AU713860B2

AU713860B2 - Photovoltaic module and electrical energy production unit employing this module

Info

Publication number: AU713860B2
Application number: AU27797/97A
Authority: AU
Inventors: Gerard Moine
Original assignee: TRANSENERGIE
Current assignee: TRANSENERGIE
Priority date: 1996-05-03
Filing date: 1997-04-30
Publication date: 1999-12-09
Anticipated expiration: 2017-04-30
Also published as: DE69703101D1; AU2779797A; FR2748351A1; EP0896737A1; FR2748351B1; ZA973810B; EP0896737B1; WO1997042664A1

Description

PHOTOVOLTAIC MODULE AND ELECTRICAL ENERGY PRODUCTION UNIT EMPLOYING THIS MODULE BACKGROUND OF THE INVENTION The invention relates to a photovoltaic module intended, in a known manner, to convert solar power into a DC electrical current.

It also relates to an electrical energy production unit employing such modules. These units employ such photovoltaic modules as electricity generators and incorporate devices which are capable of storing the electricity thus produced, for instance one or more batteries. However, it is also possible for the energy produced to be used immediately at one or more electrical receivers, after possible processing.

Such production and electrical energy storage units are most particularly adapted, especially in isolated areas, such as arid regions, areas of low population density, etc., where the electrical energy distribution via a conventional means, that is to say via a grid, proves to be prohibitively expensive.

Usage shows that the solar modules employed in these units are frequently spirited away or stolen, to be resold or installed in other places by these unscrupulous persons.

In order to counter these malicious acts, it has been proposed, in order to deter them, to provide protection in a mechanical form, especially by means of all-welded structures, especially made of stainless steel, thus constituting a tamper-proof system. Over and above the fact that such systems are heavy and generally require to be factory-produced, they also affect the modularity of the electrical energy production units using these photovoltaic modules. It has also been proposed to employ tamper-proof nuts and bolts, making use of complex bolt heads which require special spanners both for fitting them and for removing them. In either case, such mechanical protection means prove merely to be simple delaying devices, their deterrent function being -2 however insufficient to prevent such theft satisfactorily.

Electrical or electronic devices have therefore been proposed, especially alarm systems, consisting, for example of an electrical loop which passes through all the photovoltaic modules employed within a unit and which, when it is open, triggers a radio, telephone or visual alarm signal, or a combination of these signals, or even alerts a central guarding station. Given the site where these units are installed, it is readily accepted that such alarm systems generally prove to be ineffectual and in any case of little deterrence.

It has also been proposed to incorporate a specific marking or identification means into the modules. This marking may take the form of an indelible coloured coating, which can be seen from afar and can be identified to the owner of the unit or to the company providing the maintenance and hiring of such modules, or else in the form of an actual marking. Although to be sure these identification means do discourage any anxious fraudsters from perpetrating such theft for the purpose of reselling the modules, which in fact affect their market value, they do not, however, prevent the units from being used for their own use.

Finally, it has also been proposed to incorporate into the modules a micro-emitter which is supplied by the electrical energy produced by the module itself and is intended to emit, over a defined coverage area, typically over a radius of one kilometre from the module, a signal capable of being picked up by a receiver and identifying the said module. Although to be sure this signal enables the module to be identified, it does remain operational, however, so that this system proves to be of little deterrent value. Moreover, such a system turns out to be quite expensive.

3- Document EP-A-0 342 578 discloses a regulator of the charge of photovoltaic accumulators comprinsing in the load circuit a switch intended to control the load of said accumulators. Houwever, such a switch does not avoid the risks of theft of said accumulators nor to render them deterrent.

SUMMARY OF THE INVENTION The object of the invention is therefore to propose a photovoltaic module intended to discourage theft, or even simple borrowing, by making the module nonfunctional.

This photovoltaic module intended to convert solar power into electrical current, especially DC current, comprises two terminals called power terminals, a storage battery or an electrical receiver, or possibly even both, being connected directly or indirectly to these terminals.

It is characterized in that it incorporates into its structure an electrical switch which is capable of neutralizing the available power output at the power terminals, the said switch being controlled by a control circuit from outside the module.

In this way, considering that this switch cuts off or short-circuits the output terminals of the module, and hence neutralizes the supply of electrical energy delivered by the module, it renders this module nonfunctional, unacceptably compromising its market value, and nullifies any possible use of an unscrupulous acquirer.

Advantageously, this switch is embedded in the resin at the back, for example, of the active face of the module, that is to say of the face exposed to the solar radiation, or is encapsulated within the sandwich structure making up the module itself, in such a way that any attempt to remove the switch from the module results in it becoming permanently unusable.

4 Advantageously, this switch is an electronic switch of the field-effect transistor type produced in MOSFET technology, but it may also consist of an electromechanical relay or any other device giving the same result.

In a more sophisticated version of the photo-voltaic module according to the invention, this incorporates not only a switch capable of neutralizing the power delivered by the module but also a processing unit, that is to say an electronic circuit, supplied by the electrical energy produced by the module, and emitting, depending on, for example, operating parameters of the unit within which the said module is installed, a control signal which acts on the switch.

In the same manner as in the previous case, the electronic card making up this processing assembly is embedded in the resin or installed in a case secured to the back of the active face of the module, so that trying to remove it results in the said module becoming unusable.

The invention also relates to an electrical energy production unit. This comprises: at least one electrical energy generator; an electrical power or use circuit comprising at least one electrical receiver and/or one or more batteries for storing the electricity thus produced; a regulator mounted in the electrical power or use circuit and capable of opening or closing the said circuit depending especially on the parameters relating to the operation of the unit.

This unit is characterized in that the electrical energy generator consists of a photovoltaic module of the type described previously.

The manner in which the invention may be realized and the advantages which stem therefrom will appear more clearly from the following embodiments given by way of non-limiting indication, supported by the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagrammatic representation of a unit in accordance with the invention.

Figure 2 is a representation of a simplified electrical circuit diagram of the unit according to a first embodiment of the invention.

Figure 3 is a view similar to Figure 2 of another embodiment of the invention.

DETAILLED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE

INVENTION

Figure 1 shows diagrammatically a unit for producing electricity in accordance with the invention. This unit basically comprises an electrical energy production module incorporating a solar module proper, which converts solar power into a DC electrical current, the said module being, in particular, connected via a power circuit to a battery (15) intended to store the electrical energy thus produced.

This battery may furthermore, in some cases, also be supplied with energy by an electric power generator set (17) of a conventional type via a battery charger (not shown).

Connected to the terminals of this battery (15) may be either a receiver operating on DC voltage, for example 12 volts, or a receiver operating on AC voltage, for example 230 V, after the voltage has been processed by a power invertor.

Reference should be made to Figures 2 and 3 in order to understand the invention more clearly.

Shown in Figure 2 is a first embodiment of the invention. In this, the photovoltaic module is of a type known per se for converting solar radiation into DC electrical current. This module has two power terminals and to one of which terminals is connected in series a switch, in this particular case a field-effect transistor produced in MOSFET technology.

6- According to one particular feature of the invention, this transistor is incorporated into the module and, for example at the back of the active face thereof, is encapsulated in a resin made integral with the module, in such a way as to make it impossible to gain access to the said switch without ending up in destroying the active face of the said module and hence without making the latter completely unusable.

In the set-up described in Figure 2, the drain and the source of the transistor are connected to the negative power terminal of the module In other words, the transistor acting as switch is mounted in series.

However, it is conceivable for the switch to be mounted in parallel, for example when it consists of an electromechanical relay, in this case short-circuiting the two power terminals and of the module.

Moreover, the gate of the transistor is connected via a control circuit (16) to an electronic card for running the unit, this card itself being connected to the battery (15) and incorporating a management device. In fact, this energy-management device measures the voltage across the terminals of the battery and, depending on a reference voltage, causes the transistor to be turned off or on, that is to say neutralization of the said module if the rated voltage of the battery is obtained.

Other parameters may also be involved in the management of the energy, especially temperature, the state of charge of the battery, etc.

Also shown by way of illustration is a power inverter intended in a known manner to convert a DC electrical current into an AC current, as well as two application outputs, respectively a DC, for example 12 volt, output (10) and an AC, especially 230 volt, output (11).

7 Also shown by the references (13) and (14) are the shunts for measurement at the terminals of the battery and the measurement of the voltage across the terminals of the battery, these being capable of being taken into account by the energy-management device so as to control the switch In a known manner, a field-effect transistor is controlled by voltage, but at virtually zero current flow. Thus, only currents of very low amperage flow in the control circuit (16).

In another embodiment of the invention shown in Figure 3, the module incorporates not only the switch but also the processing unit This processing unit is supplied with energy directly from the module as may be seen, since it is mounted in parallel with the power terminals and (3) of the said module and upstream of the switch On the other hand, as was already stated, the transistor is mounted in series on one of the outputs of the said module the rest of the unit remaining exactly the same.

Thus, as soon as the module is disconnected from the electrical energy production unit in which it is fitted, there is no longer supply of control current in the control circuit (16) so that the switch opens the circuit of the module The latter can no longer deliver energy, since the switch is turned off, so that there can be no current output downstream thereof.

Moreover, when the switch is mounted in parallel it becomes conducting, short-circuiting the two power terminals 3) of the module.

In the embodiment described, the control signals are conveyed by an electrical link These signals may be analog (current or voltage) or digital (signal transfer carrier: RS232, RS422, RS485, etc.), or even consist of coded signals, capable of being processed by the processing unit managing the operation of the switch S 8 However, the control signals may also be transferred by radiowaves, the electronic card for running the unit being connected to a transmitter and the processing unit being connected to an appropriate receiver. In this way, it becomes possible to dispense with control-circuit wiring sytems, especially within the context of panels composed of a number of modules in accordance with the invention.

In like vein, the control signals may be forwarded by means of carrier waves conveyed by the power circuit 17). In this way, by dispensing with the control circuit the mounting of the modules is simplified, especially in the case of a number of the latter.

Of course, the invention applies to a unit employing a number of these modules these modules being capable of being mounted in series or in parallel and being connected together and to the energy- management device by means of a wiring system which provides the control circuit, capable of being replaced by the power circuit or by radiowaves, as mentioned above.

Within the context of a more complex unit employing regulation, as described for example in connection with Figures 2 and 3, it may therefore be envisaged that this additional function is provided without any real extra cost, thereby giving the system not only its tamperproofness but also its deterrent nature, since the discontinued modules no longer have any market value.

Furthermore, even for personal use, the module becomes unusable.

The switch incorporated in the module provides a decentralized regulation function, by remote neutralization of the energy delivered by the module or modules. Thus, it becomes possible to standardize the central regulation electronics, whatever the power of the photovoltaic field. This is because the power cut-off is then distrbuted over all the modules by means of the incorporated switches, this being achieved without requiring additional components.

9- Moreover, within the even more sophistcated, context of a unit for delivering electrical energy of solar orign, incorporating for example a prepayment system, the device in accordance with the invention makes it possible, should fraud be attempted, that is to say should an illegal connection be made upstream of the meter managing the prepayment, to cause immediate interruption to the supply of energy by the modules making up the unit in question, simply by turning off or opening the switches incorporated in the said modules.

The control signal for turning off or opening the switches may originate from the meter itself, when the amount of credit has been exhausted, by means of the power circuit.

Claims

1. Photovoltaic module intended to convert solar power into electrical current, especially DC current, comprising a photovoltaic module proper having two terminals called power terminals, either a battery for storing the electrical energy thus produced or an electrical receiver, or possibly even both, being connected directly or indirectly to these terminals characterized in that the module incorporates into its structure an electrical switch which is capable of neutralizing the available power output at the power terminals in order to render said module unusable, said switch being controlled by a control circuit from outside the module.

2. Photovoltaic module according to Claim 1, characterized in that the switch is embedded in a resin made integral with the back of the active face of the panel, that is to say of the face exposed to the solar radiation, or is encapsulated within the sandwich structure making up the said module, in such a way that any attempt to remove the switch from the module results in it becoming permanently unusable.

3. Photovoltaic module according to either of Claims 1 and 2, characterized in that the switch is an electronic switch of the field-effect transistor type produced in MOSFET technology.

4. Photovoltaic module according to either of Claims 1 and 2, characterized in that the switch is an electromechanical relay. -11- Photovoltaic module according to one of Claims 1 to 4, characterized in that the module furthermore incorporates a processing unit which is mounted in parallel with the terminals of the module, and upstream of the switch, in such a way as to be supplied by the electrical energy produced by the module, and which is intended to receive coded or uncoded control signals of the analog or digital form, in such a way as to manage the operation of the switch for the purpose of opening or closing it.

6. Photovoltaic module according to Claim characterized in that the processing unit is embedded in a resin made integral with the back of the active face of the module, that is to say of the face exposed to the solar radiation.

7. Photovoltaic module according to either of Claims and 6, characterized in that the control signals are transmitted to the processing unit by radiowaves.

8. Photovoltaic module according to one of Claims 1 to 6, characterized in that the control circuit consists of the power circuit emerging from its power terminals, the control signals being conveyed in the said power circuit by carrier waves.

9. Electrical energy production unit comprising: at least one electrical energy generator; an electrical power or use circuit comprising at least one electrical receiver and/or one or more batteries for storing the electricity thus produced; a regulator mounted in the electrical power or use circuit and capable of opening or closing the said circuit depending especially on the parameters relating to the operation of the unit; characterized in that the electrical energy generator consists of a photovoltaic module according to one of Claims 1 to 7. _I X -12- Electrical energy production unit according to Claim 9, characterized in that it incorporates in the power circuit an electrical power meter which operates according to the prepayment principle and which is capable of turning off or opening the switch, incorporated into each of the panels making up the said unit, as soon as the allocated amount of electricity corresponding to the prepayment is consumed, in such a way as to cause the electrical energy supply to be interrupted.