WO2021117019A1

WO2021117019A1 - Single axis solar tracker with bifacial and rod gears

Info

Publication number: WO2021117019A1
Application number: PCT/IB2020/061909
Authority: WO
Inventors: Mohammadhosein SEYYEDAN; Mostafa SEYEDAN; Mehdi AKHAVAN; Milad TAJIK; Siavash MOHEBI
Original assignee: Seyyedan Mohammadhosein
Priority date: 2019-12-14
Filing date: 2020-12-14
Publication date: 2021-06-17

Abstract

The present invention is a solar tracking system used in construction of power plants. Its driving apparatus is comprised of a combination of a small and large gear. The large gear is a curved tube with a series of holes on both sides exactly in front of each other to install the gear's bifacial teeth. The teeth are cylindrical rods which are installed through mentioned holes and remain outside from both sides. The small gear is a bifacial gear which surrounds the wheel and meshes with its teeth from both sides. This gear profile causes many advantages including maximum withstanding to loads and very low manufacturing cost. Each module row can have a driving apparatus and operate independently. However it can also link to and rotate its adjacent row to maximize the efficiency.

Description

Single axis solar tracker with bifacial and rod gears

The present claimed invention, relates to solar energy generation, and particularly to solar tracking system for rotating solar power production components toward the sun.

Power production from solar photovoltaic technology has many technical, economical, and environmental advantages. Fixed tilt solar power plants do not receive all the radiated energy and therefore do not have the required efficiency. In this regard, many solar power plants use solar trackers, particularly single axis ones to increase the yield.

Conventionally, single axis solar trackers can be classified into two categories: with distributed or central motor. In distributed motor trackers, every module row has a motor which typically is an electromotor with worm gear or an electromotor with linear actuator. In central motor trackers, a single driving apparatus rotates a group of module rows linked together and the force transfers between them by linear or rotary linkages.

For example in the US patent No. 6058930; a linear actuator rotates a group of module rows by transferring the force to linear linkages between rows. Or, in the US patent No. 8459249; a single motor rotates a group of module rows which each one has a worm gear linked to each other with rotary driving shafts.

The arts mentioned above are completely different from the present invention.

While price of solar PV technology has been coming down, solar trackers should be optimized continuously to be more efficient in terms of manufacturing, installation and operation costs.

Some problems of conventional central motor trackers are:
- Lower design flexibility and higher land preparation cost due to coordination that should be considered regarding rows linked together.
- Turning off a large part of the power plant in the event of a maintenance or failure in a motor.
- Distance between modules in the middle of each row due to presence of the linkage (lower capacity per area). Otherwise, the height of the structure should be increased (higher cost per capacity).
- Problems with cleaning vehicles which face the linkages between each row.

Distributed motor trackers don’t have the mentioned problems, but they typically should tradeoff between reliability and final cost of each motor. In this regard, they usually have complex design and high cost.

Therefore, the aim of the present invention is to reduce the costs and increase reliability simultaneously by innovations applied in its components and create a more optimal tracking system compared with existing systems.

Solar tracking system of the present invention is comprised of a driving apparatus and a structure.

Solar tracker driving apparatus consists of an electromotor, a gearbox, a combination of a small and large gear, a sensor, a limit switch, and a digital controller.

The large gear (wheel) is a curved tube (having round, square, rectangle, or any other cross section) with a series of holes on both sides exactly in front of each other to install the gear’s bifacial teeth. The teeth are cylindrical rods which are installed through mentioned holes and remain outside from both sides.

The small gear is a bifacial gear which surrounds the wheel and meshes with its teeth from both sides.

The special tooth profile designed by the inventors for these gears causes not only the excellent meshing of two gears but also their coordination with the control program of the system. Teeth of the large or small gear are used to control the angle of the solar tracker. A sensor (for ex. a proximity sensor) detects passing every tooth and signal to the controller which add 1 degree to the current angle when rotating right and reduce 1 degree when rotating left.

The large gear has another two rods at the start and the end which meet a limit switch and signal the controller the start or the end of rotating toward each direction.

The control of the tracking system is the responsibility of a programmed digital controller.

The driving apparatuses are distributed in power plant and each module row can have a driving system and operate independently. Such row is called an active row.

To maximize the efficiency or to respond to land restriction, an active row can rotate its adjacent row(s) by using an arm which transfers the force linearly. The adjacent row(s) then is called passive row(s).

The arm has two openings which solar modules place inside them at the end of their rotation. The openings are V-shaped, or U-Shaped, etc.

According to the above-mentioned points, inventive steps and advantages of the claimed invention over previous inventions will be explained:

Using the special bifacial rod tooth profile for the large gear causes maximum withstanding to loads, very low manufacturing cost, self-cleaning and lubrication-free operation, ability to inspect, and ability to replace every tooth in case of damage during work without stopping any part of the power plant.

Using bifacial small gear enhance the strength, increase reliability, balance and stabilize the movement, prevent gradual horizontal movement of the wheel over time, and cause visibility and easy operation.

Independent operation of each module row causes modularity of the system, flexibility in design and layout of the power plant. Moreover, there will be no need to zero slope of the ground or the same slope of different module rows.

By using the optional arm which also has two opening, the tracking system reaches the highest efficiency.

When an active and passive row work in pair, the system are operating at the most optimum and cost-effective situation, because the components of a driving system are shared and full capacity of it is employed. Working in pair also does not interrupt a cleaning vehicle because every row has one side to access without presence of a linkage.

When arm with two openings is used, there is no need to distance between solar modules at arm and modules crossing. Therefore, solar modules are installed next to each other with no gap and the efficiency of the power plant per unit of area will be increased. Moreover, the presence of these openings reduces the structure height and thus the cost of the structure.

Fig.1

shows the side view of a module row including the solar tracker structure and driving apparatus.

Fig.2

shows the arm that has linked an active and passive row including its parts.

Fig.3

is the front view of the solar tracker driving apparatus comprising large and small gear and shows how it is installed on the pile and gets the axis to rotate the module row.

Fig.4

shows a large gear (wheel) and the components from which it is made.

Fig.5

illustrates another example for the shape of the large gear.

Fig.6

is a close view of the bifacial profile of the small gear meshed with the wheel’s bifacial rod teeth.

Fig.7

illustrates the end of the rotation where the end indicator rod or the wheel has met the limit switch.

Fig.8

gives some examples of different geometries that the driving apparatus can be applied.

Description of reference numerals:

1: Pile
2: Bearing
3: Axis
4: Rail
5: Solar module
6: Driving apparatus
7: One row of modules (passive)
8: One row of modules (Active)
9: Arm
9.1: Handle
9.2: Pivot
9.3: horizontal link
9.4: Opening
10: Electromotor
11: Gearbox
12: Digital controller
13: Small gear
14: Large gear (wheel)
14.1: Curved tube with series of holes
14.2: Cylindrical rod teeth
14.3: End indicator rod
15: Limit Switch
16: Sensor
17: One row of modules with one motor
18: Two or more rows of solar modules with one motor and transfer arm
19: One row of double or multiple modules with one motor
20: Two or more rows of double or multiple modules with one motor and transfer arm

Solar tracker structure

The solar tracker structure in this invention consists of the following components: pile (1), bearing (2), axis (3), rail (4) and arm (9).

Piles (1) are the supporting columns which hold the whole structure and solar modules (5) on the ground. These piles are installed on a concrete foundation or driven into the ground. Bearings (2) are placed on the top of the piles. The axis (3), which can have a square, polygonal, or circular cross-section, passes through the bearings and rotate within them. The rails (4) are installed on the axis perpendicularly, and the solar modules (5) are placed on the rails.

Piles, axis, rails, and panels together are called a row (7).

The driving apparatuses (6) are distributed in the power plant and each module row can have a driving system and operate independently. Such row is called an active row (8).

To maximize the efficiency or to respond to land restriction, an active row (8) can rotate its adjacent row(s) by using an arm (9) which transfers the force linearly. The adjacent row(s) then is called passive row(s) (7).

The arm consists of a handle (9.1), pivot (9.2), and horizontal link (9.3) and transfers the force to the adjacent axis. The arm has two openings (9.4) (V-shaped, U-shaped, etc.) for solar modules to be placed inside them at the end of their rotation. By using these openings, there is no need to distance between solar modules at arm and modules crossing. Therefore, solar modules are installed next to each other with no gap, and the efficiency of the power plant per unit of area will be increased. Moreover, the presence of these openings reduces the structure height and thus the cost of the structure.

Solar tracker driving apparatus

Solar tracker driving apparatus consists of an electromotor (10), a gearbox (11), a combination of a small (13) and large gear (14), a sensor (16), a limit switch (15), and a digital controller (12).

The large gear (14) transfers the force from the small gear (13) to the solar tracker axis. The large gear (wheel) (14) is a curved tube (14.1) (having round, square, rectangle, or any other cross section) with a series of holes on both sides exactly in front of each other to install the gear’s bifacial teeth (14.2). The teeth are cylindrical rods which are installed through mentioned holes and remain outside from both sides. Using this special bifacial rod tooth profile causes maximum withstanding to loads, very low manufacturing cost, self-cleaning and lubrication-free operation, ability to inspect, and ability to replace every tooth in case of damage during work without stopping any part of the power plant.

The small gear (13) transfers the force from gearbox shaft to the large gear (14). The small gear is a bifacial gear which surrounds the wheel and meshes with its teeth from both sides. Using this bifacial gear, enhance the strength, increase reliability, balance and stabilize the movement, prevent gradual horizontal movement of the wheel over time, and cause visibility and easy operation.

The special tooth profile designed by the inventors for these gears causes not only the excellent meshing of two gears without abrasion but also their coordination with the control program of the system. Teeth of the large or small gear are used to control the angle of the solar tracker. A sensor (16) (for ex. a proximity sensor) detects passing every tooth and signal to the controller which add 1 degree to the current angle when rotating right and reduce 1 degree when rotating left.

The large gear (14) has another two rods (14.3) at the start and the end which meet a limit switch and signal the controller the start or the end of rotating toward each direction.

A digital controller (12) manages the solar tracker system. The program of this controller is developed in such a way that always the solar modules place at the best angle with rays of the sun to maximize the efficiency of the solar power plant. Using this method eliminates the need for additional equipment such as optical sensors and prevents facing related problems. The controller also has backtracking ability to prevent shadow caused by adjacent rows on each other at sunrise and sunset. In addition, this controller measures wind speed and takes the solar modules to a safe angle when the wind is strong. Furthermore, this controller detects errors and monitors solar tracking system automatically. Important and critical information of each component of the solar tracker is recorded by the controller. These logs send to a server immediately and are analyzed by an intelligent program, therefore if an error occurs, power plant operator and admin will be notified instantly, and they have the ability of online monitoring of the power plant.

The solar tracking system of this invention can be applied in different geometries:
- One row of modules with one motor (17)
- Two or more rows of solar modules with one motor and transfer arm (18)
- One row of double or multiple modules with one motor (19)
- Two or more rows of double or multiple modules with one motor and transfer (20)

This invention is used in the construction of large- or small-scale solar power plants. The use of this solar tracking system in the power plant causes the solar modules track the sun from East to West every day automatically and significantly increases the output and Investment rate of return in solar Photovoltaic power plants.

The components described in this invention have been designed to be manufactured, installed and operate, easier and more reliable, with lower cost.

This invention is applicable in both photovoltaic (PV) solar power plants and concentrated solar thermal (CSP) power plants

Claims

A system for rotating solar tracker including: an electromotor, a gearbox, a combination of a small and large gear, a sensor, a limit switch, and a digital controller; Wherein the large gear (wheel) is a curved tube (having round, square, rectangle, or any other cross section) with a series of holes on both sides exactly in front of each other to install the gear’s bifacial teeth. The teeth are cylindrical rods which are installed through mentioned holes and remain outside from both sides.
Using this special bifacial rod tooth profile causes maximum withstanding to loads, very low manufacturing cost, self-cleaning and lubrication-free operation, ability to inspect, and ability to replace every tooth in case of damage, during work without stopping any part of the power plant.
The system according to claim 1 wherein the small gear is a bifacial gear which surrounds the wheel and meshes with its teeth from both sides.
Using this bifacial gear, enhance the strength, increase reliability, balance and stabilize the movement, prevent gradual horizontal movement of the wheel over time, and cause visibility and easy operation.
The system according to claims 1 and 2 wherein the teeth of the large or small gear are used to control the angle of the solar tracker. A sensor (for ex. a proximity sensor) detects passing every tooth and signal to the controller which add 1 degree to the current angle when rotating right and reduce 1 degree when rotating left.
The system according to claims 1, 2, and 3 wherein the large gear has another two rods at the start and the end which meet a limit switch and signal the controller the start or the end of rotating toward each direction.
The system according to claims 1, 2, 3 and 4 wherein the driving apparatuses are distributed in the power plant and each module row can have a driving apparatus and operate independently.
The system according to claim 5 wherein the driving apparatus rotates the solar tracker structure including piles, bearings, axis, rails, solar modules and arm.
The system according to claim 5 and 6 wherein an arm is used to link an active row to its adjacent row(s) in order to maximize the efficiency or in response to the land restriction.
The system according to claim 7 wherein the arm consists of a handle, pivot, and horizontal link, and transfers the force to the adjacent axis.
The system according to claims 7 and 8 wherein the arm has two openings (V-shaped, U-shaped, etc.) for solar modules to be placed inside them at the end of their rotation.
By using these openings, there is no need to distance between solar modules at arm and modules crossing. Therefore, solar modules are installed next to each other with no gap, and the efficiency of the power plant per unit of area will be increased. The presence of these openings also reduces the structure height and thus the cost of the structure.
The system according to claims 1 and 2 which can be applied in different geometries:
- One row of modules with one motor
- Two or more rows of solar modules with one motor and transfer arm
- One row of double or multiple modules with one motor
- Two or more rows of double or multiple modules with one motor and transfer