GB2442994A

GB2442994A - Solar panel with AC power converter

Info

Publication number: GB2442994A
Application number: GB0620910A
Authority: GB
Inventors: David Hyman Gordon
Original assignee: Wind Save Ltd
Current assignee: Wind Save Ltd
Priority date: 2006-10-20
Filing date: 2006-10-20
Publication date: 2008-04-23
Also published as: GB0620910D0; WO2008047146A1

Abstract

The solar panel has a plurality of photovoltaic cells and means for converting the electrical power generated by the at least one solar panel into the same phase and the same voltage as the A.C. supply from the national grid.

Description

S

1 2442994 Title: Renewable Energy Resources

Description

This invention concerns renewable energy resources.

Currently, there are many sources for generating electrical power: * . * * ** renewable energies, fossil fuels, bio-fuels, fuel cells and atomic energy. Today, ..

consumers are demanding far more power as new markets for consumer electrical *..SS* goods are expanding. Often the national grid has difficulty keeping up with the S...

demand of electricity. The problem with fossil fuel power plants is that the *.

supply of fossil fuel is limited and they tend to pollute the atmosphere with unwanted "greenhouse" gases such as carbon dioxide. Atomic energy is regarded as efficient for producing electricity, however they present radiation hazards and radioactive waste disposal problems. Therefore, renewable energies have great potential because they are considered to be clean for the environment. An example of renewable energies is the conversion of solar radiation into electricity.

In order to supply the national grid with reasonable electricity, large-scale solar farms are required for converting solar energy into electrical energy.

However, the problem with large-scale commercial solar farms is that a vast amount of land is required. Due to considerable advances made in photovoltaic cells in recent years, photovoltaic cells are becoming more efficient and produce more electricity per unit area. Accordingly, smaller sized photovoltaic cells have been installed on roofs of buildings, where the photovoltaic cells are exposed to the sun. Typically, a solar panel comprises a plurality of photovoltaic cells encased between a transparent sheet (e.g. glass, plastic, etc.) and a transparent or opaque backsheet to form flat modules, known as laminates.

In other words, when there is sufficient solar radiation to generate electrical energy for an individual property's demands, that electrical energy can be used rather than the electricity supplied by the national grid. In that way the drain on the resources of the national grid can be cut, so that national supply costs S. * * can also be reduced. * * I** *.

It is proposed that an individual property to have at least one solar panel ** having a plurality of photovoltaic cells mounted in a suitable position on the property being exposed to the sun.

According to a first aspect of the present invention there is provided a solar panel arrangement for use in generating electrical power, the arrangement comprising at least one solar panel having a plurality of photovoltaic cells and means for converting the electrical power generated by the at least one solar panel into the same phase and the same voltage as the A.C. supply from the national grid.

Preferably the or each solar panel used in the invention initially produces D.C. electrical power and is preferably linked to means for converting that D.C.

into A.C. compatible with the A.C. provided to the building. Alternatively, the or each solar panel used in the invention initially produces A.C. electrical power and is preferably linked to means for converting that A.C. into A.C. compatible with the A.C. provided to the building.

Preferably the or each solar panel is mounted on a platform. Preferably * * the platform is tiltable adjustable, so that the or each solar panel can faced * substantially towards the sun. Preferably the platform is mounted on a roof or * S other suitable structure. S... * S... *...

According to another aspect of the present invention there is provided ** means for converting electrical power generated by one or more panels into A.C.

suitable for use in providing electrical power for a building to supplement or replace electrical power supply from the national grid.

The means according to this aspect of the invention preferably takes the D.C. current produced by the or each solar panel to be converted into square wave A.C., such as by means of a chopper circuit also known as an 1-1 bridge. This A.C.

is preferably then converted to sine wave A.C. by means of a constant voltage transformer or the like. This A.C. is preferably compatible with the A.C. supply from the normal utility supplier to the building. The means for converting the D.C to A.C. preferably has means for ensuring that the A.C. produced is in phase with the A.C. supply normal utility supplier to the building. Alternatively, when the or each solar panel initially generates A.C. current, the means according to this aspect of the invention preferably takes that A.C. current through a full wave internally or externally mounted rectifier to convert it to D.C., which may be smoothed further by means of capacitors prior to be converted into a square wave A.C. via the chopper circuit. * . * . q * * * * . S

This A.C. is preferably then converted to sine wave A.C., such as by S.* S. S means of a constant voltage transformer or other suitable electrical, electronic or *.S.

S S...

electromechanical device. This A.C. is preferably compatible with the A.C. S...

supply from the normal utility supplier to the building. The means for converting the D.C to A.C. preferably has means for ensuring that the A.C. produced is in phase with and at the same voltage as the A.C. supply from the normal utility supplier to the building.

Preferably the means for converting electrical power generated by one or more solar panels into A.C. suitable for use in providing electrical power for a building to supplement or replace electrical power supply from the national grid is provided in a box or case to which the solar generators can be connected and which itself can be connected into the electrical circuitry of the building to feed the load thereon.

This invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a solar generator arrangement for mounting on a roo Figures 2 to 4 are schematic diagrams of alternate solar generator arrangements for mounting onto a building; Figure 5A shows schematically a control system for converting solar

-* *

generated electrical power into A.C. for use in a building; : .:: Figure 5B shows an embodiment of Figure SA for converting solar * _,**r * generated D.C. electrical power into a suitable A.C. for use in the building; *SSS * I..

Figure 6 shows schematically a control system of the invention; S...

Figure 7A shows schematically an alternate control system for converting.

solar generated A.C. electrical power into a suitable A.C. for use in the building; and Figure 7B shows an embodiment of Figure 7A for converting solar generated electrical power into A.C. for use in the building.

Referring to Figure 1 of the accompanying drawings, an arrangement 10 of solar panels 12 for mounting on a roof 14 for use in generating electrical power, wherein each solar panel 12 is mounted on an adjustable platform 16. The adjustable platform 16 allows the solar panel 12 to be angled/tilted at an optimum position to catch most of the sunlight. The adjustable platform 16 further comprises mounting means (not shown) adapted to secure the solar panel 12 to the roof 14 of a building 20.

Figure 2 shows a further arrangement of the solar panel 12 and the platform 16 being mounted on a pole 18. The pole 18 is further secured to the building 20 via a bracketlmounting means (not shown). In this arrangement, the adjustable platform 16 allows the solar panel 12 to be angledltilted at an optimum position to catch most of the sunlight. In this arrangement, the adjustable * .* platform 16 further comprises mounting means (not shown) adapted to secure the * *.* a..

solar panel 12 to the pole 18. Referring to Figure 3, an embodiment of the ** * arrangement shown in Figure 2, whereby two solar panels 12 are secured to the structure 20 via the poles 18, so that more electricity can be generated.

It is important to reduce interference between the two solar panels 12 by mounting one solar panel 12 away from the other such that one solar panel 12 does not cast a shadow over the other solar panel 12. As shown in Figure 3, this can be achieved by position one solar panel 12 on opposite sides of the building 20. Alternatively, referring to Figure 4, this can also be achieved by mounting each solar panel 12 on height adjustable poles 22 so that one solar panel 12 is positioned above the other. As shown in Figures 2 to 4, the poles 18, 22 allow the solar panel to be rotated through 360 in order to catch as much sunlight as possible.

I

Referring to Figure 5A there is shown a typical control system for converting electrical power generated by the arrangement of Figure 1 into electrical power that can be used to supplement or replace electrical power supplied to a building from the normal utility supply. The solar panel arrangement 10 initially produces a D.C. electrical current, which is fed through a chopper circuit 52 to produce 50Hz square wave A.C. The output from the chopper circuit 52 is fed into a constant voltage transformer 58 to produce A.C. at 240 volts and 50 Hz in sine wave form. The output from the constant voltage transformer 58 is passed through a meter 60 before being fed to the power supply for the building 20, where it joins the power supply from the normal utility supply:..:.

64 after the usage meter 66 therefor. *:: : :* * S..

In a further embodiment as shown in Figure 7A, the solar panel.. : arrangement 10 initially generates A.C. current, which is fed through a full wave internally or externally mounted rectifier 50 to convert it to D.C., which can be smoothed further by means of capacitors prior to be converted into a 50Hz square wave A.C. via the chopper circuit 52. The output from the chopper circuit 52 is fed into the constant voltage transformer 58 as described above.

Across the chopper 52 is a voltage detector 54 linked to a variable tap switch unit 56 prior to the constant voltage transformer 58. The voltage detector 54 detects the D.C. supply from the solar panels 12 and adjusts the variable tap switch unit 56 such a constant voltage is being supplied to the constant voltage transformer 58. Furthermore, the variable tap switch unit 56 prevents overloading of the constant voltage transformer 58.

The output from the constant voltage transformer 58 is passed through a meter 60 before being fed to the power supply for the building 20, where it joins the power supply from the normal utility supply 64 after the usage meter 66 therefor.

S * S * * ..

It is important that the A.C. supply from the chopper 52 is in phase with the national grid A.C. supply. Therefore, a feedback loop 70 for phase angle detection is provided that connects the chopper circuit 52 to the output of the meter 60, whereby the chopper circuit 52 controls the production of A.C. of the * * *.Q. * S..

correct phase. .. : Figure SB of the accompanying drawings shows an embodiment of Figure 5A for converting the D.C. generated by the solar generator 10 into A.C. in the same phase and at the same voltage as the mains supply. The circuit is similar to that shown in Figure 5A and only the main differences will now be described.

The meter 60 is now a SAIA Burgess meter 61, which is connected by the feed back loop 70 to a logic board 71 for phase angle detection. Between the meter 61 and the mains connectors, there is a LXN protection relay 73, which is provided to protect against damage from incorrect connection of the control system to the mains. Also, there is a neon indicator 75 to show whether or not the unit is switched on.

Figure 7B of the accompanying drawings shows an embodiment of Figure 7A for converting the A.C. generated by the solar generator 10 into A.C. in the same phase and at the same voltage as the mains supply. The circuit is similar to that shown in Figure 7A and only the main differences will now be described.

The SAIA Burgess meter 61 is connected by the feed back loop 70 to the logic board 71 for phase angle detection. The LXN protection relay 73 is provided to *.

protect against damage from incorrect connection of the control system to the mains. The neon indicator 75 shows whether or not the unit is switched on. ..

S S S...

In practice, as illustrated in Figure 6 of the accompanying drawings, the means for converting the D.C output of the solar panels 12 will be fed to a portable control box 80 containing the components described above for converting the D.C. output into A.C. output. The control box 80 has a carrying handle 82 and can be plugged directly into a socket of the building's electrical circuit by means of electrical plug 84 to at least partially feed the load of the building. The control box includes a wattmetcr 86. Thus, the electricity power generator system may be installed by directing the solar generators relatively towards the sun, connecting the electricity supply therefrom to the control box 80 and connecting that into the electricity circuit of the building via a mains socket.

I

ft is proposed that a sensor is to be provided on the incoming mains electricity supply that measures wattage or in other words what the grid is supplying to the household need. The sensor is arranged to communicate with the control box 80, so that if the import wattage falls to a predetermined level, say of 20 watts, the control unit can be instructed to reduce efficiency to prevent actual export of power back to the grid. As the import wattage increases to say 50 watts due to increase electricity consumption, the control unit 80 improves efficiency to a level, whereby the maximum solar power is used.

When mains power fails, the control unit 80 has to be disconnected and S.....

S

shut down. However, if stand alone solar power electricity supply is required, the control unit may be disconnected from mains supply to be allowed to operate independently. An isolating switch may be provided, which can be automatically * ::: : or mechanically operated to allow the control unit to provide stand alone power IS and feed whatever power it can from the sun to be used by the household. The control unit may have an electrical power storage facility, such as rechargeable batteries. The control unit is provided with means for detecting when mains power is restored, which either may provide a signal to indicate that reconnection of the control unit can take place or even automatically reconnect the control unit.

The control unit is preferably arranged, so that there is no possibility of excess power being fed back to the grid. Thus, the control unit 80 is preferably arranged to supply slightly less power than the househo]d demand. However, the control unit 80 may be configured, if desired, to feed power back into the grid.

It is proposed that the solar generator 10 is earthed to prevent the transmission of electrical shocks and surge from lightening from damaging the components of the solar generator 10 and the control unit 80.

The control unit and solar generator system may incorporate the following features: 1. The solar generator may have a built-in safety switch, which is * * **.** manually resettable afier operation, in order to shut down the solar * * ***.

generator. The switch preferably comes into operation at a pre-determined U...

high intensity lighting conditions * . . 2. The control unit may have a safety facility to shut down the solar generator or put the solar generator on stand-by in the event of the voltage rising too high or at other times as the system dictates.

3. The control unit may have a manually operable switch for stopping the solar generator such as during prolonged absences, excessive lighting conditions or for maintenance purposes.

4. An additional switch may be fitted locally to the solar generator to enable the control Unit to be switched off, such as when working in close proximity or for maintenance purposes.

5. Standard electrical fuse protection is preferably provided in the control unit.

S

6. The control unit preferably includes means for preventing incorrect connection of the mains electricity supply or the generator supply.

7. The control unit preferably includes a temperature sensor. The sensor is preferably arranged to activate a cooling fan when a first pre-determined temperature is reached and preferably also to shutdown the unit when a second pre-deten-nined temperature is reached.

8. The control unit is preferably arranged to shut down the solar generator in the event of mains failure. * * * S *

S * . ***** S... * . S... S... * S S... *

S S. S

Claims

I

Claims: 1. A solar panel arrangement for use in generating electrical power, the arrangement comprising at least one solar panel having a plurality of photovoltaic cells and means for converting the electrical power generated by the at least one solar panel into the same phase and the same voltage as the A.C. supply from the national grid.
2. A solar panel arrangement as claimed in claim 1, wherein the or each solar panel used in the invention initially produces D.C. electrical power and is linked to means for converting that D.C. into A.C. compatible with the A.C. provided to the, * building.
3. A solar panel arrangement as claimed in claim 1, wherein the or each solar **s.

panel initially produces A.C. electrical power and is linked to means for converting that A.C. into A.C. compatible with the A.C. provided to the building.
4. A solar panel arrangement as claimed in claim 1, 2 or 3, wherein the or each solar panel is mounted on a platform.
5. A solar panel arrangement as claimed in claim 4, wherein the platform is tiltably adjustable, so that the or each solar panel can face substantially towards the sun.
6. A solar panel arrangement as claimed in any one of claims I to 5, wherein the platform is mounted on a roof or other suitable structure.
7. Means for converting electrical power generated by one or more solar panels into A.C. suitable for use in providing electrical power for a building to supplement or replace electrical power supply from the national grid.

S
8. Means as claimed in claim 7, wherein D.C. current produced by the or each solar panel is converted into square wave AC., such as by means of a chopper circuit also known as an H bridge.
9. Means as claimed in claim 8, wherein said A.C. is converted to sine wave A.C. by means of a constant voltage transformer or the like.
10. Means as claimed in claim 9, wherein said sine wave A.C. is compatible with the A.C. supply from the normal utility supplier to the building.
11. Means as claimed in 10, wherein the means for converting the D.C to A.C. has means for ensuring that the A.C. produced is in phase with the A.C. supply normal utility supplier to the building.
12. Means as claimed in claim 7, wherein when the or each solar panel initially generates A.C. current, the A.C. current is taken through a full wave internally or externally mounted rectifier to convert it to D.C., which may be smoothed further by means of capacitors prior to be converted into a square wave A.C. via the chopper circuit.
13. Means as claimed in claim 12, wherein said A.C. is converted to sine wave A.C., such as by means of a constant voltage transformer or other suitable electrical, electronic or electromechanical device.
14. Means as claimed in claim 13, wherein the sine wave A.C. is compatible with the A.C. supply from the normal utility supplier to the building.
15. Means as claimed in claim 14, wherein the means for converting the D.C to A.C. has means for ensuring that the A.C. produced is in phase with and at the same voltage as the A.C. supply from the normal utility supplier to the building.
16. Means as claimed in any one of claims 7 to 15, wherein the means for converting electrical power generated by one or more solar panels into A.C. suitable for use in providing electrical power for a building to supplement or replace electrical power supply from the national grid is provided in a box or case to which the solar generators can be connected and which itself can be connected into the electrical circuitry of the building to feed the load thereon.
17. A solar panel arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. * * *. * * S... S... * * * S *5 *