WO2016009236A1

WO2016009236A1 - Full angle solar tracker

Info

Publication number: WO2016009236A1
Application number: PCT/HU2014/000062
Authority: WO
Inventors: László RÉDEY
Original assignee: Rédey László
Priority date: 2014-07-17
Filing date: 2014-07-25
Publication date: 2016-01-21
Also published as: HU4457U

Abstract

Full angle solar tracker, that is able to rotate the solar panel holder around two axles. The tracker is powered with only one electric engine through the transmission that has two alternatively working output for adjusting the positions around the two axles. The tracking operation is based on the knowledge of the geographical location and the precise date and time. The tracking is automatically paused in poor lighted or dangerously windy conditions. The first axle is the base of the machine itself, the rotor unit encases the base and contains all of the sensitive mechanic and electric components. The device is equipped with wind sensor, ambient light sensor, rotation end position sensor, tilting end position sensor, coupling servo, coupling controller and communication module. A group of solar panel holders can be created with a fully equipped master unit and some simpler follower subunits.

Description

Full angle solar tracker

The subject of the utility patent is a full solid angle solar tracker fixture that is able to rotate the solar panel holder around two axes, its operation is executed by one electric motor through a coupling and a two-output-shaft self-locking transmission driven by a control electronics, according to a program stored in memory and based on the input signals of a ambient light sensor, a wind sensor and timer.

Solar (or photovoltaic, PV) panels are typically planar energy conversion devices thus are suitable only for giving maximum efficiency related to the solar energy per unit surface in a limited solid angle of the incident light therefore in a limited time of their operation. The Sun as the source of the energy is known to have a wide variable angle virtual trajectory not only in a day but also throughout the seasons. The previously sketched conditions are characteristically leading to the usually strong compromise on the Northern hemisphere to install the solar panels fixed in a southern orientation at an average tilt angle but this compromise gives a loss of 30-40% of the total energy yield compared to a continuous solar tracking solution. Due to the above loss and the significant cost of the PV panels it is worth investing into tracking systems. To accomplish the tracking task there are several mechanical solutions proposed with different technical level. In the simplest solution only one horizontal, vertical or tilted angle of rotation is defined and the PV panels follow the Sun's trajectory based on light sensor inputs with variable accuracy. Tracking around one axis is a cheaper and simpler compromise between fixed installation and perfect tracking. There are known dual-axis trackers as the one presented in CA2849537 (Al) - SOLAR TRACKER patent document where two motors rotate along the two axes and both axes have light intensity sensor assigned to determine elevation and asimuth values of the Sun, thus allowing for perfect tracking. The force demand of the rotation is reduced by a torsion spring by bearing a part of their weight. The disadvantage of the installation is that it is high accuracy (milirad) and needs expensive sensors plus we consider the two motor operation unnecessary as only one motor can solve the task with suitable transmission. Our objective is to simplify the implementation of the tracker structure. Our solution is based on the realisation that the movement of the Sun is perfectly calculable from astronomical data and on a certain geographic location of the installation the accurate tracking of the Sun is possible by knowing the date and time accurately without light sensing. Most of the known tracker systems have motor(s) extent to the environment therefore they must be weather-proof and more expensive.

So the proposed equipment is a full-solid-angle solar tracker that consists of a base fixed to the ground, a rotor unit attached to that rotatably and a panel holder tilted by a hinge mechanics, a tilting arm operating the panel holder and a movement mechanics unit connecting and moving relative to each-other the above parts. The panel holder is attached to the rotor unit by a hinge too. The movement mechanics is constituted by a motor and a transmission system. The transmission system has one input axis and two output axes. The transmission drives the two output axes alternatively. One of the two outputs provides rotation (asimuth) the second one drives a threaded shaft that has a nut. The nut is hinge connected to the tinting arm and the other end of the tilting arm is connected to the panel holder by hinge too. The base has a gear in horizontal plane and at least one horisontal plane and one vertical plane bearing in coaxial arrangement. The bearing supports the rotor unit, and the base gear connects to a gear on the rotating output shaft of the transmission system. The rotor unit has a housing that is closed from the top and around and the openings between the rotor and the tilting arm and the rotor and the base are sealed. The equipment has a power supply unit, a control unit, a wind sensor and an ambient light sensor connected to the control unit and at least one communication module, rotation and tilt end position sensors, motor rotation encoder, motor drive unit and a coupling drive unit. The motor is connected to the control electronics by a power unit and the coupling servo is also driven by the control electronics.

The equipment is further introduced by the following figures:

Figure 1 : Sideview of the full solid angle tracker

Figure 2: 3D perspective view of the equipment

Figure 3: schematics of the electronic system structure

As it can be seen on Figure 1 the implementation of the equipment is compact, the 1 base and the 2 rotor units are simple cylindrical structures and they surround the mechanics and electronics to protect them from the environmental impacts. There are hardly any protruding elements that minimises risks of injury and improves weather (wind) resistance. In the simplest case the 1 base and 2 rotor units can be implemented by tin galvanized mild steel tubes. Naturally the appearance of the 2 rotor unit can be different from cylindrical closed on the top side from aesthetic aspects but functionally this is the ideal and trivial implementation. The main function of the 1 base is to anchor the equipment to the ground that can be solved by concreting the lower part into the soil, by fixing the lower part to a concrete foundation or other known methods. The 1 base has at least one section that is cylindrical that guarantees that there is a uniform small gap between the also cylindrical lower part 2 rotor and the 1 base that can be sealed by rubber or other sealing to protect the internal parts from dust and splashing water. The 2 rotor unit sits on the 1 base from above as a cap. The 1 base connects to the 2 rotor at its cylindrical part in a rotatable way by means of a 4 horizontal bearing and 32 vertical bearing along the mantle of the 1 base cylinder. Alternatively the bearing can be installed elsewhere between these two mutually rotatable parts, ie. on the top side in the axis of symmetry of the 2 rotor. The 5 motor drives the two output shafts of the 6 transmission unit alternatively. The 5 motor practically can work from voltages upto 24 V. The first output shaft is the 7 rotating shaft that has a gear. In actual implementation the 7 rotating shaft co-operates with the 13 base (internal) gear fixed on the 1 base. Naturally the rotating can be implemented with a 13 base gear that is external so that the 7 rotating shaft connect to it from outside. The 8 second output shaft drives the vertical 9 threaded shaft directly or by a 14 tilting gear transmission that by rotation makes the 15 threaded nut move vertically. The 15 threaded nut is connected by a hinge to the lower end of the 10 tilting arm while its upper end is connected by a 11 panel tilting hinge to the 3 panel holder. The 3 panel holder can rotate around the 16 panel hinge (that is practically also horizontal) as depicted in Figure 1 showing lighter intermediate positions depending on the actual position of the 15 threaded nut and the 10 tilting arm.

Figure 2 shows the connection of the main subsystems in a 3D perspective. The 2 rotor has a 12 window in the movement range of the 10 tilting arm. In that 12 window the 10 tilting arm can move freely. The 12 window is protected against splashing water. The 6 transmission drives the 7 rotating shaft or the 8 second output shaft according to the control of the coupling. In the situations when there is no movement (alignment of position) the mechanics do not demand energy from the 5 motor neither from the coupling servoand because of the self locking properties without special brake or latch the PV panels are fixed against external forces. The switching between the two output shafts is solved by a coupling and the switching needs much lower energy than the energy transmitted (this can be done for example by making the direction of the switching movement perpendicular to the direction of transmitted force or torque). The 28 control unit has a 23 rotation endposition sensor and a 24 tilting endposition sensor and a 20 motor encoder input. The exact direction of the PV panels can be set by the 28 control unit counting motor rotations from the home position signalled by the endposition sensors. The PV panels are fixed to the 3 panel holder. The moving of the panels is practically executed around two perpendicular axes such as the vertical axis of 1 base and the horizontal axis of 16 panel hinge. The former makes asimuth following the latter facilitates elevation tracking.

Figure 3 explains the connection of the electronic sub-systems. Operation is controlled by the 28 control unit running all the programs necessary for full funcionality. To supply the energy a switching 27 power unit that charges its own battery by the power of the PV panels and in operation mode supplies the energy for the functions of the equipment. To clock all tasks accurately a 18 GPS receiver is utilised. The 28 control unit has inputs from 23 rotation endposition sensor, 24 tilting endposition sensor, 25 wind sensor, 26 ambient light sensor, 20 motor encoder, and outputs to the 5 motor through the 19 motor motor power unit and 21 coupling controller driven 22 coupling servo, and the 29 wifi module. Through the latter one the 28 control unit can control further 30 subunits based on its own settings and input signals. The 30 subunits differ from the master units shown on Figures 1,2 and right side of Figure 3 that those have no 25 wind sensor and 26 ambient light sensor, 18 GPS receiver module and 17 GSMGPRS module but they copy the settings of the master unit and they are not programmable individually. By this arrangement the trackers installed in a close vicinity of each-other can be implemented in a simpler and cheaper way. The 28 control unit communicates with a 29 wifi module with the 30 subunits, setting them to its own parametres. This module allows for parametres downloading for the program control and other service-modes with the help of an external 31 programming device (PC, Tablet, Smartphone, etc.) connected. The equipment can be complemented by a 17 GSM/GPRS module too, through which it can be remotely administered from anywhere.

Operation of the electronic control units:

The 28 control unit is timing all tasks based on a clock signal. The accurate time is gained by the 18 GPS receiver module with atomic clock accuracy. During the day in predetermined periods (ie 10-60 minutes) it moves the PV panels to the positions according to the known trajectory of the Sun.. The exact position of the PV panels is set from a home position given by the endposition sensors through counting of motor rotations by the 28 control unit. The 22 coupling servo is used to select if horizontal or vertical movement of the 3 panel holder will follow, this way the PV panels can be set ideally in the whole daylight period. The master unit can drive at each movement cycle the 30 subunits with wifi communication to the same orientation. This bi-directional, suitably coded communication assures the necessary security of data transmission. It is an important precondition for the proper tracking that the exact angular data dependent on the geographic location of the installation must be programmed. These settings can be changed anytime even remotely. The equipment can store the whole year's solar trajectories so can track the movements every day. There is no need for light sensing for the tracking function but the simple 26 ambient light sensor and 25 wind sensor shown here serves security and economic functions. In low light situations (cloud cover or fog) in order to minimise its own consumption the 28 control unit aligns the PV panels to a programmed angle and almost completely shuts down (sleep mode), saving the very limited energy available in this period. The system returns to normal operation automatically as light intensity normalises. The other special mode of operation is in case of heavy wind. In this case the PV panels are set to the most horizontal position to minimise wind drag and protect the mechanics. As wind lightens the system returns to normal mode automatically. The 30 subunits follow the master operation in both emergency modes and in case of lost communication they set themselves to the„storm" position until communication is reset to protect the system and PV panels from mechanical damages. Setting and programming of the equipment is possible on the spot and/or remotely in case a GSM module is installed. In the latter case telemetric data can be retrieved remotely so comfortable and secure remote administration is a choice.

The proposed equipment has advantages over the known one- or two-axes, intensity sensor based, solar trackers by reduced number of motors, simple building blocks built control unit and control system and encapsulation of the environmentally sensitive elements.

List of references - base

- rotor

- panel holder

- horizontal bearing

- motor

- transmission

- rotating shaft

- second output shaft

- threaded shaft

0- tilting arm

1- panel tilting hinge

2- window

3- base gear

4- tilting gear

5- threaded nut

6- panel hinge

7- GSMGPRS module

8- GPS receiver module

9- motor power unit

0- motor encoder

1- coupling controller

2- coupling servo

3- rotation endposition sensor

- tilting endposition sensor

5- wind sensor

- ambient light sensor

- power unit

8- control unit - wifi module

- subunits

- programming device- vertical bearing

Claims

Terms of claim

1. Full solid angle solar tracking fixture, that consists of a base (1) ficed to the ground, rotor (2) connected to that in a rotatable way, a panel holder (3) hinged to the rotor (2), tilting arm (10) and a mechanics connecting these above elements and moving them against each-other, characterised by, the movement mechanics made from one motor (5) and a transmission (6), the transmission (6) having one input shaft and two output shafts (7,8), the two output shafts (7,8) are alternatively driven, the first output shaft is the rotating shaft (7), to the second output shaft (8) a threaded shaft (9) is attached, the threaded shaft (9) drives a threaded nut (15), the threaded nut (15) connects by a hinge to one end of the tilt arm (10), the other end of the tilt arm (10) connects to the panel holder (3) with the help of a panel tilting hinge (11), on the base (1) there is a base gear (13) in horizontal plane, and a bearing system (4) coaxial to that, to the bearing system (4) connects the rotor (2), to the base gear (13) the rotating shaft (7) connects with a gear, the rotor (2) has a housing closed around and atop, the openings between the rotor (2) and tilting arm (10) and between the rotor (2) and base (1) are sealed, the equipment has a power unit (27), a control unit (28), to the control unit (28) there is a wind sensor (25) and an ambient light sensor (26) are connected, at least one communication module, one rotation endposition sensor (23), one tilting endposition sensor (24), one motor encoder (20), one motor power unit (19), and a coupling controller (21), the motor (5) connects to the control unit (28) through a motor power unit (19) and connects to the coupling servo (22) through a coupling controller (21).