Device for reducing the open circuit voltage of a solar system
Devices for reducing the open circuit voltages of solar systems are described. In one embodiment, a solar system includes a string of a plurality of solar modules having an open circuit voltage. The solar system also includes a device for reducing the open circuit voltage of the string of the plurality of solar modules during an open circuit configuration.
1. A solar module system coupled to a system load, the solar module system comprising:
a string of a plurality of solar modules electrically coupled in series, wherein the string is configured to provide power to the system load, wherein the string has a string open circuit voltage when the string is not providing power to the system load and an operating voltage when the string is providing power to the system load; and
a module decoupling device including a controller, a voltage measurement device, and a system relay that is coupled across two or more solar modules of the string, wherein the controller is configured to control the system relay to change from a first configuration for electrically coupling the two or more solar modules to the string to a second configuration for electrically decoupling the two or more solar modules from the string, when the voltage measurement device measures a predetermined voltage at an arrangement of points within the system relay, such that the string has a reduced open circuit voltage below the string open circuit voltage.
2. The solar module system of claim 1 , wherein the reduced open circuit voltage is between the string open circuit voltage and the operating voltage.
3. The solar module system of claim 1 , wherein the reduced open circuit voltage is below the operating voltage.
4. The solar module system of claim 1 , further comprising a second module decoupling device coupled across at least one solar module of the string, wherein the controller is configured to control a system relay to selectively decouple the at least one solar module from the string.
5. The solar module system of claim 4 , wherein the predetermined voltage is the open circuit voltage of the string, and wherein the at least one solar module is selectively decoupled from the string when the string is not providing power to the system load.
6. The solar module system of claim 1 , wherein the module decoupling device is housed in a module detachable from the string of the plurality of solar modules.
7. The solar module system of claim 1 , wherein the two or more solar modules are electrically recoupled to the string when there is sufficient current to draw the string voltage below a voltage rating of the solar module system.
8. The solar of module system of claim 1 , wherein the system relay comprises a normally closed switch and a normally open switch.
9. The solar of module system of claim 7 , wherein during open circuit conditions the normally open switch is open and the normally closed switch is closed.
10. The solar of module system of claim 1 , wherein the module decoupling device is an in-line unit in the string.
11. The solar of module system of claim 1 , wherein at least a portion of the system relay is included in an external cable coupled with the string.
12. The solar of module system of claim 1 , further comprising an inverter coupled to the string.