A solar structure

Abstract

A solar structure comprising roof 2 and front wall 3 curved around the roof, and comprising upwardly and downwardly facing panels, some of which are solar panels 6, 7. The upwardly and downwardly facing panels alternate with respect to one another to form a concertina structure and the roof comprises solar panels 9 facing towards the solar structures wall. The front wall is 3 metres high. The structure comprises a first module having a front wall portion with solar panels and roof portions having a parallel sided footprint. Second modules each comprise a front wall portion with solar panels and roof portions having a wedge-shaped footprint. The first module is flanked by second modules to form the curved shape of the structure. The solar structures may be used in stations (e.g., petrol stations and service stations) to provide electric vehicle charging which may be connected to an external grid.

Description

The present invention relates to a solar structure. In particular, it relates to a solar structure which is suitable for providing charging to electric vehicles. A sharp increase in the number of electric vehicles has created significant pressure on the electric vehicle charging network. In order to shorten the recharging time of an electric vehicle to a level convenient for users, high power (150 to 400kW) chargers are preferred. Although these can provide very quick charging times, the total power and energy requirement from the local infrastructure puts strain on the distribution grid from which it derives its power. In many cases, this requires extensive commissioning of new distribution infrastructure which is time consuming and costly. Also, even if vehicle chargers are supplied with energy which has been generated by a renewable source, this is competing with other demands for a finite amount of renewable energy. The present invention addresses these issues. According to a first aspect of the invention, there is a solar structure according to claim 1. Traditional solar generation requires large areas of land in order to generate significant electrical output. By providing solar panels on a structure which has been designed to optimise power generation in a given footprint, the space requirement can be significantly reduced. This high-density solar generation can generate sufficient power in a relatively small area (a reduction in space estimated at 3x in the summer and 10x in the winter) to be a commercially viable vehicle charging site where there is not enough space available locally to generate sufficient power using a conventional solar array. This provides a cost effective way to address the shortage of chargers. It also provides an easily scalable structure which can be deployed in areas of high demand without requiring upgrades to higher voltage substations and other costs. The approach taken by the present invention is to provide a solar generating structure from which the power can be used directly, for example, to recharge electric vehicles. The demands on the localised distribution infrastructure are reduced and may be eliminated entirely. By generating electricity directly at the point of use, transmission losses are reduced to a negligible level. The structure also creates new renewable energy rather than using existing renewable energy. In practice, the structures could be used at various sites on a road network but can be more closely spaced than existing petrol stations / service stations, but with each site having a smaller capacity / cost. This provides highly distributed generation bringing additional convenience to electric vehicle drivers to be able to recharge at a location convenient for them. Even with a rapid charge, it is likely to take at least 10 minutes in order to charge a vehicle battery to a reasonable extent. The structure can therefore be configured to accommodate facilities which provide revenue generating possibilities for the operator. The curved nature of the wall structure and arrangement of solar panels on the roof is configured to ensure a reasonably uniform level of charging throughout the day and throughout the year. In conventional solar farms, the panels are aligned in the same direction as the intention is to maximise total power generation. In the present case, the most important factors are to optimise generation within the available footprint and to generate power more uniformly across the day / year in order to more closely match the demand. When the sun is lower in the sky, the front wall does a higher proportion of the generation, while a lower proportion is done by the roof. This reverses when the sun is higher in the sky. As the sun tracks across the sky, it will track across the front wall such that one curved end generates a higher proportion of the power in the morning and there is a gradual transition across the front wall to the opposite curved end late in the day. The concertina structure of the front wall has further efficiencies as light which enters this structure may be directly absorbed by the first panel that it impinges upon. Any reflected light will be reflected back towards the facing panel which will absorb a significant proportion of this. Preferably the upwardly and downwardly facing panels are solar panels. However, it is possible that at least some of one set of these panels will be reflective panels to reflect light towards the opposite panel. The panels in the front wall may be single sided. However, preferably, the front wall is formed of double-sided solar panels. These allow additional generation from light which has entered the structure. A number of features may be provided to maximise the amount of light entering the solar structure and create a reflectivity chamber within the structure to maximise the light which will impinge on the rear of the front wall. For example, the front wall may have light transmissive gaps between the solar panels. These gaps may be left open in order to provide air flow through the structure or may be filled with a light transmitting material. There may be an intermediate wall within the structure with a reflective surface facing the front wall. This directs light which has entered the structure back towards the rear of the front wall. This may be achieved by painting the reflective surface with a light coloured paint and / or using other reflective materials. Preferably the reflective surface has a reflectivity giving the paint its total solar reflectance (TSR) rating of at least 75 (out of 100), preferably at least 95 out of 100 tested to International standard ASTM C-1549 or ASTM E-903. Its high total solar reflectance (TSR) will reduce or eliminate the absorption of heat to the facade beneath the reflective surface so the interior temperatures stay low, helping to cool the structure and maintain the operating temperatures of the solar panels. While regular white-painted surfaces absorb around 25 per cent of the sun’s rays (giving a TSR of 75), high reflectivity coatings outperform this with preferably only 5 per cent absorbed (giving a TSR of 95) and the rest reflected into the energy generating interior solar surfaces. The roof may be made of a non-opaque material and / or is open or partially open. Ideally, the roof should be made from a material which provides the required structural strength, while being as light transmissive as possible at a reasonable cost. It may, for example, be formed of ETFE or a transparent polycarbonate. In order to further improve the generating efficiency of the structure, it preferably includes a reflective layer applied to the ground in the region in front of the front wall. Such a reflective layer is preferably more than 0.5m wide, more preferably more than 2m wide and should extend across as much as possible of the perimeter of the front wall as permitted by the surroundings. The reflective layer should preferably extend for at least 70%, more preferably at least 80% of the perimeter of the front wall. If possible it should extend for the full perimeter of the front wall. In practice, the reflective layer can provide an efficiency improvement of 3 to 15%. This reflective layer is particularly effective with the concertina structure of the front wall as the downwardly facing panels are ideally positioned to receive the light reflected from the reflective layer. The reflective layer preferably has a high total solar reflectance (TSR) rating of at least 75 (out of 100), preferably at least 95 out of 100. It can be made of the same materials as the reflective surface discussed above. As mentioned above, the structure is designed to provide a much higher density output than for a conventional solar array. A typical structure would have a footprint (excluding the reflective layer) of 580 m2 and generate a peak power of 290kw. Preferably the structure has a peak power output of greater than 400w / m2, more preferably greater than 500w / m2, with the area being measured as the area of the footprint of the structure. This area measurement should exclude the area of the reflective layer. We estimate, for example, that a typical structure that is 50m wide can generate a total of over 250kwh per day in winter and over 1 Mwh per day in the summer. The structure may be built as a single unit. However, preferably, the structure is modular. A modular structure has significant advantages in terms of ease of assembly. Also, the modular structure allows the size of the structure and hence its output to be optimised to meet the local demand. In order to increase the power output of the structure, it is simply a matter of including additional modules. Preferably the structure is formed of at least one first module having a front wall portion with at least one solar panel and at least one roof portion and having a parallel sided footprint, and a plurality of second modules, each having a front wall portion with at least one solar panel and at least one roof portion and having a wedge-shaped footprint, wherein the at least one first module is flanked by second modules to form the curved shape of the structure. Typically, the structure will have a fixed number of second modules at either end in order to form the curved part of the front wall. It will then have a variable number of first modules between the two ends and this will determine the size of the structure and its power output and the number of vehicles it can serve. Preferably, each first module is at least 2m wide. This means that the width of each first module can correspond to the width of a parking space. Thus, the structure can be designed by estimating the number of vehicles that will be visiting the structure. The second modules can provide the requirements for a number of vehicles at either end of the structure, while the number of first modules corresponds to the number of additional vehicles to be accommodated. Each module may be transported to the site as a fully formed component and may be in a number of components. For example, it may take the form of a roof panel, a number of supports, and the solar panels for the front wall which may then be assembled to form a complete module which is connected to adjacent modules to form the structure. Although the solar panels on the roof may also be provided as part of the module, the current preference is to form an array of solar panels on the roof once it has been constructed from the modules. This allows the roof to be configured with all of the solar panels parallel to one another. This provides the most efficient way of generating from the roof mounted panels. Each module preferably has a peak electrical power output of derived from the solar panels of greater than 6Kw. Each module is configured to dispense co-generated solar energy of at least 24kwhper module Depending on the time of year and the frequency of users, the module may dispense previously stored or imported energy. In the simplest sense, the structure may be a standalone structure with no connection to an external grid such that all of the power generated is consumed locally. Such a structure would be suitable for remote locations. At an intermediate level, as well as generation for electric vehicles, the structure may also provide power for a small local community. Preferably the structure includes an external grid connection for power import and export. This reduces the requirements on the distribution infrastructure thereby eliminating expensive upgrades referred to above. It is also able to smooth out any mismatch between generation and demand by importing or exporting power as necessary. In its simplest form, the solar structure can provide power directly to the charging point or can export this power to a grid or to external storage. Preferably, however, the structure incorporates at least one battery to selectively receive power from the solar panels. This allows localised storage of the power in order to assist in matching the demand. The power generated by the solar structure can be exported to an external site either via the grid, or via a local network to be used elsewhere. However, preferably, the structure includes at least one vehicle charger. The vehicle charger may be configured to receive power either directly from the solar panels, or from the battery. However, preferably, the charger is connected to an external grid allowing charging from the external grid. This allows the charging to continue even when the demand exceeds supply and any stored power has been depleted. Preferably, the structure contains at least one retail unit. Preferably, the structure contains at least one plant. As well as having an aesthetically pleasing appearance, plants can help lower the temperature in the structure, which is not only beneficial for user comfort, but also reduces peak temperatures which improves the efficiency of the solar panels. Ideally, the power consumption of the solar structure itself should be as low as possible, to ensure that the maximum amount of power generated is available for vehicle charging. Preferably, the structure has at least one door which is selectively closable to regulate the temperature within the structure. This can reduce or eliminate the need for heating and / or air conditioning. The modular nature of the structure forms a second aspect of the present invention which is defined as a curved modular solar structure according to claim 18. This solar structure can have the concertina structure of solar panels of the first aspect and any of the suitable preferred features referred to above. An example of a solar structure in accordance with the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of the solar structure; Figure 2 is a rear view of the solar structure; Figure 3 is a front view of the solar structure; Figure 4 is a schematic cross-section through a central plane of the solar structure; and Figure 5 is a plan view of the solar structure. In terms of the general layout, the structure comprises an elongate front wall 1 made of solar material as described below in greater detail and a roof 2 which is supported by a front wall 1 via a plurality of vertical poles P arranged along the front wall 1. An intermediate wall 3 (shown in Fig. 1 in two separate sections) spaced from the front wall 1 provides further support of the roof 2. Other structural supports may be provided. The structure is formed as a modular construction from a number of straight modules 4 and a number of wedge modules 5 as best shown in Figure 1. The straight modules 4 form the central region of the structure, while the wedge modules 5 form curved ends. The overall size of the structure is determined largely by the number of straight modules 4 used. Typically, the structure has a width of 20-30m, an internal height of 4-6m and a variable length of from 20m for the smallest structure to 85m for the largest, although any length could be created if needed. As shown in Figure 1, each straight module 4 corresponds to a parking space S. Two additional spaces S at each end are associated with the wedge modules 5. In general, the wedge modules 5 subtend a total angle of between 60 to 80° at each end with each wedge module 5 subtending an angle of between 10 to 20°. Additional modules may be provided to create a larger angle, but there will be a drop off in the generation of additional modules. The structure is designed to be south facing if it is used in the northern hemisphere and north facing in the southern hemisphere. The structure should ideally be sited in an area devoid of objects such as trees or high buildings which would shade the structure. It is therefore well suited to roads in rural areas. Where a road runs generally east to west, the structure can be sited parallel to the road. For other road directions, the structure can be mounted at an angle to the road, or a slip road can be formed, and the structure can be sited on that. The structure can be used in a more urban environment, but more careful positioning is required. It could, for example be installed on top of an existing structure such as a multi storey car park. The front wall 1 is form of a plurality of upwardly facing solar panels 6 and a plurality of downwardly facing solar panels 7 arranged in a concertina configuration. The panels are typically angled at 30° to the horizontal (although this may be varied). In an alternative construction, the upwardly 6 or downwardly 7 facing solar panels can be replaced with reflectors, so that, rather than directly generating electrical energy, the reflector reflects the light onto the solar panel opposite. In order to further enhance the efficiency of the structure, a reflective surface 8 several metres wide is provided on the ground directly in front of the front wall 1. The roof 2 is provided with an array of solar panels 9. These may have a conventional solar panel structure and be mounted at 30° (although this may be varied) in a conventional manner. As will be appreciated from Figure 5, although the array of solar panels 9 cover almost all of the roof 2, they are all arranged in parallel rows and do not follow the curvature of the front wall 1. The roof 2 is made of a highly transparent material or may be an open or partially open frame structure such that light which bypasses the solar panels 9 or is reflected off the solar panels 9 can enter the interior space 10 of the structure. As can be seen in Figure 4, gaps 11 in the front wall also allow light to enter the interior space 10 through the front wall. These gaps may be fully open or may be formed of a transparent material. The interior wall 3 preferably has, at least on its forwardly facing surface 12, a highly reflective coating such as a light coloured paint. The inner faces of the solar panels 6, 7 are preferably bifacial solar panels such that they have solar material on both faces. As with the external surfaces, some of the internal surfaces could be substituted with a reflective surface. The purpose of the above structural features is to optimise the light which enters and is reflected within the interior space. This maximises the power generation from the internally facing solar material on the panels 6,7. The structure has been designed to smooth out generation more evenly across the course of the day and across the course of a year. With the structure facing south in the northern hemisphere and north in the southern hemisphere, the early morning sun light will impinge more upon wall 1 than the roof 2 and the east facing wall portion will generate with greater efficiency at this time. As the sun rises in the sky, a greater proportion of the generation is carried out by the solar panels 9 on the roof 2. As the sun tracks from east to west, the central part of the wall 1 and the west facing end will increase their generating efficiency while the generating efficiency of the east facing end is reduced. The generation is enhanced by light which has reflected from the reflector surface 8 onto the wall 1 which contributes significantly to the power generation throughout the day. The internally reflected light also contributes significantly to the overall generation and helps to smooth the generation throughout the day as the absorption of reflected light is less dependent on the position of the sun. During winter months, with low azimuth sun positions, a higher proportion of the generation will be done by the front wall 1, while during the summer months, high azimuth positions of the solar panels 9 generate a greater proportion of electricity. Associated with each parking space S is a charging station 20 which may contain a battery 21 or may be connected to a battery 21 positioned elsewhere. The batteries 21 are charged from the solar panels 6,7,9. The charging stations 20 may also be connected to an external grid in order to allow the export of excess power and / or to import power to compensate for a short fall in generation. The internal space 10 may incorporate retail / leisure facilities of the type typically encountered in a service station, but on a smaller scale. Fig 1 shows two food / beverage trucks 22 and seating areas 23. The illustrated structure incorporates two lavatories 24 and storage areas 25. As will be appreciated, this space is highly flexible and can be used for many purposes including retail, entertainment, educational displays of the total power generated, vending machines, display screens, video games, children’s play and the like. As shown in Figure 1, a number of plants 26 are dispersed throughout the internal space 10 in fixed troughs. These are not only aesthetically pleasing, but also have a technical role in that they are able to absorb a significant amount of heat within the internal space 10. This is significant, particularly in the summer months, as the internal space 10 can otherwise become unduly hot and this has a detrimental effect on the operating efficiency of the solar panels. As shown in Figure 1, there is a significant gap in the wall 3 as well as a significant gap at either end of the wall 3. This promotes good ventilation of the internal space 10. Some form of closure, such as sliding doors may be provided particularly in colder environments so that the internal space can be closed off either partly or completely in this area to provide temperature regulation. Alternatively, or additionally, openable vents may be provided in the roof 2. Ideally, as much of the temperature regulation as possible is done in this way, 5 rather than requiring heating and / or air conditioning.

Claims

1. A solar structure comprising a front wall and a roof, the front wall being curved around the roof, and being formed of a plurality of upwardly and downwardly facing panels at least some of which are solar panels, wherein the upwardly and downwardly facing panels are alternated with respect to one another to form a concertina structure; andthe roof being provided with a plurality of solar panels facing towards the front wall.

2. A solar structure according to claim 1, wherein the front wall is formed of doublesided solar panels.

3. A solar structure according to claim 1 or claim 2, wherein the front wall has light transmissive gaps between the solar panels.

4. A solar structure according to any preceding claim, further comprising an intermediate wall within the structure with a reflective surface facing the front wall.

5. A solar structure according to any preceding claim, wherein the roof is made of a non-opaque material and / or is open or partially open.

6. A solar structure according to any preceding claim, including a reflective layer applied to the ground in the region in front of the front wall.

7. A solar structure according to any preceding claim, wherein the structure has a peak power output of greater than 300w / m2, preferably more than 500w / m2 with the area being measured as the area of the footprint of the structure.

8. A solar structure according to any preceding claim, wherein the structure is modular.

9. A solar structure according to claim 8, wherein the structure is formed of at least one first module having a front wall portion with at least one solar panel and at least one roof portion and having a parallel sided footprint, and a plurality of second modules each having a front wall portion with at least one solar panel and at least one roof portion andhaving a wedge-shaped footprint, wherein the at least one first module is flanked by second modules to form the curved shape of the structure.

10. A solar structure according to claim 8 or claim 9, wherein each module has a peak electrical power output derived from the solar panels of greater than 6kwkw .

11. A solar structure according to any of claims to 10 wherein each module is configured to dispense co-generated solar energy of at least 24 kwh per module.

12. A solar structure according to any preceding claim, wherein the structure includes at least one battery to selectively receive electrical energy from the solar panels.

13. A solar structure according to any preceding claim, wherein the structure includes at least one vehicle charger.

14. A solar structure according to claim 10, wherein the vehicle charger is connected to an external grid to allow charging from the external grid.

15. A solar structure according to any preceding claim, wherein the solar panels are connected to an external grid to allow export of electrical power to the external grid.

16. A solar structure according to any preceding claim, wherein the structure contains at least one retail unit.

17. A solar structure according to any preceding claim, wherein the structure contains at least one plant.

18. A solar structure according to any preceding claim, wherein the structure has at least one door which is selectively closable to regulate the temperature within the structure.

19. A curved modular solar structure comprising a front wall and a roof,the front wall being at least 3 metres high and being curved around the roof, and being formed of a plurality of solar panels;the roof being provided with a plurality of solar panels facing towards the front wall;the structure being formed of at least one first module having a front wall portion with at least one solar panel and at least one roof portion and having a parallel sidedfootprint, and a plurality of second modules each having a front wall portion with at least one solar panel and at least one roof portion and having a wedge-shaped footprint, wherein the at least one first module is flanked by second modules to form the curved shape of the structure.

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