WO2009010549A2 - Photovoltaic electricity production installation - Google Patents

Abstract

A photovoltaic electricity production installation comprises a plurality of supports (4) fixed on a platform (3), at least one photovoltaic panel (40) being mounted on each support (4). Each support (4) comprises individual orientation means for mounting the panels (40) pivoting about a following axis (A). The installation comprises a single control unit (6) driving the orientation means of each support (4) to determine the position of the panels (40) about the following axis (A).

Description

 Installation of photovoltaic electricity production.

The invention relates to a photovoltaic power generation installation.

Photovoltaic panels make it possible to convert solar radiation directly into electricity. Such energy is free and widely available. High power installations are made using a plurality of panels electrically connected to a converter. The converter supplies the energy produced to an electrical network at a suitable voltage and frequency. The first installations are carried out by fixing the panels on inclined supports. The orientation of the panels is fixed and does not allow to follow the sun in its daily or seasonal race. The performance of such an installation is therefore not optimal.

Document WO2004 / 044502 discloses a photovoltaic electricity production installation comprising an assembly of several panels mounted on a tracking device. The set of panels is pivotally mounted about a horizontal axis and a vertical axis. The set is large in size and fits poorly in an inhabited environment.

This type of installation is necessarily fixed to the ground and, because of its size, can not be fixed on a roof in a discrete way.

Document DE 197 18 358 also discloses a photovoltaic installation comprising a plurality of panels, in which each panel is pivotally mounted along a vertical axis. The panels are rotated by a chain running on gears mounted on the pivot axes of each panel. The chain drive is unreliable in the face of climatic conditions, in particular.

The aim of the invention is to provide an installation photovoltaic array comprising a plurality of panels, which is reliable, easy to maintain and allows a high yield.

With these objectives in view, the invention relates to a photovoltaic power generation installation comprising a plurality of supports attached to the ground or on a building, at least one photovoltaic panel being mounted on each support. Each support comprises individual orientation means for mounting the pivoting panels around at least one tracking axis and the installation comprises a single control unit controlling the orientation means of each support to determine the position of the panels around the tracking axis. Thus, the orientation means make it possible to follow at least one axis the course of the sun during the day. The panels are better exposed, especially at the beginning and end of the day. The orientation means are freed from a mechanical transmission between the supports, such as the chain, which allows a greater reliability of the installation. Each support is driven independently, and a malfunction of one of the supports does not compromise the operation of the other supports. Moreover, a single control unit is used, which simplifies the installation by avoiding to provide a control unit by support.

In particular, the installation comprises electricity delivery drivers connecting each photovoltaic panel to converters. The converters are conventionally used to adapt the direct current supplied by the panels to the voltage and frequency of the distribution network. Here, several panels can be connected to the same converter, in parallel or in series, to centralize the electricity provided by the panels. According to his size, the installation comprises several converters, preferably in the control unit, but also possibly separately. In this case, the converters and the control unit are connected to report information on the state of the converters to the control unit.

According to a particular arrangement, the individual orientation means comprise an electric motor, each motor being connected to the control unit. Each motor thus receives the operating power from the control unit. Electromechanical or electronic relays are arranged in the control unit and the installation does not require any means of relaying or distributing the power at the level of the supports.

Preferably, the tracking axis is vertical. This orientation provides a good return for daily monitoring. The bracket is easy to adjust in this orientation. In addition, even if the masses are unbalanced relative to the axis, no permanent torque is generated on the orientation means.

According to a particular arrangement, the orientation means comprise a motor for orienting the panel around the tracking axis, the control unit sending periodic pulses to operate the motor. It is thus possible to orient the panel along the axis of follow-up thanks to the motor. In addition, by sending pulses, it is not necessary to use a motor whose speed is controlled, but we can be content with a fixed speed motor. The amplitude of the displacement is adjusted by controlling the frequency and duration of the pulses.

According to a complementary feature, the motor is reversible and the orientation means comprise an initial position sensor for determining an initial position of the panel. We can thus rotate the panel regularly during the day in a direction of rotation to follow the sun's course, and reverse the direction of pivoting at the end of the day in a direction of return. The initial position sensor provides information that the panel has been returned to the initial position, which ensures that the panel finds a good orientation every day, even if positional deviations between the ideal position and the actual position appeared during the previous day.

According to a constructive arrangement, the orientation means comprise a mobile part pivotally mounted on a base, the movable part comprising bars forming a fixing plane for the panel. The bars may have different sections such as a section of square or rectangular tube, U or angle. They are preferably arranged in a cross whose intersection is on the tracking axis. They support the standard fastening means of the panels. According to one improvement, the platform is covered with a reflective film. This increases the albedo of the platform. The panels thus benefit from indirect radiation by the solar radiation reflected by the film, which adds additional power to the power they receive directly from the sun.

According to a particular characteristic, the installation comprises a structure fixed on the platform and on which the supports are fixed. The bases of the supports are fixed on the rails.

The structure comprises for example rails parallel to each other. It can be completed by ties, connecting the rails between them.

In the case of a fragile platform, such as a flat roof covered with a sealing layer, soft pads are interposed between the rails and the platform. This avoids the deterioration of the fragile surface of the platform.

In this configuration, the reflective film is placed between the platform and the structure. The film is thus maintained directly by the support of the skates on the film.

The installation can be supplemented by sensors determining the effective position of the panels, the control state of the actuator, the panel temperature, the panel voltage, and sending this information to a supervisor via a fieldbus and a PLC. .

The invention also relates to a method of controlling an installation as described above, according to which the panels are oriented according to the position of the sun. The desired position of the panels is determined for example by a calculation according to the date and time, and according to the location of the installation. This optimizes the electricity production of the installation. In the case of supports with an initial position sensor, the panels are controlled in a first direction to follow the sun during the day, and the panels are controlled to the initial position after sunset. Return to the home position can be done at any time after sunset and before sunrise the next day. The movement of the support is thus alternating, and the flexibility of the electrical connections is sufficient to adapt to all the positions taken by the support. In a safety mode of the installation, all rotation is stopped. This security mode may correspond to situations in which blocking of the panels could occur, such as heavy snow or frosty fog. The security mode can be triggered automatically by a weather station connected to the central unit, or manually, on site or remotely by any suitable remote control means.

It is also possible to provide a storm-arresting mode, according to which the panels are oriented in a position depending on the wind. It can be triggered by means equivalent to those previously stated.

According to a refinement of the method, a malfunction alert is generated if the power difference provided by each panel exceeds a predetermined threshold. An imbalance in the power provided by each panel results from an anomaly if the panels are normally exposed to the same radiation. Such an anomaly can be a deterioration of the electrical connection cables, a screen brought by the wind in front of a panel, a malfunction of certain cells of the panel ...

The invention will be better understood and other features and advantages will appear on reading the description which follows, the description referring to the appended drawings in which: FIG. 1 is a side view of an installation conforming to FIG. invention; Figure 2 is a perspective view of a panel support forming part of the installation of Figure 1; Figure 3 is a sectional view of the support of Figure 2; Figure 4 is a perspective view of a bar assembly forming part of the support of Figure 2; - Figure 5 is a partial top view of the support Figure 6 is a schematic view of the electrical connection of the supports.

A photovoltaic power generation installation 1, as shown in FIG. 1, comprises a structure 2 deposited on a platform 3, and a plurality of supports 4 each supporting a photovoltaic panel 40 in a position inclined relative to the horizontal. Each panel 40 has a surface of the order of 1 to 3 m ² and is preferentially monocrystalline silicon or polycrystalline, to provide a peak power of between 100 and 300 W.

The platform is here a flat roof 3 covered by a waterproof film 30. The structure 2 comprises a series of rails 20 arranged parallel to each other. The rails 20 rest on the roof by means of pads 21 of flexible material, such as extruded polystyrene, and rigid plates 22 having substantially the same surface as the pads 21, placed between the rails 20 and the pads 21. A reflective film 5 is disposed between the roof waterproofing film and the pads 21.

A control unit 6 is preferably placed on the structure 2. The control unit 6 is connected to the electrical network and to each support 4. It comprises a programmable controller, not shown, to manage the commands, one or more converters, no represented, to receive the electricity supplied by the photovoltaic panels 40 and supply this electricity on the network. The control unit 6 is optionally connected to a telecommunications network to receive commands or to provide information on the installation 1, such as the cumulative electricity supplied. The controller comprises an annual cycle clock, which allows it to calculate at any moment the desired position of the supports 4 so that the panels 40 are oriented at best with respect to the position of the sun in the sky.

Each support 4 comprises a base 41 and a movable portion 42. The base 41 is fixed on two adjacent rails 20. It comprises a base plate 410 and a base tube 411 welded vertically on the plate of base 410. The mobile part 42 comprises a vertical mobile tube 420, fitted on the base tube 411. Bearings 412, for example made of polymer or balls, provide pivotal guidance of the movable tube 420 on the base tube 411, around an A tracking axis, vertical. The movable tube 420 has an upper end cut at an angle, for example at 45 °, and comprises two bars 421 welded to the movable tube 420 in the plane at an angle. The bars 421 are, for example, angles joined together by welding, as shown in FIG. 4. The bars 421 comprise notches 4210 in which the wall of the movable tube 420 is inserted before the bars 421 are welded to the mobile tube 420. The photovoltaic panel 40 is fixed by conventional means on the bars 421. Delivery conductors 7, coming from the panels 40 enter the mobile tube 420 through the upper end and join the control unit 6, possibly with a grouping of the delivery conductors 7 of several supports 4. The assembly of the structure 2 and the supports 4 are intended to be insensitive to corrosion.

The support 4 also comprises orientation means comprising a geared motor 43, fixed on the base 41, to drive a toothed belt 44. The geared motor comprises an electric motor 430. The toothed belt 44 is wound around the movable tube 420 at an angle greater than 270 ° with the aid of two guide rollers 45. The movable tube 420 comprises a finger 422 projecting and able to actuate an initial position sensor 46. The motor 430 is of the asynchronous and bidirectional type, for example with two windings.

The set of supports 4 is divided into one or more groups. As shown in FIG. 6, the control unit 6 is connected by three conductors to each group of supports 4. A first of the three The second conductor P1 is connected to a first of the windings of the motor group 430 to control the rotation in a solar direction. The third conductor P2 is connected to the second winding of the set of motors 430, to control the rotation in an anti-solar direction, opposite to the solar direction. The third conductor P2 is connected to the winding via a contactor 460 normally closed, actuated by the initial position sensor 46. Thus, when the return control is in the initial position, the power supply of the motor 430 is cut as soon as the switch is actuated by the finger 422 when the movable portion 42 of the support 4 has returned to its initial position. The set of moving parts 42 of the supports 4 are, at the beginning of the day, in the initial position, so that the panels 40 are oriented towards the East, for example at -120 ° with respect to the South. Optionally, the initial position is determined between -90 ° and -120 °. Depending on the day and the time indicated by the clock, the initial position and the speed of rotation of the supports 4, the automaton determines pulses at a frequency and durations adapted to obtain the placement of the moving parts in an optimal orientation with respect to the position of the sun. The pulses are sent on the second conductor Pl of the supports 4, to control the rotation in the solar direction.

At the end of the day, a continuous command is sent on the third conductor P2, in order to control the return to the initial position, for a time sufficient to obtain the return of all the supports 4. The actuation of the contact 460 guarantees that all panels are in the initial position.

The invention is not limited to the mode of realization which has just been described by way of example. The motors 430 may be of the step-by-step type, electromagnet ratchet ... The control could be a control of the speed of rotation. The drive can be performed by a flat belt, a chain, a gear or live.

Claims

Photovoltaic power plant comprising a plurality of supports (4) fixed on a platform (3), at least one photovoltaic panel (40) being mounted on each support (4), the installation being characterized in that each support (4) comprises individual orientation means for mounting the panels (40) pivoting about at least one tracking axis (A) and in that it comprises a single control unit (6) controlling the means orienting each support (4) to determine the position of the panels (40) around the tracking axis (A). 2. Installation according to claim 1, characterized in that it comprises delivery conductors (7) of electricity connecting each panel (40) photovoltaic converters. 3. Installation according to claim 1, wherein the individual orientation means comprise an electric motor (430), each motor being connected to the control unit (6). 4. Installation according to claim 1, wherein the tracking axis (A) is vertical. 5. Installation according to claim 1, wherein the individual orientation means comprise a movable portion (42) pivotally mounted on a base (41), the movable portion (42) having bars (421) forming a fixing plane for the panel (40). 6. Installation according to claim 1, wherein the platform (3) is covered with a reflective film. 7. Installation according to claim 1, characterized in that it comprises a structure (2) fixed on the platform (3) and on which the supports (4) are fixed. 8. Installation according to claim 7, in which the structure (2) comprises rails (20) parallel to each other. 9. Installation according to claim 8, wherein pads (21) are interposed between the flexible rails (20) and the platform (3). 10. Installation according to claims 6 and 7 taken in combination, wherein the reflective film is placed between the platform (3) and the structure (2). 11. Control method of an installation according to one of claims 1 to 10, characterized in that the panels (40) orients according to the position of the sun. The method of claim 11 for an installation in which the individual orientation means comprises a reversible motor (430) for orienting the panel (40) around the tracking axis (A), and the individual orientation means comprise an initial position sensor (46) for determining an initial position of the panel (40), wherein the panels (40) are controlled in a first direction by sending periodic pulses to the motor (430) to track the sun during the day, and control panels (40) to the initial position after sunset. 13. The method of claim 11, wherein any rotation is stopped if the installation is in a security mode. The method of claim 11, wherein the panels (40) are oriented in a wind-dependent position if the installation is in a storm-arresting mode. 15. The method of claim 11, wherein generates a malfunction alert if the power difference provided by each panel (40) exceeds a predetermined threshold.