GB2455421A

GB2455421A - Storage, distribution and supply of locally generated electricity

Info

Publication number: GB2455421A
Application number: GB0822337A
Authority: GB
Inventors: David Bruce Withington; Robert George Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-12-07
Filing date: 2008-12-08
Publication date: 2009-06-10
Also published as: GB0822337D0; GB0723940D0

Abstract

The invention relates to a method of controlling storage, distribution and supply of locally generated (e.g. by solar panels or wind turbine) in a localised electricity network such as a home ring circuit which is also connected to a nationalised electricity network such as a national grid. An electricity generating apparatus 18, 20 supplies a source of direct current electricity to the localised electricity network and to a means for storing electricity, such as batteries 12. The method concerns storing electricity generated by the electricity generating apparatus in the storage means, selectively distributing stored electricity from the storage means to the home ring circuit and selectively connecting portions of the home ring circuit to the national grid dependent upon the time of day i.e. whether electricity is supplied at a peak or off peak rate. The storage means may also be charged from the national grid during off peak periods. Also disclosed are power units having appliances connected where the power units are controlled to switch appliances on or off according to the rate offered by the national electricity network. A further method comprises determining whether a loss of supply from a national grid has occurred, and if so, isolating the local network from the national grid and drawing power from a storage means.

Description

Method of Controlling Storage, Distribution and Supply of Electricity The present invention is concerned with a method of controlling storage, distribution and supply of electricity in a localised electricity network, particularly, but not exclusively, electricity generated by renewable electricity generating apparatus such as solar photovoltaic panels and wind turbines.

Electricity is generally provided by electricity suppliers to end users on a nationalised electricity network, commonly referred to as a national grid.

At peak periods of activity the demand for electricity from end users, business etc. causes a large peak in the quantity of electricity which must be made available on the national grid in order to satisfy every end user requirement. Individual power stations each have a limited capacity to produce electricity and, in order to ensure the user demands are met, complex control systems are employed to selectively power up and shut down additional power stations to cope with these swings in demand. This arrangement is expensive, inefficient and is continually placed under great strain, during periods of particularly high demand. There are also political and environmental problems with the current arrangement.

One way of easing some of these problems would be if end users themselves were to choose to generate at least some of their own electricity on their own premises using e.g. generators, renewable power sources such as photovoltaic solar panels and wind turbines etc. However, to date, there has been very little incentive for individual users to install such systems and the uptake has been correspondingly low.

According to the present invention there is provided a method of controlling storage, distribution and supply of electricity in a localised electricity network, the method comprising:-providing the localised electricity network with electricity generating apparatus for supplying a source of direct current electricity to the localised electricity network; providing the localised electricity network with capacitive means for storing electricity; storing electricity generated by the electricity generating apparatus in the capacitive means; selectively distributing stored electricity from the capacitive means to the localised electricity network; and selectively connecting portions of the localised electricity network to the nationalised electricity network dependent upon a time of day signal.

According to the present invention, there is also provided a method of controlling a power unit on a localised electricity network, the method comprising:-providing a controller on a localised electricity network; providing at least a power unit on the localised electricity network at a location which is remote from the controller; determining whether electricity being offered on a nationalised electricity network is being offered at a peak or off-peak rate; sending a control signal from the controller to switch on the or each remote power unit when it is determined that electricity is being offered by the nationalised electricity network at an off peak rate such that any appliance connected thereto may switch on; and sending a control signal from the controller to switch off the or each remote power unit when it is determined that electricity is being offered by the nationalised electricity network at a peak rate such that any appliance connected thereto may not switch on.

According to the present invention there is also provided a method of controlling electrical isolation of a localised electricity network from a nationalised electricity network, the method comprising;-providing a controller, a grid tied inverter device and capacitive means On a localised electricity network; providing an isolating interface device at the junction between the localised electricity supply and a nationalised electricity network; monitoring whether a loss of electricity supply from the nationalised electricity network has occurred and, in the event of such a loss of electricity supply, further comprising the step of sending a control signal from the controller to the isolating interface device to electrically isolate the localised electricity network from the nationalised electricity network; determining whether said isolation has been successful and, if so, sending a control signal from the controller to the grid tied inverter device to draw electricity from the capacitive means.

Further features and advantages of the invention will be made apparent from the following description and from the claims.

Embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which:-Fig. 1 is a schematic view of a control system operating according to the method of the present invention during an overnight off-peak period; Fig. 2 is a schematic view of a control system operating according to the method of the present invention during a transitional morning / evening peak period; Fig. 3 is a schematic view of a control system operating according to the method of the present invention during a mid-day peak period; Fig. 4 is a schematic diagram showing the layout of components of the invention installed in premises as well as the connections provided therebetween; Fig. 5 is a flow diagram illustrating the logic followed by the controller according to the method of the present invention; Fig. 6 is a flow diagram illustrating the logic followed by the remote power management unit and controller according to the method of the present invention; Fig. 7 is a flow diagram illustrating the logic followed by the protection interface modules and controller according to the method of the present invention; Figs. 8 to 12 are conceptual illustrations of the operational advantages provided by the methods of the present invention; Fig. 13 is schematic flow diagram showing the operation of the remote power unit and controller on a localised electricity network; Fig. 14 is a schematic flow diagram showing the operation of the protection interface modules and controller on a localised electricity network; Fig. 15 is a schematic illustration of a controHer which controls the system according to the method of the present invention; Fig. 16 is a side, front and perspective views of the protection interface modules which isolate the localised electricity network from the nationalised electricity network according to the method of the present invention; Fig. 17 is a side, front, perspective and plan view of remote power units which in conjunction with the controller control power to appliances on the localised electricity network according to the method of the present invention; Fig. 18 is an illustrative graph showing illustrates the typical demand and photovoltaic panel electricity generation over a typical twenty four hour period; and Fig. 19 is a schematic circuit diagram of the localised electricity network and its interaction with the nationalised electricity network.

In the present description, the term "electricity" has been used to simplify and clarify the way in which the various aspects of the system interact with one another. The skilled person will be aware that this terminology may not be typical in the context of certain aspects of the invention (for example, the skilled person will be aware that it is not typical to refer to the quantity of electrical potential energy stored on a battery simply as "electricity") however, this is immaterial to the operation of the invention described and use of the term "electricity" in such portions of the description is therefore appropriate, clear and concise.

In the following description, the term "off peak" is used to describe times at which the demand for electricity from users is below a threshold set by the electricity supplier and conversely the term "peak" describes times at which the demand for electricity is above that threshold. In a typical twenty four hour period, the off peak period may run from say 23.30 hrs to 06.30 hrs local time, and the peak period may run outside of that time period; however, it will be appreciated that user demand is influenced by an infinite number of external factors, such as weather conditions, day of the week, large sporting events etc. and that these time periods may be shifted accordingly. This may be controlled by a radio time signal sent out to dual rate meters such that they switch between the peak and off peak rates as required.

Referring to Fig. 1, during an off peak period, such as during the night, it is desirable to draw electricity into the localised electricity network (for example a home ring circuit) from a nationalised electricity supply (national grid). At such times, off peak rates are normally offered by electricity suppliers as a limited incentive for users to use electricity during the off peak period if possible. During such off peak periods the controller 10 will command the system to use electricity drawn from the national grid to charge capacitive means such as batteries 12, hybrid electric cars etc. on the home ring circuit. The controller 10 will also command the system to power selected non-time dependent appliances 14 on the home ring circuit via remote power units 16 (described in more detail subsequently). Non-time dependent appliances are those which can substantially fulfil their task at any time of the day with little or no inconvenience to the user, for example washing machines, tumble dryers, dishwashers etc. The home ring circuit is also provided with electricity generating apparatus which produces a source of direct current. Examples of such apparatus includes generators or renewable energy sources such as solar photovoltaic panels 18, wind turbines 20 etc. As shown in Fig. 1, the controller can also direct electricity supplied by the electricity generating apparatus to capacitive means 12 during the off peak period. This process of electricity transfer is conceptualised by the illustration on Fig. 12.

Referring to Fig. 2, in a transitional evening I morning peak period, it becomes desirable to draw, into the home ring circuit, electricity from the national grid as well as use electricity derived from the batteries 12.

During such periods the controller 10 commands the system to use both electricity derived from the national grid and electricity derived from the charged batteries 12. In this configuration since a portion of the electricity being used is coming from the national grid at the more expensive peak rate, it may be desirable for remote power units 17 to interrupt the electricity supply for short time period to non-critical appliances 19. This process of electricity transfer is conceptualised by the illustrations in Fig. 8 This illustrates that renewable energy sources have stored power on the batteries connected to the localised electricity network when household consumption has been low. It also shows that this electricity is then being used to supplement electricity from the national grid until that stored energy is exhausted. Note any renewable energy being produced during this time is used immediately as it is produced whilst the system is set up in this configuration). Fig. 9 conceptualises the situation where the electricity previously stored on the batteries has been exhausted and the household electricity demand must be satisfied by electricity from the national grid supplemented by any source of electricity from the renewable electricity generating apparatus.

Referring to Fig. 3, in a peak period, such as during the middle of the day, it is not desirable to draw electricity into the ring circuit from the national grid. Instead as much electricity as possible is sourced from the electricity generating apparatus. During such peak periods the controller 10 commands the system to draw electricity into the home ring circuit from the renewable energy source(s) 18, 20. Any surplus energy provided by the renewable energy source(s) is directed to the batteries 12 such that the are charged thereby. This process of electricity transfer is conceptualised by the illustration in Fig. 10, This illustrates the situation where the electricity produced by the renewable energy source(s) exceeds the household demand and so the surplus electricity is stored in the batteries on the localised electricity network. With this arrangement no electricity is required from the national grid.

In the following description, the steps described have been numbered for reference purposes only. The sequence of these numbers does not imply any chronological order to the steps carried out. The order of the steps is

made apparent from the context of the description.

Referring to Fig. 5, the steps followed by the controller 10 in accordance with the method of controlling storage, distribution and supply of electrical power in a localised electricity network of the present invention will now be described.

The controller 10 may be a stand alone dedicated box such as that shown in Fig. 15 or a may be embodied by appropriate software and interface components provided on a PC. Starting at step 1, the controller firstly considers, at step 2, whether capacitive means (such as batteries) are provided on the localised electricity network. If not, the renewable energy source must be connected (via a grid tied inverter (Gil)) to the home ring circuit, at step 7. If the controller determines that batteries are indeed installed, the controller next considers the current time of day, at step 3.

The controller is supplied with a clock signal provided either via the internet or a PC to facilitate this step. Depending upon a time of day signal, the controller is able to determine whether the electricity being offered by the national grid would be offered at a peak or off-peak rate.

If the controller determines that the national grid is offering electricity at a peak rate it then considers, at step 4, whether any request has been received from the electricity supplier to export electricity to the national grid (a description of when this situation would arise is described subsequently). If so, electricity is discharged to the national grid, at step 5, for a given time period, e.g. thirty minutes, or until the electricity stored in the battery is exhausted. Once this has occurred step A feeds back to step 3 as shown.

If the controller determines, at step 4, that a request has been received to export electricity to the national grid, at step 6, the controller diverts such electricity from the batteries to the national grid until the batteries are substantially exhausted.

If the controller determines that the national grid is offering electricity at an off-peak rate it then considers, at step 8, whether the rate of electricity production from the renewable electricity generating apparatus is sufficient to fully charge the batteries before the national grid will switch to offering electricity at a peak rate. If not, at step 11, the controller switches on the mains charger in order to charge the batteries using electricity from the national grid at the off peak rate, until either the batteries are fully charged or until the national grid switches to offering electricity at the peak rate. If on the other hand, the controller decides, at step 8, that the rate of electricity being produced by the renewable electricity generating apparatus is sufficient to fully charge the batteries before the national grid will switch to offering electricity at a peak rate, the controller then determines, at step 9, whether the batteries are substantially fuDy charged (this state being determined when the batteries are charged to above e.g. 80% of their maximum capacity). If not, at step 11, the controller switches on the mains charger in order to charge the batteries using electricity from the national grid at the off peak rate, until either the batteries are fully charged or until the national grid switches to offering electricity at the peak rate. If, on the other hand, the controller determines, at step 9, that the batteries are substantially fully charged it will, at step 10, divert the electricity produced by the renewable electricity generating apparatus to the home ring circuit until a condition is reached whereby the battery charge drops below the fully charged level (this state possibly being determined when the battery charge drops below e.g. 70% of maximum capacity). In other words, step 10 occurs in order to provide an outlet for surplus electricity created by the renewable electricity generating apparatus when the batteries are substantially full.

Throughout this process, the controller monitors the quantity of electricity sourced from the national grid to supplement the localised electricity network and also saves this information for future analysis.

As well as the previously mentioned advantages, steps 4, 5 and 6 of the invention open up the opportunity of the owner of the localised electricity supply (which may be a home user) to sell electricity back to electricity supplier. As conceptualised by Fig. 11, if previously agreed between the electricity supplier and the home user, the household can sell electricity to the grid at times of peak demand. Non essential household electricity consumption is reduced and stored energy is used to both supply the household and to export to the national grid. This process may be controlled via commands from the a electricity supplier control centre transmitted across the internet, or other means, to the localised electricity network controller. This step may also include the step of measuring the quantity of electricity exported from the localised network to the nationalised network and reporting this back to the electricity supplier control centre, again via the Internet or other means. The layout of components in such a system is also illustrated in Fig. 4.

Referring to Fig. 6, the steps followed by the controller in managing remote power units provided on the localised electricity network of the present invention will now be described. In this regard, the controller orchestrates the process and communicates via the localised network connections and / or alternative communication means with the remote power units in order to arrive at the desired effect described subsequently.

Starting at step 1, the controller firstly considers, at step 2, the current time of day. Depending upon the time of day, the controller is able to determine whether the electricity being offered by the national grid would be offered at a peak or off-peak rate.

If the controller determines that the national grid is offering electricity at an off peak rate, at step 5, it sends an "on" signal to remote units on the network to switch on appliances connected to the localised electricity network.

In the embodiment described, the remote units comprise plug units 20 as shown in Fig. 17. The plug units 20 are configured such that communication with the controller is carried out over the house ring circuit electric wiring although alternative forms of communication may be utilised. Referring to Fig. 13, the remote power unit has a relay switch 40.

This may be operated between the on and off positions by the controller 42 which is also provided with a communications module 44 to remotely control whether the localised electricity supply (mains power from the socket) is connected to the appliance plugged into the remote unit 20.

If, at step 2, the controller determines that the national grid is offering electricity at a peak rate, it then considers, at step 3, whether the user has activated any manual override. The manual override may be activated by e.g. a simple push button on the control unit which can also be configured to automatically reset itself when the next peak period arrives. If the manual override has been activated by the user, the controller sends an "on" signal, at step 4, to remote units on the network to switch on appliances connected to the localised electricity network.

If, at step 3, the controller determines that no manual override has been activated by the user, the controller then considers, at step 6, whether minimal electricity use is required at that time. If not, the controller sends an "on" signal, at step 7, however, if a manual override has been activated on the remote unit, at step 13, the remote unit will remain off, at step 14, until the next off peak period arrives. In other words, a button can be activated on the remote unit itself to switch the power off to the connected appliance until the next off-peak period arrives. This is a useful feature which allows, for example, an appliance plugged into the remote unit to run through part of its process, be stopped by the user activating the manual override, and then automatically restart again when the next off-peak period arrives.

If, at step 6, the controller determines that minimal electricity is required at that time it then considers, at step 8, whether any manual overrides have been activated by the user. If so, the controller sends an "on" signal, at step 9, to remote units on the network to switch on appliances connected to the localised electricity network. If not, the controller sends an "off' signal, at step 10, to remote units on the network to switch off appliances connected to the localised network for a set time period, such as 30 minutes. Even if the controller arrives at step 10 (which would otherwise switch the appliances off) it then considers, at step 11, whether any overrides have been activated by the user (for example if they don't want an active appliance to be switched off even if minimal electricity consumption is desirable). If so, at step 12, the controller sends an "on" signal, at step 12, to remote units on the network to switch on appliances connected to the localised electricity network.

It can be seen that the controller and remote unit interaction described allows appliances connected to the localised electricity network to be intelligently and dynamically switched on at off peak times. This arrangement allows straightforward use of off peak electricity whilst minimising any adverse affects to the user in terms of the availability of electricity for powering individual appliances.

Referring to Fig. 7, the steps followed by the controller in isolating a localised electricity network from a nationalised electricity network of the present invention will now be described. In this regard, the controller orchestrates the process and communicates, via the localised network connections and I or alternative communication means, with protection interface modules in order to arrive at the desired effect described subsequently.

In the embodiment described, the connection interface module comprises units 22 as shown in Fig. 16. The units 22 are designed to allow direct installation into a standard consumer box and may have a status indicator such as an LED, The units 22 can be manually switched on and off by the user as desired. The units 22 can communicate with the controller over the house ring circuit electric wiring although alternative forms of communication may be utilised. Referring to Fig. 14, the protection interface module has a gated switch 30. This may be operated between the on and off positions manually or by the controller 32 which is also provided with a communications module 34 to remotely control whether the national electricity supply (mains grid) is connected to the localised electricity supply (home ring circuit).

Starting at step 1, the controller firstly considers, at step 2, whether there has been a loss of power from the national grid. If not, the controller loops back to step 1. If so, the controller (which has a back up electricity supply from the batteries) commands, at step 3, the protection interface module to isolate the home ring circuit from the national grid. The controller then considers, at step 4, whether this has been successful. If not, at step 6, the controller identifies that a fault has occurred and operates as though no protection interlace module is provided. If so, at step 5, the controller instructs the GTI to activate, thereby providing electricity to the home ring circuit from the batteries and / or renewable electricity generating apparatus sources only.

Arriving at step B, the controller continually considers, at step 6, whether the electricity supply from the national grid has been restored. If not, the controller continues to consider this at step B. If so, at step 7, the controller deactivates the GTI and then considers, at step 8, whether this has been successful. If not, the controller identifies that a fault has occurred. If so, at step 9, the controller resets the protection interlace module thereby restoring electricity to the home ring circuit from the national grid.

It is known to design GTIs on small scale renewable electricity networks such that they switch off if the national grid electricity supply fails. The UK safety standard for this is G.83. However, known systems have the drawback that in the event of the national grid electricity supply failing the home ring circuit will loose all electrical power even though renewable sources may be available. The present invention maintains the electricity supply on the home ring circuit from the renewable electricity generating apparatus and / or batteries during the loss of electricity supply from the national grid, without any manual switchover being required.

It should be noted that given current controller processing speeds, the steps of the process carried out above occur so quickly that they can for these purposes be considered to be near instantaneous and accordingly, there is virtually no noticeable interruption in the power supply to the user on the localised network when switching between the various modes of operation.

The previously describe arrangements allow the energy consumption and production of thousands or even millions of participating households on a national grid to be managed remotely by a central control centre managed by the electricity supplier over e.g. the internet or other means. In this way, the control centre can actively respond to large swings in demand by commanding electricity from participating households to supplement the electricity available on the nationalised network for non-participating households, business etc. (for an appropriate financial incentive; discussed subsequently). This is a "win-win" situation. The individual user gets the benefit of a reduced electricity tariff due to a combination of their charges being reduced in return for their participation in the scheme, any income received from selling a portion of their self generated electricity to the national grid, and a reduced quantity of electricity being used at the peak rate. In turn, the electricity supplier gets the benefit of having a large and flexible network of households available to be brought online onto the national grid very quickly in response to peaks in electricity demands.

Another important aspect of the invention described is that it provides a frame work which encourages users to reduce their electricity consumption and hence reduce CO2 emissions. For example, statistics demonstrate that a household without the system of the present invention installed on their electricity supply will, over a given twenty four hour period, typically only consume approximately 18% of their electricity during off-peak times.

It is currently only financially worthwhile switching to a dual rate meter (one which distinguishes between electricity used during peak periods and electricity used during off-peak periods) if approximately 25% or more of electricity consumption occurs during the off-peak period. Therefore even if a user is aware that operating appliances during the off peak period may be beneficial for the environment and the electricity supply network infrastructure there is no incentive for the majority of house holders to do this with current systems.

The invention described clearly has the advantage of providing this incentive to the user by making it straightforward for the user to operate non-time sensitive appliances during off peak periods due to the steps described (which are carried out with minimum user input). The cumulative effective of such an invention if installed in numerous households is significant since it provides a "time-shift" of demand which reduces peaks and troughs in the daily electricity demand cycle. In addition, the time-shift provided by the invention lends itself well to managed battery storage and feed-in, so that e.g. during winter months, when relatively little electricity might be produced by a given renewable energy source, such as solar photovoltaic panels (Fig. 18 illustrates the typical demand and photovoltaic panel electricity generation over a typical twenty four hour period) the batteries can be charged during the overnight off peak period with relatively cheap and low CO2 emission electricity.

This stored electricity can then be used during the peak morning and evening demand periods.

The invention also allows internet and multi system monitoring software to be used to minimise the financial and logistical problems with large swings in electricity demand and can reduce national CO2 emission because an overall greener and cheaper energy supply is provided by a more steady off-peak generation concept.

An example of how this could be implemented is where controllers, operating according to the method of the present invention, installed in thousands of homes could simultaneously discharge Megawatts of electricity from storage for a couple of hours into the households themselves, or in case of excess storage supply could feed electricity back into the national grid at times of peak demand and peak price for use by others. The same controllers could switch off freezers and fridges (using the remote power units) and so reduce the absolute demand for power at pinch points.

The financial benefits of this arrangement can be shared between the system supplier, the electricity distributors and their customers.

As well as the previously mentioned benefits of CO2 emission reductions, the invention also reduces CO2 emissions by allowing replacement of national grid electricity with electricity generated and stored locally, allowing winter time storage of off peak (low carbon) electricity and usage at peak time, and providing a more active method of monitoring and recording use of electricity. Furthermore, the system gives more flexible control over whether the user sells electricity to the supplier i.e. electricity generated on the localised electricity network from renewable sources is always used locally when it is most valuable and is only exported to the grid if required to do so from the electricity supplier's central control room via commands across e.g. the internet.

Modifications and improvements may be made to the foregoing without departing from the scope of the invention, for example:-Although the localised electricity network is described with reference to a home ring circuit, it could alternatively be a larger network such as a small business I farm network etc. Method of Controlling Storage, Distribution and Supply of Electricity The present invention is concerned with a method of controlling storage, distribution and supply of electricity in a localised electricity network, particularly, but not exclusively, electricity generated by renewable electricity generating apparatus such as solar photovoltaic panels and wind turbines.

made apparent from the context of the description.

Modifications and improvements may be made to the foregoing without departing from the scope of the invention, for example:-Although the localised electricity network is described with reference to a home ring circuit, it could alternatively be a larger network such as a small business I farm network etc.

Claims

1. A method of controlling storage, distribution and supply of electricity in a localised electricity network, the method comprising:-providing the localised electricity network with electricity generating apparatus for supplying a source of direct current electricity to the localised electricity network; providing the localised electricity network with capacitive means for storing electricity; storing electricity generated by the electricity generating apparatus in the capacitive means; selectively distributing stored electricity from the capacitive means to the localised electricity network; and selectively connecting portions of the localised electricity network to the nationalised electricity network dependent upon a time of day signal.

2. A method according to claim 1, wherein the steps of selectively distributing stored electricity from the capacitive means to the localised electricity network and selectively connecting portions of the localised electricity network to the nationalised electricity network is dependent upon whether electricity offered by the nationalised electricity network is offered at a peak or an off-peak rate.

3. A method according to any preceding claim, further comprising providing a grid tied inverter between the localised electricity network and the electricity generating apparatus.

4. A method according to any preceding claim, further comprising providing a grid tied inverter between the localised electricity network and the capacitive means.

5. A method according to any of claims 2 to 4, wherein when it is determined that the nationalised electricity network is offering electricity at a peak rate, the method further comprises the step of determining whether any request has been received to export electricity to the nationalised electricity network and, if so, connecting the capacitive means to the nationalised electricity network and diverting stored electricity derived from the capacitive means to the nationalised electricity network until the electricity stored in the capacitive means is at least partially exhausted and, if not, connecting the capacitive means to the localised electricity network and diverting stored electricity derived from the capacitive means to the localised electricity network until the capacitive means is at least partially exhausted.

6. A method according to any of claims 2 to 5, wherein, when it is determined that the nationalised electricity network is offering electricity at an off-peak rate, the method further comprises the step of determining whether the source of direct current from the electricity generating apparatus is sufficient to charge the capacitive means before the nationalised electricity network is expected to offer electricity at a peak rate.

7. A method according to any of claims 2 to 6, wherein if it is determined that the source of direct current from the electricity generating apparatus is sufficient to charge the capacitive means before the nationalised electricity network is expected to offer electricity at a peak rate, determining whether the capacitive means are substantially charged, and if so, diverting the electricity generated by the electricity generating apparatus for use on the localised electricity network and, if not, charging the capacitive means from the nationalised electricity network until the capacitive means are substantially charged or the nationalised electricity network offers electricity at a peak rate.

8. A method according to any of claims 2 to 6, wherein if it is determined that the source of direct current from the electricity generating apparatus is not sufficient to charge the capacitive means before the nationalised electricity network is expected to offer electricity at a peak rate, charging the capacitive means from the nationalised electricity network until the capacitive means are substantially charged or the nationalised electricity network offers electricity at a peak rate.

9. A method of controlling a power unit on a localised electricity network, the method comprising:-providing a controller on a localised electricity network; providing at least a power unit on the localised electricity network at a location which is remote from the controller; determining whether electricity being offered on a nationalised electricity network is being offered at a peak or off-peak rate; sending a control signal from the controller to switch on the or each remote power unit when it is determined that electricity is being offered by the nationalised electricity network at an off peak rate such that any appliance connected thereto may switch on; and sending a control signal from the controller to switch off the or each remote power unit when it is determined that electricity is being offered by the nationalised electricity network at a peak rate such that any appliance connected thereto may not switch on.

10. A method according to claim 9, wherein when it is determined that the electricity being offered on the nationalised electricity network is being offered at a peak rate, the method further comprises the step of determining whether any manual override has been activated by a user and, if so, overriding the control signal sent to switch the or each remote power unit on or off such that any appliance connected thereto may be switched on or off regardless of whether the nationalised electricity network is offering electricity at a peak or off peak rate.

11. A method according to claim 10, wherein when it is determined that no manual override has been activated by the user, the method further comprises the step of determining whether the controller is requesting that a minimal quantity of electricity be used on the localised network and, if not, sending a control signal from the controller to switch on the or each remote power unit such that any appliance connected thereto may be switched on.

12. A method according to claim 11, wherein when it is determined that the controller is requesting that a minimal quantity of electricity be used on the localised network, the method further comprises the step of determining whether any whether any manual override has been activated by a user and, if so, overriding the control signal sent to switch the or each remote power unit on or off such that any appliance connected thereto may be switched on or off regardless of whether the controller is requesting that a minimal quantity of electricity be used on the localised network.

13. A method according to claim 12, wherein when it is determined that no manual override has been activated, further comprising the step of sending a control signal from the controller to switch off the or each remote power unit, for a nominated time period, then determining whether any overrides have been activated and then sending a control signal from the controller to switch on the or each remote power unit such that any appliance connected thereto may switch on.

14. A method of controlling electrical isolation of a localised electricity network from a nationalised electricity network, the method comprising;-providing a controller, a grid tied inverter device and capacitive means on a localised electricity network; providing an isolating interface device at the junction between the localised electricity supply and a nationalised electricity network; monitoring whether a loss of electricity supply from the nationalised electricity network has occurred and, in the event of such a loss of electricity supply, further comprising the step of sending a control signal from the controller to the isolating interface device to electrically isolate the localised electricity network from the nationalised electricity network; determining whether said isolation has been successful and, if so, sending a control signal from the controller to the grid tied inverter device to draw electricity from the capacitive means.

15. A method according to claim 14, further comprising the step of determining whether the nationalised electricity supply has been restored and, if so, sending a control signal from the controller to the grid tied inverter device to cease drawing electricity from the capacitive means; and sending a control signal from the controller to the isolating interface device to reconnect the localised electricity network to the nationalised electricity network.

16. A method of controlling storage, distribution and supply of electricity in a localised electricity network according to the description and drawings.

17. A method of controlling a power unit on a localised electricity network

according to the description and drawings.

18. A method of controlling electrical isolation of a localised electricity network from a nationalised electricity network according to the description and drawings.

17. A method of controlling a power unit on a localised electricity network

according to the description and drawings.