METHOD AND APPARATUS TO ENABLE SAFE SERVICING OF PV MODULES
An apparatus and method for reducing the voltage in a photovoltaic system to allow servicing of solar modules. The apparatus includes a switch that electrically shorts conductors of the system, thereby reducing high voltage conditions at the modules. The apparatus and method can also include use of a detector that measures voltage and/or current in the system to control switch operations.
1 . A photovoltaic system comprising:
at least one solar module electrically connected to a pair of conductors; and
a switch electrically connected across the conductors, the switch in a closed position electrically shorting the conductors, and the switch in an open position electrically isolating the conductors.
2 . The photovoltaic system of claim 1 , further comprising an inverter, wherein the switch is located between the at least one solar module and the inverter.
3 . The photovoltaic system of claim 1 , further comprising a detector for measuring at least one of a voltage across the conductors or a current carried by the conductors.
4 . The photovoltaic system of claim 3 , wherein the detector measures the voltage across the conductors, wherein when the switch is in the open position, the switch is prevented from closing if the measured voltage exceeds a voltage threshold value.
5 . The photovoltaic system of claim 3 , wherein the detector measures the current carried by the conductors, wherein when the switch is in the open position, the switch is prevented from closing if the measured current exceeds a current threshold value.
6 . The photovoltaic system of claim 3 , wherein the detector measures the voltage across the conductors, wherein when the switch is in the closed position, the switch is prevented from opening if the measured voltage exceeds a voltage threshold value.
7 . The photovoltaic system of claim 3 , wherein the detector measures the current carried by the conductors, wherein when the switch is in the closed position, the switch is prevented from opening if the measured current exceeds a current threshold value.
8 . The photovoltaic system of claim 3 , further comprising a switch controller for controlling operation of the switch.
9 . The photovoltaic system of claim 8 , wherein the switch controller receives at least one of a voltage or current measurement from the detector.
10 . The photovoltaic system of claim 9 , wherein the switch controller prevents the switch from opening or closing based on the at least one of voltage or current measurement from the detector.
11 . The photovoltaic system of claim 9 , wherein the switch controller alerts a user if the at least one of voltage and/or current rises above thresholds after the switch is closed.
12 . The photovoltaic system of claim 11 , wherein the user is alerted over a network.
13 . The photovoltaic system of claim 8 , wherein the switch controller locks the switch upon receipt of a password from a user.
14 . The photovoltaic system of claim 13 , wherein the switch controller unlocks the switch upon receipt of the password from the user.
15 . The photovoltaic system of claim 8 , further comprising a user operated device for communicating with the switch controller.
16 . The photovoltaic system of claim 8 , wherein the switch controller communicates with the switch over a network.
17 . The photovoltaic system of claim 9 , wherein the switch controller communicates with a user over a network.
18 . The photovoltaic system of claim 17 , wherein the network is wireless.
19 . The photovoltaic system of claim 8 , wherein the switch controller alerts a user that the switch has been closed.
20 . The photovoltaic system of claim 1 , further comprising an array of solar modules connected to the positive and negative conductors.
21 . The photovoltaic system of claim 20 , wherein said array of solar modules further comprises a plurality of groups of solar modules.
22 . The photovoltaic system of claim 21 , further comprising a plurality of switches, each switch in the plurality of switches electrically connected across one group of solar modules in the plurality of groups of solar modules.
23 . The photovoltaic system of claim 22 , further comprising a plurality of detectors, each detector for measuring at least one of a voltage across one group of solar modules in the plurality of groups of solar modules.
24 . The photovoltaic system of claim 22 , further comprising a switch controller for controlling the plurality of switches.
25 . The photovoltaic system of claim 21 , wherein the plurality of groups of solar modules are connected in series.
26 . The photovoltaic system of claim 21 , wherein the plurality of groups of solar modules are connected in parallel.
27 . The photovoltaic system of claim 21 , wherein the plurality of groups of solar modules are connected in a combination of series and parallel connections.
28 . The photovoltaic system of claim 22 , further comprising a plurality of in-line switches, each in-line switch in the plurality of in-line switches being electrically connected in series between one group of solar modules in the plurality of groups of solar modules and an inverter.
29 . The photovoltaic system of claim 28 , further comprising a controller for commanding each in-line switch of the plurality of in-line switches to open or close.
30 . The photovoltaic system of claim 2 , wherein the switch further comprises a manually operable switch arm that can toggle the switch between the open and closed position.
31 . The photovoltaic system of claim 30 , wherein the switch arm further comprises a locking mechanism for preventing the switch from toggling between the open and closed position.
32 . The photovoltaic system of claim 31 , wherein said locking mechanism locks and unlocks the switch arm in response to a user entering a password.
33 . A photovoltaic system comprising:
an inverter;
an array of solar modules;
an plurality of positive and negative conductor pairs, where each positive and negative conductor pair is connected to at least one solar module within the array of solar modules;
a first conductor connected to and between the positive conductors and the inverter;
a second conductor connected to and between the negative conductors and the inverter;
at least one switch electrically connected across one pair of the first and second conductors, the at least one switch in a closed position electrically shorting the first and second conductors, and the at least one switch in an open position electrically isolating first and second conductors.
34 . The photovoltaic system of claim 33 , further comprising a plurality of switches, where each switch in the plurality of switches is electrically connected across one positive and negative wire pair.
35 . The photovoltaic system of claim 33 , wherein each conductor pair is connected to a plurality of solar modules.
36 . The photovoltaic system of claim 33 , further comprising a detector for measuring at least one of a voltage across or current carried by the conductor pair coupled to the at least one switch.
37 . The photovoltaic system of claim 34 , further comprising a plurality of detectors, each detector of the plurality of detectors for measuring at least one of a voltage across or current carried by each conductor pair coupled to one of the plurality of switches.
38 . The photovoltaic system of claim 33 , further comprising a controller for commanding the at least one switch to open or close.
39 . The photovoltaic system of claim 34 , further comprising a controller for commanding each switch of the plurality of switches to open or close.
40 . The photovoltaic system of claim 34 , further comprising a plurality of in-line switches, each in-line switch in the plurality of in-line switches electrically connected in series between one group of solar modules in the plurality of groups of solar modules and the inverter.
41 . The photovoltaic system of claim 40 , further comprising a controller for commanding each in-line switch of the plurality of in-line switches to open or close.
42 . A method for reducing high voltage levels in a photovoltaic system comprising:
closing a switch to electrically short conductors to reduce a voltage across the conductors, the conductors being electrically connected to solar modules.
43 . The method of claim 42 , further comprising measuring at least one of a voltage across the conductors or a current carried by the conductors when the switch is open.
44 . The method of claim 43 , wherein the switch is closed only after the measured voltage and/or current is below set thresholds.
45 . The method of claim 42 , further comprising indicating to a user that the voltage level has been reduced.
46 . The method of claim 45 , wherein the indication is sent over a wireless-network to the user.
47 . The method of claim 42 , further comprising locking the switch in its current position.
48 . The method of claim 47 , wherein the switch is locked after receiving a password from a user.
49 . The method of claim 47 , further comprising unlocking the switch.
50 . The method of claim 49 , wherein the switch is unlocked after receiving a password from a user.
51 . The method of claim 42 , wherein the switch is closed with a switch controller.
52 . The method of claim 42 , wherein the switch is closed manually.
53 . The method of claim 42 , further comprising measuring at least one of a voltage across the conductors or a current carried by the conductors while the switch is closed.
54 . The method of claim 52 , further comprising sending an indication to a user if the measured voltage and/or current exceeds set thresholds.
55 . The method of claim 54 , wherein the indication is sent over a wireless-network to the user.
56 . The method of claim 42 , further comprising opening the switch after the switch has been closed to restore the voltage across the conductors.
57 . The method of claim 56 , further comprising measuring at least one of a voltage across the conductor or a current carried by the conductors when the switch is closed.
58 . The method of claim 57 , wherein the switch is opened only after the measured voltage and/or current is below set thresholds.