GB2599338A

GB2599338A - Power generation system

Info

Publication number: GB2599338A
Application number: GB2008418.2A
Authority: GB
Inventors: Hyman Gordon David
Original assignee: Own Energy Ip Ltd
Current assignee: Own Energy Ip Ltd
Priority date: 2020-06-04
Filing date: 2020-06-04
Publication date: 2022-04-06
Also published as: GB202008418D0

Abstract

A power generation system 10 comprising a tubular support structure 12, a solar photovoltaic (PV) panel 16, means for connecting the solar PV panel 16 to the support structure 12, an inverter 20 and electrical connections 18 between the solar PV panel 16 and the inverter 20, and between the inverter 20 and a mains electricity supply (e.g. a grid), wherein the solar PV panel 16 comprises an active front surface, which is curved and which faces away from the tubular support 12 and a curved rear surface facing towards the tubular support 12. The tubular support structure 12 may be a lamppost. The power generation system 10 may also comprise a battery which is adapted to be charged by both the solar PV panel 16 and the grid via the inverter 20.

Description

POWER GENERATION SYSTEM

This invention relates to localised power generation systems.

Localised, or micro-power generation systems are nowadays becoming more commonplace.

The advantages of being able to generate power locally near to where it is consumed, as opposed to incurring the power losses through distribution networks, is becoming increasingly important in a world where energy is becoming scarcer and where energy costs are increasing. In addition, there is also an advantage to be had by locally generating power insofar as excess power generation can be fed into a power distribution system ("the grid") to offset any power consumed from the grid. The linking of micro-power generation sources to a larger networks is known as "feed-in" generation and this type of configuration requires an interface to ensure that the power being fed into the grid is compatible with it, and does not cause broader network disruption.

In order to ensure this, certain standards have been implemented, which place limitations on the maximum amount of power that can be exported to the grid via a single interface, and this limitation is designed to avoid excessive feed-in, which could overload consumer power networks and/or disrupt the proper operation of conventional power stations. In addition to this, the voltage and frequency of electricity being fed into the grid must also be matched to that of the grid itself to avoid causing interference issues and overloading.

These problems have been largely solved in recent years by the development of specialised feed-in inverters, which condition the power generated from a micro-generation source and convert it into a grid-compatible output power supply. For example, a solar PV panel, generating 48 VDC could be converted, via the feed-in inverter, to output 50 Hz, 220 VAC power, which is synchronised with the grid. Synchronisation is important because if power is fed-in out of phase with the power on the grid, then this could result in cancellation or superposition of the phases, thereby causing network disruption. A feed-in inverter therefore usually comprises: a DC-AC converter; a step-up transformer; and a phase-shifter/synchronizer to ensure that the power generated locally is suitably matched to the connected power grid.

In order to meter the amount of power consumed from the grid and the amount of power exported to the grid, it is commonplace for a feed-in inverter to be coupled to a metering device, which calculates the amount of energy consumed from, or fed into, the grid. In its simplest form, a feed-in meter runs in one direction (counting up) when consuming power from the grid, but operates in an opposite direction (counting down) when power is being fed into the grid. This aggregates the amount of power consumed with the amount of power fed in to give an offset, which is the difference between the amount of power consumed and the amount of power fed-in. Simple feed-in meters of this type are relatively well-known.

Our own earlier patent (EP2627900) describes an alternative type of feed-in system whereby two separate meters are provided that operate in parallel. A first meter monitors the amount of power consumed from the grid, whereas the other meter monitors the amount of power fed into the grid. This system provides a more accurate representation of the amount of power consumed and the amount of power fed-in, as well as enabling differential tariffs to be applied to power consumed versus power fed-in. This enables the end user to benefit from certain advantages, such as differential pricing, etc. From a technical standpoint, it can also more easily identify "dead" systems, that are neither powering into, nor powering off, the grid, which would otherwise be indistinguishable from devices where the feed-in and consumed power are roughly the same (a zero nett result in either case).

The aforesaid patent also describes attaching a micro-power generator, such as a wind turbine or solar PV panels, to lamp posts, which are used for powering the lamp and/or for exporting power to the grid. An accumulator or battery is incorporated into that system, which enables the device to store sufficient power during the day to run the light at night, but to export any excess power generated to the grid. In the event of a shortfall of power, power can be consumed from the grid to power the street light. The use of solar PV panels or wind turbines affixed to lamp posts, in combination with feed-in inverters, is therefore known from the prior art.

However, there are certain practical considerations that need to be considered when designing lamp post-mounted micro-generation systems.

Firstly, because most street lights are typically between 5 and 12 meters high, mounting a wind turbine or a solar PV panel at the top of that pole creates a significant lever arm when the wind is blowing. Specifically, the windage of the solar PV panel creates a strong bending movement, which can cause the lamp post to bend, or even break. This necessitates the provision of thicker wall sections in the lamp post or using specially designed lamp posts for this purpose. This therefore makes it more difficult to retrofit a local power generation system to existing street lighting and thus potentially increases capital outlay and/or wastage if street lights have to be replaced merely to incorporate a local power generation system into them.

A further consideration is that of aesthetics. In particular, certain local authorities place restrictions on the amount of adaptation that can be made to avoid ruining the "street scene". Simply adding a flat-panel solar PV panel or a wind turbine to the top of a lamp post can be aesthetically unpleasing or at the very least conspicuous.

Furthermore, to fit a solar PV panel to an existing street light requires complicated bracketry to hold the solar PV panel at the required angle to make optimum use of the instant sunlight.

A need therefore exists for a solution to one or more of the above problems, which the present invention aims to provide.

Aspects of the invention are set forth in the appended independent claim or claims. Preferred and/or optional features are set forth in the appended dependent claims.

According to a first aspect of the invention, there is provided a power generation system comprising a tubular support structure, a solar PV panel, means for connecting the solar PV panel to the support structure, an inverter and electrical connections between the solar PV panel and the inverter, and between the inverter and a mains electricity supply, wherein the solar PV panel comprises an active front surface, which comprises an at least part-curved portion that which faces away from the tubular support, and an at least part-curved rear surface facing towards the tubular support.

It will be appreciated that the provision of a solar PV panel, which wraps around the tubular support structure gives rise to a more compact design. Where the tubular support structure is, or comprises part of, a lamp post, the configuration of the invention gives rise to a more compact overall design with the solar PV panel conforming at least somewhat to the outer profile of the street light. By making the solar PV panel "hug around" the outer surface of the tubular structure, the additional windage created by adding a solar PV panel to the tubular support structure is minimised. Moreover, because the overall appearance of the lamp post is largely unaffected, the visual impact of retro-fitting a power generation system in accordance with the invention to existing street furniture is also minimised.

It will be appreciated from the foregoing that the invention addresses one or more of the aforesaid problems.

Suitably, the tubular support structure is or comprises part of a lamp post. The means for connecting the solar PV panel to the support structure may comprise a bracket. The bracket could be interposed between the rear surface of the solar PV panel and a surface of the tubular support structure. In one embodiment, there is a gap between the solar PV panel and the tubular support structure within which the inverter can be accommodated. In other embodiments of the invention, a fly lead is provided, which extends from the solar PV panel, passes through an aperture in the tubular support structure, and connects to an inverter located within the tubular support structure.

Wherein the bracket is interposed between the rear surface of the solar PV panel and a surface of the tubular support structure leaving a gap therebetween to accommodate the inverter.

Suitably, the means for connecting the solar PV panel to the support structure permits the solar PV panel to be detachably connected to the support structure. This is a useful modification because it enables the solar PV panel to be replaced/removed for maintenance, servicing, cleaning, and repair, etc. It also permits the solar PV panel to be retro-fitted to an existing tubular support structure, such as a lamp post.

Suitably, the inverter comprises a bi-directional inverter having a DC input/output side and an AC input/output side. The advantage of using a bi-directional inverter is that it enables input DC to be converted to output AC, as well as permitting input AC to be converted to output DC. This is extremely useful for a localised power generation system, where power may be being consumed at certain points in time, but exported at other times.

Suitably, the inverter is adapted, in use, to convert a DC electrical voltage output of the solar PV panel into a mains-compatible AC voltage. The mains-compatible AC voltage suitably has substantially the same polarity, phase, frequency, and RMS voltage to the mains supply to which it is connected. This ensures that the power generation system can be reliably connected to a grid supply. The mains-compatible AC voltage has substantially the same polarity, phase, frequency, and RMS voltage as the mains electricity supply to which it is connected.

Suitably, the inverter comprises a power-limiting circuit, which limits the wattage of the power fed into the mains electricity supply to a predetermined threshold value. The predetermined threshold value, or the output wattage limit, is suitably configured to correspond to a feed-in standard.

The invention utilises a solar PV panel which, of course, is only capable of generating power during daylight hours. However, street lighting is required at night time, which means that the power generated by the power generation system is not generated simultaneously with the power consumption of the street light. In addition, there may be certain days where the sun is particularly bright, and excess power is generated, whereas on other, duller days, insufficient power may be generated over a given time period to meet the requirements of a connected load.

In order to ameliorate against this, a rechargeable battery may be provided, which is connected via a supplementary connection of the inverter, and a batter charge/discharge circuit may be provided. The battery charge/discharge circuit is suitably adapted, in use, to charge the batter when the power-limiting circuit limits the wattage of the power fed into the mains electricity supply. This configuration means that when excess power is being generated above the export limit, that power is not simply wasted, but is stored in the rechargeable battery. The battery charge/discharge circuit can thus be configured to charge the battery during periods of excess power generation, and to supplement power exported to the grid by discharging the battery at other times.

Further comprising a rechargeable battery connected to a supplementary connection of the inverter, and a battery charge/discharge circuit.

Wherein the battery charge/discharge circuit is adapted, in use, to charge the battery when the power-limiting circuit limits the wattage of the power fed into the mains electricity supply.

The battery charge/discharge circuit is suitably adapted, in use, to detect the battery charge level and: upon detection of the battery charge level being below a first predetermined threshold value, to divert incoming power from the solar PV panel to charge the battery. The first predetermined threshold value may be a given discharge level, for example 20% charged and so, when the battery becomes discharged, power generated by the solar PV panel is used to re-charge the battery. The battery charge/discharge circuit may additionally or alternatively be configured such that upon detection of the battery charge level being above a second predetermined threshold value, to divert incoming power from the solar PV panel to a DC input side of the inverter. In other words, when the battery has been recharged to a sufficient level, for example, 80% charged, excess power is fed in to the DC input side of the inverter, for onward exporting to the grid, for example.

Suitably, the battery charge/discharge circuit is adapted, in use, to detect the battery charge level and the instantaneous power output of the solar PV panel. Upon detection of the battery charge level and the power output of the solar PV panel being below respective first and third predetermined threshold values, the battery charge/discharge circuit is suitably adapted to draw power from the DC output side of the inverter to charge the battery. This ensures that if the battery falls below a certain charge level and the solar PV panel has insufficient power available to recharge it, then power from the connected mains supply can be used to recharge the battery.

Additionally or alternatively, upon detection of the battery charge level being above a first predetermined threshold value and the power output of the solar PV panel being below a third predetermined threshold value, the battery charge/discharge circuit could be configured to connect the battery to the DC input side of the inverter, thereby enabling excess power generation to be exported to the grid.

A meter is suitably provided, for metering the power consumed by the power generation system and/or the power generated by the power generation system and fed into the connected mains power supply. In one embodiment, these two tasks, namely metering power consumed, and metering power exported, are performed by a single meter, which counts up or counts down, respectively, depending on the direction of energy flow. However, in a preferred embodiment of the invention, two separate meters are provided -one for metering the power consumed by the power generation system, and the other for independently metering the power generated by the power generation system and fed into the connected mains power supply. The advantage of providing two meters is that the power import/export differential can be monitored, which permits taking advantage of differential pricing/tariffs, and also for detection of non-functioning power generation systems. A "smart meter" may be provided, for exporting data regarding power consumption and power export to a remote monitoring station.

Comprising a first meter for metering the power consumed by the power generation system and a second meter for independently metering the power generated by the power generation system and fed into the connected mains power supply.

The active front surface of the solar PV panel comprises a transducer, which converts light energy into electrical energy.

The radius of curvature of the rear surface of the solar PV panel is suitably a radial offset of an outer radius of the tubular support structure. This enables the solar PV panel to be fitted around the tubular support structure snuggly, for example using a resiliently deformable bracket or cushioning device between the two. In one embodiment of the invention, the solar PV panel is affixed to the tubular support structure using a bead of sealant/adhesive and/or double-sided adhesive tape. The radial offset may be useful for accommodating such adhesion means, or even a bracket.

Suitably, the radii of curvature of the rear surface of the solar PV panel at different axial positions are radial offsets of corresponding outer radii of the tubular support structure.

Suitably, the solar PV panel comprises first and second lateral edges which are a given angle apart about a centreline of the tubular support structure; the given angle being any one or more of the group comprising: less than substantially 180 degrees; substantially 180 degrees; greater than substantially 90 degrees.

In one embodiment of the invention, the overall shape of the solar PV panel is a semi-annular extrusion, that is to say a half-tube. The advantage of this is that it extends through 180 degrees about the axis of the tubular support structure, and this enables it to capture sunlight from dawn until dusk -provided it is correctly orientated when installed. Specifically, the mid-line of the solar PV panel is suitably directed in a southerly direction in much the same way that solar PV panels are generally orientated to face South to capture the optimum sunlight. However, the precise orientation of the mid-line of the solar PV panel will depend on the latitude and longitude of the power generation apparatus's installation, and this angle/bearing can be readily ascertained by calculation, which will be well-understood to the person skilled in the art.

It is generally accepted in the art that flat solar PV panels are more efficient at capturing sunlight than curved ones are. Therefore, in one possible embodiment of the invention, the solar PV panel comprises a flat surface portion, as well as curved or faceted side edge portions. This particular configuration provides the advantage of having a flat (e.g. South-facing) portion, which is optimised for sunlight collection, whilst also having "wrap-around" wings or side parts, which conform to, or wrap around the tubular support structure. This particular configuration gives the best of both worlds, namely a flat solar PV panel, as well as the wrap-around advantages described above.

A second aspect of the invention provides a lamp post comprising a power generation system as described herein. The lamp post suitably comprises an inverter, which can be located in its base, or which can be incorporated into part of the solar PV panel itself.

Embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Figures 1-4 are, respectively, rear, perspective, side, and plan views of a power generation system in accordance with the invention; Figure 5 is a schematic internal view of Figure 2; Figures 6, 7 and 8 are, respectively, front, perspective, and plan views of an alternative configuration of the solar PV panel shown in Figures 1-5; and Figure 9 is a schematic, perspective view of an embodiment of the invention providing public Wi-Fi and EV charging.

Referring to Figures 1-5 of the drawings, a power generation system 10 in accordance with the invention comprises a tubular support structure 12, which in the illustrated embodiments, is a lamp post. The tubular support structure 12 has a base part 14, which is sunk into the ground to anchor the tubular support structure 12 in a manner that will be well-understood by the skilled reader. A wrap-around solar PV panel 16 is affixed to the tubular support structure 12, and wraps around it through 180 degrees. Typically, the vertical height of the solar PV panel 16 would be around one meter, and it typically wraps around the tube 12 through about 180 degrees. Ideally, the orientation of the solar PV panel 16 is configured to face South as indicated by the arrow shown in Figure 4.

A small aperture (not visible) is provided in the tubular support 12 to pass a fly lead 18 down inside the tube 12 and into the base portion 14, where the fly lead 18 connects to the DC input/output side of a feed-in inverter 20. The feed-in inverter 20 is suitably bi-directional, and this permits power to be exported to the grid, or imported from the grid. The inverter 20 comprises an integral metering system, which meters power exported to the grid, or consumed from the grid either independently, or as an aggregate. It also suitably comprises a smart metering system, which emits a wireless signal reporting the meter readings at intervals. An antenna 22 provided atop the tubular support structure 12 could be useful for this purpose.

Although not shown in the drawings, the solar PV panel 16 is affixed to the tubular support structure 12 by a bead of sealant/adhesive. This creates a permanent, or semi-permanent connection between the solar PV panel 16 and the underlying tubular support 12, which also prevents or inhibits the ingress of rainwater, etc., into the interior of the tube 12, via the fly lead's 18 aperture.

Referring to Figures 6, 7 and 8 of the drawings, an alternative type of solar PV panel 16 is shown in front, perspective, and plan view, respectively. Here it can be seen that the solar PV panel 16 still has the same "wrap-around" configuration as previously described, thus enabling it to be relatively easily installed on a tubular support structure, such as a lamp post. However, in this case, the solar PV panel 16 has a flat portion 24, which is suitably configured to face South, as well as curved or faceted wing portions 26, which wrap around the tubular support structure to reduce its windage and visual impact.

Further, in certain embodiments of the invention, the power generation system of the invention further comprises a wind turbine whose power output is connected to a power input of the inverter. Where the tubular support comprises a lamppost, this can conveniently position the wind turbine at an elevated position so as to efficiently capture wind energy and convert it to electrical power without the need for a separate support structure, tower or pole to be installed.

It is mostly envisaged that the invention will be incorporated into lampposts in urban areas.

There is therefore potential to use power generated by the power generation system for other uses besides, or in addition to, feed-in or powering the street light itself. The need for Wi-Fi communications in public spaces often requires the installation of Wi-Fi access points in those areas. The range of a Wi-Fi connection is strongly linked to the positioning, elevation (to increase range), and free space surrounding the Wi-Fi antenna (so as to avoid "dead spots"). The invention provides an ideal opportunity to collocate public Wi-H with power generation, and this can be accomplished, as shown in Figure 9 of the drawings, by incorporating a Wi-Fi access point 40 into the tubular support. It should be noted that incorporating a Wi-Fi access point into a streetlight could be accomplished using any lamppost-mounted power generation system, such as a wind turbine, a conventional flat-panel PV panel, or indeed a wrap-around PV panel as described herein.

The Wi-Fi access point 40 is suitably powered of a power output of the inverter and connects, via a fly lead 42, to the previously-described antenna 22, or a dedicated Wi-Fi antenna mounted atop the support tube. This configuration locates the antenna 22 at an elevation position in free space. Further, as streetlights are typically spaces 30m or so apart, it is possible to create a reliable mesh WiFi network using this embodiment of the invention.

In addition, and because streetlights are often located adjacent the kerb of pavements (sidewalks), the is an opportunity here also to provide electric vehicle (EV) charging points in streetlights incorporating the invention. It should be noted that incorporating an EV charging point into a streetlight could be accomplished using any lamppost-mounted power generation system, such as a wind turbine, a conventional flat-panel PV panel, or indeed a wrap-around PV panel as described herein. To accomplish this, as shown in Figure 10, a power output of the inverter 20 could be connected to an EV plug-in point 46, such that the charging cable 48 of an EV could be plugged into it when parked. In this embodiment, the power generation system may additionally comprise a user interface module 50, which could include a touchscreen or keypad, such that a user can pay for electricity consumed by suitable means, such as contactless payment, online payment or the like.

Here, the provision of separate feed-in and consumption meters provides the additional benefit of being able to individually meter the amount of power exported to the grid, or provided for EV charging.

It will be appreciated from the foregoing that the invention is not limited to the specifics of this description, which is merely exemplary of certain embodiments of the invention. The scope of protection is defined by the appended claims.

Claims

CLAIMS1. A power generation system comprising a tubular support structure, a solar PV panel, means for connecting the solar PV panel to the support structure, an inverter and electrical connections between the solar PV panel and the inverter, and between the inverter and a mains electricity supply, wherein the solar PV panel comprises an active front surface, which is curved and which faces away from the tubular support and a curved rear surface facing towards the tubular support.
2. The power generation system of claim 1, wherein a radius of curvature of the rear surface of the solar PV panel is a radial offset of an outer radius of the tubular support structure.
3. The power generation system of claim 1 or claim 2, wherein the radii of curvature of the rear surface of the solar PV panel at different axial positions are radial offsets of corresponding outer radii of the tubular support structure.
4. The power generation system of any preceding claim, wherein the solar PV panel comprises first and second lateral edges which are a given angle apart about a centreline of the tubular support structure; the given angle being any one or more of the group comprising: less than substantially 180 degrees; substantially 180 degrees; greater than substantially 90 degrees.
5. The power generation system of any preceding claim, wherein the means for connecting the solar PV panel to the support structure permits the solar PV panel to be detachably connected to the support structure.
6. The power generation system of any preceding claim, wherein the means for connecting the solar PV panel to the support structure comprises a bracket.
7. The power generation system of claim 6, wherein the bracket is interposed between the rear surface of the solar PV panel and a surface of the tubular support structure leaving a gap therebetween to accommodate the inverter.
8. The power generation system of any preceding claim, wherein the inverter comprises a bidirectional inverter having a DC input/output side and an AC input/output side.
9. The power generation system of any preceding claim, wherein the inverter is adapted, in use, to convert a DC electrical voltage output of the solar PV panel into a mains-compatible AC voltage.
10. The power generation system of any preceding claim, wherein the mains-compatible AC voltage has substantially the same polarity, phase, frequency, and RMS voltage as the mains electricity supply to which it is connected.
11. The power generation system of any preceding claim, wherein the inverter comprises a power-limiting circuit, which limits the wattage of the power fed into the mains electricity supply to a predetermined threshold value.
12. The power generation system of any preceding claim, further comprising a rechargeable battery connected to a supplementary connection of the inverter, and a battery charge/discharge circuit.
13. The power generation system of claim 12, wherein the battery charge/discharge circuit is adapted, in use, to charge the battery when the power-limiting circuit limits the wattage of the power fed into the mains electricity supply.
14. The power generation system of claim 12 or claim 13, wherein the battery charge/discharge circuit is adapted, in use, to detect the battery charge level and: upon detection of the battery charge level being below a first predetermined threshold value, to divert incoming power from the solar PV panel to charge the battery; and/or upon detection of the battery charge level being above a second predetermined threshold value, to divert incoming power from the solar PV panel to the DC input side of the inverter.
15. The power generation system of claim 12, 13 or 14, wherein the battery charge/discharge circuit is adapted, in use, to detect the battery charge level and the instantaneous power output of the solar PV panel and: upon detection of the battery charge level and the power output of the solar PV panel being below respective first and third predetermined threshold values, to draw power from the DC output side of the inverter to charge the battery.
16. The power generation system of claims 12 to 15, wherein the battery charge/discharge circuit is adapted, in use, to detect the battery charge level and the instantaneous power output of the solar PV panel and: upon detection of the battery charge level being above a first predetermined threshold value and the power output of the solar PV panel being below a third predetermined threshold value, to connect the battery to the DC input side of the inverter.
17. The power generation system of any preceding claim, further comprising a meter for metering the power consumed by the power generation system and/or the power generated by the power generation system and fed into the connected mains power supply.
18. The power generation system of any preceding claim, further comprising a first meter for metering the power consumed by the power generation system and a second meter for independently metering the power generated by the power generation system and fed into the connected mains power supply.
19. The power generation system of any preceding claim, wherein the active front surface comprises a transducer, which converts light energy into electrical energy.
20. The power generation system of any preceding claim, wherein the tubular support structure is, or comprises part of, a lamppost.
21. The power generation system of any preceding claim, further comprising a wind turbine connected to the inverter.
22. The power generation system of any preceding claim, further comprising an EV charging module connected to the inverter.
23. The power generation system of any preceding claim, further comprising a Wi-Fi transceiver, an antenna, and a data connection, the Wi-H transceiver acting as a Wi-H access point between the data connection and in-range Wi-Fi client devices.
24. The power generation system of any preceding claim, wherein the solar PV panel comprises a flat portion and one or more curved or faceted portions.
25. A lamppost comprising the power generation system of any preceding claim.