DE102021006104A1 - Shutdown PV system - Google Patents

Abstract

This results in the following advantages over the prior art: If there is a fire or a fault in a PV system, solar modules can now be switched off individually or as a string, and the PV system can be reliably disconnected from the grid. The variant with a series connection of the thermal fuse (27) / bimetallic switch (37) interrupts the current flow at the points where an impermissibly high temperature occurs. The variant with a parallel connection to the solar module of the thermal fuse / bimetallic switch (37) short-circuits the current of the solar module or/and derived by mass. This reduces the tension in the strings. The more solar modules fail due to a fire, the lower the voltage in the system, since each solar module is short-circuited and bridged. The signals from the monitoring function are routed from the live socket (19) via e.g. SAT cable to the electronics. By evaluating the individually transmitted frequency with its specific values (e.g. voltage, power) of each individual solar module, these can now be saved or forwarded. These can then be visualized/sent, e.g. by SMS, email or other media. The control function for the solar modules is also led from the control socket (20) to an electronic system by means of a cable (e.g. satellite cable). The control electronics sends an individual frequency as a carrier signal for the execution of the control command to the electronics box (Fig. 8) of the solar module. For all versions, the advantageous galvanic isolation results from the type of signal transmission to the solar module. This is implemented using the optocoupler principle.

Description

With solar photovoltaic systems, there is the issue that, for safety reasons, they must always be able to be switched off (DC disconnector). This ensures that no reverse current from the PV system can get into the supply line. In the event of force majeure, e.g. fire or other possible damage to the PV system, it must be possible for it to be de-energized. This serves in particular to ensure safety when working on roofs equipped with solar modules. These are e.g. maintenance work, roof fires and their extinguishing.

Due to the function, a complete power shutdown of the PV system is not possible, since the DC circuit breaker cannot switch off in front of each solar module. Individual strings cannot be switched off in the danger area on the roof. Since the individual strings here can have a system voltage of up to 900V DC (peak), work of any kind is dangerous for people and animals. According to the state of the art, monitoring and controlling individual modules or switching them off is only possible with great effort. The modules are usually connected in series per string or in parallel in the case of several roof areas with different compass orientations.

The invention specified in claim 1 is based on the problem that the new requirements cannot be implemented easily by conventional system components or only with considerable effort.

This problem is solved by the features listed in claims 1-10.

A thermal fuse (40) is installed here, for example in the PV module (connection housing 3), which immediately interrupts the current circuit in the event of a fire. This makes it possible to cost-effectively protect each individual module or entire string against dangerous voltages. Above a certain temperature, the thermal fuse (40) interrupts the circuit. Subsequent components are thus separated from the remaining modules and the dangerous voltage is no longer on the PV lines. The thermal fuse (40) can be built into the solar module (connection box 3), for example, or independently as a temperature fuse (27) in an adapter plug ( 9 ), fuse holder (21), in the PV connection cables.

If a bimetallic switching element (33) is used instead of the thermal fuse (40), the voltage can be interrupted and/or short-circuited directly at the solar module, depending on how the bimetallic switching element (33) is designed (changeover / single / multi-pole switching contacts). . A version with "forced grounding" via the bimetallic switching element (33) would also be an option for deriving the voltage immediately on the solar module via the grounding strap (18) to the frame (7). For this application, it must be earthed in accordance with the regulations. The thermal fuse (40) and the bimetallic switching element (33) are expediently attached directly above the solar cell plate (1). In this way, an excessively high temperature, which can also be caused by the solar cells themselves, can be recognized and lead to the solar module being switched off safely. If the temperature falls below again, the solar module switches itself on again automatically. According to the invention, both components (thermal fuse (40) and bimetallic switching element (33)) can also be installed in the PV switch-off, e.g. for redundancy.

Furthermore, it is possible to read out relevant PV data of each individual solar module via the new live socket (19) according to the invention. This is done in principle via an optocoupler. This reliably separates the high voltage of the string (up to 900V) from the measuring line, which is connected to the live socket (19). According to the invention, the optocoupler is constructed in such a way that the solar module voltage is tapped. The voltage is connected to a resistor (35) connected in series to the flashing LED (15). The flashing LED (15) works with a flashing frequency that is individually adjusted for each module. In addition to the series resistor, a zener diode ((36) and/or a varistor (34) can protect the LED from excessively high voltage. A cooling element (10) protects the LED from excessively high temperatures. A photo cell is located opposite the flashing LED (15). (4), which receives the light signal emitted by the flashing LED (15).The particular advantage of this version is the galvanic isolation of both systems (high-voltage solar module, primary circuit board (6), 5 / Measurement System -> Secondary Board (8) 6 . Depending on the solar voltage, the intensity of the flashing LED (15) light radiation changes at the same time. The light intensity is converted back into a voltage via the photo cell (4). This then goes to the live jack (19). The voltage from the flashing LED (15) is functionally clocked by the flashing process. The measuring line is connected to the live socket (19) using a standard SAT plug, for example.

These connectors & associated cables are inexpensive, resistant to environmental influences and easy to use. The advantage of this version is that the live sockets (19) can all be connected in series. The output signal of each solar module in a string has a different flashing frequency and can therefore be clearly assigned to the solar modules. The output signal becomes central fed back into a separate electronics module and evaluated. The parameters can then be made available to the system operator via software. A drop in performance of a solar module can be analyzed quickly and the defective module can be easily replaced. The flashing frequency can be inexpensively integrated into the LED or generated via on-board electronics (e.g. IC (14). On-board generation is advantageous because it enables the flashing frequency to be adjusted via a potentiometer, for example. There are therefore superimposed signals in the measuring line DC voltages with different frequencies, which are permanently assigned to the respective solar module.If a more economical variant is required, a series optocoupler can also be used instead of the separate optocoupler components.Here there are function-related reductions in the overvoltage resistance, i.e. the safety of the voltage - Separation of both circuits Instead of the optocoupler, a transformer with the corresponding control electronics could also transmit the signals.

A second possible embodiment of the invention is the controllability of the solar module. The electronic circuit of the solar module is addressed via a clocked DC voltage via the separate control socket (20). The response frequency of each individual solar module is set individually to the same. The signal is converted via the electronics on the secondary circuit board (8) and can, for example, control the relay (23).

The relay (23) can be designed conventionally with contacts or as a solid-state variant. The relay (23) can interrupt or short-circuit the circuit of the solar module on the primary circuit board (6) or switch to ground. According to the invention, the functions can also be combined as desired. The control signal is wired back in series with cables centrally via control electronics with e.g. SAT plugs and other dimensions (Poka-Joka safe compared to the live socket (19)).

In a third embodiment of the invention, the inverse function of the optocoupler is used. Here the control signal (modulated DC signal) is converted via onboard electronics of the primary circuit board (6) and used for control functions, e.g. via a relay (23). The relay (23) is a special relay that has the "opposite" terminals. This results in a particularly high flashover resistance and galvanic isolation of both circuits. The electronics are powered by the solar module. In this case, it is not possible to short-circuit the solar voltage, because otherwise the power supply to the primary circuit board (6) would be interrupted. It is fed in via a control cable with series connection. Only one cable is required to control all solar modules.

For a cost-effective variant in which the string voltages are lower, all components can also be installed on a common circuit board.

Another advantage of the invention is the possible control of the laser (5). In the area of the laser (5), the solar cell plate is structurally recessed/interrupted and translucent. If this is controlled via the electronics, you can quickly find out which solar module has a fault. The laser (5) is also clearly visible in daylight. This function can also take place directly: if the laser (5) is connected directly to the thermal fuse (40) via a series resistor (35). The thermal fuse (40) is connected in series with the solar module. If the thermal fuse (40) melts, the full operating voltage of the solar module or of the entire string connected is applied to the laser (5) with the appropriate wiring. The voltage of the laser is limited via a varistor (34) and/or a Zener diode (36) in order to prevent an overvoltage that is harmful to the laser component (5). If the solar system is "externally powered" (e.g. to melt snow), the laser and the conspicuous solar module can also be located in the dark.

The advantageous embodiments of the invention are listed in claims 1-10.

• 1 ISO Schnitt Gehäuse Mitte
• 2 ISO,
• 3 ISO, Schnitt Gehäuse versetzt
• 4 ISO, Schnitt längs
• 5, ISO, Primär-Platine
• 6, ISO, Sekundär-Platine
• 7, ISO, Schirmblech
• 8, ISO, ohne Gehäuse
• 9, Schnitt, Thermosicherung

The embodiment of the invention is based on 1 until 9 shown.

• 1 ISO cut housing middle
• 2 ISO,
• 3 ISO, cross section offset housing
• 4 ISO, longitudinal section
• 5 , ISO, primary board
• 6 , ISO, secondary board
• 7 , ISO, shroud
• 8th , ISO, without housing
• 9 , cut, thermal fuse

Reference List

(1)

solar panel

(2)

protective glass

(3)

Housing

(4)

photocell

(5)

Laser

(6)

primary board

(7)

Frame

(8th)

secondary board

(9)

spacers

(10)

cooling element

(11)

shield plate

(12)

Lid

(13)

cable contact

(14)

IC

(15)

LEDs

(16)

PV+ cable

(17)

PV cable

(18)

ground strap

(19)

live jack

(20)

control socket

(21)

backup recording

(22)

cable grommet

(23)

relay

(24)

pin contact

(25)

Plug

(26)

socket sleeve

(27)

thermal fuse

(28)

compression sleeve

(29)

cable clamp

(30)

socket

(31)

Contact

(32)

sealing element

(33)

bimetallic element

(34)

varistor

(35)

resistance

(36)

zener diode

(37)

bimetallic switch

(38)

capacitor

(39)

power storage

(40)

thermal fuse

(41)

Mother

(42)

screw

Claims (10)

Characterized in that the execution of a thermal fuse (27) are connected in series with the PV solar modules. The thermal fuses (27) can be accommodated separately as individual components in a fuse holder (21), for example. This usually consists of a non-conductive material such as plastic or elastomers or a composite of materials. Alternatively, the thermal switch (27) can also be mounted in the electronics in the housing (3) on the primary circuit board (6). Another possibility is to intrigue the thermal fuses (27) directly to a PV solar module cable (PV+ cable, (16) and/or PC cable (17). Characterized in that instead of the thermal fuses (27) alternatively bimetallic switches (37) are used. The bimetallic switches have the advantageous function of resetting. The solar module switches on again when the temperature falls below a preselected value. If the bimetallic switch (37) is connected in parallel to the solar module, it short-circuits its voltage in the event of impermissible heating. In this way, the solar modules that are exposed to too high a temperature are switched off. The more solar modules are affected, the lower the string voltage. Alternatively, the solar module can also be switched off via the thermal fuse (27) and additionally short-circuited via the bimetallic switch (37). Characterized in that the solar cell plate (1) in the area of the laser (5) has a recess or light-permeable layer. In this way, the light from the laser (5) can exit unhindered and be used there as an indicator for a function (e.g. failure, short to ground, etc.). To ensure that the laser does not pose a hazard, its power is limited to 50 mW, for example. Different colors of the laser (5) can also be used for different strings for better identification. Alternatively, another light source can be used instead of the laser (5), for example an LED. Characterized in that a measurement signal by means of an optocoupler is built up from the components LED (15) and an opposite galvanically isolated photocell (4). The advantage here is the very high flashover resistance against the high PV operating voltages (900V DC). The components are designed in such a way that they are each connected to a separate circuit board (primary (16) & secondary circuit board (8). The LED (15) or alternatively a laser are equipped with an independent flashing circuit. The frequencies are graded around these respectively to assign a solar module, eg 2 Hz, 4 HZ, 6 Hz, etc. A version using a standard optocoupler on a central circuit board is also possible, but the isolating voltage / galvanic isolation is then not optimal. Alternatively, the frequency can also be generated via an electronic circuit, IC, (14). The external energy required can be provided via a transformer with galvanic winding separation via appropriate control electronics, IC (14) on the primary circuit board (which is tapped from the solar module). Characterized in that a separating plate separates both circuit boards, primary (6) & secondary (8) by a shielding plate (11). The design provides additional protection against possible voltage flashovers. The shielding plate (11) is connected to the frame (7) via a conductive ground strap (18). Characterized in that the individual solar modules are all connected in series via a cable using the live socket (19). The live socket (19) is designed by means of a sealing element (32) in such a way that it is screwed tightly against environmental influences into the fully assembled housing (3) with the socket (30) opposite it. Characterized in that a relay (23) can interrupt or short-circuit the voltage in the string of the PV solar module in a controlled manner. The relay (23) is controlled via the electronics, IC, (14). The connection with opposing contacts is advantageous here. Characterized in that a further control socket (20) is equipped with different dimensions or, for example, a left-hand thread. This prevents a risk of confusion when connecting the wiring. The control socket (20) is advantageously designed as a reliable and cost-effective SAT socket design. Characterized in that the secondary circuit board (connection cable of the solar module, PV + (16), PV cable (17) is designed as a pluggable variant with sealing element (32) and cable clamp (29) and cable contact (13). So it is easily possible to assemble the cable lengths or versions depending on the requirement. Characterized in that the live sockets (19) & the control sockets (20) are advantageously connected to the ground strap (18) via the secondary circuit board (8). Since the cables are designed as coax cables, for example, and are therefore grounded, they have a high level of security against dangerous voltages in the PV solar modules and are also immune to interference.

Images