Field

This disclosure relates to solar-powered streetlights.

Background

Streetlights are used to illuminate streets, roads, walkways, and public spaces. The power requirement of a single streetlight is relatively low, but the cumulative power requirement of all streetlights in an urban setting is significant.

Streetlights are typically powered using mains power. If the mains power is derived from non-renewable sources, such as coal or gas-fired power stations, this represents a significant generation of potential CO2 emissions to power the lights. The CO2 emissions can be reduced by switching to renewable power sources, but this is not always possible given the sheer amount of power required to power streetlights.

Standard mercury vapour or high-pressure sodium streetlights can be replaced with LED lights that are fitted with a battery and photovoltaic cell. The photovoltaic cell recharges the battery during the day, and the battery powers the LED light at night. On an individual basis, these LED lights are useful. However, at a mass scale, and when used for street lighting, the reliability and redundancy of these lights to ensure continuous illumination at night are lacking.

It is to be understood that, if any prior publication is referred to herein, such reference does not constitute an admission that the publication forms part of the common general knowledge in the art, in Australia, or any other country.

Summary

An embodiment provides a streetlight system comprising: a LED light; a battery for powering the LED light; a photovoltaic cell for recharging the battery; a transformer that in use converts a mains power supply down to an output having an operational voltage of the LED light; and a control unit for detecting the voltage of the battery, the control unit being configured so that when the control unit detects that the voltage of the battery is above a threshold value the LED light is powered using the battery, and when the control unit detects that a voltage of the battery is below the threshold value the LED light is powered using the output having the operational voltage of the LED light.

In an embodiment, the control unit is configured so that when the control unit detects that a voltage of the battery is below the threshold value the LED light is powered only by the output having the operational voltage of the LED light. In an embodiment, the battery cannot be recharged by the mains power supply or the output having the operational voltage of the LED light. The term “mains power supply” as used herein is to mean public or municipal power that is derived from a power station, such as that used to power streetlights and other public lighting infrastructure. The term “battery” as used herein is to mean one or more batteries and/or battery units that collectively form a battery that can supply power. For example, the battery may include a first battery module and a second battery module that are electrically connected and which together form the battery.

The control unit may be a voltage-sensitive relay. The voltage-sensitive relay may be configured to: electrically isolate the transformer from the mains power supply when the voltage in the battery is above the threshold value; and electrically connect the transformer to the mains power supply when the voltage in the battery is below the threshold value. The threshold value may be 10V. The mains power supply may have a voltage ranging from 110V to 240V. The operational voltage of the LED light may be < 48V. The transformer may be an AC/DC transformer. The streetlight system may meet Australian EMC regulations. The LED light may meet Australian EMC regulations.

The transformer and/or the control unit may be locatable towards or at a base of a light pole. The transformer and/or the control unit may be locatable towards or at a top of a light pole. The transformer may be locatable within a spigot to which the LED light is attachable to. The battery may be locatable in a pit remote from the LED light. The battery may be located in a housing or assembly that houses the LED light and the photovoltaic cell. The streetlight system may further comprise a regulator electrically connected to the photovoltaic cell and the battery. The regulator may be further electrically connected to the output having the operational voltage and the LED light. In an embodiment, the battery is connected to a plurality of LED lights. For example, a single battery may power two or more LED lights. In an embodiment, the battery may be connected to a plurality of photovoltaic cells. An embodiment of the streetlight system further comprises a surge protector that is electrically connectable to an input of the transformer. The surge protector and transformer may be mounted to one another. An embodiment provides a streetlight comprising an embodiment of the streetlight system as set forth above.

An embodiment provides a streetlight having a light pole and a LED light located towards or at a top of the light pole, the streetlight comprising: a lighting system comprising: the LED light, a battery for powering the LED light, and a photovoltaic cell for recharging the battery; a transformer that in use converts a mains power supply down to an output having an operational voltage of the LED light; and a control unit for detecting a voltage of the battery, the control unit being configured so that when the control unit detects that a voltage of the battery is above a threshold value the LED light is powered using the battery, and when the control unit detects that a voltage of the battery is below the threshold value the LED light is powered using the output having the operational voltage of the LED light, wherein the battery cannot be recharged by the mains power supply or the output having an operational voltage of the LED light.

In an embodiment, the control unit is configured so that when the control unit detects that a voltage of the battery is below the threshold value the LED light is powered only by the output having the operational voltage of the LED light. The streetlight may comprise the system as set forth above.

An embodiment provides a method of installing a LED light on a streetlight, comprising: installing on a light pole one or more components of a lighting system, the lighting system having a LED light, a battery for powering the LED light, and a photovoltaic cell for recharging the battery; connecting an input side of a transformer to a mains power supply and an output side of the transformer to the LED light; and connecting a control unit to the battery and to the transformer, the control unit being configured so that: when the control unit detects that a voltage of the battery is above a threshold value, the LED light is powered using the battery; and when the control unit detects that a voltage of the battery is below the threshold value, the LED light is powered using a voltage output from the transformer. In an embodiment of the method, the control unit is configured so that when the control unit detects that a voltage of the battery is below the threshold value the LED light is powered only by the output having the operational voltage of the LED light. In an embodiment of the method, the battery cannot be recharged by the mains power supply or the output having an operational voltage of the LED light. The method may further comprise removing an existing light that is powered by the mains power supply before the LED light is installed towards or at a top of the light pole. The step of connecting the transformer to the mains power supply may include installing the transformer towards a top of the light pole. The transformer may be installed within a spigot to which the LED light is attachable to. The step of connecting the battery to the control unit may include installing a voltage-sensitive relay that is electrically connected to the mains power supply and the battery. The LED light and the photovoltaic cell may be installed in a single step. The LED light and the photovoltaic cell may form part of a common unit. The common unit may include the battery. The battery and the LED light may be installed onto the light pole in a single step. The battery may be installed towards a base of the light pole and/or in a pit of the light pole. The battery may be installed in a cabinet.

One or more embodiments may advantageously use solar power to recharge the battery and be the primary power source to make best use of green renewable energy for the running of the LED light but only relying on the mains power supply as a redundancy back up. By not using the mains power supply to recharge the battery, one or more embodiments may advantageously eliminate the need for complex electrical systems and regulation compliance compared to situations where the mains power is used to recharge the battery.

Brief Description of Figures

Embodiments will now be described by way of example only with reference to the accompanying non-limiting Figures in which:

Figure 1 shows a schematic representation of a streetlight;

Figure 2 shows a schematic representation of an embodiment of a streetlight system;

Figure 3 shows a schematic representation of another embodiment of a streetlight system; Figure 4 shows a schematic representation of another embodiment of a streetlight system; and

Figure 5 shows a schematic representation of another embodiment of a streetlight system. Figure 6 shows a cross-sectional view of an embodiment of a connection between a LED light and a light pole. Detailed Description

Embodiments of the disclosure are directed to streetlights, specifically streetlights that use one or more LED lights.

A streetlight 10 is depicted in Figure 1. The streetlight 10 has a light pole 11 that is mounted or fixed to a ground 12. The ground 12 could also be or include a support, structure, or similar. The light pole 11 has a lower section 14 that extends from a base 24 up a short distance e.g. < 2m. The base 24 may be embedded within the ground 12. The light pole 11 also has an upper section 16 at an opposite end to lower section 14. In the embodiment shown in Figure 1 , the light pole 11 also has an extension 18 that extends away from the upper section 16. A LED light 20 is mounted to the extension 18. The extension 18 is not required in all embodiments, for example the LED light 20 could be attached directly to the light pole 11. The extension 18 could also form part of or be a mounting structure that is used to mount the LED light 20 to the light pole 11 . A pit 22 is also shown in Figure 1. The pit 22 can be used to house components of the streetlight 10, such as a transformer. The pit 22 generally has an access point where components located in the pit are accessed. The streetlight 10 as shown in Figure 1 is not drawn to scale. In an embodiment, the lower section 14 is provided with a cavity (not shown) in which components of the streetlight 10 can Be located. The cavity may be in place of or in addition to the pit 22.

The term “LED light” as used herein means one or more LED lights that can be used individually or grouped together e.g. to form a bank of lights that collectively form a light source. The term “LED light” as used herein also includes components associated with a LED lighting system such as a LED driver and LED light head.

Now referring to Figure 2, a streetlight system 100 will now be described. Streetlight system 100 has a LED light 110 that includes a LED driver 118 and a LED light head 120. The LED light head 120 can have a plurality of individual LED lights. The system 100 has a battery 112 that is electrically connected to the LED driver 118 of the LED light 110 by connection 130. The streetlight system 100 also has a photovoltaic cell 114, and a regulator 116 that electrically connects the photovoltaic cell 114 to the battery 112. In an embodiment, the LED light 110 and photovoltaic cell 114 form part of a common unit e.g. a housing that has the photovoltaic cell 114 and the LED light 110.

The streetlight system 100 also has a mains power supply 126. The mains power supply 126 varies from 110V AC to 240V AC depending on the country and power plant that supplies the mains power supply. A transformer 122 is electrically connected to the mains power supply 126. An input side of the transformer is 110V AC to 240V AC. An output of the transformer is an operational voltage of the LED light 110. In an embodiment, the operational voltage of the LED light is < 48V. For example, the operational voltage may be 48V, 24V, 12V, 6V, 3V or 1.5V. The operational voltage at the output side of the transformer 122 may be AC or DC. If the operational voltage requires DC, the transformer 122 includes an AC/DC converter. The transformer 122 may be provided with a surge protection device.

In an embodiment, a surge protector 125 is electrically connected to an input of the transformer 122. In an embodiment, the surge protector 125 and transformer 122 are mounted to one another. For example, the surge protector 125 and transformer 122 may be mounted on a structure such as a plate. Having the surge protector 125 and transformer 122 be mounted to one another may assist during installation as they can be installed simultaneously.

The streetlight system 100 is also provided with a control unit in the form of voltage-sensitive relay 124. Throughout this disclosure, the terms “voltage sensitive-relay” and “relay” are used interchangeably. Relay 124 is electrically connected to the input side of the transformer 122, optionally via surge protector 125 if used. The relay 124 is also electrically connected to the battery 112 via connection 134. The relay 124 operates so that if a voltage of the battery 112 is below a threshold value, the relay 124 is triggered to electrically connect the transformer 122 to the mains power supply 126. If a voltage of the battery 112 is above a threshold value, the relay 124 electrically isolates the transformer 122 from the mains power supply 126, preventing the transformer 122 from generating an output having the operational voltage.

A diode or set of diodes 128 are positioned on the connection 130. The connection 134 are connected to the connection 130 on an anode side of the diode 128. The output of the transformer 122 is electrically connected to the LED light 110 by connection 132. In an embodiment, and as shown in Figure 2, the connection 132 are connected to connection 130 on a cathode side of a diode 128.

The diode 128 prevents the operational voltage output from the transformer 122 from recharging the battery 112. This helps to ensure that the operational voltage output from the transformer 122 can only ever be used to power the LED light 110. Providing a diode or similar arrangement to prevents the operational voltage output from the transformer 122 from recharging the battery 112 may be advantageous for a number of reasons. First, the relay 124 is only ever operated depending on the voltage of the battery 112 and not from any feedback from the output of the transformer 122. Second, by not recharging the battery, the use of the mains power to power the LED light 110 eliminates the need for more complex electrical systems and regulation compliance compared to situations where the mains power is used to recharge the battery 112. Although diode 128 is depicted in Figure 2 as preventing the operational voltage output from the transformer 122 from recharging the battery 112, the diode 128 could be embodied in other forms, such as electrical arrangements and systems, to achieve the same outcome as using diode 128. Accordingly, the diode 128 is not specifically required in all embodiments.

In streetlight system 100, the battery 112 is the first or primary power source for the LED light 110 and is only ever charged by the photovoltaic cell 114. Only when a voltage of the battery 112 falls below a threshold value does the LED light 110 become powered using the mains power supply 126. In this way, the use of the transformer 122 and relay 124 acts to provide a backup power supply only for the LED light 110. Furthermore, only using solar power to recharge the battery 112 can also allow for the use of green renewable energy to run the LED light 110, with mains power supply 126 only acting as a redundancy backup.

The threshold value that triggers the relay 124 is dependent on the total voltage capacity of the battery 112 and the operational voltage of the LED light 110. For example, if the operational voltage of the LED light is 12V DC and the battery 112 has a 12V capacity, the threshold value to trigger the relay 124 may be 10V. It should be appreciated that the threshold value can vary depending on the specific electrical requirements of the streetlight system 100.

Although not shown in Figure 2, the streetlight system 100 further comprises a light sensor. The light sensor is used as a switch to turn the LED light 110 on at dusk and to turn the LED light 110 off at dawn. In normal operation, the battery 112 should be recharged during the day by the photovoltaic cell 114. If the battery 112 has a capacity above the threshold value when the LED light 110 is switched on, the LED light 110 will be powered by the battery 112. However, if the LED light 110 is turned on and the battery 112 has a capacity below the threshold value, the LED light 110 will be powered by the mains power supply 126. If the capacity of the battery 112 falls below the threshold value during the night, the relay 124 can be triggered so that the LED light 110 is powered by the mains power supply 126.

An advantage of streetlight system 100 is that using the mains power supply 126 as a backup power supply means that the LED light 110 can be illuminated should there be a failure with the photovoltaic cell 114 and/or battery 112. This can help to improve a reliability and a redundancy of the streetlight 10 for the occasions where the LED light 110 does not function on battery 112 power, while still allowing for the use of the photovoltaic cell 114 and battery 112 to provide the majority of the power for the LED light 110. Accordingly, streetlight system 100 can make the most of renewable power (i.e. use of battery 112 and photovoltaic cell 114) for normal operation while still having a simple redundancy system if the renewable power fails. This can help to reduce the need to rely on mains power to power the LED light 110.

The positioning of the components of the streetlight system 100 on the streetlight 10 will now be described in more detail with reference to Figure 3, Figure 4, and Figure 5, with, respectively, streetlight system 200, streetlight system 200a, and streetlight system 300. Streetlight system 200, 200a and 300 can also be considered as being, respectively, arrangement 200, arrangement 200a and arrangement 300. The components used in streetlight system 200, streetlight system 200a and streetlight system 300 are the same as those used in streetlight system 100 and streetlight 10, and therefore the like parts will be identified using the same reference numerals and will not be described again in detail.

In streetlight system 200, the mains power supply 126 is provided as underground power. The transformer 122 and relay 124 are located in the lower section 14 of streetlight 10. In an embodiment, the transformer 122 and relay 124 are located in the base 24 of the streetlight 10. In an embodiment, the transformer 122 and relay 124 are located in the pit 22. The photovoltaic cell 114, regulator 116, battery 112, LED driver 118 and LED light head 120 are located in a single unit that forms the LED light 20. Connection 130 and 132 extend from the base 24 up through the light pole 11 , through extension 18 if present, and into LED light 20. An advantage of the arrangement of streetlight system 200 is that it may be easy to retrofit existing streetlights, making access to the transformer 122 and relay 124 more accessible, which may eliminate the need for working at height equipment such as cherry pickers.

Streetlight system 200a is a modification of streetlight system 200. In streetlight system 200a, the mains power supply 126 extends up through the light pole 11 , with the transformer 122 and relay 124 being positioned in the upper section 16 or optionally the extension 18. The connection 130 and connection 132 only then need to extend a short distance to the LED light 20.

In an embodiment, the transformer 122 fits within a tube or pipe section that forms part of the extension 18. For example, as best shown in Figure 6, the LED light 20 has a socket 26 that receives a spigot 28 from the extension 18. If the extension 18 is replaced with a mounting structure, the mounting structure includes the spigot 28. In an embodiment, an inner diameter of the tube or pipe that forms part of the extension 18 is 54 mm. In the embodiment shown in Figure 6, the transformer 122 fits within the spigot 28. In an embodiment, the relay 124, and if used also the surge protector 125, also fits within the extension 18 and/or spigot 28 in addition to the transformer 122.

Streetlight system 300 shows an embodiment of another streetlight 10 arrangement. In streetlight system 300, the mains power supply 126 extends up from the ground 12 through light pole 11 into the lower section 14. In an embodiment, the relay 124, transformer 122 and regulator 116 are positioned in the lower section 14 of the light pole 11. In an embodiment, the relay 124, transformer 122 and regulator 116 are positioned in the base 24 of the light pole 11 . The battery 112 is positioned in the pit 22. The pit 22 may be a lockable pit. The pit 22 may alternatively be a ground-mounted lockable cabinet. Accordingly, the pit 22 more generally forms a cavity of location positioned near the base 24 that can accommodate components of the streetlight system 300. Having the battery 112, relay 124, transformer 122 and regulator 116 be positioned at ground level can eliminate the need for working at height equipment such as cherry pickers to service and maintain these components. This may make maintenance and servicing easier, quicker, and cheaper.

In streetlight system 300, the photovoltaic cell 114 is connected to the regulator 116 by connection 312. Photovoltaic cell 114 can be positioned anywhere that has access to sunlight. In an embodiment, photovoltaic cell 114 is mounted to the light pole 11 , the upper section 16, extension 18 and/or the LED light 20. In an embodiment, a single photovoltaic cell may be used to recharge a plurality of separate batteries 112 that are each used with a different streetlight. Whatever form the photovoltaic cell 114 takes, it is connected to the regulator 116. The LED light 110 is positioned on the upper section 16, on the extension 18 or in the LED light 20.

In streetlight system 300, the LED driver 118 is connected directly to the regulator 116 via connection 314. Connection 314 extends up through the light pole 11 and into upper section 16, extension 18 if fitted, and into the LED light 20. The LED driver 118, and thus the LED light 20/110 is connected to the battery 112 via the regulator 116.

In streetlight system 300, the battery 112 is located remote from the light pole 11 , such as in pit 22. The battery 112 is connected to the regulator 116 via connection 310. The voltage- sensitive relay 124 is connected to the battery 112 via connection 134. In this way, the voltage-sensitive relay 124 is able to detect a voltage of the battery 112. Connection 134 g branches from connection 310. The regulator 116 prevents the battery 112 from being recharged by the operational voltage output from the transformer 122. Accordingly, in streetlight system 300 the arrangement of the regulator 116 relative the transformer 122 and battery 112 replaces the need for diode 128.

To recharge the battery 112 in streetlight system 300, power generated by the photovoltaic cell 114 passes through connection 312, into regulator 116, and then into the battery 112. If the voltage-sensitive relay 124 detects that a voltage of the battery 112 is below a threshold value and then electrically connects the transformer 122 to the mains power supply 126, the operational voltage output from the transformer 122 is fed into the regulator 116. When the regulator 116 receives the operational voltage output from the transformer 122 it can trigger a switch in the regulator 116 that only directs power to the LED light 20 and also prevents voltage being sent to the battery 112 to recharge the battery 112.

In an embodiment, LED light 20 meets Australian EMC regulations. In an embodiment, streetlight system 100, 200, 200a, and 300 meets Australian EMC regulations.

Methods of installing a streetlight and street light system will now be described. In an embodiment, the streetlight 10 and/or system 100, 200, 200a, and/or 300 is installed at a greenfield site.

LED light 20 is installed on light pole 11. In an embodiment, if the light pole 11 has an existing light attached thereto, the existing light is removed before LED light 20 is installed on the light pole 11 . Installation of the LED light 20 comprises securing the LED light 20 towards or at a top of the light pole 11. If connector 18 is used, the step of installing the LED light 20 on light pole 11 includes connecting connector 18 to the light pole 11. In an embodiment, the connector 18 and LED light 20 are connected together prior to installation on the light pole 11 . In an embodiment, the connector 18 is first attached to the light pole 11 , and then the LED light 20 is connected to the connector 18. If the LED light 20 and the photovoltaic cell 114 are part of a single or common assembly/unit, they can be installed in a single step.

An input (or upstream) side of the transformer 122 is connected to a mains power supply and the output (or downstream) side of the transformer 122 is connected to the LED light 20. The output side of the transformer 122 has an operational voltage of the LED light 20. The connection of the transformer 122 to the LED light 20 is such that the battery cannot be recharged by the mains power supply or the output side of the transformer having an operational voltage of the LED light. A control unit, such as relay 124, is then connected to the battery 112 and transformer 122.

In an embodiment, the step of connecting the transformer 122 to the mains power supply includes installing the transformer 122 at or towards a top of the light pole 11 , such as in the upper section 16. In an embodiment, the surge protector 125 is installed in electrical communication to an upstream or input side of the transformer 122. In an embodiment, the surge protector 125 is installed prior to the transformer 122. In an embodiment, the surge protector 125 is electrically connected to the transformer 122 and then electrically connected to the mains power. In an embodiment, the surge protector 125 and transformer 122 are mounted to one another prior to installation. This step allows the surge protector 125 and transformer 122 to be simultaneously installed at or towards a top of the light pole 11 , such as in upper section 16.

In an embodiment, installing the transformer includes placing or mounting the transformer 122 into a spigot 28 to which the LED light 20 is then attached to.

If system 200/200a is being installed, the battery 112 and the LED light 20 are installed on or secured to the light pole 11 in a single step as the battery 112 forms part of the LED light 20 housing or assembly. If system 300 is being installed, the battery 112 is installed towards a base 14 of the light pole 11 and/or in pit 22.

Throughout this disclosure, the term “photovoltaic cell” includes within its scope a plurality of photovoltaic cells, a solar panel, and a plurality of solar panels and should not be interpreted as defining a specific type of photovoltaic cell.

Those in the art will understand that a number of variations and modifications may be made in the disclosed embodiments, all without departing from the scope of the disclosure, which is defined solely by the appended claims.

In the claims which follow and in the preceding description of the disclosure, except where context requires otherwise due to expressed language or necessary implications, the word “comprise” or variants such as “comprises” or “comprising” is used in an inclusive sense i.e. to specify the presence of the state features but not to preclude the presence or addition of further features in various embodiments