NL2032369B1

NL2032369B1 - A process for generating electric power with a hybrid wind-photo voltaic energy converting system

Info

Publication number: NL2032369B1
Application number: NL2032369A
Authority: NL
Inventors: Theodorus Van Kaathoven Hendricus
Original assignee: Theodorus Van Kaathoven Hendricus
Priority date: 2022-07-05
Filing date: 2022-07-05
Publication date: 2024-01-19

Abstract

The invention pertains to a process for generating electric power using a hybrid wind- photo voltaic energy converting system supported on an in essence horizontally 5 extending supporting surface, the energy converting system comprising an in essence rectangular solar panel having an upper and lower edge as well as two lateral edges, wherein the upper and lower edges extend in a horizontal direction and the two lateral edges extend in a vertical direction such that the panel forms an upright angle with the supporting surface, and connected to the solar panel adjacent its upper edge a wind 10 turbine, wherein the energy converting system is rotatable around a vertical axis, the process comprising for optimising a conversion of sun light into electricity, spatially directing the panel to the sun by rotating the system around the said vertical axis, and for optimising a conversion of wind into electricity, spatially directing the wind turbine to the wind by rotating the system around the said vertical axis.The invention also pertains 15 to s system suitable for use in this process. (fig. 1A)

Description

A PROCESS FOR GENERATING ELECTRIC POWER WITH A HYBRID WIND-

PHOTO VOLTAIC ENERGY CONVERTING SYSTEM

FIELD OF THE INVENTION

The present invention in general pertains to the conversion of energy into electric power, in particular the conversion of wind and sunlight into electricity.

BACKGROUND OF THE INVENTION

In the art several options are known to convert energy that is freely available in the atmosphere into electric energy. Typical examples are solar panels and wind turbines and are described here below.

Solar panels

In the art the technology of converting light into electric energy is well known. Already in 1839, the ability of some materials to create an electrical charge from light exposure was first observed by the French physicist Edmond Becquerel. The initial solar panels were too inefficient for even simple electric devices, they were used as an instrument to measure light. In 1881, the American inventor Charles Fritts created the first commercial solar panel, which was reported by Fritts as “continuous, constant and of considerable force not only by exposure to sunlight but also to dim, diffused daylight.” However, these solar panels were very inefficient, especially compared to coal-fired power plants. In 1939, Russell Ohl created the solar cell design that is used in many modern solar panels. He patented his design in 1941. In 1954, this design was first used by Bell Labs to create the first commercially viable silicon solar cell. In 1957, Mohamed M. Atalla developed the process of silicon surface passivation by thermal oxidation at Bell Labs.

The surface passivation process has since been used to create efficient solar cells.

Solar panels (also referred to as modules in the art and in this specification) based on such solar cells use light energy (photons) from the sun to generate electricity through the so-called photo voltaic (PV) effect. Most photo voltaic systems use wafer-based crystalline silicon cells or thin-film cells. The structural (load carrying) member of a module can be either the top layer or the back layer. Cells must be protected from mechanical damage and moisture. Most modules are rigid, but semi-flexible ones based on thin-film cells are also available. The cells are usually connected electrically in series, one to another to the desired voltage, and then in parallel to increase current. The power (in watts) of the module is the mathematical product of the voltage (in volts) and the current (in amperes) of the module. Most solar panels also use metal frames consisting of racking components, brackets, reflector shapes, and troughs to better support the panel structure.

A single solar module (consisting of multiple cells) can produce only a limited amount of power; most installations contain multiple modules adding voltages or current to the wiring and PV system. A photovoltaic system typically includes an array of photovoltaic modules, an inverter, a battery pack for energy storage, charge controller, interconnection wiring, circuit breakers, fuses, disconnect switches, voltage meters, and optionally a solar tracking mechanism. Equipment is carefully selected to optimize output, energy storage, reduce power loss during power transmission, and conversion from direct current to alternating current.

Several companies have begun embedding electronics into PV modules. This enables performance management for each module individually, for monitoring and fault detection at module level. Some of these solutions make use of power optimizers, a DC- to-DC converter technology developed to maximize the power harvest from solar photovoltaic systems. As of about 2010, such electronics can also compensate for shading effects, wherein a shadow falling across a section of a module causes the electrical output of one or more strings of cells in the module to fall to zero, but not having the output of the entire module fall to zero.

Solar panels are typically connected in series of one or more panels to form strings to achieve a desired output voltage, and strings can be connected in parallel to provide the desired current capability (amperes) of the PV system. Such an arrangement of panels is often also regarded as “a solar panel”, although in fact it is an assembly of smaller individual panels (which are then in fact sub-panels).

To maximize total energy output, solar panels are often oriented to face South in the

Northern hemisphere or North in the Southern hemisphere) and tilted to allow for the latitude. The panels typically form an angle of between 30 and 60° with the ground surface. Large utility-scale solar power plants usually use ground-mounted photovoltaic systems. Their solar modules are held in place by racks or frames that are attached to ground-based mounting supports. Ground based mounting supports include pole mounts, which are driven directly into the ground or embedded in concrete; foundation mounts, such as concrete slabs or poured footings; and ballasted footing mounts, such as concrete or steel bases that use weight to secure the solar module system in position and do not require ground penetration. The latter type of mounting system is well suited for sites where excavation is not possible such as capped landfills and simplifies decommissioning or relocation of solar module systems. Roof-mounted solar power systems consist of solar panels held in place by racks or frames attached to roof-based mounting supports.

Typically, fixed racks can hold panels stationary throughout the day at a given tilt (upright angle of the panel with the horizontal ground surface, corresponding to the so- called solar zenith angle) and facing a given direction (azimuth angle). Fixed tilt angles equivalent to an installation’s latitude are common. Some systems may also adjust the tilt angle based on the time of year.

Solar trackers (wherein the panel track the sun by being continuously positioned for example perpendicular to the sun) increase the energy produced per module at the cost of mechanical complexity and increased need for maintenance. They sense the direction of the sun (or are preprogrammed with the proper software) and tilt and rotate the modules as needed for maximum exposure to the light by directing the panels perpendicular to the sun (Shingleton, J. “One-Axis Trackers — Improved Reliability,

Durability, Performance, and Cost Reduction” (PDF). National Renewable Energy

Laboratory, retrieved 30 December 2012; Mousazadeh, Hossain; et al. “A review of principle and sun-tracking methods for maximizing” (PDF). Renewable and Sustainable

Energy Reviews 13 (2009) 1800-1818. Elsevier, retrieved 30 December 2012).

On the other hand, east- and west-facing arrays (covering an east-west facing roof, for example} are commonly deployed. Even though such installations will not produce the maximum possible average power from the individual solar panels, the cost of the panels is now usually cheaper than the tracking mechanism and they can provide more economically valuable power during morning and evening peak demands than north or south facing systems.

In general with solar panels, if not enough current is taken from PVs, then power isn’t maximized. If too much current is taken then the voltage collapses. The optimum current draw depends on the amount of sunlight striking the panel. Solar panel capacity is specified by the MPP (maximum power point) value of solar panels in full sunlight. Solar inverters typically convert the DC power to AC power by performing the process of maximum power point tracking (MPPT): solar inverter samples the output Power (I-V curve) from the solar cell and applies the proper resistance (load) to solar cells to obtain maximum power.

Wind turbines

Wind turbines are commonly used since centuries to convert wind into work. A wind turbine typically is an impulse turbine. The turbine changes the direction of flow of the wind and the resulting impulse spins the turbine and leaves the wind with diminished kinetic energy. If the mechanical energy is used to produce electricity, the device is typically called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or pumping water, the device is usually called a windmill or wind pump. Developed for over a millennium, today's wind turbines are manufactured in a range of vertical and horizontal axle types. The most common and oldest ones are the horizontal axle turbines wherein the axles are positioned in line with the direction of the wind (i.e. the direction in which the wind blows). The smallest turbines are used for applications such as battery charging or auxiliary power on sailing boats, while large grid-connected arrays of turbines are becoming an increasingly large source of commercial electric power.

One of the developments of the last decades is to devise wind turbines that are suitable for low wind velocities (typically below 10 m/s, about 5 Beaufort). In particular at lower heights, above land and in the presence of buildings, wind velocity is often too low to economically extract energy from common wind turbines. Recent developments include the Darrieus (including giromill and cycloturbine) and Savonius wind turbines which may generate mechanical energy even at a wind velocity below 5 m/s (about 3 Beaufort).

Unlike the Savonius wind turbine, the Darrieus is a lift-type turbine. Rather than collecting the wind in cups dragging the turbine around, a Darrieus uses lift forces generated by the wind hitting aerofoils to create rotation. With these turbines, the axles 5 are positioned transverse to the wind (as opposed to “in line” with the wind) which has the additional advantage that the vanes do not need to be pointed to the wind. In most cases the axles are positioned vertically (which explains the commonly used acronym

VAWT: vertical axle wind turbine), but they may also be positioned horizontally as long as the axle is transverse to the wind. These wind turbines however have several disadvantages. Firstly, the overall rate of conversion of kinetic into mechanical energy of these turbines might be improved. Secondly, in particular Darrieus wind turbines are not self-starting. Therefore a small powered motor is required to start off the rotation, and then when it has enough speed the wind passing across the aerofoils starts to generate torque and the rotor is driven around by the wind. An alternative constitution is the use of one or two small Savonius rotors that are mounted on the shaft of the Darrieus turbine to start rotation. These Savonius rotors however slow down the Darrieus turbine when it gets going.

There has been increasing interest in mounting wind turbines with horizontally extending axes of rotation on the roof ridges of buildings, to take advantage of the wind focus effect, by which the wind passing up a roof to a ridge is compressed into a high speed

Aeolian flow band. Empirical measurement has shown that for a usual 30 degree to 45 degree pitched roof, this band extends approximately 300 mm above the ridge top and 450 mm forward along the roof facing the incident wind. At this point, measured speeds may be of the order of three times that of the prevailing wind speed. However, the unpredictable aerodynamic influences of nearby buildings and trees can lead to variable wind conditions, complicating wind turbine design. WO2011010159 discloses a roof ridge mountable wind turbine having an elongate cylindrical wind turbine rotor, a variable flow regulator within the rotor housing, and a control system, such that the regulator can be used to variably reduce the wind flow through the rotor. It is also known to provide shutters that can be closed in high wind conditions. US 9,732,728 discloses a roof ridge mountable wind turbine comprising a generally cylindrical wind turbine rotor that is supported by a rotor support and operable to rotate about a rotational axis, the rotor comprising a plurality of aerofoil blades with each aerofoil blade having a leading edge, a trailing edge, a suction surface, a pressure surface, and an aerofoil chord having a chord length between the leading edge and the trailing edge. A commercial type of wind turbine with a horizontally extending axis of rotation is the RidgeBlade® of

The Power Collective, Kingston Ontario, Canada. These turbines have a fixed spatial position with respect to the wind since the roof guides the wind to turbine anyway.

Hybrid wind-photovoltaic systems

In the art hybrid wind-photovoltaic systems are also known. These systems have the advantage that in the absence of (sufficient) sun light, the wind can be used to generate power. Although considerably more expensive to produce, these systems in particular make use of the fact that on average, wind levels are higher when the level of sun light is low (e.g. during stormy weather) or even absent (e.g. at night).

KR 10-1696584 (2016) discloses a hybrid wind-photovoltaic system, wherein a large solar panel in combination with an upper edge mounted wind turbine is positioned on a vertically extending pole having a fixed position to optimally receive sun light and catch wind well above ground surface. The panel has a fixed zenith and azimuth angle to try and prevent damage due to catching too much wind.

KR 10-2079765 (2019) discloses a similar a hybrid wind-photovoltaic system, however using a spiral rotating blade and a wind collecting pipe collecting wind toward the rotating blade to guide the wind, designed using a plurality of wind power generation devices in series. The wind power generation device can perform solar power generation and wind power generation by further including a flat panel for guiding wind from the front toward the rotating blade. This way, variation of the direction in which the wind blows has hardly any effect on the maximum power output of the turbine.

KR 10-2010768 (2019) discloses a hybrid wind-photovoltaic system similar to KR 10- 1696584, with the difference that wherein the solar panel in combination with an upper edge mounted wind turbine are positioned on a fixed frame instead of a pole. Advantage is the higher stability needed at higher wind velocities.

A common denominator of all of these hybrid systems is the fixed spatial arrangement of the panel and wind turbine with respect to the sun and wind.

OBJECT OF THE INVENTION

It is an object of the invention to provide a process for generating electric power using a hybrid wind-photo voltaic energy converting system, which process is able to even more efficiently generate electric power. It is a further object to the invention to provide a hybrid wind-photo voltaic energy converting system that can be run using this process.

SUMMARY OF THE INVENTION

In order to meet the object of the invention, a process has been devised for generating electric power using a hybrid wind-photo voltaic energy converting system supported on an in essence horizontally extending supporting surface (such as the earth surface or the roof of a building), the energy converting system comprising an in essence rectangular solar panel (which may be comprised of multiple smaller sub-panels) having an upper and lower edge as well as two lateral edges, wherein the upper and lower edges extend in a horizontal direction and the two lateral edges extend in a vertical direction such that the panel forms an upright angle with the supporting surface (thus incorporating a tilting to meet the zenith angle), and connected to the solar panel along its upper edge a wind turbine, wherein the energy converting system is rotatable around a vertical (imaginary) axis, the process comprising for optimising a conversion of sun light into electricity, spatially directing the panel to the sun (e.g. by positioning the panel perpendicularly to the direction wherein the sun light travels, also denoted as “perpendicular to the sun”) by rotating the system around the said vertical axis, and for optimising a conversion of wind into electricity, spatially directing the wind turbine to the wind (e.g. by positioning the system perpendicularly to the direction wherein the wind blow, also denoted as “perpendicular to the wind”) by rotating the system around the said vertical axis.

The inventors recognised that it is advantageous from a power converting efficiency point of view that also when there is no or too little sunlight and the power generation depends on converting wind energy, that the system can rotate towards or away from the wind in order to optimise energy conversion {which can be maximising, or adapting to momentary need, etc. all dependent om the criterion for what optimal is). In the art tracking is only used for solar panel only systems. For hybrid systems, only fixed arrangements are foreseen which is indeed typical for ridge mounted wind turbines. In the art these are consistently used in fixed spatial arrangements. However, it was found that energy conversion can be improved by being able to direct also the turbine with respect to the wind (not only for increasing but also if needed for decreasing the amount of energy conversion). This way there is more freedom to operate the wind turbine and thus to fine tune its use. The type of turbine is not essential to the invention in its widest scope, as long as the wind is properly deflected towards the turbine. However, it was found that a particularly advantageous type of turbine is a turbine of the type having a horizontally extending axis of rotation that extends in essence in parallel to the upper edge of the panel. This type of turbine is known as such in the art and often used on edges of (inclined) roof tops.

In a straightforward embodiment, when the level of sunlight is below a predetermined threshold, the process is such that the system will rotate for optimising the spatial arrangement of the turbine with respect to the wind only. This can be such that the energy output is at maximum, but may e.g. also be such the output meets the momentary demand, or such that the system can withstand the force of the wind on the combination of panel and turbine. In a less straightforward embodiment, at each moment in time a calculation is made of the optimum total energy conversion based on the strength of the sunlight, the wind and its direction, and the system is rotated to the position for optimum energy conversion which can be a mix of any ratio between conversion of sunlight and wind.

The invention also pertains to a hybrid wind-photo voltaic energy converting system, the energy converting system comprising an in essence rectangular solar panel having an upper and lower edge as well as two lateral edges, wherein the upper and lower edges extend in a horizontal direction and the two lateral edges extend in a vertical direction, and adjacent the upper edge of the solar panel a wind turbine, for example connected along the upper edge of the panel and of the type having a horizontally extending axis of rotation that extends in essence in parallel to the upper edge of the panel, and wherein the combination of the panel and wind turbine is rotatable around a vertically extending axis, and a central processing unit (CPU) that is programmed to enable optimising the conversion of energy by the system by adjusting the spatial position of the solar panel and wind turbine by rotation of these around the said vertically extending axis.

DEFINITIONS

A solar panel is a photo voltaic panel, capable of converting light into an electric signal.

A line to extend in a horizontal direction means that the line runs horizontally or at maximum 10 degrees diverting from this, in particular at maximum 9, 8,7, 6, 5, 4, 3, 2, or 1 degree.

An in essence horizontally extending supporting surface is a surface that locally, in particular on a scale of 0.1 to 1 or at maximum 10 meters is flat (not excluding local indentations or bulges}, but on a larger scale may rise and/or descend {being sloping etc.).

Aline to extend in a vertical direction means that the line diverts at least 10 degrees from running horizontally, in particular at least 20, 30, 40, 50, 80, 65, 70, 75, 80, 85 up to 90 degrees.

A panel directed perpendicular to the sun means that the direction in which the photons travel is perpendicular to the area in which the panel extends.

Wind is the perceptible natural movement of the air, especially in the form of a current of air blowing from a particular direction (wind inherently has a direction).

A turbine directed perpendicular to the wind means that the turbine extends in a direction perpendicular to the direction in which the wind blows.

A central processing unit (CPU) is a combination of hardware and software that is programmed to have a system perform particular (typically predetermined) operations.

The hard- and software do not need to be present in one tangible location, but may be spread over various tangible and intangible components (e.g. some hardware locally, some hardware remotely, software on a local memory and software on various remote locations accessible via wired or wireless connections).

FURTHER EMBODIMENTS OF THE INVENTION

In a further embodiment of the process according to the invention, during the day the panel is directed to the sun and during the night the wind turbine is directed to the wind.

In an alternative further embodiment of the process according to the invention, during the day the optimum energy conversion is provided for by directing the system (i.e. the panel in combination with the wind turbine) with respect to the sun and wind such that the total energy conversion is optimised. Depending on the strength of the sunlight and position of the sun, as well as the force of the wind and the direction its blows from, a total energy conversion can be calculated for each and every obtainable spatial arrangement of the panel. Depending on the required output and/or other requirements {anything that might be relevant for the system, which can for example be mechanical stability, or even aesthetics or environmental impact such as sound as a result of the positioning) any spatial arrangement can be chosen that meets the requirements.

In yet a further embodiment of the process according to the invention, the process comprises altering the said angle of the panel with respect to the supporting surface for optimising a conversion of sun light and/or wind into electricity. In particular with respect to the wind it has been recognised that altering the upright angle of the panel may have a substantial impact on the conversion of wind into electricity. In the art, in hybrid systems the panel has a fixed upright angle and it was believed that due to guidance of the wind over the panel, the exact value for the angle did not have an impact on energy conversion. However, not only was it found that the angle does have an impact, it was also recognised that in case the wind force is too strong, the panel can be arranged to lie (almost) flat such that the wind has hardly any mechanical impact on the system.

In yet a further embodiment of the process according to the invention, the process comprises establishing the direction of the wind and using the established value for optimising the energy conversion. For this a sensor for measuring the direction of the wind could be provided at the site where the system is located. Although one could make use of data provided by third parties regarding the direction of the wind (e.g. all kinds of weather forecast stations and websites), it was found that locally establishing the actual direction of the wind is advantageous. For example, buildings and big trees nearby can have a substantial impact an the direction in which the wind blows at the site of the system.

In yet a further embodiment of the process according to the invention, the process comprises establishing the force of the wind and using the established value for optimising the energy conversion. For this a sensor for measuring the force of the wind could be provided at the site where the system is located. Although one could make use of data provided by third parties regarding the force of the wind as indicated here above, it was found that locally establishing the actual force of the wind is advantageous. As with the direction of the wind, buildings and trees nearby can have a substantial impact on the force at which the wind blows at the site of the system.

In still a further embodiment of the process according to the invention, the process comprises altering the vertical position of the wind turbine with respect to the upper edge of the panel. In case of a turbine that has an axis of rotation that runs in parallel with the upper edge of the panel, it is best to maintain the axis of rotation in parallel with this upper edge. It was found that not only the upright angle of the panel may have impact on the energy conversion by the wind turbine, also its position with respect to the upper edge of the panel may have so. In particular, with varying wind force and varying upright angle of the panel, the energy conversion of the turbine can vary would the turbine have a fixed spatial relationship with respect to the panel. By introducing that this relationship may vary, there is more freedom to operate to optimise the energy conversion by the turbine.

In again a further embodiment of the process according to the invention, the process comprises using one or more wind conductors that extend from the lateral edges of the panel, to guide the wind towards the wind turbine. The guides were found to be able and direct a higher amount of wind and thus energy towards the turbine.

In yet again a further embodiment of the process according to the invention, in which embodiment the energy converting system including the panel and wind turbine is rotatably connected to a vertically extending supporting axis, the process comprises rotating the system around said supporting axis (for example by rotating the axis itself, or a mounting head that is rotatably connected to said supporting axis) for the said positioning of the solar panel and wind turbine. A vertical support was found to be suitable for supporting the system and at the same time be able to rotate this system.

In still again a further embodiment of the process according to the invention, process comprises using as a wind turbine an in essence cylindrical wind turbine comprising a plurality of blades that are rotatably arranged around an axis of rotation of the wind turbine, which axis runs in parallel with the upper edge of the panel. Such a turbine is known i.a. from the above mentioned patent US 9,732,728 and was found to be very suitable for use in the process according to the invention.

The above further embodiments correspond to further embodiments of the system according to the invention.

The invention will now be further explained using the following specific example of an embodiment of the invention.

EXAMPLE

Figure 1 schematically depicts a hybrid wind-photo voltaic energy converting system according to the invention.

Figure 1

Figure 1, composed of sub-figures 1A and 1B, schematically depicts a hybrid wind- photo voltaic energy converting system 1 according to the invention. Figure 1A is a side view of the system and depicts a fixed pole 2, connected to the in essence horizontal ground surface 3 using a concrete foundation 4. At the top of the pole 2 there is a rotatably mounted head section 5, which can rotate with respect to the fixed part of the pole 2 as indicated with arrow X. To the head section is connected a frame 6, which frame carries the solar panel 7, in this embodiment provided with lateral wind conductors 8 (for details see front/side view in figure 1B). These conductors are relatively simple upwardly extending panels to focus the wind towards the wind turbine 9. This turbine is of the RidgeBlade® type, having a horizontally extending axis of rotation 10 that runs in parallel with the upper edge 72 (see Figure 1B) of the panel 7.

The spatial position of the wind turbine with respect to the upper edge 72 can be varied using actuator 11. This way, the position of the axis 10 with respect to the panel 7 can be varied. The in essence rectangular panel is arranged such that the lower edge 71 and upper edge 72 of the panel extend in a horizontal direction and the two lateral edges 73 and 74 extend in a vertical direction, such that the panel is tilted and thus forms an upright angle a (indicated with reference number 15) with the supporting ground surface 3. This angle can be varied between -10 degrees (wherein the panel is inclined slightly backwards) and 90 degrees (wherein the panel runs exactly vertically).

This is to accommodate any optimal positions depending on the criteria which define the optimum. For example, during very heavy storm, the criterion for optimum use could be “prevent damage to the system”, upon which an angle a of for example 0 or even -10 degrees is chosen.

The system is able to convert two types of atmospheric energy into electricity, namely the energy of the sun light 12 using the photo voltaic panel, and the energy of the wind 13 using the wind turbine 9. The wind 13 is deflected towards the turbine 9 by the arrangement of the panel and the wind conductors, as indicated with arrow 14.

For controlling the use of the system 1, the system is provided with a CPU 20 that comprises the local hard- and software needed for control of the system 1, such as the angle of rotation (X), the upright angle a of the panel, and the position of the wind turbine with respect to the upper edge 72. The CPU is remotely controlled via a wire- less connection to the internet, enabling remote control, software updates, retrieving data regarding the local weather etc. The CPU also makes use of data regarding the wind direction and force using combination sensor 16 which is devised to establish both the wind force as well as the direction.

When in normal mode, during the day as long as the sun light that can be received by the panel is above a predetermined threshold, the angle of rotation X and upright angle a are such that the panel is directed perpendicular to the sun light 12 such that energy conversion of the sun light is at maximum. The required data for spatially positioning the panel are publicly available. It could be that for some reason (for example too much momentary electricity produced) the spatial configuration is altered to divert from an exact perpendicular configuration. When the sun light is below the said threshold, and optimum position is found where the combined wind and solar efficiency is optimal (e.g. at maximum). During the night this means that only the direction of the wind needs to be taken into account and the system is typically positioned such that the wind turbine 9 is directed perpendicular to the wind, with the angle being such that there is a maximum deflection of the wind towards the turbine.

The above is just an example of the system and its use.

Any deviation hereof within the limits of the claims are covered by the present patent.

Claims

CONCLUSIONS

1. Method of generating electrical power using a hybrid wind-photovoltaic energy conversion system supported by a substantially horizontally extending support surface, the energy conversion system comprising: - an essentially rectangular solar panel having an upper and lower edge and in addition two side edges, the upper and lower edges extending in a horizontal direction and the two side edges extending in a vertical direction such that the panel forms an upward angle with the supporting surface, - and a wind turbine, attached to it solar panel near its top edge and protruding above the panel; wherein the energy conversion system is rotatable around and vertical axis, comprising the method for optimizing a conversion of sunlight into electricity, directing the panel in space towards the sun by rotating the system around said vertical axis, and for optimizing a conversion of wind into electricity, directing the wind turbine in space towards the wind by rotating the system around the said vertical axis, characterized in that the method comprises changing the vertical position of the wind turbine relative to the top edge of the panel.

A method according to claim 1, characterized in that during the day the solar panel faces the sun and at night the wind turbine faces the wind.

A method according to claim 1, characterized in that during the day the optimal energy conversion is provided by directing the system towards the sun and the wind in such a way that the total energy conversion is optimized.

A method according to any one of the preceding claims, characterized in that the method comprises changing the said angle that the panel makes with the supporting surface to optimize a conversion of sunlight and/or wind into electricity.

A method according to any one of the preceding claims, characterized in that the method comprises determining the wind direction and using the determined value to optimize the energy conversion.

A method according to any one of the preceding claims, characterized in that the method comprises determining the wind force and using the determined value to optimize the energy conversion.

A method according to any one of the preceding claims, characterized in that the method comprises using one or more wind deflectors protruding from the side edges of the panel to guide the wind to the wind turbine.

A method according to any one of the preceding claims, wherein the energy conversion system including the panel and the wind turbine is rotatably attached to a vertically extending supporting axis, characterized in that the method comprises rotating the system about said supporting axis for the aforementioned alignment of the panel and the wind turbine.

9. A method according to any one of the preceding claims, characterized in that the method comprises using an essentially cylindrical wind turbine comprising a plurality of blades that are rotatably arranged around an axis of rotation of the wind turbine, which axis runs parallel to the top edge of the panel.

10. A hybrid wind-photovoltaic energy conversion system, the energy conversion system comprising: - an essentially rectangular solar panel having an upper and lower edge and in addition two side edges, the upper and lower edges extending in a horizontal direction and the two side edges extending in a vertical direction, - a wind turbine in proximity to the upper edge of the solar panel extending above the panel, the combination of the panel and the wind turbine being rotatable about a vertically extending axis, - and a central processing unit (CPU) which is programmed to enable optimization of the energy conversion by the system by adjusting the spatial position of the solar panel and the wind turbine by rotating them around the said vertically extending axis, the CPU further is programmed to change the vertical position of the wind turbine relative to the top edge of the panel.