Power balancing in a multi-phase system

1. A multi-phase power system comprising:

a plurality of photovoltaic modules;

a plurality of micro-inverters organized into a plurality of sets of micro-inverters, each set of micro-inverters operable to convert DC power from at least one of the photovoltaic modules into AC power to be injected into one of three-phases of a three-phase AC power grid; and

a wireless gateway;

wherein each of the plurality of micro-inverters wirelessly transmits a signal to the wireless gateway indicative of that micro-inverter's current power output, and the wireless gateway calculates an aggregate power output of each set of micro-inverters based on the signal and balances an output voltage supplied by each of the plurality of sets of micro-inverters to each of the three phases of the AC power grid by sending a command to at least one micro-inverter to control an output voltage of that micro-inverter; and

wherein each of the plurality of micro-inverters transmits the signal at a predetermined point of an AC cycle of the power line that the micro-inverter is coupled to and the wireless gateway uses the signal and a timing of when the signal is transmitted to determine a phase of that power line.

2. The multi-phase power system of claim 1 , wherein the signal includes an identification message comprising properties of a voltage on a power line of the three-phase AC power grid that the micro-inverter is coupled to.

3. The multi-phase power system of claim 1 , wherein the wireless gateway is operable to balance the AC power to be injected into the AC power grid by of each of the plurality of sets of micro-inverters by controlling an output of each set of micro-inverters within a threshold value of an output of the other sets of micro-inverters.

4. The multi-phase power system of claim 1 , wherein the wireless gateway sends control signals to each of the plurality of micro-inverters such that voltages of the AC power to be injected into each of the three-phases are balanced.

5. The multi-phase power system of claim 4 , wherein the wireless gateway balances voltages of the AC power to be injected into each of the three-phases by computing an average peak voltage of each of the plurality of sets of micro-inverters.

6. The multi-phase power system of claim 4 , wherein the control signals comprise instructions to prevent a micro-inverter from injecting power into the three-phase AC power grid.

7. The multi-phase power system of claim 1 , wherein each of the plurality of micro-inverters comprises a wireless transmitter for transmitting information and a wireless receiver for receiving control signals.

8. A multi-phase power system comprising:

a first set of micro-inverters for injecting AC power into a first power line of a multi-phase AC grid mains;

a second set of micro-inverters for injecting AC power into a second power line of a multi-phase AC grid mains;

a third set of micro-inverters for injecting AC power into a third power line of a multi-phase AC grid mains; and

a wireless gateway for (i) receiving a set of information comprising an individual power output from each micro-inverter of the first, the second and the third sets of micro-inverters, (ii) calculating an aggregate power output of each of the first, the second and the third sets of micro-inverters, and (iii) balancing the injected power into the first, the second and the third power lines of the multi-phase AC grid mains by controlling a power output of at least one micro-inverter of the first, the second and the third sets of micro-inverters;

wherein each inverter of the first, second and third sets of micro-inverters transmits the set of information at a predetermined point of an AC cycle of the power line that each respective micro-inverter is coupled to and the wireless gateway uses the transmitted set of information and a time of the transmission to determine a phase of the power line for each respective micro-inverter.

9. The multi-phase power system of claim 8 , wherein the identification message comprises properties of a voltage on the power line that micro-inverter is coupled to.

10. The multi-phase power system of claim 8 , wherein the wireless gateway is operable to balance the AC power injected into the AC grid mains by each micro-inverter of the first, the second and the third sets of micro-inverters by controlling an output of each of the first, the second and the third sets of micro-inverters within a threshold value.

11. The multi-phase power system of claim 8 , wherein the wireless gateway sends control signals to each micro-inverter of the first, the second and the third sets of micro-inverters such that voltages of the AC power injected into the first, the second and the third power lines are balanced.

12. The multi-phase power system of claim 8 , wherein each micro-inverter of the first, the second and the third sets of micro-inverters comprises a wireless transmitter for transmitting information and a wireless receiver for receiving control signals.

13. A method for balancing injected power into a multi-phase AC grid mains, the method comprising:

controlling the injection of AC power into a first power line of the multi-phase AC grid mains with a first set of micro-inverters;

controlling the injection of AC power into a second power line of the multi-phase AC grid mains with a second set of micro-inverters;

controlling the injection of AC power into a third power line of the multi-phase AC grid mains with a third set of micro-inverters;

receiving, by a wireless gateway, a set of information comprising an individual power output from each micro-inverter of the first, the second and the third sets of micro-inverters;

identifying, by the wireless gateway, a power line that each micro-inverter of the first, second and third sets of micro-inverters is coupled to by receiving the set of information at a predetermined point of an AC cycle of the power line that each micro-inverter is coupled to;

calculating, by the wireless gateway, an aggregate power output of each of the first, the second and the third sets of micro-inverters; and

balancing the injected power into the first, the second and the third power lines by controlling a power output of at least one micro-inverter of the first, the second and the third sets of micro-inverters.

14. The method of claim 13 , wherein controlling the power output of the at least one micro-inverter comprises setting a threshold output level for the at least one micro-inverter that is different from a threshold output level of a micro-inverter in a different set of micro-inverters coupled to a different power line.