Dual-Axis Solar Tracker with Hybrid Control and Possibility of Full Rotation

Abstract

In this invention, a dual-axis solar tracker is presented to increase the energy produced by solar panels. The control strategy of this tracker is based on a hybrid of both astronomical algorithms and optical sensors and is designed in such a way that both actuators are not active at the same time. Also, the mechanical structure of the tracker is such that it is possible to rotate the solar panel 360 degrees around both axes. This makes it possible to track the sun in the early or late hours of the day or in some geographical areas where the direction of the sun ray is significantly inclined. Furthermore, the invented tracker consists of modular and ready-made mechanical and electronic components, and all the connections are in the form of bolts and nuts, which makes it fast and easy to assemble, install, disassemble and transport while having sufficient strength.

Claims

1-5. (canceled)

6. A dual-axis solar tracker, comprising: A lower frame including a horizontal H-shaped structure (1) and a vertical U-shaped structure (2) to support the total weight of the tracker; An upper frame including a rectangular structure (15), columns (16) and (17), and a counterweight (3); The upper frame being attached to the lower frame to rotate around an east-west axis (19); Vertical columns of the U-shaped structure (2) with lengths more than half of the length of the rectangular structure (15) being long enough to allow a 360-degree rotation of the upper frame around the east-west axis (19); A solar panel (18) being attached to the upper frame to rotate around a north-south axis (20); The columns (16) and (17) with lengths more than half of the length of the solar panel (18) being long enough to allow a 360-degree rotation of the solar panel (18) around the north-south axis (20); Two DC motors with gearboxes (4) and (14) to rotate the solar panel (18) and the upper frame around the rotation axes (20) and (19); and A method for controlling the dual-axis solar tracker being applied by activation of both of the DC motors once a day; activation of one of the DC motors at other times in a day; activation of a sensor-based sun tracking once a day.

7. The dual-axis solar tracker according to claim 1, wherein worm gearboxes with an inherent mechanical self-locking feature are used to make DC motors safe from damages caused by a person or environment and also, prevent the rotation of the solar panel (18) and the upper frame (15) not within their defined rotation angles due to the deactivation of DC motors, gravity, or wind.

8. The dual-axis solar tracker according to claim 1, wherein the upper and lower frames comprise connections of components; the connections of components are in the form of bolts and nuts.

9. The method for controlling the dual-axis solar tracker according to claim 1, comprising: Rotating the upper frame around the east-west axis (19) using the DC motor with gearbox (14) once a day, when the tracker starts to operate, based on a declination angle computed by astronomical algorithms; Rotating the solar panel (18) around the north-south axis (20) using the DC motor with gearbox (4) during the day, according to an hour angle computed by astronomical algorithms; Making corrections to the position of the solar panel (18) using both of the DC motors (4) and (14) once a day, at midday, according to the feedback received from optical sensors to compensate for the possible position errors made by the inaccuracy of astronomical algorithms or external disturbances, such as wind or impact.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0032] FIG. 1 shows the front and side view of the dual-axis solar tracker including its components.

[0033] FIG. 2 illustrates the bottom view of the dual-axis solar tracker including its components.

[0034] FIG. 3 depicts the isometric view of the dual-axis solar tracker including its components.

DESCRIPTION OF EMBODIMENTS

[0035] [FIG. 1], [FIG. 2] and [FIG. 3] show different views of the dual-axis solar tracker and its components.

[0036] According to these figures, a lower frame includes a horizontal H-shaped structure (1) and a vertical U-shaped structure (2) to support the total weight of the tracker.

[0037] An upper frame includes a rectangular structure (15), columns (16) and (17), and a counterweight (3).

[0038] A DC motor with worm gearbox (14) rotates the upper frame about a declination axis (19) only once a day based on the declination angle computed by astronomical algorithms, adjusting its position.

[0039] Also, a DC motor with worm gearbox (4) rotates a solar panel (18), mounted on aluminum profiles (7) and (8), around an houa axis (20) during the day accourding to the hour angle computed by astronomical algorithms, adjusting its position.

[0040] In this tracker, worm gearboxes with an inherent mechanical self-locking feature are used to make the DC motors safe from damages caused by a person or environment. Also, the mentioned feature prevents the rotation of the solar panel (18) and the upper frame not within their defined rotation angles due to the deactivation of DC motors, gravity, or wind.

[0041] It should be noted that bearings (5), (6), (12), and (13) are used to minimize friction against the rotation of the solar panel (18) and the upper frame about the rotation axes (20) and (19).

[0042] The counterweight (3) is used to reduce the resistant torque (due to gravity) applied to the DC motor with worm gearbox (14).

[0043] Aluminum profiles (9) and (10) with a slope of 45 degrees are used to strengthen the vertical columns of the U-shaped structure (2).

[0044] The upper frame is attached to an aluminum profile (11). The long columns (16) and (17) are installed on the rectangular (15).

[0045] The length of the columns (16) and (17) is more than half of the length of the solar panel (18) to be long enough to provide a suitable space for the 360-degree rotation of the solar panel (18) around the axis (20).

[0046] The length of the vertical coulumns of the U-shaped structure (2) is more than half of the length of the rectangular structure (15) to be long enough to provide a suitable space for a 360-degree rotation of the upper frame around the axis (19).

[0047] All of the connections are in the form of bolts and nuts.

[0048] In this tracker, the solar panel (18) can be rotated 360 degrees about both axes, and also, due to the use of bolt-nut connections, it can be assembled, disassembled, and transported easily and quickly.

INDUSTRIAL APPLICABILITY

[0049] The presented tracker in this invention can be used to increase the efficiency of solar panels in remote or impassable areas that face problems such as the transmission of electrical energy and electricity shortage.

[0050] In this tracker, the solar panel can be rotated 360 degrees, and therefore, it will be effective in early or late hours of the day when the direction of sun rays is significantly inclined. Also, this tracker will be effective in all geographical regions, even in areas close to the North or South Poles, where the direction of the sun ray is inclined during most of the day.

[0051] This tracker can be installed on the roof of the houses or industrial units to provide the required electricity. Also, it can be redesigned to control a group of solar panels and therefore can be widely implemented in solar farms to increase the generated power.

REFERENCE SIGNS LIST

Reference to Deposited Biological Material

Sequence Listing Free Text

Citation List

[0052] PTL1: US Patent Application 2019/0190441 A1, “Dual Axis Solar Tracking System”, Publication Date: Jun. 20, 2019.

[0053] PTL2: U.S. Pat. No. 8,895,836 B2, “Dual Axis Solar Tracking Apparatus and method”, Date of Patent: Nov. 25, 2014.

[0054] PTL3: US Patent Application 2019/0253020 A1, “Solar Tracker and Solar Energy Collection System”, Publication Date: Aug. 15, 2019.

[0055] PTL4: CA Patent CA139970S, “Dual axis solar tracker”, Publication Date: Jan. 31, 2012.

[0056] NPL1: Yao, Y., Hu, Y., Gao, S., Yang, G., & Du, J. (2014). A multipurpose dual-axis solar tracker with two tracking strategies. Renewable Energy, 72, 88-98.

[0057] NPL2: Robles Algarin, C. A., Ospino Castro, A. J., & Naranjo Casas, J. (2017). Dual-axis solar tracker for using in photovoltaic systems. International Journal of Renewable Energy Research, 7 (1), 139-145.

[0058] NPL3: Alexandru, C. (2013). A novel open-loop tracking strategy for photovoltaic systems. The Scientific World Journal, pp. 1-12.

PATENT LITERATURE

[0059] As mentioned in section “Background Art”, hybrid control strategies are more effective in comparison with open-loop and closed-loop strategies. Furthermore, dual-axis solar trackers can generate more electrical energy in comparison with one-axis trackers.

[0060] In all the hybrid strategies proposed to control the motion of dual-axis solar trackers, both actuators are involved simultaneously, which reduces the efficiency of the tracker. Also, in existing dual-axis solar trackers, full rotation (360 degrees) of the solar panel around one or both axes is not possible. This makes it impossible to track the sun in some early or late hours of the day or in geographical regions, where the direction of the sun ray is inclined during most of the day. Furthermore, components in most existing dual-axis solar trackers cannot be disassembled, transported, assembled, installed, and setting up quickly and easily.

[0061] Currently, various mechanisms and control strategies have been presented for dual-axis solar trackers in patent and non-patent literature:

[0062] PTL1 discloses a mechanism for a dual-axis solar tracker that has limitations on rotation about one of the axes. The dual-axis solar tracker described in PTL2 employs an open-loop control strategy based on astronomical algorithms. Also, this patent has limitations on rotation about both axes.

[0063] PTL3 presents a dual-axis solar tracker with the azimuth-elevation mechanism. The related control strategy is in a way that both actuators are involved simultaneously and therefore power consumption of the actuator will be high that reduces the net generated electric energy.

[0064] PTL4 discloses a mechanism for a dual-axis solar tracker that has limitations on rotation about both axes. Furthermore, according to the control strategy presented in this patent, both actuators are active simultaneously that reduces the efficiency of the tracker.

Non Patent Literature

[0065] In NPL1, a mechanism for a dual-axis solar tracker is presented that has a limitation on rotation about one of the axes. Also, in this mechanism, it will be possible that in some hours of the day, the structure of the tracker cast a shadow on the solar panel that reduces the efficiency of the tracker.

[0066] In the dual-axis solar trackers presented in NPL2 and NPL3, limitations on rotation about both axes are observable.