Indian Patents. 272042:LED BASED SOLAR STREET LIGHT

Title of Invention	LED BASED SOLAR STREET LIGHT
Abstract	An LED based solar street light comprising a luminaire (1.1), a solar module (1.2), battery box (1.3) containing battery (2.1), charge controller (2.2) and duck to dawn controller with switch (2.3), characterized in that the luminaire has a power rating of about 6 W.

Full Text	FIELD OF THE INVENTION: The invention relates to solar powered elective lighting in general and to illumination of streets by LED based solar lights in particular. BACKGROUND AND PRIOR ART: Solar powered street lights are known in prior art. Such street lights have typically one 11 watt CFL (compact fluorescent lamp) as the light source. As generation and storage of solar electricity is relatively very costly, constant efforts were made to reduce the power consumption of the light source. Although LED have been tried successfully in domestic lighting and for low level illumination, an LED based luminaire suitable for street lights was typically rated at 20 watts so far, which made such street lights expensive, as bigger solar module as well as battery were needed. Battery size contributes greatly to the total weight of the street light as the battery is housed in a battery box which is mounted on the pole of the street light. The present invention seeks to overcome these drawbacks of the prior art. OBJECTS OF THE INVENTION: An object of the invention is to provide LED based luminaire suitable for solar powered street lights that have low power consumption. Another object of the invention is to provide solar street lights that have smaller solar modules. Yet another object of the invention is to provide solar street lights with smaller battery size. A further object of the invention is to reduce the weight of a solar street light. A still further object is to reduce the cost of a solar street light and increase life of the luminaire. DESCRIPTION OF THE INVENTION: A solar street light in the prior art requires a 70-watt solar module and a 12-volt 65 to 80 Ah lead acid battery to power an 11-watt CFL based luminaire for dusk to dawn operation. According to the invention, with the current available performance of LEDs and a proper design of the luminaire and its electronics, a LED lamp of 6 watts can replace an 11-watt CFL providing same level of illumination. With 6 watt LED lamp, a 36-watt solar module with a 12 volt 40 Ah capacity battery is sufficient for dusk to dawn operation of the street light, thereby reducing the cost of the light significantly. The recurring expenditure on the battery replacement will also reduce due to the requirement of lower capacity battery in the case of LED based light. Also as the LED's life is expected to be about 50000 to 100000 hrs of illumination, the LED lamps will run without maintenance for longer durations (a serious maintenance problem for the street lights with CFLs). According to the invention, the LED based street light luminaire is made with special care on its light output and energy consumption. Ultra bright narrow angle white LEDs of low power can be arranged in series and parallel configuration to suit the voltage of the system. A voltage control circuit is required to prevent the excess flow of current to the LEDs. Alternately, ultra bright wide angle high power white LEDs can be used to cover illumination in a larger area. However, the confinement of light to a particular area is better in narrower angle LEDs and the fraction of light escaping to the surroundings or to the sky is also reduced in the case of narrow (~20 degree) angle LEDs. The luminaire is made plane if small area illumination is required and convex if large area illumination is required. The convex angle of the LED mounted plate can be varied from 0 to 20 degrees from the tangent on the center point of the plate to get variable area illumination. For covering larger areas, wide angle high power LEDs are used. With these features, a streetlight has been devised which consumes much less energy for its operation. The invention will be described in detail with the help of the accompanying drawings. An exemplary embodiment of the invention is described, but there can be several other embodiments of the invention, all of which are deemed covered by this description. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS: Fig: 1 shows an LED based solar street light in accordance with the invention. Fig: 2 shows the schematic of the solar street light. The streetlight according to the invention has a luminaire (1.1) which has a cluster of either narrow angle LEDs of low power of about 0.1 watt each or wide angle LEDs of about 1-watt each. The LEDs are connected in series and parallel combination to provide uniform illumination on the required area on the street or pavement. The luminaire has been made convex to cover a 2.5m diameter area. The angle of the LED mounted plate has been kept around 10 degress from the tangent to the center point. A sealed maintenance free battery (2.1) of 12 Volt, 40 AH is installed in a battery box (1.3). The battery of the street light is charged with a crystalline silicon solar module (1.2). Alternatively amorphous silicon based or other thin based solar module can also be used. The module is mounted facing south on the top of the street pole and the angle of the module is kept at the latitude angle of the place where the street light is installed. A specially designed circuit is installed in the luminaire/ battery box. The circuit has a charge controller (2.2), pulsing and dusk to dawn control circuit (2.3) with switch. The circuit is powered by the battery and consumes very little power. The mounting arrangement is show in fig. 1. All components of the light are installed on a pole (1.4), which is grouted up to the required depth in the ground. The schematic of the operation of the light is shown in fig. 2. The solar module (1.2) charges the battery of the street light during the daytime through a charge controller (2.2). There are various set points and indications in the charge controller to display and control overcharging and over discharging of the battery, so that the battery does not get damaged. The glowing hours of the LED Luminaire is controlled automatically by dusk to dawn control circuit (2.3) which switches the luminaire on at dusk and off at dawn without any human intervention. WE CLAIM: 1. An LED based solar street light comprising a luminaire (1.1), a solar module (1.2), battery box (1.3) containing battery (2.1), charge controller (2.2) and duck to dawn controller with switch (2.3), characterized in that the luminaire has a power rating of about 6 W. 2. An LED based solar street light as claimed in claim 1, wherein the luminaire (1.1) has a cluster of LEDs of either narrow angle type or wide angle type, 3. An LED based solar street light as claimed in claim 1, wherein the luminaire(l.l) has an LED mounted plate which is either convex or flat. 4. An LED based solar street light as claimed in claim 1, wherein the convex angle of said LED mounted plate can be between 5 to 20 degrees from the tangent on the center point of the plate. 5. An LED based solar street light as claimed in claim 1, wherein the luminaire (1.1) has a special LED driver circuit with voltage regulation. An LED based solar street light comprising a luminaire (1.1), a solar module (1.2), battery box (1.3) containing battery (2.1), charge controller (2.2) and duck to dawn controller with switch (2.3), characterized in that the luminaire has a power rating of about 6 W.

Full Text

FIELD OF THE INVENTION:
The invention relates to solar powered elective lighting in general and to illumination of streets by LED based solar lights in particular.
BACKGROUND AND PRIOR ART:
Solar powered street lights are known in prior art. Such street lights have typically one 11 watt CFL (compact fluorescent lamp) as the light source. As generation and storage of solar electricity is relatively very costly, constant efforts were made to reduce the power consumption of the light source. Although LED have been tried successfully in domestic lighting and for low level illumination, an LED based luminaire suitable for street lights was typically rated at 20 watts so far, which made such street lights expensive, as bigger solar module as well as battery were needed. Battery size contributes greatly to the total weight of the street light as the battery is housed in a battery box which is mounted on the pole of the street light. The present invention seeks to overcome these drawbacks of the prior art.
OBJECTS OF THE INVENTION:
An object of the invention is to provide LED based luminaire suitable for solar
powered street lights that have low power consumption.
Another object of the invention is to provide solar street lights that have smaller
solar modules.
Yet another object of the invention is to provide solar street lights with smaller
battery size.
A further object of the invention is to reduce the weight of a solar street light.
A still further object is to reduce the cost of a solar street light and increase life
of the luminaire.

DESCRIPTION OF THE INVENTION:
A solar street light in the prior art requires a 70-watt solar module and a 12-volt 65 to 80 Ah lead acid battery to power an 11-watt CFL based luminaire for dusk to dawn operation. According to the invention, with the current available performance of LEDs and a proper design of the luminaire and its electronics, a LED lamp of 6 watts can replace an 11-watt CFL providing same level of illumination. With 6 watt LED lamp, a 36-watt solar module with a 12 volt 40 Ah capacity battery is sufficient for dusk to dawn operation of the street light, thereby reducing the cost of the light significantly. The recurring expenditure on the battery replacement will also reduce due to the requirement of lower capacity battery in the case of LED based light. Also as the LED's life is expected to be about 50000 to 100000 hrs of illumination, the LED lamps will run without maintenance for longer durations (a serious maintenance problem for the street lights with CFLs).
According to the invention, the LED based street light luminaire is made with special care on its light output and energy consumption. Ultra bright narrow angle white LEDs of low power can be arranged in series and parallel configuration to suit the voltage of the system. A voltage control circuit is required to prevent the excess flow of current to the LEDs. Alternately, ultra bright wide angle high power white LEDs can be used to cover illumination in a larger area. However, the confinement of light to a particular area is better in narrower angle LEDs and the fraction of light escaping to the surroundings or to the sky is also reduced in the case of narrow (~20 degree) angle LEDs. The luminaire is made plane if small area illumination is required and convex if large area illumination is required. The convex angle of the LED mounted plate can be varied from 0 to 20 degrees from the tangent on the center point of the plate to get variable area illumination. For covering larger areas, wide angle high power

LEDs are used. With these features, a streetlight has been devised which consumes much less energy for its operation.
The invention will be described in detail with the help of the accompanying drawings. An exemplary embodiment of the invention is described, but there can be several other embodiments of the invention, all of which are deemed covered by this description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Fig: 1 shows an LED based solar street light in accordance with the invention. Fig: 2 shows the schematic of the solar street light.
The streetlight according to the invention has a luminaire (1.1) which has a cluster of either narrow angle LEDs of low power of about 0.1 watt each or wide angle LEDs of about 1-watt each. The LEDs are connected in series and parallel combination to provide uniform illumination on the required area on the street or pavement.
The luminaire has been made convex to cover a 2.5m diameter area. The angle of the LED mounted plate has been kept around 10 degress from the tangent to the center point.
A sealed maintenance free battery (2.1) of 12 Volt, 40 AH is installed in a battery box (1.3). The battery of the street light is charged with a crystalline silicon solar module (1.2). Alternatively amorphous silicon based or other thin based solar module can also be used. The module is mounted facing south on the top of the street pole and the angle of the module is kept at the latitude angle of the place where the street light is installed.

A specially designed circuit is installed in the luminaire/ battery box. The circuit has a charge controller (2.2), pulsing and dusk to dawn control circuit (2.3) with switch. The circuit is powered by the battery and consumes very little power.
The mounting arrangement is show in fig. 1. All components of the light are installed on a pole (1.4), which is grouted up to the required depth in the ground. The schematic of the operation of the light is shown in fig. 2. The solar module (1.2) charges the battery of the street light during the daytime through a charge controller (2.2). There are various set points and indications in the charge controller to display and control overcharging and over discharging of the battery, so that the battery does not get damaged. The glowing hours of the LED Luminaire is controlled automatically by dusk to dawn control circuit (2.3) which switches the luminaire on at dusk and off at dawn without any human intervention.

WE CLAIM:
1. An LED based solar street light comprising a luminaire (1.1), a solar module
(1.2), battery box (1.3) containing battery (2.1), charge controller (2.2) and
duck to dawn controller with switch (2.3), characterized in that the luminaire
has a power rating of about 6 W.
2. An LED based solar street light as claimed in claim 1, wherein the luminaire
(1.1) has a cluster of LEDs of either narrow angle type or wide angle type,
3. An LED based solar street light as claimed in claim 1, wherein the
luminaire(l.l) has an LED mounted plate which is either convex or flat.
4. An LED based solar street light as claimed in claim 1, wherein the convex
angle of said LED mounted plate can be between 5 to 20 degrees from the
tangent on the center point of the plate.
5. An LED based solar street light as claimed in claim 1, wherein the luminaire
(1.1) has a special LED driver circuit with voltage regulation.

An LED based solar street light comprising a luminaire (1.1), a solar module (1.2), battery box (1.3) containing battery (2.1), charge controller (2.2) and duck to dawn controller with switch (2.3), characterized in that the luminaire has a power rating of about 6 W.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=44NfS08I6V+Zmg83//d/Cg==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

272042

Indian Patent Application Number

784/KOL/2008

PG Journal Number

12/2016

Publication Date

18-Mar-2016

Grant Date

15-Mar-2016

Date of Filing

28-Apr-2008

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO : 9/1, DJ BLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA - 700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI – 110049

Inventors:

#	Inventor's Name	Inventor's Address
1	SON PAL SINGH	C/O. BHARAT HEAVY ELECTRICALS LIMITED, REGIONAL OPERATIONS DIVISION (ROD), PLOT NO : 9/1, DJ BLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA - 700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI – 110049
2	NAGENDER SINGH	C/O. BHARAT HEAVY ELECTRICALS LIMITED, REGIONAL OPERATIONS DIVISION (ROD), PLOT NO : 9/1, DJ BLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA - 700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI – 110049
3	VIRENDRA DIXIT	C/O. BHARAT HEAVY ELECTRICALS LIMITED, REGIONAL OPERATIONS DIVISION (ROD), PLOT NO : 9/1, DJ BLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA - 700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI – 110049

PCT International Classification Number

F21S8/00; F21S9/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA