WO2018211272A1

WO2018211272A1 - Enhancement of electric vehicles and their effective battery storage capacity

Info

Publication number: WO2018211272A1
Application number: PCT/GB2018/051327
Authority: WO
Inventors: Declan Nigel PRITCHARD
Original assignee: Pritchard Declan Nigel
Priority date: 2017-05-18
Filing date: 2018-05-16
Publication date: 2018-11-22
Also published as: EP3625076A1

Abstract

A method and system for extending the range of an electrically powered vehicle, the vehicle comprising a solar array power source capable of delivering electrical power when illuminated by solar radiation and a battery storage system, the method comprising the steps of: estimating a solar exposure for the solar array power source over a future period of time; estimating a voltage output value for the solar array power source based on the estimated solar exposure; determining a whether the storage system has capacity for the estimated photovoltaic output value; and in response to determining that the battery storage system has capacity for the estimated photovoltaic output, causing charging of the battery storage system by the solar array power source.

Description

ENHANCEMENT OF ELECTRIC VEHICLES AND THEIR EFFECTIVE BATTERY

STORAGE CAPACITY

BACKGROUND OF THE INVENTION

The present invention relates generally to electric vehicles and more specifically it relates to an enhancement of electric vehicles and their effective battery storage capacity for manufacturers of electric and hybrid electric vehicles to correctly size solar panels to be incorporated into their vehicle design, in a way that is predictable in any part of the world and according to local conditions such as solar insolation, annual or seasonal hours of sunshine, ambient temperature and actual photo-electric panel design and operating performance, to effectively increase effective battery capacity for the average commuter.

SUMMARY OF THE INVENTION

The invention generally relates to an electric vehicle which includes estimating the surface area of an electric vehicle or hybrid electric vehicle amenable to being covered with flexible photo-voltaic solar panels and then to predict the output of the solar panels according to the environmental conditions near the location where the vehicle is to be sold and used, thus enabling predictions to be made as to the time interval between electric utility re-charges based on the users daily travel requirements.

There has thus been outlined, rather broadly, some of the features of the invention in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter.

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction or to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting.

An object is to provide an enhancement of electric vehicles and their effective battery storage capacity for manufacturers of electric and hybrid electric vehicles to correctly size solar panels to be incorporated into their vehicle design, in a way that is predictable in any part of the world and according to local conditions such as solar insolation, annual or seasonal hours of sunshine, ambient temperature and actual photo-electric panel design and operating performance, to effectively increase effective battery capacity for the average commuter.

Another object is to provide an Enhancement of Electric Vehicles and Their Effective Battery Storage Capacity that is implemented by the use of correctly designed photo-voltaic solar panels which will increase the driving range for average commuters.

Another object is to provide an Enhancement of Electric Vehicles and Their Effective Battery Storage Capacity that results in an increased lifetime for the vehicle batteries as they are subjected to less deep discharge over their expected life, due to the addition of the correctly designed solar panels.

Another object is to provide an Enhancement of Electric Vehicles and Their Effective Battery Storage Capacity that substantially reduces the carbon dioxide and other pollutants associated with operating the electric or hybrid vehicle due to less dependence on charging the vehicle from the electric utility and substituting the energy with benign solar power.

Another object is to provide an Enhancement of Electric Vehicles and Their Effective Battery Storage Capacity that enables manufacturers of electric and hybrid electric vehicles to correctly estimate the performance of their vehicles when supplemented with on-board solar photo-voltaic panels in any part of the world.

Another object is to provide an Enhancement of Electric Vehicles and Their Effective Battery Storage Capacity that benefits the vehicle owner by reducing the frequency of charging the vehicle from the electric utility grid thereby reducing running costs and pollution from the point of view of the owner. In accordance with a first aspect of the present invention there is method of extending the range of an electrically powered vehicle, the vehicle comprising a solar array power source capable of delivering electrical power when illuminated by solar radiation and a battery storage system, the method comprising the steps of:

estimating a solar exposure for the solar array power source over a period of time; estimating an energy output value for the solar array power source based on the estimated solar exposure;

determining a range of the vehicle based on the estimated energy output value; displaying the determined range of the vehicle to a driver of the vehicle;

determining whether the storage system has capacity for the estimated energy output value; and in response to determining that the battery storage system has capacity for the estimated energy output, causing charging of the battery storage system by the solar array power source. In accordance with a second aspect of the present invention there is a system for extending the range of an electrically powered vehicle, the vehicle comprising a solar array power source capable of delivering electrical power when illuminated by solar radiation and a battery storage system, the system comprising:

means for estimating a solar exposure for the solar array power source over a future period of time;

means for estimating a voltage output value for the solar array power source based on the estimated solar exposure;

means for determining a range of the vehicle based on the estimated energy output value;

means for displaying the determined range of the vehicle to a driver of the vehicle; means for determining a whether the storage system has capacity for the estimated photovoltaic output value; and

in response to determining that the battery storage system has capacity for the estimated photovoltaic output, causing charging of the battery storage system by the solar array power source.

In accordance with a third aspect of the present invention there is a method of optimising solar energy capture for a vehicle, the method comprising:

estimating a solar exposure at a geographic location;

estimating an energy output value for a solar cell of a solar array based on the estimated solar exposure;

determining an energy input requirement for a desired range of the vehicle; and configuring the number of cells within the array based on the estimated energy output value of the solar cell and the determined energy input requirement, wherein estimating the solar exposure comprises determining a capacity factor of the solar cell.

In accordance with a fourth aspect of the present invention there is a system for optimising solar energy capture for a vehicle, the system comprising:

means for estimating a solar exposure at a geographic location;

means for estimating an energy output value for a solar cell of a solar array based on the estimated solar exposure;

means for determining an energy input requirement for a desired range of the vehicle; and means for configuring the number of cells within the array based on the estimated energy output value of the solar cell and the determined energy input requirement, wherein estimating the solar exposure comprises determining a capacity factor of the solar cell. Other objects and advantages of the present invention will become obvious to the reader and it is intended that these objects and advantages are within the scope of the present invention. To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of this application.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIGURE 1 : In the equation of figure 1 , the time interval T, in days, between charging an electric vehicle battery bank is given by the equation in Figure 1 , where R is the maximum storage capacity of an electric vehicle battery storage system expressed in total miles of available travel, and D is the actual average daily travel in miles (but this does not account for any additional loads that may be used at driver discretion, such as air conditioning, lights, etc.).

FIGURE 2: The equation of figure 2, gives the average additional storage capacity (expressed as travel distance), Rs, provided in one day by an array of photo-voltaic solar panels. Where P is the maximum power rating of the solar array, expressed in kilowatts (kW), PT is the total temperature coefficient reduction in power, C is the Capacity Factor, as defined by this invention, at the approximate latitude of the solar array and at the approximate time of year, expressed as a ratio and E is the efficiency of the electric vehicle expressed in miles or kilometres per kilowatt-hour (kWh).

All manufacturers of photovoltaic cells publish data regarding the degradation of power output with increased ambient temperature, (temperature coefficient) and is usually in the range of minus 0. 4 to minus 0. 5 % per degree Celsius of temperature increase from the standard test temperature of 20 degrees Celsius. For the purposes of this invention the total correction to the base power capacity of the PV cell or array, PT, is given by the multiplication of the temperature coefficient by the ambient temperature difference between the base station and the target location, such that an increase in temperature results in a decrease of power and vice versa.

FIGURE 3: The equation of figure 3 gives the new time interval, Ts, between vehicle recharging when the vehicle is fitted with a photo-voltaic solar panel array. FIGURE 4: The equation in figure 4 is the expansion of the equation in figure 3 using the equations of figures 1 and 2.

FIGURE 5: Figure 5 is an example of a graph of solar insolation vs. Earth latitude, showing seasonal and annual values. In this example the units of solar insolation (vertical axis) are kcal per square centimetre, however as this invention uses a relative correction, the absolute values are not relevant. The horizontal axis is the Earth latitude. The solid curved line is the annual average insolation vs. Latitude, and the dotted curved lines represent seasonal insolation curves in the northern and southern hemispheres of the Earth. The vertical and horizontal dotted lines represent the intercepts of latitude and insolation at the base station, B and target location, T. FIGURE 6: With reference to figure 5, the equation in figure 6 gives the Insolation Correction Factor (ICF) applicable between base station, B, and target location, T. This is true regardless of the relative positions of T and B on the insolation curve, and regardless of whether the annual or seasonal curves are used, as appropriate to the need at T.

FIGURE 7: The equation of figure 7 derives the Daylight Correction Factor (DCF), provided that the meteorological systems used to measure daylight or sunshine hours in the neighbourhood of the base station are similar to those found at the target location, where Bd is the total daily, monthly, seasonal or annual sunshine hours at the base station, and Td is the total daily, monthly, seasonal or annual sunshine hours at the target location.

FIGURE 8: The equation in figure 8 gives the final Capacity Factor, C, to be used in the equations of figures 2, 3 and 4 above, where CB is the actual Capacity Factor established at the base station according to the description below, and ICF is the Insolation Correction Factor and DCF is the Daylight Correction Factor as described herein.

FIGURE 9: Figure 9 is a graph showing the relationship between the days between utility charging of the vehicle batteries (vertical axis) plotted against the average daily travel distance of the electric vehicle (horizontal axis) according to equation of figure 3 above. The dark curve is for the basic vehicle without solar power input. The dotted curve is for the vehicle fitted with 500 watt of solar panels, operated at latitude 45 degrees N and the dashed curve at latitude 35 degrees N. All corrections mentioned above have been applied. For the graph in figure 9, the dashed vertical line corresponding to an average daily commute of about 21 . 25 miles, is asymptotic to the dark dashed line corresponding to 35 degree latitude. This implies that if the daily commute is, on average, substantially lower than 21 . 5 miles, then the electric vehicle may never need to be re-charged from the utility main electricity supply.

Similarly, the vertical dashed line at about 13. 75 miles is asymptotic to the dotted curve corresponding to 45 degree latitude, the implication is that if the daily commute is, on average, substantially lower than 13. 75 miles, then the electric vehicle may never need to be recharged from the utility main electricity supply. FIGURE 10: Figure 10 is a graph showing the relationship between the days between utility charging of the vehicle batteries (vertical axis) plotted against the average daily travel distance of the electric vehicle (horizontal axis). The dark curve is for the basic vehicle without solar power input. The dotted curve is for the vehicle fitted with 250 watt of solar panels, operated at latitude 45 degrees and the dashed curve at latitude 35 degrees. FIGURE 11 : Figure 1 1 is a top view of the present invention. Figure 11 is a bird's eye view of a typical electric vehicle with differing photo-voltaic solar panel sizes according to this invention. The total area of the photo-electric cell arrays on the vehicle is determined by design, based on latitude of the vehicle/user and the average daily travel of the vehicle, according to the present invention. This maximizes the potential of the vehicle to deliver more commuter miles between utility recharge sessions, and minimizes the deep cycling of the batteries.

These concepts will translate into more accurate marketing material and information for customers.

FIGURE 12: Figure 12 is an alternative embodiment of the present invention. Circuit diagram showing some of the circuits in an electric vehicle, along with the solar panel arrays according to one embodiment of the present invention.

FIGURE 13: Figure 13 is a second alternative embodiment of the present invention. Circuit diagram showing some of the circuits in an electric vehicle, along with the solar panel arrays according to another embodiment of the present invention. FIGURE 14: Figure 14 is a third alternative embodiment of the present invention. Circuit diagram showing some of the circuits in an electric vehicle, along with the solar panel arrays according to another embodiment of the present invention. FIGURE 15: Figure 15 is a fourth alternative embodiment of the present invention. Circuit diagram showing some of the circuits in an electric vehicle, along with the solar panel arrays according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

Overview

Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the figures illustrate estimating the surface area of an electric vehicle or hybrid electric vehicle amenable to being covered with flexible photo-voltaic solar panels and then to predict the output of the solar panels according to the environmental conditions near the location where the vehicle is to be sold and used, thus enabling predictions to be made as to the time interval between electric utility re-charges based on the users daily travel requirements.

Figures 1 to 15 illustrate elements of a method and system for extending the range of an electrically powered vehicle. As illustrated in Figures 1 1 to 15, the vehicle comprises a solar array power source capable of delivering electrical power when illuminated by solar radiation and a battery storage system. Figure 5 illustrates a graph of solar insolation vs. Earth latitude, showing seasonal and annual values used to estimate a solar exposure for the solar array power source over a period of time. This allows for calculating an estimate of an energy output value for the solar array power source based on the estimated solar exposure at a specific geographical location (described in more detail below under the heading "A Method for Estimating the Solar Insulation at the Market Location"). The estimated energy output can be used to determine a range that the vehicle will be able travel before being required to recharge, which can be displayed to the driver of the vehicle (described in more detail below under the heading "Establishing the Daily Driving Range of Potential Ev Customers"). Figures 12 to 15 illustrate example circuit diagrams of the solar array power source connected to the storage system. If the storage system has capacity for the estimated energy output of the solar array power source then a condition switch or a solar controller will cause the solar array power source to charge a battery of the storage system. Figures 1 to 15 also illustrate elements of a method and system for optimising solar energy capture for a vehicle. Figure 5 illustrates a graph of solar insolation vs. Earth latitude, showing seasonal and annual values used to estimate a solar exposure of a solar cell of a solar array power source over a period of time. This allows for calculating an estimate of an energy output value for the solar array power source based on the estimated solar exposure at a specific geographical location. The number of solar cells within the solar array can then be configured based on the estimated energy output of the solar cell and a determined energy input requirement of the vehicle for a desired range (described in more detail below under the heading "Re-design of Available Surface Area of Electric or Hybrid-electric Vehicle for Solar Panel Enhancement"). The equations of Figures 1 to 4 and 6 to 8 are used to determine a capacity factor of the solar cell at the geographic location. A Method for Estimating the Solar Insolation at the Market Location

By using the latitude of the market location and knowing the latitude of a known control base station, then a solar insolation correction factor can be used as a component to help predict the effective capacity factor of the solar array at the market location, as specified in this invention, by using readily available, and well documented seasonal, or annual solar insolation data. This element will be effective if the power output characteristics of the solar array to be used at the market location are largely similar to those used at the control base station. Including orientation to input sun light. There are many solar insolation data and graphs available with many different insolation units, for example, imperial, metric or SI units. However, for the purposes of this invention, the absolute units are not relevant as long as they are consistent at all latitudes of interest.

Many solar insolation graphs and data are merely theoretical estimates of solar insolation based on the geometrical relationship of earth and incident solar radiation. Many of these estimates are equally valid but may be less reliable as latitude increases to the polar regions of earth.

Correcting for Seasonal or Annual Ambient Temperature at the Market Location

Manufacturers of photo-voltaic solar cells publish data regarding the degradation of power output with increased ambient temperature, (temperature coefficient) and is usually in the range of minus 0. 4 to minus 0. 5 % per degree Celsius of temperature increase from the standard test temperature of 20 degrees Celsius and vice versa for a temperature decrease. This correction for temperature coefficient between the base station and the target market location can be used to modify the Capacity Factor at the market location according to the present invention. Provided that the methods used for measuring the ambient temperature (daily, monthly, seasonal or annual) at the control base station and the target market location are similar, then the ambient temperature correction factors can be used as described in this invention.

It may be that at some target market locations, reliable ambient temperature data are not available and in such cases estimates will need to be made.

Correcting for Seasonal or Annual Hours of Daylight at the Market Location

Provided that the meteorological systems used to measure daylight or sunshine hours in the neighbourhood of the base station are similar to those found at the target market location, then a Daylight Correction Factor (DCF) can be calculated so as to modify the Capacity Factor at the market location, according to this invention.

Provided that the methods used for measuring the hours of daylight (daily, monthly, seasonal or annual) at the control base station and the target market location are similar, then the daylight correction factors can be used as described in this invention. Clearly, the orientation of the solar arrays at the control station should be largely similar to those to be used at the target location. For most practical applications this orientation would be flat, with no vertical inclination.

It may be that at some target market locations, reliable daylight hours data are not available and in such cases estimates will need to be made.

Establishing the Daily Driving Range of Potential Ev Customers

Many government, regional and city authorities publish data related to the average commuting distances of car drivers within their jurisdictions. By knowing these figures in a target market area, a solar power enhanced solution for EVs or HEVs can be formulated and produced with known average performance characteristics under known average environmental conditions. Clearly the end users themselves are fully aware of their daily mileage requirements and commute distances. Referring to figures 9 and 10, by using the methods described in this invention, the interval between electric utility re-charging of the EV or HEV can be calculated as a function of daily driving range requirement and the peak power output of the solar panels fitted on the vehicle. The desired daily driving range can be established from published data or the knowledge of the potential customers of the EV or HEV.

Even as photo-voltaic solar panel efficiencies improve with time, due to product improvements, the methods described herein will still hold true provided that bench marks have been established at base stations using the new and improved solar panel technology.

Establishing the Available Surface Area of the Ev or Hev for Solar Panel Installation The available surface areas are those areas that afford an exposure to daylight from above and whose surfaces are largely parallel to the horizontal with a tolerance of + or - 45 degrees from horizontal.

Referring to figure 1 1 , the suitable surface areas available for hosting photo-voltaic solar panels must be near parallel to horizontal within approximately plus or minus 45 degrees.

Due to the use of flexible plastic or resin mounted solar arrays (not excluding stiff glass arrays), most eligible surfaces of the vehicle can be utilized to host the solar arrays. Establishing the Solar Panel Capacity of the Electric or Hybrid Electric Vehicle

Manufacturers of photo-electric solar panels publish data regarding the peak energy output of their solar cells, typically in watts per square meter. By deriving the capacity factor of the solar cells according to this invention, then performance curves can be drawn that will predict the performance of the solar enhanced EV at different latitudes, ambient temperature and total daylight conditions.

Power density in watts per square meter. Creating Appropriate Marketing Information

Once the performance characteristics have been established according to this invention, the marketing and publicity information can be created accurately so that it is targeted at specific locations, commuters and markets in various countries.

Predicting output. Re-design of Available Surface Area of Electric or Hybrid-electric Vehicle for Solar Panel Enhancement

In circumstances where the surface area available for effective deployment of photo-voltaic solar panels according to this invention is insufficient for the target market, due to insolation, daylight hours, ambient temperature or increased daily commuter needs, then the vehicle may be re-designed to enable a larger effective surface area. Sheets of photovoltaic cells configured within plastic and/or resin support matrices are readily available on the market. These can be cut and configured to provide many various voltage and current combinations for the end user, such as a car manufacturer. These can be glued or otherwise attached to the body of EVs and HEVs.

Connecting the Solar Array to the Ev by Condition Switch When the vehicle is in use and disconnected from the electric utility it may be advantageous for the direct current (DC) output of the solar array to be connected directly to a DC to DC converter on the vehicle so as to step up the voltage to the desired charging voltage of the battery bank as shown in figure 12. Alternatively, when the vehicle is stationary and connected the electric utility, it may be more advantageous to connect the output of the solar array through a DC to AC inverter. The position of the "Condition Switch" is determined by electronic means whereby the state of the vehicle connection to the electric utility is determined.

Connecting the Solar Array to the Ev by a Dc to Ac Inverter Referring to figure 13, the output of the solar array may be permanently connected to the EV via a DC to AC inverter regardless of the connection or otherwise to the electric utility.

Connecting the Solar Array to the Ev by an Intermediate Battery, Charge Controller and Dc to Ac Inverter

Referring to figure 14, the output of the solar array is connected to an intermediate battery via a commercially available charge controller. When the voltage of the intermediate battery is sufficient, then the Solar Charge Controller will allow current to pass to the DC to AC inverter and thence to the vehicle AC charging system.

Connecting the Solar Array to the Ev by an Intermediate Battery and Charge Controller Only Referring to figure 15, the output of the solar array is connected to an intermediate battery via a commercially available charge controller. When the voltage of the intermediate battery is sufficient, then the Solar Charge Controller will allow current to pass to the DC side of the vehicle's main AC to DC inverter.

Operation of Preferred Embodiment

A measuring base station is established whereby the particular PV array is installed at a location and connected to an electric utility or load such that the output is measured (for example in kilo-watt hours), for at least an equivalent period of time as will be required at other sites. This period will typically be more than one year, but is not necessarily so, as there might be applications that are seasonally based. The latitude of the measuring base station is established and the solar insolation at that latitude is either calculated or read from readily available graphs. This is then interpolated, along the curve of insolation vs. Earth latitude to derive an insolation correction factor for the other desired location. The appropriate equation or graph for solar insolation can be hourly, seasonally or annually averaged. The absolute units of the solar insolation are not important for the purpose of this invention, as we only require a correction factor or ratio between the base station and the desired location. This will be described with the aid of figure 5, below.

The capacity factor applicable to any given location, in addition to insolation, is also very dependent on local weather conditions, such as ambient temperature and hours of sunshine. Provided that the methods used to derive the hours of sunshine are similar, then a correction factor can also be derived between the base station and the desired location to account for differences in hours of sunshine.

Temperature coefficients for output power are typically about -0. 4 to -0. 5% per degree Centigrade, but vary with type and manufacturer of the PV cells. This factor should also be used when calculating the capacity factor at the target location.

The available surface area is established and a photo-voltaic solar array is designed to maximize the use of this area, subject to the constraints described herein. The actual output of the solar array is predicted by the methods described herein and accurate marketing material is produced that will allow target markets to be defined and vehicles to be sold with integrity in those areas. What has been described and illustrated herein is a preferred embodiment of the invention along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention in which all terms are meant in their broadest, reasonable sense unless otherwise indicated. Any headings utilized within the description are for convenience only and have no legal or limiting effect.

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Claims

1 . A method of extending the range of an electrically powered vehicle, the vehicle

comprising a solar array power source capable of delivering electrical power when illuminated by solar radiation and a battery storage system, the method comprising the steps of:

determining whether the storage system has capacity for the estimated energy output value; and

in response to determining that the battery storage system has capacity for the estimated energy output, causing charging of the battery storage system by the solar array power source.

2. The method of claim 1 , wherein in response to determining that the battery storage

system does not have capacity for the estimated energy output, causing charging of the battery storage system by the solar array power source to stop.

3. The method of claim 1 , wherein estimating the solar exposure comprises determining a capacity factor of the solar array power source.

4. The method of claim 3, wherein determining a capacity factor of the solar cell power source comprises analysing one or more following parameters:

a capacity factor at a geographic location;

size and/or configuration of the solar array;

historical weather data; and

one or more temperature coefficients.

5. The method of claim 4, wherein the geographic location parameters and historical

weather data parameters are measured at a base station corresponding to a target location of the vehicle.

6. The method of claim 5, wherein a correction factor is applied to the capacity factor.

7. The method of claim 6, further comprising determining a correction factor based on the temperature coefficient and an ambient temperature difference between the base station and the target location.

8. The method of claim 6, further comprising determining a Daylight Correction Factor "DCF" based on a difference between a number of hours of sunshine recorded at the base station and the target location.

9. The method of claim 6, further comprising determining an Insolation Correction Factor "ICF" based on recorded insolation at the base station and the target location.

10. The method of claims 8 and 9, wherein the DCF and ICF are used to determine the capacity factor.

1 1 . The method of any preceding claim, further comprising a DC to DC converter to convert a DC output of the solar array power source from one voltage level to another.

12. The method of any preceding claim, further comprising a DC to AC inverter to convert a DC output of the solar array power source from DC to AC.

13. The method of any preceding claim, further comprising an AC to DC inverter to convert an external AC domestic input source from AC to DC.

14. The method of claim 2, further comprising an electronic by-pass switch configured to electrically disconnect the battery storage from the solar power source.

15. The method of any preceding claim, wherein the battery storage comprises one or more traction batteries.

16. A system for extending the range of an electrically powered vehicle, the vehicle

comprising a solar array power source capable of delivering electrical power when illuminated by solar radiation and a battery storage system, the system comprising: means for estimating a solar exposure for the solar array power source over a future period of time;

means for estimating a voltage output value for the solar array power source based on the estimated solar exposure; means for determining a range of the vehicle based on the estimated energy output value;

17. The system of claim 16, wherein in response to determining that the battery storage system does not have capacity for the estimated photovoltaic output, causing charging of the battery storage system by the solar array power source to stop.

18. The system of claim 16, wherein estimating the solar exposure comprises means for determining a capacity factor of the solar array power source.

19. The system of claim 18, wherein determining a capacity factor of the solar cell power source comprises means for analysing one or more following parameters:

a capacity factor at a geographic location;

size and/or configuration of the solar array;

historical weather data; and

one or more temperature coefficients.

20. The system of claim 19, wherein the geographic location parameters and historical

21 . The system of claim 20, wherein a correction factor is applied to the capacity factor.

22. The system of claim 21 , further comprising means for determining a correction factor based on the temperature coefficient and an ambient temperature difference between the base station and the target location.

23. The system of claim 21 , further comprising means for determining a Daylight Correction Factor "DCF" based on a difference between a number of hours of sunshine recorded at the base station and the target location.

24. The system of claim 21 , further comprising means for determining an Insolation

Correction Factor "ICF" based on recorded insolation at the base station and the target location.

25. The system of claims 23 and 24, wherein the capacity factor at the geographic location, the DCF and ICF are used to determine the capacity factor.

26. The system of any of claims 16 to 25, further comprising a DC to DC converter to convert a DC output of the solar array power source from one voltage level to another.

27. The system of any of claims 16 to 26, further comprising a DC to AC inverter to convert a DC output of the solar array power source from DC to AC.

28. The system of any of claims 16 to 27, further comprising an AC to DC inverter to convert an external AC domestic input source from AC to DC.

29. The system of claim 17, further comprising an electronic by-pass switch configured to electrically disconnect the battery storage from the solar power source.

30. The system of any of claims 16 to 29, wherein the battery storage comprises one or more traction batteries.

31 . A method of optimising solar energy capture for a vehicle, the method comprising:

estimating a solar exposure at a geographic location;

32. The method of claim 31 , wherein determining the capacity factor of the solar cell

comprises analysing one or more following parameters:

a capacity factor at the geographic location;

historical weather data; and

one or more temperature coefficients.

33. The method of claim 32, wherein the geographic location parameters and historical weather data parameters are measured at a base station corresponding to a target location of the vehicle.

34. The method of claim 33, wherein a correction factor is applied to the capacity factor.

35. The method of claim 34, wherein determining the correction factor is based on the one or more temperature coefficients and an ambient temperature difference between the base station and the target location.

36. The method of claim 34, further comprising determining a Daylight Correction Factor "DCF" based on a difference between a number of hours of sunshine recorded at the base station and the target location.

37. The method of claim 34, further comprising determining an Insolation Correction Factor "ICF" based on recorded insolation at the base station and the target location.

38. The method of claims 36 and 37, wherein the determined DCF and ICF are used to

determine the capacity factor.

39. The method of any of claims 31 to 38, wherein the battery storage comprises one or more traction batteries.

40. A system for optimising solar energy capture for a vehicle, the system comprising:

means for estimating a solar exposure at a geographic location;

means for determining an energy input requirement for a desired range of the vehicle; and

means for configuring the number of cells within the array based on the estimated energy output value of the solar cell and the determined energy input requirement, wherein estimating the solar exposure comprises determining a capacity factor of the solar cell.

41 . The system of claim 40, wherein determining the capacity factor of the solar cell

comprises means for analysing one or more following parameters:

a capacity factor at the geographic location; historical weather data; and

one or more temperature coefficients.

42. The system of claim 41 , wherein the geographic location parameters and historical weather data parameters are measured at a base station corresponding to a target location of the vehicle.

43. The system of claim 42, wherein a correction factor is applied to the capacity factor.

44. The system of claim 43, wherein determining the correction factor is based on the one or more temperature coefficients and an ambient temperature difference between the base station and the target location.

45. The system of claim 43, further comprising means for determining a Daylight Correction Factor "DCF" based on a difference between a number of hours of sunshine recorded at the base station and the target location.

46. The system of claim 43, further comprising means for determining an Insolation

47. The system of claims 45 and 46, wherein the determined DCF and ICF are used to

determine the capacity factor.

48. The system of any of claims 40 to 47, wherein the battery storage comprises one or more traction batteries.