Lighting fixture load flicker correction

Abstract

1. A method of operating a lighting fixture, the lighting fixture having or coupled to a battery, the battery being coupled to a mains power grid via a grid charging unit, and the lighting fixture having or coupled to a solar unit, comprising the steps of: detecting whether a condition indicative of a lighting condition in an environment of the lighting fixture is below a predetermined threshold; determining whether the battery is charging; if the condition indicative of the lighting condition is detected to be below the predetermined threshold and it is determined that the battery is charging, detecting load flicker of the lighting fixture, the load flicker being due to load ripple through the battery, the load ripple being due to coupling of the grid charging unit and the battery; and if load flicker of the lighting fixture is detected, correcting the load flicker of the lighting fixture.

Description

[Technical Field]

[0001] This disclosure relates generally to load flickering in lighting fixtures, and certain embodiments relate to operating lighting fixtures to correct for such load flickering. [Background technology]

[0002] Some modern lighting fixtures include or are coupled with a battery and a solar unit (which includes one or more solar panels and a solar charge controller that couples the solar panels to the battery). Power from the solar unit can be used to charge the battery during the day and can be drawn from the battery at night, i.e., after dusk, to output light from the lighting fixture's light unit, such as an LED (light emitting diode) or LED array.

[0003] Sometimes, operators add a grid charging unit to charge the battery at night to prevent blackouts that occur when the lighting fixtures do not output light at night. Such a grid charging unit is typically installed later as an external element and is typically coupled directly to the battery.

[0004] However, although such grid charging units are not suitable for optimal charging of batteries, luminaires are usually compatible with grid charging units and allow their use, as this is considered by operators to be more convenient for customers.

[0005] However, coupling such a grid charging unit to a battery couples the battery to the mains grid, which can result in ripples in the battery charging voltage and therefore in the load output and light output that can be unpleasant for the user of the lighting fixture.

[0006] US2018238563 A1 relates to the efficient use of photovoltaic energy. The problem addressed in this document is to mitigate the problems associated with AC and DC power provided to water heating units using photovoltaic energy. US2018238563 A1 provides a technique for prioritizing the supply of energy from variable energy sources to an internal consumption system before utility grid feed-in.

[0007] WO2018007182 A1 relates to a lighting and power control system with improved dynamic response for improved light quality. WO2018007182 A1 aims to reduce ripple components by using a notch filter configured to filter out ripple frequencies in a regulated current output supplied to a load. Summary of the Invention [Problem to be solved by the invention]

[0008] It is therefore an aim of at least some embodiments of the present disclosure to address this problem. [Means for solving the problem]

[0009] Thus, in a first aspect of the present disclosure, there is provided a method of operating a lighting fixture, the lighting fixture may have or be coupled to a battery, the battery may be coupled to a mains power grid via a grid charging unit, the lighting fixture may have or be coupled to a solar unit, the method comprising: - detecting whether a condition indicative of a lighting condition in the environment of the lighting device (e.g., one or more of twilight, darkness, night, etc.) is below a predetermined threshold; - determining whether the battery is being charged; - if the condition indicative of the illumination state is detected to be below the predetermined threshold and it is determined that the battery is being charged, detecting load flicker of the lighting fixture, the load flicker being due to load ripple through the battery, the load ripple being due to coupling of the grid charging unit and the battery; and if load flicker of the lighting fixture is detected, correcting the load flicker of the lighting fixture.

[0010] It should be noted that the solar unit may include one or more solar panels and a solar charge controller coupling the battery and the solar panels, but those skilled in the art will understand that this is not necessary to understand the above method embodiments, and that the method embodiments only require the lighting fixture to be coupled to a mains power grid via a grid charging unit and include a solar unit, or to be coupled to a solar unit and include a battery, or to be coupled to a battery. It should also be understood that the lighting fixture may include a light unit configured to output light, and examples of such a light unit may include an LED (light-emitting diode) or an LED array including multiple LEDs. The grid charging unit is generally directly coupled to the battery and is not part of the lighting fixture itself, and therefore may be considered an element external to the lighting fixture. Naturally, logical decisions and operations performed by the lighting fixture may be performed by a controller. Such a controller may form part of the lighting fixture and may include, for example, a computer processor and memory, or may be, for example, a dedicated electronic hardware assembly. In another exemplary embodiment, such a controller may not be embodied within the lighting fixture, but may instead be a remote, e.g., cloud-based, computer processor with associated memory.

[0011] The expression "state indicative of the lighting state" may be interpreted as referring to a parameter or indication that represents the external situation of the light intensity in the surroundings / environment of said lighting fixture.

[0012] In an embodiment, the method may comprise maintaining the output state of the lighting fixture (i.e., the light output setting of the light unit) if load flicker of the lighting fixture is not detected or if it is determined that the battery is not charging.

[0013] It should be understood that a lighting fixture generally has an output state, i.e., a light output setting, that indicates whether the lighting fixture is emitting light or not (or, more precisely, whether the light units of the lighting fixture are emitting light or not). Furthermore, in more advanced models of the lighting fixture's state, additional output states may be considered, such as a startup state or a deactivated state, i.e., a kind of warm-up state or a cool-down state, respectively, or any other relevant state. As is well known, a lighting fixture (or, more precisely, a light unit of a lighting fixture) may emit light by driving a load, such as an LED load. This means that the output state of the lighting fixture is determined by whether the load is being driven (and, in more advanced models, how the load is being driven). This means that the output state of the lighting fixture is affected by electrical conditions to which the load is exposed, such as load ripple, which is a variation in the voltage or current applied to the load, that may result in relevant changes in the output state of the lighting fixture that are imperceptible or perceptible (to the human eye or even to a digital camera with a certain shutter frequency). In that case, the lighting fixture may suffer from, for example, load flicker. Load flicker is a situation in which the light output from the lighting fixture appears to change by periodically increasing and decreasing intensity (and optionally color). This effect on the output state of the lighting fixture is generally undesirable if it is too noticeable to the human eye or to a digital camera with a certain shutter frequency. However, if the effect is imperceptible, the output state of the lighting fixture may be maintained, which means that even if there is load ripple present across the load, the light output may be maintained because the load ripple may be deemed inconsequential to the end user of the lighting fixture.

[0014] In embodiments, the method comprises: if the condition indicative of the lighting state is not detected to be below the predetermined threshold and it is determined that the battery is being charged, adapting a charging profile of the battery of the luminaire to increase power extracted from the grid charging unit.

[0015] In an embodiment, the condition indicative of the lighting condition being below the predetermined threshold is detected by detecting a lack of photovoltaic current reaching the battery from the solar unit.

[0016] In an embodiment, the condition indicative of the lighting condition being below the predetermined threshold is detected by consulting a predetermined timetable and using a date and time clock.

[0017] In an embodiment, the step of determining whether the battery is charging is performed by measuring the state of charge of the battery to determine whether the voltage of the battery is increasing.

[0018] In an embodiment, the step of detecting load flicker of the lighting fixture comprises detecting load current ripple that deviates from the load current setpoint by more than 3.5%, preferably more than 5%.

[0019] In an embodiment, the predetermined threshold represents a cut-off between daytime, higher lighting conditions, and nighttime, lower lighting conditions.

[0020] In an embodiment, the predetermined threshold varies depending on the date and / or the season.

[0021] Further, in a second aspect of the present disclosure, there is provided a computer program comprising instructions that, when said program is executed by a computer, cause said computer to carry out a method according to any of the above embodiments.

[0022] Furthermore, in a third aspect of the present disclosure, there is provided a computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform a method according to any of the above embodiments.

[0023] Furthermore, in a fourth aspect of the present disclosure, there is provided a computing device having a processor and a memory, wherein the memory stores instructions that, when executed by the processor, cause the computing device to perform a method according to any of the above embodiments.

[0024] Furthermore, in a fifth aspect of the present disclosure there is provided a luminaire having or coupled to a battery, the battery being coupled to a mains power grid via a grid charging unit, the luminaire having or coupled to a solar unit, the luminaire comprising a controller configured to cause the luminaire to perform a method according to any preceding embodiment.

[0025] Those skilled in the art will understand that the various considerations and advantages that apply to the various embodiments of the method may be applied mutatis mutandis to the various embodiments of the computer program, the computer-readable storage medium, the computer device, and the lighting fixture. In particular, any one or more steps of the method embodiments described herein may correspond to logic and / or hardware in any of the listed elements.

[0026] In yet another aspect of the present disclosure, there is provided a method of operating a lighting fixture, wherein the lighting fixture may include or be coupled to a battery, and the battery may be coupled to a mains power grid via a grid charging unit, and the lighting fixture may include or be coupled to a solar unit, the method comprising: - detecting whether a condition indicative of a lighting condition in the lighting device's environment (e.g., any one or more of twilight, darkness, night, etc.) is below a predetermined threshold; - determining whether the battery is being charged; - if the condition indicative of the illumination state is detected to be below the predetermined threshold and it is determined that the battery is being charged, detecting load flicker of the lighting fixture, the load flicker being due to load ripple through the battery, the load ripple being due to coupling of the grid charging unit and the battery; and maintaining the output state (i.e., light output setting) of the lighting fixture if load flicker of the lighting fixture is not detected or if it is determined that the battery is not charging.

[0027] In yet another aspect of the present disclosure, there is provided a method of operating a lighting fixture, wherein the lighting fixture may include or be coupled to a battery, and the battery may be coupled to a mains power grid via a grid charging unit, and the lighting fixture may include or be coupled to a solar unit, the method comprising: - detecting whether a condition indicative of a lighting condition in the lighting device's environment (e.g., any one or more of twilight, darkness, night, etc.) is below a predetermined threshold; - determining whether the battery is being charged; - if the condition indicative of the lighting state is not detected to be below the predetermined threshold and it is determined that the battery is being charged, adapting a charging profile of the battery of the lighting device to increase power extracted from the grid charging unit.

[0028] It should be understood that any of the considerations and advantages that apply to the above more detailed embodiments of the method of the first aspect of the present disclosure may be applied analogously to the additionally provided further developed embodiments of the method of the other aspects listed immediately above.

[0029] Furthermore, in certain embodiments of any of the above methods, it should be understood that the methods may be computer-implemented. [Brief explanation of the drawings]

[0030] The present disclosure and the above-described embodiments may be more fully understood with the aid of the following detailed description of the accompanying drawings. [Figure 1] 1 shows a flow chart that schematically illustrates an embodiment of a method according to the present disclosure. [Figure 2] 1 illustrates schematically an embodiment of a lighting fixture 100 according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0031] 1 shows a flow chart that schematically illustrates an embodiment of a method 10 according to the present disclosure. The method is a method of operating a lighting fixture. The lighting fixture has or is coupled to a battery, which is coupled to a mains power grid via a grid charging unit. The lighting fixture has or is coupled to a solar unit. Please refer to the additional considerations above for details regarding the implicit presence of a solar unit, a light unit, and the optional presence of a controller, where any or all of these are necessarily or advantageously included in various embodiments.

[0032] An embodiment of the method includes the following steps.

[0033] In the first step labeled "BC?", it can be determined whether the battery is charged. Note that the label "BC?" can be interpreted as referring to the English expression "battery charging?" as a convenient abbreviation.

[0034] If it is determined that the battery is not charged, or rather, if it is determined that the battery is not being charged, no specific further measures need to be taken and the method embodiment can stop.

[0035] However, if it is determined that the battery is charged, the operation of the method embodiment can continue.

[0036] In the second step labeled "LC<T?", it is detected whether the state indicating the lighting condition in the environment of the lighting fixture is below a predetermined threshold. Note that the label "LC<T?" can be interpreted as referring to the English expression "lighting conditions less than threshold" as a convenient abbreviation.

[0037] If it is not detected that the lighting condition in the environment is below the predetermined threshold, or rather, if it is detected that the lighting condition is above the threshold, which in the industry's abbreviated expression may be called "dawn" in some embodiments, no specific further measures need to be taken and the method embodiment can stop (not shown, but this simply connects the negative "N" option from the "LC<T?" determination to the "STOP" node). In some other embodiments, instead, an explicit step labeled "ACP" may be required, which is to adapt the charging profile of the lighting fixture's battery in order to increase the power extracted from the grid charging unit. Note that the label "ACP" can be interpreted as referring to the English expression "adapting charging profile" as a convenient abbreviation.

[0038] Operation of the method embodiment may continue if a condition is detected that indicates that the lighting conditions in the environment are below a predetermined threshold, in other words, if the lighting conditions are detected to be below a threshold that is sometimes referred to as "twilight" in industry shorthand.

[0039] It should be noted that in some further developed embodiments, the thresholds and conditions may be reversed so that the cut-off for the decision is whether the lighting condition is above a given threshold, rather than whether it is below. Thus, depending on the threshold chosen and / or the meaning of "above" and "below" (i.e., "greater than" and "less than"), it is equivalent to restating the mathematical comparison made in the second step as "LC>T?" or "LC<=T?" or "LC>=T?"

[0040] It should be noted that the order of the first and second steps may in other instances be reversed, i.e., in some embodiments the second step may occur before the first step, while in some other embodiments the first step may occur before the second step. In some further developed embodiments, the first and second steps may instead be simultaneous, i.e., they may occur at the same time.

[0041] In the third step, labeled "LF?", the load flicker of the luminaire is detected. Load flicker can be attributed to load ripple through the battery, which in turn is due to the coupling of the grid charging unit and the battery. This is because inherent ripple due to the grid can pass through the grid charging unit, into the battery, and into the load, thus resulting in a perceptible ripple in the output of the load, which in the context of a luminaire is called "load flicker." Note that the label "LF?" can be interpreted as a convenient shorthand to refer to the English expression "load flickering?"

[0042] If no load flicker is detected, in other words if it is detected that there is no load flicker, no specific further action needs to be taken and the method embodiment may stop, since if the load flicker is corrected, i.e. the ripple is reduced, when the battery is not charging and therefore when the grid charging unit is not coupled to the battery, this may degrade the performance of the system (battery discharge mode + load).

[0043] However, if load flicker is detected, then method embodiments may proceed to correcting load flicker of the lighting fixture, labeled "CLF." Note that the label "CLF" may be interpreted as convenient shorthand to refer to the English expression "correcting load flickering."

[0044] Therefore, in other words, load flicker is corrected, i.e., ripple is reduced, only if a grid charging unit is present during reduced lighting conditions. An advantage is that no hardware modifications may be required. A further advantage is that the luminaire can be compatible with many readily available types of grid charging units.

[0045] Those skilled in the art will appreciate that various other embodiments may be derived from the above embodiments, in accordance with the embodiments described in the summary above and / or in accordance with the claims. Furthermore, those skilled in the art will appreciate that any or all of the above logical decisions and operations may be performed by an appropriate element of the lighting fixture, for example, a controller such as the controller described above.

[0046] Furthermore, in some further developed embodiments, any of the following preferred features may be implemented:

[0047] An example of such a preferred feature is that a condition indicative of a lighting condition falling below a predetermined threshold may be detected by detecting a lack of photovoltaic generated current reaching the battery from the solar unit.

[0048] Another example of such a preferred feature is that the detection of a condition indicative of a lighting condition falling below a predetermined threshold is done by referring to a predetermined timetable and using a date and time clock, which allows the determination to be made in a more predictable manner.

[0049] Another example of such a preferred feature is where the step of determining whether the battery is charging is performed by measuring the state of charge of the battery to determine whether the voltage of the battery is increasing.

[0050] Another example of such a preferred feature is that the step of detecting load flicker in a lighting fixture includes detecting load current ripple that deviates from the load current setpoint by more than 3.5 percent, preferably more than 5 percent, which allows correction to be initiated only when it is worthwhile, i.e., only when load flicker is likely to be noticeable by a user.

[0051] In practical implementation, the correction of load flicker may be performed by a PWM controller through PID (proportional-integral-derivative) control. The controller may be configured to determine PID components and generate new coefficients for each grid frequency, so that the controller may be configured to control the PWM of a lighting output driver (e.g., an LED driver) so that the ripple impact on the load is less than 3.5% or less than 5%. In this regard, any suitable PID algorithm may be used, and the parameters of the PID algorithm may be the voltage V and current I of the load and battery.

[0052] As merely an example of such a practical implementation, one skilled in the art may consider the following parameter settings to implement a PID control algorithm:

[0053] Measures current and voltage parameters of both the battery and the lighting / LED load.

[0054] The battery voltage and current are used to measure the battery's AH, state of charge.

[0055] Pled = Iled × Vled

[0056] Perror=SetPower-Pled

[0057] Kp=Kfactor / SetPower

[0058] Ki=0 (or other value, as this can be adjusted according to requirements)

[0059] Kfactor = 20 (to provide a faster control loop if load flicker is not detected, however, this value of Kfactor can be other than 20)

[0060] Kfactor = 5 (if load flicker above a 5% threshold is detected, this may mean a slower control loop adjusted according to the amount of load flicker observed; however, this value of Kfactor may be other than 5)

[0061] Pout = Pout + Perror × (Kp + Ki)

[0062] Set the MOSFET PWM = Pout x PwmCoff.

[0063] PwmCoff=1.0

[0064] Those skilled in the art will appreciate that the above parameter setting examples are provided merely as examples to illustrate how load flicker should be corrected, and are not intended to unduly limit the embodiments of the present disclosure.

[0065] Another example of such a preferred feature is that the predetermined threshold represents a cutoff between daytime, higher lighting conditions, and nighttime, lower lighting conditions.

[0066] Another example of such a preferred feature is that the predetermined threshold varies depending on the date and / or the season.

[0067] Another example of such a preferred feature is that the load current can be measured for at least 100 cycles to provide more assurance that it is worthwhile to initiate a correction for load flicker.

[0068] In a first exemplary embodiment, an appropriate element of the lighting fixture, such as the lighting fixture controller or the solar unit, may be configured to detect a so-called "dusk" condition, i.e., a condition indicating that the lighting conditions in the lighting fixture's environment are below a predetermined threshold. The appropriate element of the lighting fixture, such as the lighting fixture controller, may also be configured to determine whether the battery is charging. If the controller detects such a "dusk" condition and detects that the battery is still charging (e.g., by measuring the battery's state of charge, where a change in the state of charge may indicate that the battery voltage is increasing), this means that a grid charging unit (i.e., a charging unit connected to the mains grid), and thus an external current source, is likely coupled to the battery and is charging it. If, in this condition, the appropriate element of the lighting fixture, such as the lighting fixture controller, measures or detects load flicker, then the load flicker can be corrected. This can be implemented, for example, in an output load control algorithm, and the load factor of the load can be adjusted. This can be advantageously done without any communication between the lighting fixture controller and any external charging controller.

[0069] In the context of this disclosure, the controller may be considered a single integrated element, or in other examples, a combination of several separate elements, such as a solar charge controller, a load driver, and various other electronic hardware components, as described below with reference to FIG. 2.

[0070] In a second exemplary embodiment, an appropriate element of the lighting fixture, such as the lighting fixture's charging controller, may be configured to detect a so-called "dusk" condition, i.e., a condition indicating that lighting conditions in the lighting fixture's environment are below a predetermined threshold. An appropriate element of the lighting fixture, such as the lighting fixture's controller, may also be configured to determine whether the battery is charging. If the controller detects such a "dusk" condition and detects that the battery charge is neither increasing nor decreasing, the controller may be configured to detect whether any external grid charging unit is connected. The external grid charging unit may be, for example, an AC / DC SMPC (Alternating Current to Direct Current Switched Mode Power Supply). If the controller detects the presence of such a grid charging unit (e.g., because the battery voltage is not decreasing), then the controller may be configured to perform load flicker detection and correction.

[0071] In a third exemplary embodiment, an appropriate element of the lighting fixture, such as the lighting fixture's controller, may be configured to detect a so-called "dawn" condition, i.e., a condition indicating that lighting conditions in the lighting fixture's environment exceed a predetermined threshold. The appropriate element of the lighting fixture, such as the lighting fixture's controller, may also be configured to determine whether the battery is being charged with more power than the solar unit is providing. If the controller detects such a "dawn" condition, detects that the battery is being charged, and thus detects the presence of a grid charging unit, the controller may then adapt the battery's charging profile so that the battery extracts maximum power from the grid via the grid charging unit and / or from the solar unit during the "dawn" condition, i.e., only during the daytime, and remains fully charged. The advantage of charging the battery from the grid during the daytime is that once the battery is charged during the day, it can then supply the lighting load of the lighting fixture overnight without the need for an external grid charging unit. This approach may also help completely avoid the risk of load flicker from disconnecting the lighting fixture's light output from the grid.

[0072] In a fourth exemplary embodiment, an appropriate element of the lighting fixture, such as a charging controller of the lighting fixture, may be configured to detect a so-called "dusk" condition, i.e., a condition indicating that lighting conditions in the lighting fixture's environment are below a predetermined threshold. An appropriate element of the lighting fixture, such as the lighting fixture's controller, may also be configured to determine whether the battery is being charged. If the controller detects such a "dusk" condition and detects that the battery is being charged, for example, by a grid charging unit such as an external DC power source, the controller may then detect the presence of load flicker. If there is no load flicker, no correction may need to be performed.

[0073] In further developed embodiments, the luminaire may be configured to disable any new components, as these may be sized according to grid conditions and may not be required when driving normal DC loads, as these new components may otherwise pose a risk of degrading the performance of the light unit's light output driver when operating on DC.

[0074] FIG. 2 schematically illustrates an embodiment of a lighting fixture 100 according to the present disclosure. The lighting fixture 100 may include or be coupled to a battery 101. There may be a grid charging unit 102 coupled to the battery 101. The grid charging unit 102 may be powered from a mains power grid 107. The lighting fixture 100 may include or be coupled to a solar unit including at least one solar panel 103 and a solar charge controller 104, which may form part of the overall controller of the lighting fixture 100. The solar charge controller 104 may be coupled to the at least one solar panel 103 and the battery 101. The lighting fixture 100 may also include a load driver 105 configured to drive a load 106, such as an LED or LED array, although any other suitable lighting technology may be used. The lighting fixture 100 may include a controller 108 configured to identify a load current from the load 106 and to feed back a control signal to the load driver 105 to effect a change in the load output setting.

[0075] Controller 108 may be implemented as a custom electronic hardware device in some embodiments, or as one or more off-the-shelf electronic units in other embodiments. Controller 104 and controller 108 may be considered a single integrated element, or in other examples, may be considered a combination of several separate elements, and in some embodiments may even include other elements of a lighting fixture, such as load driver 105, if this is convenient.

Claims

1. 1. A method of operating a lighting fixture, the lighting fixture having or being connectable to a battery, the battery being coupled to a mains power grid via a grid charging unit, and the lighting fixture having or being coupled to a solar unit, comprising: detecting whether a condition indicative of lighting conditions in the environment of the lighting device is below a predetermined threshold; determining whether the battery is charging; detecting load flicker of the lighting fixture when the condition indicative of the illumination state is detected to be below the predetermined threshold and when it is determined that the battery is being charged, the load flicker being due to load ripple through the battery, the load ripple being due to coupling of the grid charging unit and the battery; and if load flicker of the lighting fixture is detected, correcting the load flicker of the lighting fixture.

2. 2. The method of claim 1, further comprising maintaining the output state of the lighting fixture if load flicker of the lighting fixture is not detected or if it is determined that the battery is not charging.

3. 3. The method of claim 1 or 2, further comprising adapting a charging profile of the battery of the lighting fixture to increase power extracted from the grid charging unit if the condition indicative of the lighting condition is not detected to be below the predetermined threshold and the battery is determined to be charging.

4. 4. The method of claim 1, wherein the condition indicative of the lighting condition is detected to be below the predetermined threshold by detecting a lack of photovoltaic generated current reaching the battery from the solar unit.

5. 5. The method of any one of claims 1 to 4, wherein the condition indicative of the lighting condition being below the predetermined threshold is detected by: consulting a predetermined timetable and using a date and time clock.

6. 6. The method of claim 1, wherein the step of determining whether the battery is charging is performed by measuring the state of charge of the battery to determine whether the voltage of the battery is increasing.

7. 7. A method according to any one of claims 1 to 6, wherein the step of detecting load flicker of the lighting fixture comprises detecting load current ripple that deviates from a load current setpoint by more than 3.5%, preferably by more than 5%.

8. 8. The method of claim 1, wherein the predetermined threshold represents a cutoff between daytime conditions with higher lighting and nighttime conditions with lower lighting.

9. 9. The method of any one of claims 1 to 8, wherein the predetermined threshold varies depending on the date and / or the season.

10. A computer program comprising instructions that, when said program is run by a computer, cause said computer to carry out the method of any one of claims 1 to 9.

11. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 9.

12. A computing device having a processor and a memory, the memory storing instructions that, when executed by the processor, cause the computing device to perform a method according to any one of claims 1 to 9.

13. 10. A luminaire having or connectable to a battery, the battery being coupled to a mains power grid via a grid charging unit, the luminaire having or being coupled to a solar unit, the luminaire comprising a controller configured to cause the luminaire to perform a method according to any one of claims 1 to 9.

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