GB2506850A

GB2506850A - Street light assembly comprising solar panels

Info

Publication number: GB2506850A
Application number: GB1217306.8A
Authority: GB
Inventors: Tom Marren
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-09-27
Filing date: 2012-09-27
Publication date: 2014-04-16
Also published as: WO2014048575A2; GB201217306D0; WO2014048575A3

Abstract

A street light assembly 1 comprises a pole 3 for supporting a light 5 thereon and a plurality of tracking solar panels 7 mounted on the pole. The tracking solar panels are rotatable about a pair of axes. Each tracking solar panel has a motor for causing tracking movement of the tracking solar panel and there is provided a controller 11 for causing the motor to move the tracking solar panel about its two axes to track the sun. The plurality of tracking solar panels are mounted on the pole spaced apart vertically from each other along the pole. Preferably, each of the tracking solar panels is independently moveable of the other tracking solar panels. In this way, the yield obtained from the tracking solar panels may be maximised and, advantageously, the tracking solar panels may be arranged so as not shade and interfere with each other. In use, the design may also allow smaller and more compact solar panels to be used.

Description

"A Street light assembly"

Introduction

This invention relates to a street light assembly. More specifically, the present invention relates to a street light assembly of the type comprising a pole for supporting a light thereon and a plurality of tracking solar panels mounted on the pole, the tracking solar panels being rotatable about a pair of axes, each tracking solar panel having a motor for causing tracking movement of the tracking solar panel and in which there is provided a controller for causing the motor to move the tracking solar panel.

It is known to mount tracking solar panels on utility poles. This is seen as an efficient use of space on the existing utility pole as it allows for the capture of solar power in an unobtrusive manner and obviates the need for substantial pockets of land to be put aside for use as solar farms. Furthermore, pole mounted tracking solar panels are simpler and less expensive to install than other equivalent systems such as roof mounted solar panel installations.

Typically, a single solar panel is mounted on the pole and used to power a light on the pole or used to power electronic signage for motorists. In some cases, the solar panel may be tied back into the electricity grid. One such device is the Single Panel Tracker (SPT) developed by Advanced Technology and Research Corporation of Columbia, Maryland, United States of America. This device provides a limited degree of tracking of the sun and is more efficient than alternative fixed-mount panels. However, this device appears to only provide tracking about a single axis and therefore is not entirely suitable for use with concentrated photovoltaic (CPV) solar panels thereby limiting the amount of energy that may be harvested by the solar panel. Furthermore, as the device is quasi-fixed in position, it is potentially susceptible to failure in very high winds and prone to damage with excessive snow or ice loading.

One device that addresses some of these issues is that described in US Patent Application No. US2O11/0041834 in the name of Liao. US2O11/0041834 describes a two-axes solar tracker system that may be mounted on a light pole. The system described can track the sun in two axes allowing the use of CPV panels and thereby providing more efficient energy harvesting. However, the device described does not optimise the yield potential of the pole as a maximum of only two panels can be fitted without causing shading. Furthermore, the functionality of the device is relatively limited and maintenance of the panels will be relatively time consuming and complicated to perform as maintenance will have to be performed at height unless the entire device is dismantled and removed from the pole.

It is an object of the present invention to provide a tracking solar panel that overcomes at least some of the disadvantages of the known tracking solar panels and that provides a useful choice to the consumer.

Statements of Invention

According to the invention there is provided a street light assembly comprising a pole for supporting a light thereon and a plurality of tracking solar panels mounted on the pole, the tracking solar panels being rotatable about a pair of axes, each tracking solar panel having a motor for causing tracking movement of the tracking solar panel and in which there is provided a controller for causing the motor to move the tracking solar panel, characterised in that the plurality of tracking solar panels are mounted on the pole spaced apart vertically from each other along the pole.

By having such a street light assembly, it is possible to maximize the energy capture potential (also referred to as yield potential) of the utility poles as more tracking solar panels may be mounted on the pole and these tracking solar panels will operate in a more efficient manner than many of the known solutions. By providing multiple tracking solar panels mounted spaced apart vertically on the pole, the tracking solar panels will be able to accurately track the sun without being shaded by the pole or other solar panels. Furthermore, the present invention also enables the use of smaller, more compact tracking solar panels than was heretofore the case. This also has numerous benefits including the ability to provide lighter devices that will cause less windage and will not tend to exert the same forces on the pole as other systems as well as providing a more compact, aesthetically pleasing device.

In one embodiment of the invention there is provided a street light assembly in which each of the tracking solar panels is independently moveable with respect to the other tracking solar panels. This is seen as a particularly preferred embodiment of the present invention. By having independently moveable tracking solar panels, the tracking solar panels may be manoeuvred in such a manner to ensure that they do not shade other solar panels below and may also allow the panels to be moved in and out of vertical alignment at will.

In one embodiment of the invention there is provided a street light assembly in which there are provided at least three tracking solar panels mounted on the pole and spaced apart vertically with respect to each other.

In one embodiment of the invention there is provided a street light assembly in which each of the tracking solar panels is rotatable around the pole about a first, substantially vertical axis, and is tiltable relative to the pole and that first, substantially vertical axis about a second, substantially horizontal axis. In this way, the tracking solar panels can track the position of the sun very accurately so that the tracking solar panels are substantially perpendicular to the incident rays from the sun at all times.

In one embodiment ot the invention there is provided a street light assembly in which the tracking solar panel is tiltable to and from a position substantially parallel to the vertical axis and a position substantially perpendicular to the vertical axis.

In one embodiment of the invention there is provided a street light assembly in which there are provided a plurality of LEDs mounted on the panels to provide street lighting.

This is seen as a particularly preferred embodiment of the present invention as the LED lights will be more cost effective and longer lasting than existing ballast lighting and other lighting solutions that may be in place on the pole. The LED lights can over time replace the lighting provided by the ballast or other lighting circuitry provided on the pole and therefore the unit, if retrofitted to an existing pole with lighting circuitry already mounted thereon, will reduce the cost of maintenance of the existing street lighting infrastructure as the existing lighting circuitry will become redundant. The tracking solar panels can therefore provide dual functionality, energy capture and lightin9 provision.

In one embodiment of the invention there is provided a street light assembly in which the plurality of LEDs is powered by the mains electricity supply.

In one embodiment of the invention the street light assembly is provided with an inverter and the tracking solar panels are connected to the electricity grid as electricity generators. This is also particularly preferred as the street light assemblies all effectively become electricity generators that can be used to supply electricity to nearby installations such as homes or offices. In this way, the electricity is being generated locally and there are insignificant transmission losses to consider.

In one embodiment of the invention there is provided a street light assembly in which the tracking solar panels are rotatable about a third, substantially horizontal axis which is substantially orthogonal to the first and second axes. By being able to rotate the tracking solar panel about a third axes, the solar panel may be inverted with the solar panel facing downwards towards the ground in a relatively simple manner.

In one embodiment of the invention there is provided a street light assembly in which the tracking solar panels are concentrated photovoltaic (CPV) panels and in which the CPV panels are rotatably mounted to allow rotation of the tracking solar panel through approximately 180° so that the CPV panels face towards the ground.

In one embodiment of the invention, a CPV panel's light concentrator is operable in reverse so that the CPV panel is operable as a light source with the CPV concentrator dispersing the light.

In one embodiment of the invention there is provided means to raise and lower the tracking solar panels on the pole. By being able to raise and lower the tracking solar panel on the pole, it will be easier to install and maintain the tracking solar panel.

In one embodiment of the invention there is provided an anemometer mounted on the pole in communication with the controller. By providing an anemometer, it is possible to ensure that if the wind strength rises above a predetermined threshold, the control can configure the tracking solar panels in such a manner that they will be least exposed to the elements and will be unlikely to be damaged or cause damage to the pole.

Detailed Description of the Invention

The invention will now be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawing, in which:-Figure 1 (a) is a diagrammatic representation of a street light assembly according to the invention.

Figure 1(b) is a top plan view of the street light assembly shown in Figure 1(a); Figure 2(a) is a diagrammatic representation of the street light assembly with the tracking solar panels configured to catch the midday sun; Figure 2(b) is a top plan view of the street light assembly shown in Figure 2(a); Figure 3(a) is a diagrammatic representation of the street light assembly with the tracking solar panels configured for night time operation; and Figure 3(b) is a top plan view of the street light assembly shown in Figure 3(a); Referring to Figures 1(a) and 1(b), there is shown a diagrammatic representation of a street light assembly, indicated generally by the reference numeral 1. The street light assembly I comprises a pole 3 for supporting a light 5 thereon. The street light assembly further comprises a plurality of tracking solar panels 7 mounted on the pole 3 by way of collars 9. The plurality of tracking solar panels 7 are mounted on the pole 3 spaced apart vertically from each other along the height of the pole 3.

The tracking solar panels 7 are rotatable about a pair of axes, one of which is substantially vertical and coincident with the longitudinal axis of the pole 3 and the other of which is substantially horizontal and perpendicular to the vertical axis. Accordingly, the tracking solar panels are able to track the sun along two axes, one of which allows rotation of the tracking solar panels around the pole to match the solar azimuth angle and the other of which permits tilting of the tracking solar panel relative to the vertical axis to permit tracking of the solar elevation angle. The direction of movement of the panels when tilting relative to the vertical axis is represented graphically by the dashed arrow A in Figure 1(a) and the direction of movement of the panels about the pole is represented graphically by the dashed arrow B in Figure 1(b). Each of the tracking solar panels 7 has a motor (not shown) for causing tracking movement of the tracking solar panel and there is provided a controller 11 for causing the motor to move the tracking solar panel 7.

An anemometer (not shown) is provided atop the pole 3 to measure wind speed and the controller is in communication with the anemometer. The street light assembly is provided with an inverter 13 to permit supply of electricity from each of the tracking solar panels 7 back on to the electricity grid. Cabling (not shown) is provided between each of the tracking solar panels and the inverter. There is further provided a Global Positioning System (GPS) unit and grid tie accessories (not shown) provided in the pole.

In use, the controller 11 operates the motor of each tracking solar panel 7 to correctly align the tracking solar panels 7 to the appropriate solar azimuth angle and solar elevation angle so that the plane of the tracking solar panel is substantially perpendicular to the sun's incident rays. As the sun travels across the sky, the controller operates the motor periodically so that each of the panels will track the sun, keeping the planar face of the solar panel substantially orthogonal to the incident rays of the sun. The controller will be able to use the GPS co-ordinates of the street lamp in conjunction with time and date data to calculate the likely position of the sun in the sky. As the tracking solar panel is kept substantially orthogonal to the sun's incident rays, the solar panels will be more efficient at generating electricity and preferably concentrated photovoltaic (CPV) solar panels can be used to good effect.

Advantageously, each of the tracking solar panels 7 is moveable independently of the others which will allow the controller to ensure that the lowermost and intermediate tracking solar panels are not shaded by a tracking solar panel located above them. A likely configuration of the tracking solar panels of a street light assembly that is located close to the equator at midday is shown in Figures 2(a) and 2(b). II can be seen that the three tracking solar panels are appropriately circumferentially spaced about the pole at approximately 900 offset with respect to the nearest tracking solar panel. This ensures that the tracking solar panels below are not shaded. It will be understood that the specific angle of offset is not important, what is important is that the angle of offset is sufficient so that the panels are not shaded by either the pole or a tracking solar panel located above.

Referring to Figures 3(a) and 3(b), there is shown another configuration of the tracking solar panels. The tracking solar panels 7 are each provided with at least one, but preferably several, light emitting diode (LED) lamps thereon. The light emitting diode lamps are powered by the mains supply. Alternatively, a rechargeable battery could be provided and housed within the pole. The rechargeable battery could be recharged by the tracking solar panels during the day and the battery could be used to power the LEDs by night. Preferably though, the LEDs will be powered by the mains supply and power from the solar panels during the day will be supplied to the mains through the inverter 13. The LEDs may be on the opposite, rear face of the tracking solar panel to that normally presented to the sun's rays. This will obviate the need to tilt the tracking solar panels through 180°. However, if desired, the solar panels can be rotated through 180° if the LEDs are mounted on the same face of the tracking solar panels as the face normally presented to the sun or if CPV devices are used and it is desirable to route light backwards through the CPV and use the concentrator in reverse to disperse light across a wider area. If desired, the tracking solar panels may be rotatable about a third axis, perpendicular to the first and second axes. The direction of movement of the panels about this third axis is represented graphically with reference to the movement of the lowermost panel 7 by the dashed arrow C in Figure 2(a). It is envisaged that the third axis will be substantially parallel and coincident with the longitudinal axis of the tracking solar panel. This will facilitate tracking and also can facilitate rotation of the entire tracking solar panel so that the side normally facing the sun can face downwardly at night time.

Again, in the implementation shown, the tracking solar panels are offset by approximately 90° from the nearest neighbouring tracking solar panel however this offset could be 120° to evenly space the three tracking solar panels circumferentially about the pole 3 or another desired angle depending on the geometry of the tracking solar panels 7 and the direction in which it is desired to direct the light. The tracking solar panels shown are rectangular shaped however it is envisaged that other shapes such as pie or wedge shapes could be put to good effect. In the embodiment shown in Figure 3(a), it can be seen that the three tracking solar panels and their collars have been moved upwards on the pole 3 to ensure maximum coverage area of the light from the LEDs. It will be understood that the tracking solar panels are also moveable downwards towards the base 15 of the pole 3 to allow maintenance to the tracking solar panels and easy installation of the tracking solar panels. The collars may be provided with means to releasably grip the pole or indeed a track may be provided on the pole to allow movement of the collars upwards and downwards on the pole.

The anemometer will be able to detect when the wind strength is such that it may cause damage to the tracking solar panels or the windage of the tracking solar panels is likely to cause damage to the pole. In these instances, the contioller can cause each of the tracking solar panels to assume a protection configuration, similar to that shown in Figures 2(a) and 2(b), where they are positioned so that they are least likely to be damaged or cause damage. The anemometer will also be able to detect wind direction in some instances in which case, the tracking solar panels could all be positioned on the leeward side of the pole in the shelter of the pole. The tracking solar panels can also be tilted about one or more of their axes to minimize the likelihood of damage caused by the wind.

Various other modifications could be made to the street light assembly without departing from the spirit of the invention. For example, there are three tracking solar panels in the embodiments shown however more or less than three could be provided. In addition to the above, in the embodiments described, CPV solar panels are used however PV solar panels could be used instead if desired although these will be less efficient than the CPV panels but will also be less expensive at present rates. It will be understood by the skilled practitioner that various different connections and attachments could be used to ensure that the tracking solar panels are able to track the sun about at least two axes.

Furthermore, the electrical wiring has been removed from the drawings for clarity and the implementation of the wiring would be understood by the skilled addressee. If desired a temperature sensor may be provided to determine when there is a risk of snow or ice buildup and the controller may be responsive to the temperature sensor in much the same way that it is responsive to an anemometer.

Each of the controllers may be provided with a GAS unit or alternatively, the GAS co-ordinates may be programmed into the controller on initial set up so that a dedicated GAS unit on the controller is not required. As a further alternative, the tracking system to ensure that the panels are directed towards the sun may not incorporate GAS technology. Instead, there may be provided an alternative tracking system which could be incorporated that would operate without reference or need for GAS positioning. For example, one alternative tracking system would be a system with light detection equipment and measurement equipment to continuously locate the sun and direct the panels accordingly. Furthermore, there may simply be a tracking program pre-programmed into memory accessible by the controller for causing the controller to operate the motors appropriately and cause the panels to follow a predetermined path.

The controller 11 may be provided with communication means such as a radio transceiver or other transceiver/communication device for communication with a remote control centre or to allow the controller to be remotely programmed, queried, or to allow the controller to transmit data remotely. The controller 11 could be provided with monitoring means to detect the amount of electricity generated by the tracking solar panels and this information could be transmitted to a remote control centre. The controller may have equipment to monitor the tracking solar panels and their operation as well as the operation of the LEDs and even the lightS mounted on the pole.

In this specification the terms "comprise, comprises, comprised and comprising" and the terms "include, includes, included and including" are all deemed interchangeable and should be afforded the widest possible interpretation.

The invention is in no way limited to the embodiments hereinbefore described but may be varied in both construction and detail within the scope of the claims.