Patent Application
20150280642
This invention relates to a solar photovoltaic sensing, control and monitoring system consisting of a sensing and control device that is connected to the DC output of a solar photovoltaic module, collects the output voltage and current values of the solar module and may collect other parameters, such as the ambient temperature value, generates derivative values thereof, such as power and cumulative energy values, and transmits the values to a monitoring device by means of a wireless or wired communication channel. The monitoring device may constitute a local display interface or may be connected to a database or another device by means of a communication medium such as the internet.
In some preferred configuration, the sensing and control device constitutes an automatic switch or automatic switches in series with the current carrying conductors connected to the solar module output. The switches are operated so as to disconnect the solar module output from the load in the case of maintenance or in the case of development of a safety issue such as ground fault. In another preferred configuration, the sensing and control device includes a switch in parallel with the current carrying conductors, in addition to a switch or switches in series. Such a switch, if used in conjunction with the aforementioned switch connected in series, is provided so as to be used to bypass the solar module output, thereby enabling adjacent devices or solar modules to continue to provide power to the load. The disconnection feature may be desirable in an installation with multiple solar modules.
Solar photovoltaic module manufacturers, installers and system owners are increasingly demanding visibility of their photovoltaic solar systems performance. In the more prevalent installation configuration, solar modules are grouped together in a parallel, a series or a series and parallel combination and connected to a string or central inverter or load. This configuration provides a barrier to monitoring the performance of each individual solar module on the system.
In a system such as described in 0003, in the event of a failure of a single solar module on an installation, it is possible that the system owner would fail to notice that the installation is generating energy under capacity. The unnoticed downtime may result in lost revenue for the owner.
Furthermore, in a system such as described in 0003, maintenance workers may struggle to locate a failed solar module in a large installation that is already identified as underperforming. Locating the affected solar module may be a costly process for the owner; expensive techniques, such as thermal imaging, may be employed to identify a failed solar module.
Additionally, solar module manufacturers increasingly demand field performance data in order to improve their product performance and innovate for the next generation solar modules.
An important aspect of a solar photovoltaic installation is its safety. There are many instances of fire breaking out in solar installations. A fire breakout may result in damage to property the installation is located on, in addition to damage of the solar installation itself. Fire may result from a gradual degradation of a solar module element such as wiring, damage to a solar cell system in the module or a ground fault condition.
Currently existing systems are not equipped to solve these problems.
Herein are described techniques to address these problems.
According to the present invention there is therefore provided a sensing and control device that connects to the output terminals of a solar module and collects the output voltage value and the output current value of the solar module and transmits such collected values or derivative values thereof to a monitoring device. Additionally, the sensing and control device may be configured to collect values including temperature and other parameters associated with an installation of a solar module. The values thus collected by the sensing and control device are transmitted to a monitoring device, which may constitute a local display and may connect to a database via a communication channel such as the internet. The transmission of the values between the sensing and control device and the monitoring device is conducted by either a wired or wireless communication channel. The monitoring device may constitute a display interface and may transmit the values to a secondary display device or database through media such as the internet. Furthermore, the monitoring device may transmit instructions to the sensing and control device. Additionally, the sensing and control device may comprise an automatic switch or automatic switches to disconnect the solar module from the load or to bypass the solar module output.
In embodiments the sensing and control device may constitute a current sensor, a voltage sensor, a temperature sensor and other sensors such as provided. In the embodiments the current sensor comprises either a magnetic coil around the current carrying conductor or a sensor resistor in series with a current carrying conductor and an amplifier. In the embodiments the current sensor or the amplifier is connected to the input of an analogue to digital converter; the output of the analogue to digital converter is connected to a processing unit. The processing unit is connected to a transceiver and a memory element. The output of the transceiver may be terminated with an antenna in the case of wireless communication or a cable in case of a wired channel.
In embodiments the voltage sensor may comprise a potential divider or an amplifier connected on the output of the solar module or across the current carrying conductors that transmit power from the solar module to the load. The current carrying conductors form the electrical connection between the solar module, which generates energy, and the load, which receives the energy. The load is connected on the output of the sensing and control device. The voltage sensor or amplifier is connected to the input of an analogue to digital converter; the analogue to digital output is connected to a processing unit. The processing unit is connected to a transceiver and a memory element. The output of the transceiver may be terminated with an antenna in the case of wireless communication or a cable in case of a wired channel.
In some preferred embodiments the sensing and control device constitutes both input and output terminals. The input terminals of the sensing and control device are connected to the solar module output terminals. The output terminals of the sensing and control device are connected to a load, such as an inverter, a similar sensing and control device, a battery, a solar module or a suitable load such as provided.
In some preferred embodiments the sensing and control device may be integrated into the junction box of a solar module or may replace the junction box altogether, thereby forming a smart solar module. In the embodiment of a smart solar module, wherein the sensing and control device replaces the junction box, the sensing and control device input connections are fitted to the solar module output conductors in the same manner the junction box input connections would have been fitted. In the embodiment of a smart solar module, wherein the sensing and control device is fitted inside the junction box, the sensing and control device input connections are fitted to the solar module output conductors in a similar manner as the junction box input connections are fitted, the output connections of the sensing and control device are connected to the output conductors of the junction box. In the embodiment of a smart solar module, wherein the sensing and control device replaces the junction box, the sensing and control device includes bypass diodes between the output conductors of the solar module, in a similar manner as those in the junction box are fitted.
In some preferred embodiments the values thus collected by the sensing and control device is transmitted wirelessly to the monitoring device by means of such media as ZigBee, Bluetooth or other ISM band platforms.
In embodiments the sensing and control device may receive instructions from the monitoring device by means of the established communication channel.
In embodiments the monitoring device may have a local display or may transmit values to another device or database via a media such as the internet.
A system constituting a sensing and control device and monitoring device such as described above may be used to overcome problems associated with lack of visibility of each individual solar module performance and may enhance system safety. Values or data transmitted from the sensing and control device may be used not only to ensure optimal performance of an installation but also to provide a early warning in case of safety issues developing. This visibility may be unlocked by the temperature, voltage or current reporting feature or an alarm system such as implemented on the sensing and control device.
Furthermore, the availability of an automatic switch or automatic switches on the sensing and control device may improve safety. The switch may be configured to disconnect the solar module from the load in the event of safety violations such as may result from a ground fault or arcing on the system.
These and other aspects of the invention will now be further described, by way of example only, with reference to the accompanying figures in which:
Broadly speaking, herein is described a system constituting an electronic sensing and control device that connects on the output of a solar photovoltaic module, collects output voltage value and current value, and other parameters such as a temperature value, and transmits the values or derivative values thereof to a monitoring device by means of a wired or wireless communication channel. Furthermore, the sensing and control device may constitute an automatic switch or automatic switches to disconnect the solar module from the load.
The monitoring device may constitute a local display and may transmit values or data to a secondary device or database by media such as the internet. The monitoring device may transmit instructions to the sensing and control device by means of an existing communication channel.
The sensing and control device collects the output voltage value of a solar photovoltaic module by means of a voltage sensor connected on the output of the module and collects the output current value by means of a current sensor; the current sensor may be a resistor in series with the current carrying conductor or a magnetic coil around the current carrying conductor transferring current between the solar module and a load. Additionally, the device may collect a temperature value or other values by means of a corresponding sensor such as provided. The output values of the sensors such as provided may be amplified or attenuated by an amplifier. The output values of the sensors such as provided or the output of an amplifier such as used are converted to digital format by an analogue to digital converter. A processing unit receives the output values of the analogue to digital converter corresponding to the current, voltage and temperature values. Derivative values, including power and cumulative energy, may be generated by the processing unit. The processing unit processes the values into a format suitable for transmission. A transceiver connected to the output of the processing unit transmits the data by means of a wired or wireless channel to a monitoring device. In the case of a wireless system, an antenna is connected to the transceiver. In the case of a wired system, a cable is connected to the transceiver. Additionally, the sensing and control device may receive instructions from the monitoring device.
Herein is described the mechanism of operation of the sensing and control device 1 by way of examples.
Herein is described the mechanism and operation of the monitoring device 2.
Herein is described the system examples of the sensing and control device 1.
Herein is described, broadly speaking, some preferred embodiments. In some preferred embodiment the sensing and control device comprises input and output terminals. The input terminals are connected to the output terminals of the solar module, either in a factory, during installation or after installation of the solar module. The output terminals may be connected to the output of another sensing and control device, an inverter, a battery or a suitable load such as provided. Multiple loads or devices may be connected on the output of the sensing and control device.
In another preferred embodiment the sensing and control device is integrated onto the solar module and either replaces the junction box or is embedded into the junction box. In the embodiment the device may be built into the solar module structure during the manufacturing process of the solar module or may be attached afterwards in such a way that it becomes an integrated part of the solar module. In the embodiment, wherein the sensing and control device replaces the junction box, the sensing and control device is integrated in the same way that a junction box is integrated on the solar module.
In another preferred embodiment the sensing and control device may be fitted with an automatic switch or automatic switches that can break the circuit of the current carrying conductor of a solar module in case of safety violation or maintenance. Furthermore, a switch may be closed so as to bypass the output of the solar module by creating a short circuit on to the load. In the first mode, the sensing and control device may be pre-programmed to break the circuit under specific conditions such as high sensed temperature or ground fault. In the second mode, the sensing and control device may be instructed to break the circuit of the current carrying conductor via an instruction sent from the monitoring device. Switches such as used may be semiconductor or electromechanical in construction.
The sensing and control device is primarily for use in installations of solar photovoltaic systems wherein individual solar module monitoring and control and system safety are sought. Alternatively, the sensing and monitoring device can be used in modular battery systems wherein visibility of performance and safety is desirable. The device provides significant benefits in terms of data monitoring and safety provision in installations.
