GB2526281A

GB2526281A - Improvements in solar power

Info

Publication number: GB2526281A
Application number: GB1408851.2A
Authority: GB
Inventors: Edward Matos; Oliver Kynaston; Alexander Smith; Paul Wolfson; Sebastian Conran
Original assignee: SHAMBA TECHNOLOGIES Ltd
Current assignee: SHAMBA TECHNOLOGIES Ltd
Priority date: 2014-05-19
Filing date: 2014-05-19
Publication date: 2015-11-25
Also published as: WO2015177493A1; GB201408851D0

Abstract

A mini solar-powered system 600a, 600b for supplying power to a dc load appliance from a dc power source such as a solar cell comprises a dc power source 602a, 602b, energy storage means 606b, a dc appliance 608a, 608b, a controller, and a throttle to limit the output of the dc power supply. The controller allows the dc appliance 608a, 608b to draw power from either the dc power source 602a, 602b or the energy storage means 606b. The controller monitors the voltage of the energy storage means 606b and deactivates the throttle when the voltage of the energy storage means exceeds some threshold. The throttle may use a minimum input voltage regulation loop to ensure maximum power extraction from the dc power source 602a, 602b. Multiple mini solar-powered systems 600a, 600b may be connected together to allow sharing of stored energy in the energy storage means between appliances 608a, 608b. Low power and high power systems may be connected together with a low power bus and a high power bus (figure 7). Also disclosed is a resilient connector (figure 8e).

Description

Improvements in Solar Power

Field of the Invention

The invention relates to improvements in solar-powered systems and apparatuses which make use of a solar panel, such as a photovoltaic solar panel, to supply power.

Background of the Invention

A solar-powered system in its most basic form consists of a solar panel to generate electricity and some electronic components to safely and efficiently regulate that electricity. If the main purpose of the system is to supply power to devices at night (e.g. an LED light) then the system must also have a battery or other means for energy storage. Any such battery must have the necessary electronics so that it may be charged and discharged safely and efficiently whilst maximising the lifetime of the battery.

In recent years, the demand for solar-powered systems designed specifically for off-grid households in developing countries has grown. Existing systems designed for this purpose tend to include one or more lights and/or a mobile phone charger. Normally they are easy-to-use and can be assembled/installed by the end-user. Fig. 1 shows such a known system 100, comprising a solar panel 102 and the circuitry necessary to enable the drawing of electrical power from it, circuitry 104, a battery 106, and a useful appliance 108, such as a light or a mobile phone adapter.

At present, a significant barrier preventing off-grid households from purchasing a solar-powered system is the up-front cost of available systems. Even with an awareness of the long-term savings which are clearly offered by such systems, the vast majority of households do not have, or are unwilling to risk, the up-front capital needed. As a result, efforts in this sector have been focused on making very low-power, low-functionality products that can be manufactured cheaply enough to be sold at prices that target households can afford. To achieve this, every superfluous feature of a product is typically stripped out, and only the most essential functionality is retained. Therefore, the need exists for added functionality over that of available basic systems of minimal extra cost.

A specific problem with "mini" solar-powered systems is that they have to be extremely small in order to become affordable. Because of this, at some point, a household will probably want to increase the amount of power it has beyond what is offered by a mini system. However, simply increasing the amount of power in these mini systems is not possible, and users must instead purchase a second independent mini solar-powered system. Two such mini solar-powered systems would be electronically isolated from each other; they would not be capable of sharing power. This results in two major problems: 1. The solar panels and batteries in multiple isolated systems cannot be used to their maximum capacity: In most households some appliances will be used more than others.

Therefore, if multiple systems which each serve a different appliance are isolated from one another, they cannot share power between them to supply the most popular appliances with extra power. There will therefore be times when available solar power cannot be utilised to its maximum potential, despite the high demand for extra power to certain appliances. This is because the energy stored in batteries which drive the most popular systems is depleted more quickly than the energy stored in those serving less popular appliances, but it would not be possible to harness excess power from the systems serving the less popular appliances to drive the more popular appliances.

2. Mini solar-powered systems cannot supply electricity to higher-powered appliances: Appliances requiring a higher power supply, such as bright lights, a small TV, or a small fridge, cannot be powered by a small battery, not even for a short period of time. This is because the internal resistance of each battery limits the amount of current it can deliver.

There is a tendency for an increasing amount of stored energy to be lost as heat, the higher the discharge current is. There is also an upper limit which the discharge current should not exceed to protect the cell from being damaged. Thus, users are limited to small, low-powered appliances even if they have a very large combined capacity in their numerous mini solar systems.

Thus, larger solar-powered systems which are capable of powering larger appliances would be highly advantageous, but currently available larger systems involve a substantial capital investment and are generally not affordable to most users in developing countries.

Fig. 2 shows a household using an exemplary known system 200. The system 200 comprises four mini solar-powered systems 200a, 200b, 200c and 200d which are isolated from each other such that power cannot be shared between them. Each mini system 200a, 20Db, 200c, 200d comprises a respective solar panel 202a, 202b, 202c, 202d and the circuitry to enable electrical power to be drawn from it, as is known in the art, a respective battery 206a, 206b, 206c, 206d, and a respective appliance 208a, 208b, 208c, 208d which is configured to draw power from its respective solar panel 202a, 202b, 202c, 202d and/or its respective battery 206a, 206b, 206c, 206d. It can be seen from Fig. 2 that appliance 208d has been used more heavily than appliances 208a, 208b and 208c, meaning that the battery 206d associated with the appliance 208d has less remaining stored energy than batteries 206a, 206b and 206c. However, the energy stored in batteries 206a, 206b and 206c cannot be used to power appliance 2USd, and the appliance 208d can be used for a shorter period of time than that dictated by the cumulated power available in the system.

Therefore, there exists a need for systems and apparatuses which address the problems described above.

Summary of the Invention

In accordance with an aspect of the invention, there is provided a system comprising: a first direct current (DC) power supply; energy storage means; a first DC appliance; control means configured to connect the first DC appliance to the energy storage means and the first DC power supply to permit the first DC appliance to draw power from the energy storage means or the first DC power supply; and throttling means for throttling an output power of the first DC power supply, wherein the control means is operative to monitor a voltage across the energy storage means and deactivate the throttling means when the voltage across the energy storage means exceeds a first threshold.

The deactivation of the throttling means may permit the first DC appliance to draw power from the energy storage means. The first threshold may be zero.

The control means may be further configured to activate the throttling means when the voltage across the energy storage means does not exceed the first threshold. The throttling means may comprise a minimum input voltage regulation loop. Additionally or alternatively, the control means may comprise a step-down voltage converter.

The system may further comprise a second DC appliance connected to the energy storage means and configured to draw power from the energy storage means. The first DC power supply may be connected to the energy storage means, and the energy storage means may be configured to store power drawn from the first DC power supply. The first DC power supply may comprise a power supply bus. Alternatively or additionally, the first DC power supply may comprise a solar panel. The first and/or second DC appliances may comprise one or more of a mobile phone, a lamp, a television, a computer, a music player.

At least one of the control means and the energy storage means may be contained within a housing. The control means may be contained within a first housing and the energy storage means may be contained within a second housing. The first housing and the second housing may be configured to be connected to one another in a stacked arrangement.

In accordance with another aspect of the invention, there is provided a system comprising: circuitry to interface a high current bus and a low current bus; a low current connector for connecting to the low current bus; and a high current connector for connecting to the high current bus.

The circuitry may comprise a current limiter connected between the low current bus and the high current bus. The current limiter may comprise a 3A current limiter.

The circuitry may further comprise an energy storage means. The system may further comprise a DC power supply, such as a solar panel, connected to the circuitry. The system may be a solar-powered system. The system may further comprise a DC appliance which is connected to the circuitry and is configured to draw power from the energy storage means and/or the DC power supply. The circuitry may further comprise a battery charge controller and battery discharge protection circuitry.

The system may further comprise a high current system or a low current system, wherein the circuitry is contained within a first housing and the high current system or low current system is contained within a second housing. The first and second housings may be configured to be connected to one another in a stacked arrangement.

According to another aspect of the invention, there is provided a device for supporting an electrical connector comprising a body and one or more elongate electrical contacts, wherein the device is configured to be attached to the connector such that it at least partially surrounds a portion of the one or more contacts.

The device may comprise one or more apertures which are configured to accommodate one or more electrical contacts. For example, the one or more apertures may be configured to permit one or more electrical contacts to be inserted therethrough. The device may comprise three apertures.

The device may be configured to accommodate the pins of a PC/i 04 connector.

There may also be provided a kit comprising: a connector comprising a body and one or more elongate electrical contacts; and a device as described above and configured to be attached to the connector such that the device at least partially surrounds a portion of the one or more contacts.

The kit may further comprise circuitry.

There may also be provided an apparatus comprising: circuitry; a connector comprising a body and one or more elongate electrical contacts which extend from the circuitry; and a device as described above attached to the connector such that the device at least partially surrounds a portion of the one or more contacts.

The apparatus may further comprise a housing in which the circuitry is located. The one or more contacts may protrude from an interior of the housing to an exterior of the housing. The device may support insertion of the one or more contacts through one or more apertures in the housing. The device may support a portion of the one or more contacts which is located inside the housing.

The apparatus may further comprise a recess on an internal surface of the housing which matingly engages the device. The apparatus may further comprise a shroud located on an exterior surface of the housing which is configured to surround at least a portion of the one or more contacts which emerge to an exterior of the housing.

The apparatus may further comprise a second component located outside the housing to which the connector is configured to be connected, wherein the second component may comprise an indent which is shaped to be matingly engaged by the shroud of the first component. The second component may comprise a second connector into which the first connector is shaped to be inserted. The connector(s) may comprise a P0/104 connector, such as a 3 pin PC/i 04 connector.

Brief Description of the Drawings

The invention will now be described with reference to the accompanying drawings, in which: Fig. 1 shows a simple known solar-powered system; Fig. 2 shows a household using multiple known solar-powered systems; Fig. 3 shows a household using a solar-powered system according to an aspect of the invention; Fig. 4 shows a perspective view of a stack of solar-powered systems according to an aspect of the invention; Figs. 5, 6 and 7 show schematic views of systems according to aspects of the invention; Figs. Sa to 8h show perspective views of an apparatus according to an aspect of the invention.

Detailed Description of the drawings

As described in the Background of the Invention and shown in Fig. 2, the use of multiple independent mini solar-powered systems reduces the opportunity for solar panels and batteries to be used to their full potential, and limits the use of such systems to small, low-powered appliances.

It will be understood by a person skilled in the art that the term "solar panel" is used herein to refer to an assembly comprising one or more solar cells and/or solar modules, preferably photovoltaic cells and/or modules. Photovoltaic cells utilise incident light, such as sunlight for example, and convert the energy of that light into electricity as known to the skilled person.

Some known solar-powered systems are capable of sharing solar panel power provided by a plurality of solar panels within a system. Equally, some known systems are capable of sharing battery energy provided by a plurality of batteries within a system. However, both of these scenarios limit the potential for sharing power within systems because each is constrained by the available power provided by a given solar panel or battery.

In contrast, Fig. 3 depicts a household using multiple solar-powered systems which are capable of sharing solar panel power provided by a plurality of solar panels and battery power provided by a plurality of batteries. Thus, individual systems are not constrained to the use of a single solar panel or a single battery as a source of power.

The system 300 of Fig. 3, like that of Fig. 2, comprises four solar panels 302a, 302b, 302c, 302d, four batteries 306a, 306b, 306c, 306d, and four appliances 308a, 308b, 308c, 308d which are configured to draw power from the solar panels 302a, 302b, 302c, 302d and/or the batteries 306a, 306b, 306c, 306d. However, unlike the system of Fig. 2, the four mini solar-powered systems making up the system 300 of Fig. 3 are integrated with one another such that power can be shared between them. Any given appliance 308a, 308b, 308c, 308d can draw power from a common battery bus which is connected (via suitable circuitry) to batteries 306a, 306b, 306c, 306d and a common solar panel bus or power supply bus to which are connected (via suitable circuitry) solar panels 302a, 302b, 302c, 302d. Therefore, the most popular appliances can draw power from any or all of the solar panels and batteries within the system. This way, the most popular appliances can run for longer and their batteries can be recharged faster. An additional benefit of being able to share power between the multiple mini solar-powered systems is that appliances which drain more power, such as televisions 310, can be powered.

The present invention relates to systems and apparatuses in which power is shared between multiple mini solar-powered systems in the manner shown in exemplary form in Fig. 3. In some embodiments, the different mini systems offer different levels of functionality and complexity, and can be manufactured at a range of costs, making them available to households with a wide range of income levels. In some embodiments, the mini systems are configured to be mechanically and electrically integrated with one another in a stacked arrangement, with power being shared throughout the stack such that the multiple mini solar-powered systems behave as a single larger solar-powered system. Fig. 4 shows one example of such a stack 400. Each mini solar-powered system within the stack comprises a solar panel 402, a block or housing 410 comprising circuitry, and a useful appliance 408. Some blocks may additionally comprise a battery or another means for storing energy. Power is shared throughout the stack, and the mini solar-powered systems can be detached, reconfigured and rearranged according to demand and/or financial constraints. The mechanical and electrical configurations which permit the stacking depicted in Fig. 4 are described in detail below.

Fig. 5 is a schematic view showing in an exemplary manner how multiple mini solar-powered systems 500 can be integrated to share power therebetween, and more particularly how the mini solar-powered systems share power provided by all solar panels and batteries in the multiple mini solar-powered systems 500.

The exemplary embodiment shown in Fig. 5 comprises two mini solar-powered systems, but the skilled person will understand that any number of systems could be connected in a similar manner.

Each system 500 shown in Fig. 5 comprises a direct current (DC) power supply 502 (such as a solar panel and the circuitry to enable electrical power to be drawn from it, as is known in the art), circuitry 504 including battery discharge protection circuitry 505 and battery charge control circuitry 507, a battery 506 or other energy storage means, and a useful appliance 508, such as a light or a mobile phone adapter. In an alternative embodiment, either or both systems may not comprise a battery and therefore may not comprise battery discharge protection circuitry and battery charge control circuitry either. The circuitry 504 also comprises a minimum input voltage regulation loop 512, the function of which will be described in detail below with particular reference to Fig. 6.

Connecting multiple mini solar-powered systems as shown in Fig. 5 presents a number of challenges, including connecting multiple battery charge controllers in parallel on a single bus, sharing battery power between multiple systems, and providing bus connections, such as 3-wire bus connections, at a low cost. The present invention provides solutions to these problems.

Fig. 6 is a schematic view showing a system 600 according to an aspect of the invention in which a first mini solar-powered system 600a is electronically integrated with a second mini solar-powered system 600b such that the first and second mini solar-powered systems 600a, 60Db can share power between them. More particularly, battery power provided by batteries within the system and solar panel power provided by solar panels within the system can be shared between the first and second mini solar-powered systems. It is an aim of this aspect of the invention to achieve maximum power output from the system even when the solar panel(s) are exposed to low levels of sunlight, for example at the very beginning or very end of the day.

As shown in Fig. 6, the first system 600a comprises a first DC power supply 602a (such as a solar panel and the circuitry to enable electrical power to be drawn from it, as is known in the art), first circuitry 604a, and a first DC appliance 608a, such as a light, or a mobile phone adapter.

The second system 600b comprises a second DC power supply 602b (such as a solar panel and the circuitry to enable electrical power to be drawn from it, as is known in the art), second circuitry 604b, and a second useful appliance 608b, such as a light, a television or a mobile phone adapter.

The second system also comprises a battery bus 605 connected to a battery or any other energy storage unit 606b for storing energy provided by a power supply bus 601 (see below), battery charge control circuitry 611b connected between the power supply bus 601 and the battery 606b, and battery discharge protection circuitry 613b for regulating the power supplied by the battery 606b and connected between the battery 606b and the battery bus 605. As shown in Fig. 6, the first and second systems 600a, 600b are integrated with one another via the battery bus 605.

The first and second DC power supplies 602a 602b are integrated with one another via a power supply bus 601 by means of one or more blocking diodes 609a, 609b, for example. As may be seen, the power supply bus 601 is present in both subsystems 600a, 600b.

The first and second power supplies 602a and 602b and the power supply bus 601 are operable as a single power supply. Diodes 609a, 609b allow the transfer of power from the DC power supplies 602a, 602b to the power supply bus 601 and thereby to the circuitry 604a, 604b, but prevent power from flowing back in the opposite direction (i.e. from the power supply bus 601 to the power supplies 602a, 602b). In an exemplary embodiment, the circuitry 604b comprises battery charge controller circuitry and battery discharge protection circuitry. This circuitry and its functions are known in the art.

As mentioned above, the first and second systems 600a, 600b are integrated with one another via the battery bus 605 also. In the second subsystem 60Db, the battery 606b is connected, via battery discharge protection circuitry, and through a blocking diode 614b to the battery bus 605.

This enables the provision of power from the battery to the battery bus, and prevents flow of current in the opposite direction. One or more appliance connected to the battery bus may therefore be provided with power in this way.

In the first subsystem 600a, the battery bus 605 is connected through a blocking diode 614a to a voltage converter (described further below) which is connected to an appliance 608a. In this way, power from the battery bus 605 can be drawn by the appliance 608a. The diode 614a prevents flow of current in the opposite direction.

The first circuitry 604a is configured to connect the first appliance 608a to the power supply bus 601 or the battery bus 605 such that power may be drawn from one or other, as discussed below.

The second circuitry 604b is configured to connect the battery 606b to the power supply bus 601 and to the battery bus 605 to enable charging and discharging of the battery 606b, that is charging of the battery and the provision of power to the battery bus to power one or more appliance.

Existing systems which comprise one or more DC power sources (e.g. a solar panel) having a maximum power point use an active maximum power point tracking algorithm to obtain the maximum power possible from the one or more DC power sources. IC chips which implement active maximum power point tracking may utilise a perturb and observe" algorithm or an "open-circuit voltage measurement" algorithm to seek out the maximum power point. However, such techniques result in expense and, in examples where multiple charge controllers are connected on a single bus, can cause instability and therefore inefficiency in the system due to interference between the multiple complex active maximum power point tracking algorithms. Existing integrated circuit (IC) controllers which implement active maximum power point tracking include ST Microelectronics' SPV104O, which is known to the skilled person and uses a "perturb and observe" algorithm.

In the embodiment shown in Fig. 6, a minimum input voltage regulation loop is used to achieve the same result as an active maximum power point tracking system (i.e. obtaining the maximum power possible from the one or more DC power sources). As well as being cheaper, simpler and more reliable than active maximum power point tracking systems, minimum input voltage regulation loops have the additional advantage that a plurality of such loops can be used to draw power from the same power supply bus without interfering with each other in the manner of the more complex maximum power point tracking systems. Integrated circuit (IC) controllers which implement minimum input voltage regulation loops include Texas Instrument's BQ24650, and Linear Technology's LT3652.

In the embodiment shown in Fig. 6, the first circuitry 604a comprises control means which controls a minimum input voltage regulation loop 612a. In the embodiment shown in Fig. 6, the minimum input voltage regulation loop throttles the power output which is supplied to the first appliance 608a from the power supply bus 601 when the power supply bus 601 voltage does not exceed a minimum value. This stops the power supply bus 601 voltage from dropping any further. The minimum value utilised in the minimum input voltage regulation loop corresponds to a maximum power point which has conventionally been used in maximum power point tracking systems.

In its most basic form, the first system 600a is a step-down DC-DC converter that, in an exemplary embodiment, converts a voltage of 17-21V drawn from the power supply bus 601 into 5V that is then output to the first appliance (via a USB port, for example) 608a. This exemplary first system 600a alone will only provide by, even when there is plenty of sunlight incident on the first solar panel 602a and/or the second solar panel 602b and/or any other solar panels on the power supply bus 601. As described above, the first circuitry 604a is configured to allow the first appliance 608a to draw power from the battery bus 605, which is also connected to it as described above, as well as the power supply bus 601. Generally, the battery bus 605 voltage is lower than the power supply bus 601 voltage. If no (or practically no) sunlight is available (e.g. at night) then in order to utilise the appliance 608a, it must be able to draw power from a connected battery bus 605. If there is no connected battery bus, and no sunlight available, the appliance 608a will be unusable.

However, there is a problem with this arrangement. At times of little sunlight (e.g. at the very beginning or very end of the day), the minimum input voltage regulation loop 612a will prevent the power supply bus 601 voltage from dropping below the voltage on the battery bus 605. Thus, the first appliance 608a will be unable to draw power from the battery bus 605 by virtue of the higher voltage on the power supply bus 601, and very little power can be drawn by the first appliance 608a from the power supply bus 601 as there is little power available from the power supply bus 601 due to the limited sunlight.

To solve this problem, the first circuitry 604a (i.e. the control means) is configured to deactivate the minimum input voltage regulation loop 612a when a voltage is detected on the battery bus 605 (indicating that there is a battery connected to the battery bus 605, if required). When the loop is deactivated, the power supply bus voltage will be allowed to drop below the battery bus 605 voltage, as would happen normally when there is insufficient sunlight for the solar panels to keep the power supply bus 601 voltage high. Thus, the battery bus 605 is able to supply power to the first circuitry 604a, meaning that surplus power stored in the battery 606b during periods of high environmental solar power can be drawn by appliances effectively during periods of low environmental solar power (i.e. at the very beginning or very end of the day). The circuit described above and shown in exemplary form in Fig. 6 achieves the desired functionality at minimal cost.

In some embodiments, other mini solar-powered systems within the system 600, such as the second mini solar-powered system 600b, comprise a minimum input voltage regulation loop.

However, in mini solar-powered systems which comprise a battery, the minimum input voltage regulation loop is not activated and deactivated in the manner described above; it is always active.

The minimum input voltage regulation loop is only activated and deactivated as described above in mini solar-powered systems which do not comprise a battery, because it is in such systems that throttling of the power supply becomes a problem at times of low sunlight (e.g. at the very beginning or very end of the day).

In one embodiment, this aspect of the invention is achieved using an analog circuit. In alternative embodiments, the above-described functionality can be achieved using higher cost components and/or achieved digitally. In one embodiment, the above-described functionality is achieved using a microcontroller.

Whilst Fig. 6 shows the energy storage unit 606b (i.e. the battery) being a part of the second system 600b, the skilled person will understand that, in alternative embodiments, the battery can be provided as a stand-alone unit. The skilled person will also understand that, whilst Fig. 6 shows just two mini-systems, any number of systems can be connected in the manner described above with reference to Fig. 6 whilst providing the desired functionality.

In some embodiments, the systems 600a, 600b each comprise a housing (not shown) and the circuitry 604a, 604b is contained within its respective housing. The housings may be configured to be connected to one another in a stacked manner.

Fig. 7 is a schematic view of a system 700 in which a high current bus 701a is connected to or interfaced with a low current bus 701b. The high current bus 701a and low current bus 701b are distinguished from each other by the current ratings of the connectors used to connect devices on each bus. For example, the bus may be made up of a number of bus segments joined to one another using such connectors. The high current bus 701a utilises generally more expensive connectors, rated for a high current-carrying capacity, and the low current bus utilises generally cheaper connectors, rated for a low current-carrying capacity. This aspect of the invention will be described in further detail below.

The high current bus 701a is used to connect a plurality of high current mini solar-powered systems 700a which are current-rated to be connected to one another via high current connectors.

In contrast, the low current bus 701b is used to connect a plurality of low current mini solar-powered systems 700b which are current-rated to be connected to one another via low current connectors. The exemplary embodiment shown in Fig. 7 comprises two high current systems 700a and one low current system 700b, but the skilled person will understand that other suitable combinations of high current 700a and low current systems 70Db could equally be used in the high current 701a and low current 701b buses, respectively.

Each of the systems 700a, 700b depicted in the exemplary embodiment shown in Fig. 7 comprises a DC power supply 702a, 702b (such as a solar panel and the circuitry to enable electrical power to be drawn from it, as is known in the art), circuitry 704a, 704b, an energy storage unit, such as a battery 706a, 706b, and a useful appliance 708a, 708b, such as a light or a mobile phone adapter, for example. In one embodiment, the DC power supplies 702a, 702b are connected to one another on a power supply bus 701, and the energy storage units 706a, 706b are connected to one another on a battery bus 705, as described previously with reference to Fig. 6.

In an alternative embodiment, one or more of the systems 700a, 700b may not comprise an energy storage unit. In an exemplary embodiment, the circuitry 704a, 704b, comprises battery charge controller circuitry 711a, 711b and battery discharge protection circuitry 713a, 713b. The skilled person will understand that other circuitry may also be provided. For example, in one embodiment, each of the systems 700a, 700b comprises a minimum input voltage regulation loop and one may comprise a control means as described above with reference to Fig. 6 to provide the advantageous power flow features associated with the arrangement shown in Fig. 6.

As described above, the high current mini solar-powered systems 700a are current-rated to be connected to each other via high current connectors. In contrast, the low current mini solar-powered systems 70Db are current-rated to be connected to one another via low current connectors. In other words, a low current system 70Db is one which is designed to draw a current (e.g. from the power supply bus 701) and supply a current (e.g. to a battery bus 705) which is unlikely to result in the connectors which connect the low current systems on the low current bus 701b carrying a total current exceeding their rated capacity. In an exemplary embodiment, the low current connectors on the low current bus 701b are 7 Amp (7A) connectors, and each low current system 70Db on the low current bus 701b is designed to draw and supply a maximum current of 200mA. Therefore, it is possible to connect up to 35 such low current systems 70Db on the low current bus 701b without exceeding the current rating of the 7A connectors. In another exemplary embodiment, the low current connectors on the low current bus 701b are 7A connectors, and each system 70Db on the low current bus 701 b is designed to supply a maximum current of 0.8A from its battery 706b. Therefore, it is possible to connect up to 9 such low current systems 700b without the cumulative current provided by the integrated batteries exceeding the current rating of the 7A connectors. The skilled person will understand! however, that these embodiments are merely exemplary and explanatory. In contrast, high current systems 700a on the high current bus 701a can be designed to draw and supply a higher current by virtue of the higher current ratings of the typically more expensive connectors on the high current bus 701a.

In the embodiment shown in Fig. 7, the low current bus 701b is connected to the high current bus 701a via a low current connector 714 and through a current limiter, such as a 3A current limiter.

The skilled person will understand that any other suitable current limiting means and/or any other current limit (e.g. a 5A current limiter or a 7A current limiter) could be used. Thus, the high current bus 701a is connected to the low current bus 701b using the low current connector 714 as opposed to a costly high current connector, thereby vastly reducing the cost of manufacture of the system. It is also highly advantageous to integrate low current systems 70Db together using a low current bus 701b so that the power output of these low current systems 70Db can be maximised whilst minimising the risk of damage to the low current connectors 714 due to excessive drawing/supplying of power by low current systems 70Db on the low current bus 701 b.

The extra cost of requiring both high and low current connectors (i.e. two types of connectors), as well as the necessary current-limiting circuitry, on systems such as 700a, is minimal in relation to the total cost of systems such as 700a, and permits lower cost systems (where the connector cost is relatively significant) such as 70Db to utilise low-cost, low-current connectors. Therefore, the aspect of the invention shown in Fig. 7 provides a very cost-effective means by which high current buses and low current buses can be integrated with one another such that they can share power between them.

In some embodiments, the systems 700a, 700b each comprise a housing (not shown) and the circuitry 704a, 704b is contained within its respective housing. Two or more of the housings may be configured to be connected to one another in a stacked manner.

The embodiment shown in Fig. 7 may be combined with the embodiment shown in Fig. 6 to achieve the advantages afforded by both embodiments in a single system.

It has been mentioned in the embodiments of the invention described above that various components, units, apparatuses and/or systems providing different levels of functionality can be connected or coupled to one another in a stacked arrangement. Figs. 8a to 8h show an aspect of the invention by means of which such components, units, apparatuses and/or systems can be stacked.

Fig. 8a shows an apparatus 800 comprising circuitry 854 mounted on a mounting element, such as a printed circuit board (FCB) 856. Fig, 8b shows a first apparatus 800, the apparatus of Fig. 8a, which is connected in a stacked arrangement to a second apparatus 802 which is substantially the same as the first apparatus 800. The PCB 856 of the first apparatus, with all circuitry 854, is connected to the second component via a connector 858, for example a, a P0/104 stacking connector having one or more contacts, or in a preferred embodiment a 3 contact PC/i 04 stacking connector.

PC/104 connectors are very cheap connectors that are designed to be stacked on top of each other with minimum design difficulty and cost. However, they can be difficult to utilise successfully.

PC/i 04 connectors are fragile and susceptible to deformation if they are subjected to excessive force, and thin exposed pins can be damaged easily. An aspect of the present invention which will now be described with reference to Figs. 8c to Bh provides a device and associated apparatus by which the cheap P0/104 connectors, or similar low-cost but fragile connectors, can be used to stack various components, units, apparatuses and/or systems providing different levels of functionality.

The connector 858 shown in Figs. Ba to 8h comprises a body 872 and one or more electrical contacts 859 extending from the body 872, Typically, each PCB 856 is contained in its own plastic housing 860 (a poition of which is shown in Fig. Se), meaning that the one or more electrical contacts 859 of the connector 858 must extend through the housing 860 such that the housing 860 can be connected to another external component in a stacked arrangement. To achieve this, as shown in Fig. Be, the pins 859 of the connector 858 will have to push through apertures or holes 863 in the plastic housing 860.

Since the electrical contacts 859 of the connector 858 would typically be fragile and/or susceptible to deformation, ideally, the connector 858 should be inserted perfectly perpendicularly to the FCB 856. To assist with this, a device 864, such as a low-tolerance manufactured plastic sleeve or grommet, is fitted to the connector 858 during PCB assembly to ensure that the connector 858 is inserted perpendicularly. This device 864 is shown in Figs. 8d and 8e.

The device 864 is configured to support an electrical connector 858 comprising one or more elongate electrical contacts 859 (e.g. pins), wherein the device 864 is configured to be attached to the connector 858 such that it at least partially surrounds a portion of the one or more contacts 859, such as a portion of the contacts 859 adjacent to the body 872. This way, the exposed length of the contacts 859 is reduced, meaning that damage and deformation of the contacts 859 is less likely. In other words, a length of a free end of the contacts 859 is shortened by virtue of the device 864 surrounding a portion of the contacts 859, reducing the likelihood of the contacts 859 being bent or broken. The device 864 comprises one or more apertures 865 which are configured to permit the one or more electrical contacts 859 (e.g. pins) of the connector 858 to be inserted therethrough. In the case of a 3-pin connector, such as a 3-pin PC/i 04 connector, the device 864 comprises three apertures 865. In alternative configurations, the connector, such as a PC/104 connector, can comprise any number of contacts and the device can comprise any number of apertures. In one exemplary embodiment, the device 864 may take the form of a sleeve and comprise a single aperture which is configured to surround all of the contacts of a connector.

Alternatively, the device may comprise a plurality of apertures, each aperture being configured to surround a plurality of contacts.

The device 864 provides support to the fragile pins 859 of the connector 858. As shown in Fig. 8e, when the PCB 856 is mounted on the plastic housing, the device 864 fits into (i.e. matingly engages) a recess 868 moulded into an interior surface of the housing 860 to ensure that the pins 859 of the connector 858 emerge from the housing 860 perpendicularly to the housing 860 wall.

Only after the pins 859 of the connector 858 have been correctly aligned are mounting screws (not shown) inserted and tightened. This is highly advantageous, because securing the connection using mounting screws whilst the connector is not correctly aligned significantly increases the risk of the connector or another component being damaged and/or prevents the pins from being bent or misdirected such that they are no longer perpendicular to the PCB and/or the housing. In other words, misalignment of the connector or any other component is apparent and can be rectified at the time of assembly, and before any mounting screws have been applied. In one embodiment, an interference fit is provided between the device 864 and the recess 868.

Moreover, as shown in Fig. 8e, the device 864 has a substantially rectangular cross-sectional shape which is optionally tapered. The recess 868 is shaped to match the rectangular cross-sectional shape of the device 864 thereby achieving a keying effect between the device 864 and the recess 868. Thus, the device 864 can only be inserted into the recess 868 if the device 864 and the recess 868 are oriented correctly with respect to one another. The keying effect also prevents twisting of the device 864 within the recess 868, and therefore further prevents damage and deformation of the contacts 859. Whilst an exemplary keying configuration between the device 864 and the recess 868 is shown in Fig. 8e, the skilled person will understand that any suitable alternative keying configuration can also be used.

During insertion of the connector 858 through the housing 860, both ends of the connector 858 will be subject to strains that should not propagate across the PCB 856. Mounting holes 862 (Figs. 8a, 8b, 8c and Sd) through which mounting screws (not shown) are inserted and secured are provided through the PCB 856 either side of the connector 858 to contain this strain. Retaining features in the form of a pair of projections 866, which can be seen in Fig. 8e, are provided on an interior surface of the housing 860 and receive the mounting screws. The mounting holes 862 and mounting screws are positioned close to the connector 858 to provide good structural support, since stresses will be large near the connector 858.

Additionally, in one embodiment, the mounting holes 862 have a larger diameter than shafts of the mounting screws. This means that even if one or more mating components (e.g. device 864, pins 859, mounting screws, projections 866) are misaligned slightly, the mounting screws can be inserted through the mounting holes 862 and tightened without causing damage to any misaligned components.

As shown in Fig. 81, the pins 859 of the connector 858 emerge from the other side (the outside) of the housing 860. Here the pins are optionally surrounded by a plastic shroud 876 which serves two purposes: 1. it protects the pins from being damaged; and 2. it provides a mechanical means to be inserted into the enclosure of another component.

The shroud 876 may be integrally formed (e.g. moulded) with the housing 860, or provided as a separate part which is removably attachable to the housing 860.

Fig. 8g shows a body 872a of a second connector 858a which is substantially similar to the connector 858. The body 872a of the second connector comprises three apertures 873a into which the contacts 859 of the first connector may be inserted in a male-female connection.

The body 872a of the second connector 858a forms a mating connection with a socket 880a of a second housing 860a such that the apertures 873a of the body 872a are accessible from outside the second housing 860a. The portion of the second housing 860a surrounding the socket 880a forms an indent 882a which is the female counterpart to the plastic shroud 876 which surrounds a portion of the contacts 859 of the connector 858 which extends outwardly from the housing 860 i.e. the two portions are complimentarily shaped. In one embodiment, an interference fit is provided between the shroud 876 and the indent 882a.

Moreover, the shroud 876 itself has an internal recess 877 which is a female part which is shaped to receive and be engaged matingly by the socket 880a. In one embodiment, an interference fit is provided between the recess 877 and the socket 880a.

Therefore, the stacking connection between connectors 858, 858a involves three male-female mating connections.

The elongated shape of the socket 880a and the portion of the second housing 860a which surrounds it, along with the elongated shape of the shroud 876, is intended to permit two PCBs that are connected together to be able to resist a certain amount of "twist" without damage.

Moreover, as shown in Figs. 8f and 8g, the shroud 876 has a cross-sectional shape with two straight edges and two curved edges resulting in a keyed shape. The indent 882a of the second housing is shaped to match the keyed shape of the shroud 876 to achieve a keying effect between the shroud 876 and the indent 882a. Thus, the shroud 876 can only be inserted into the indent 882a if the shroud and the indent 882a are oriented correctly with respect to one another.

In a similar manner, a keying arrangement is provided between the socket 880a and the internal recess 877 of the shroud. However, in the exemplary embodiment shown in Figs. 8f and 8g, the recess 877 and the socket 880a have complimentary cross-sectional shapes with three straight edges and one curved edge. Thus, there is only one orientation in which the socket 880a can be inserted into the recess 877.

Whilst exemplary keying configurations are shown in Figs. Se to 8g, the skilled person will understand that any suitable alternative keying configuration can also be used. Moreover, the skilled person will achieve that the keying, as described above in a preferred embodiment, ensures that the connectors are presented in an exact manner such that stacking is facilitated.

Protective caps 878 may also be applied to protect the pins and the sockets from water and dust, as shown in Fig. 8h.

In one embodiment, at least a portion of the housing 860 is made from acrylonitrile butadiene styrene (ASS) plastic, which provides good impact strength and rigidity. Alternatives to ASS plastic include carbon dioxide-based composite materials, polyvinyl chloride (PVC) and polylactic acid (PLA). In some embodiments, one or more of the female mating components, such as the apertures 863, recess 868, indent 882a and/or recess 877, is constructed from a flexible or semi-rigid plastic, such as polypropylene. Alternatives to polypropylene for this purpose include polyethylene and polybutylene. The skilled person will understand that any other suitable materials can be used to construct the apparatuses and systems described herein. The provision of mating components one of which is rigid and one of which is flexible or semi-rigid creates a mating/retaining force when a male mating component is inserted into a female mating component.

For example, the flexible or semi-rigid component may deform resiliently when connected matingly to the rigid component. This resilient deformation causes an interference fit between the male and female mating components which reinforces and retains the mating connection between the male and female mating components. The skilled person will understand that, in one embodiment, the male mating component can be rigid and the female mating component can be flexible or semi-rigid and, in another embodiment, the female mating component can be rigid and the male mating component can be flexible or semi-rigid. Alternatively, the male mating component and the female mating component can be semi-rigid or flexible. It is envisaged that any combination of rigid and semi-rigid/flexible mating components could equally be used to achieve the desired interference fit.

The skilled person will understand that the stacking arrangement shown in Figs. 8a to 8e and described above can be combined with any or all of the systems and/or apparatuses described previously to provide an easily stackable and expandable system of low and high power modules allowing solar power to be acquired easily and cheaply initially, and expanded to a versatile and efficient overall system after a given period of time.

In particular, the stacking arrangement shown in Figs. 8a to Se can be combined with the embodiments shown in Fig. 6 and/or Fig. 7. Thus, the advantages afforded by all of these embodiments or any two of these embodiments can be achieved in a single system.

The present invention has been described above in exemplary form with reference to the accompanying drawings which represent embodiments of the invention. It will be understood that many different embodiments of the invention exist, and that these embodiments all fall within the scope of the invention as defined by the following claims.

Claims

Claims 1. A system comprising: a first direct current (DC) power supply; energy storage means; a first DC appliance; control means configured to connect the first DC appliance to the energy storage means and the first DC power supply to permit the first DC appliance to draw power from the energy storage means or the first DC power supply; and throttling means for throttling an output power of the first DC power supply, wherein the control means is operative to monitor a voltage across the energy storage means and deactivate the throttling means when the voltage across the energy storage means exceeds a first threshold.
2. A system according to claim 1, wherein the deactivation of the throttling means permits the first DC appliance to draw power from the energy storage means.
3. A system accoiding to claim 1 or claim 2, wherein the first threshold is zero.
4. A system according to any one of the preceding claims, wherein the control means is further configured to activate the throttling means when the voltage across the energy storage means does not exceed the first threshold.
5. A system according to any one of the preceding claims, wherein the throttling means comprises a minimum input voltage regulation loop.
6. A system according to any one of the preceding claims, wherein the control means comprises a step-down voltage converter.
7. A system according to any one of the preceding claims, further comprising a second DC appliance connected to the energy storage means and configured to draw power from the energy storage means.
8. A system according to any one of the preceding claims, wherein the first DC power supply is connected to the energy storage means, and wherein the energy storage means is configured to store power drawn from the first DC power supply.
9. A system according to any one of the preceding claims, wherein the first DC power supply comprises a power supply bus.
10. A system according to claim 8 or claim 9, wherein the first DC power supply comprises a solar panel.
11. A system according to any one of claims 7 to 10, wherein the first and/or second DC appliances comprise one or more of a mobile phone, a lamp, a television, a computer, a music player.
12. A system according to any one of the preceding claims, wherein at least one of the control means and the energy storage means is contained within a housing.
13. A system according to claim 12, wherein the control means is contained within a first housing and the energy storage means is contained within a second housing.
14. A system according to claim 13, wherein the first housing and the second housing are configured to be connected to one another in a stacked arrangement.
15. A system comprising: circuitry to interface a high current bus and a low current bus; a low current connector for connecting to the low current bus; and a high current connector for connecting to the high current bus.
16. A system according to claim 15, wherein the circuitry comprises a current limiter connected between the low current bus and the high current bus.
17. A system according to claim 16, wherein the current limiter comprises a 3A current limiter.
18. A system according to any one of claims 15 to 17, wherein the circuitry further comprises an energy storage means.
19.A system according to any one of claims 15 to 18, further comprising a DC power supply connected to the circuitry.
20. A system according to any one of claims 15 to 19 being a solar-powered system.
21.A system according to claim 1901 claim 20, wherein the DC power supply comprises a solar panel.
22. A system according to any one of claims 19 to 21, further comprising a DC appliance which is connected to the circuitry and is configured to draw power from the energy storage means and/or the DC power supply.
23. A system according to any one of claims 15 to 22, wherein the circuitry further comprises a battery charge controller and battery discharge protection circuitry.
24. A system according to any one of claims 15 to 23, further comprising a high current system or a low current system, wherein the circuitry is contained within a first housing and the high current system or low current system is contained within a second housing.
25. A system according to claim 24, wherein the first and second housings are configured to be connected to one another in a stacked arrangement.
26. A device for supporting an electrical connector comprising a body and one or more elongate electrical contacts, wherein the device is configured to be attached to the connector such that it at least partially surrounds a portion of the one or more contacts.
27. A device according to claim 26, the device comprising one or more apertures which are configured to accommodate one or more electrical contacts.
28. A device according to claim 26 or claim 27, wherein the one or more apertures are configured to permit one or more electrical contacts to be inserted therethrough.
29. A device according to any one of claims 26 to 28, wherein the device comprises three apertures.
30. A device according to any one of claims 27 to 29, wherein the device is configured to accommodate the pins of a PC/104 connector.
31. A kit comprising: a connector comprising a body and one or more elongate electrical contacts; and a device according to any one of claims 26 to 30 and configured to be attached to the connector such that the device at least partially surrounds a portion of the one or more contacts.
32. A kit according to claim 31, further comprising circuitry.
33. An apparatus comprising: circuitry; a connector comprising a body and one or more elongate electrical contacts which extend from the circuitry; and a device according to any one of claims 26 to 30 attached to the connector such that the device at least partially surrounds a portion of the one or more contacts.
34. An apparatus according to claim 33, further comprising a housing in which the circuitry is located.
35. An apparatus according to claim 34, wherein the one or more contacts protrude from an interior of the housing to an exterior of the housing.
36. An apparatus according to claim 35, wherein the device supports insertion of the one or more contacts through one or more apertures in the housing.
37. An apparatus according to claim 35 or claim 36, wherein the device supports a portion of the one or more contacts which is located inside the housing.
38. An apparatus according to any one of claims 34 to 37, further comprising a recess on an internal surface of the housing which matingly engages the device.
39. An apparatus according to any one of claims 34 to 38, further comprising a shroud located on an exterior surface of the housing which is configured to surround at least a portion of the one or more contacts which emerge to an exterior of the housing.
40. An apparatus according to claim 39, further comprising a second component located outside the housing to which the connector is configured to be connected, wherein the second component comprises an indent which is shaped to be matingly engaged by the shroud of the first component.
41. An apparatus according to claim 40, wherein the second component comprises a second connector into which the first connector is shaped to be inserted.
42. An apparatus according to any one of claims 33 to 41, wherein the connector(s) comprise a PC/104 connector, such as a 3 pin PC/i 04 connector.
43. A system, kit or apparatus as hereinbefore described with reference to the accompanying drawings.