency that can be tuned while the outer and climate layers are fully transparent to light.
  11. 11 . A photovoltaic, PV, screen to be used to cover a greenhouse, the PV screen comprising: a first PV panel including plural PV cells configured to transform solar energy into electrical energy; a second PV panel including plural PV cells configured to transform solar energy into electrical energy; a connecting mechanism configured to suspend each of the first and second PV panels from a hanging wire, the connecting mechanism including a bracket and first and second fabric layers, the first fabric layer connecting the first PV panel to the bracket and the second fabric layer connecting the second PV panel to the bracket; and an electrical connection mechanism configured to electrically connect the first PV panel to the second PV panel, wherein the electrical connection mechanism includes an electrical cable that extends through each of the first and second fabric layers.
  12. 12 . The PV screen of claim 11 , wherein the connecting mechanism comprises: a clip configured to directly connect to the hanging wire; the bracket configured to fixedly receive first ends of the first and second fabric layers; and the first and second fabric layers.
  13. 13 . The PV screen of claim 12 , wherein second ends of the first and second fabric layers are configured to fixedly attach to the first and second PV panels, respectively.
  14. 14 . The PV screen of claim 11 , wherein the electrical connection mechanism comprises: the electrical cable; and first and second electrical connectors attached to first and second ends of the electrical cable, wherein the first electrical connector is configured to attach to a first junction box of the first PV panel and the second electrical connector is configured to attach to a second junction box of the second PV panel.
  15. 15 . The PV screen of claim 14 , wherein the electrical cable extends through holes made in the first and second fabric layers.
  16. 16 . The PV screen of claim 11 , wherein each of the first and second PV panels is integrally connected to an additional PV panel, at a given interface, and each of the first and second PV panels and the corresponding additional PV panels fold at the given interface so that the PV screen is in a retracted state.
  17. 17 . A structure with a multi-tier foldable roof, the structure comprising: plural walls that define an enclosure; and the multi-tier foldable roof that covers the enclosure, wherein the multi-tier foldable roof comprises: a climate layer configured to close the enclosure and also configured to control temperature and humidity of the enclosure; a PV screen having plural PV panels, each PV panel configured to include plural PV cells; and an outer layer configured to protect the PV screen from soiling, wherein the climate layer, the PV screen and the outer layer are spaced apart from each other with a given distance (H), and wherein each of the climate layer, the PV screen and the outer layer is configured to independently change from a retracted state to an expanded state.
  18. 18 . The structure of claim 17 , further comprising: plural connecting mechanisms configured to suspend each of the climate layer, the PV screen and the outer layer from a corresponding hanging wire; and an electrical connection mechanism configured to electrically connect a first PV panel of the PV screen to a second PV panel of the PV screen.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Stage Application of International Application No. PCT/IB2023/055874, filed on Jun. 7, 2023, which claims priority and benefit to U.S. Provisional Patent Application No. 63/350,110, filed on Jun. 8, 2022, entitled “RETRACTABLE PHOTOVOLTAIC ROOF AND METHODS,” the disclosures of which are incorporated herein by reference in their entirety. BACKGROUND Technical Field Embodiments of the subject matter disclosed herein generally relate to a photovoltaic roof used for a structure, and more specifically, to a multi-tier, foldable roof that covers the structure and is configured to control two or more of an amount of air flow, light, and heat entering the structure, and also to simultaneously generate electrical energy so that the structure approaches energy self-sufficiency. Discussion of the Background The United Nations declared Clean Energy, Food and Water security as part of the 17 most pressing challenges for our global society. This is particularly critical in hot and arid climates like in the Arabian Peninsula, where roughly 80% percent of food is imported, water scarcity is an enduring problem and fossil fuels dominate the energy supply. The hot climate combined with the scarcity of groundwater makes open-land farming economically and environmentally impracticable in many regions of the world. Thus, these regions rely today on greenhouses for controlling the climate and water provided to the plants. Modern greenhouses with controlled environments and smart water irrigation systems enable year-round growing of produce at reduced levels of water consumption. While greenhouses could deliver the desired increase in food security, this comes at the cost of additional energy needs, which requires a solution. To sustain optimal crop growth in greenhouses located in areas with intense solar irradiation, the amount of sunlight has to be reduced by as much as 50-70% during peak solar irradiation hours. This is typically accomplished using passive shading systems as illustrated in FIG. 1. The shading system 100 of FIG. 1 has plural flexible fabric folds 110, each end of the fold 110 being provided with a solid rod 112A, 112B. The rods 112A, 112B are configured to be placed into corresponding brackets 114, and these brackets are suspended from a hanging wire (not shown) with corresponding clips 116. FIG. 1 also shows fixed structures 118, belonging to the building that is using the system 100, and end of system brackets 120. The flexibly fabric folds 110 are made of a fabric, that may be partially transparent to the solar light. The system 100 is shown in FIG. 1 being in a retracted state. When the system 100 needs to be expanded, to cover the corresponding building, a motor (not shown) actuates an end of the system bracket 120 and spreads the brackets 114 along the hanging wires to unfold the folds 110. This single layer roof system is capable to control the amount of light and air flow entering the building protected by this roof. Alternatively, plastic wires are pulled between the two ends of the room structure. The very lightweight screen is sitting on the plastic wire bed and pulled/pushed by a front bar that is powered by a motor. However, controlling only the light and air flow entering the building is not enough for many greenhouses in the arid areas. In addition to shading, greenhouses employ expensive active cooling. Notably, the energy consumption for greenhouse cooling in hot climates (desert regions) is about 80-100 kWh/m2/yr for evaporative-cooled greenhouses (water consumption: for cooling about 80 L/kg of tomatoes, for irrigation about 50 L/kg of tomatoes) and 500-600 kWh/m2/yr using mechanical cooling (water consumption: for cooling OL/kg of tomatoes, for irrigation about 10 L/kg of tomatoes). This added operation cost limits the financial viability of greenhouses and thus adversely impacts overall crop yield potential in these areas. Adding to this negative scenario, recent and predicted increases in the cost of electricity will further disincentivize the large-scale development of greenhouse farming and perpetuate the arid areas' dependence upon imported foods. The shade system 100 illustrated in FIG. 1 might be a good fit for countries in central Europe, which have abundant levels of fresh water, e.g., the Netherlands, and climatic conditions diametrically opposed to the Middle East, in which greenhouses are mostly used to maintain heat and maximize the penetration of sunlight for a certain latitude and climate (increased sunlight in the winter). Practical experience over the past years in the arid regions of the Earth, as the Arabian Peninsula, has shown that (1) mainstream glass greenhouses with a static glass roof and with highly controlled environment and (2) greenhouses with a foldable roof (as in FIG. 1), produce high crop yields even in the desert, but have either a large water footprint when combined with evaporativ