Microinverters for use with renewable energy systems

Abstract

An apparatus configured for use with an energy management system is provided and comprises a three-phase system connection comprising three power production wires and a neutral wire, the three-phase system connection configured to transpose the three power production wires so that multiple single-phase microinverters are equally distributed over the three-phase system connection and a power line communication (PLC) filter connected to the three-phase system connection and PLC signal wires which are transposed via the three-phase system connection and connected to the multiple single-phase microinverters, the PLC filter is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation.

Description

PATENT APPLICATIONAttorney Docket No. EE395WOMICROINVERTERS FOR USE WITH RENEWABLE ENERGY SYSTEMSBACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to microinverters, and for example, to single-phase microinverters configured for use with a three-phase microinverter cabling configuration.Description of the Related Art

[0002] Microinverters configured for use with energy management systems are known. For example, some microinverters are configured for single / split-phase operation, and some microinverters are configured for three-phase operation. In some instances, it may prove advantageous to connect multiple single-phase microinverters to a three-phase system connection. In a three-phase system connection, there are two variants that can be used. For example, a wye connected microinverter can be used for outputting power between line and neutral for use in 400 / 230 Vac (rest of world (RoW)) and 480 / 277 Vac (USA), e.g., three phase applications. Similarly, a delta connected microinverter can be used for outputting power line to line for use in 208 / 120 Vac (USA), e.g., three phase applications. While the delta connected microinverter is relatively easy to deploy, the same cannot be said of the wye connected microinverter.

[0003] For example, wye connected microinverter production makes use of two connectors (N and L1 , which are, typically, the top two connectors), and the bottom two connectors (L2 and L3) can be used for power line communication (PLC) use. While such connector configurations are suitable for wye connected microinverters, the connector configuration can result in each single-phase microinverter only being able to measure a corresponding single-phase output voltage, i.e., each single-phase microinverter is not able to directly measure the other phase voltages. Conventional methods used to overcome such shortcomings transmitted measured RMS average voltage for the other phase voltages to each single-phase microinverter using the PLC. Although transmitting the RMS average voltage via PLC does provide some of the information required by each single-phase microinverter, there is not enough information in the RMS average voltage to properly control the single-phase microinverter (e.g., for three-phase applications). As a result of the missing1733371 v1 1PATENTAttorney Docket No.: EE395P information, each single-phase microinverter is not sequence aware, which is a fundamental requirement stipulated by grid interconnection standards for three-phase systems.

[0004] Therefore, the inventor provides herein improved single-phase microinverters configured for use with a three-phase microinverter cabling configuration.SUMMARY

[0005] In accordance with at least some embodiments of the present disclosure, there is provided an apparatus configured for use with an energy management system. The apparatus can comprise a three-phase system connection comprising three power production wires and a neutral wire. The three-phase system connection can be configured to transpose the three power production wires so that multiple single-phase microinverters are equally distributed over the three-phase system connection. A power line communication (PLC) filter can be connected to the three- phase system connection and PLC signal wires which are transposed via the three- phase system connection and connected to the multiple single-phase microinverters. The PLC filter is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation.

[0006] In accordance with at least some embodiments of the present disclosure, there is provided an energy management system comprising a distributed energy resource comprising a renewable energy source coupled to a first microinverter and an AC battery. A three-phase system connection can comprise three power production wires and a neutral wire. The three-phase system connection can be configured to transpose the three power production wires so that multiple single-phase microinverters of the AC battery are equally distributed over the three-phase system connection. A power line communication (PLC) filter can be connected to the three- phase system connection and PLC signal wires which are transposed via the three- phase system connection and connected to the multiple single-phase microinverters. The PLC filter is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation.1733371 v1 2PATENTAttorney Docket No.: EE395PBRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0008] Figure 1 is a block diagram of a system, in accordance with one or more embodiments of the present disclosure;

[0009] Figure 2 is a schematic diagram of a power conversion system comprising a converter (e.g., a switched mode power converter), in accordance with embodiments of the present disclosure;

[0010] Figure 3 is a diagram of a three-phase system connection comprising a PLC filter for connecting to three single-phase microinverters, in accordance with one or more embodiments of the present disclosure; and

[0011] Figure 4 is a diagram of a three-phase system connection comprising a PLC filter for connecting to three delta connection single-phase microinverters (LHS) and three wye connection single-phase microinverters (RHS), in accordance with one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0012] As noted above, embodiments of the present disclosure relate to improved to single-phase microinverters configured for use with a three-phase microinverter cabling configuration. For example, in at least some embodiments, an apparatus can be configured for use with an energy management system. The apparatus can comprise a three-phase system connection comprising three power production wires and a neutral wire. The three-phase system connection can be configured to transpose the three power production wires so that multiple single-phase microinverters are equally distributed over the three-phase system connection. A power line communication (PLC) filter can be connected to the three-phase system connection and PLC signal wires which are transposed via the three-phase system connection and connected to the multiple single-phase microinverters. The PLC filter1733371 v1 3PATENTAttorney Docket No.: EE395P is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation. The apparatus described herein allows multiple single-phase microinverters to be connected to three-phase system connections (e.g., commercial and residential). Additionally, the apparatus described herein can be used in either delta connected microinverters (e.g., 400 / 230 Vac (RoW) and 480 / 277 Vac (USA), e.g., three phase applications) or a wye connected microinverters (e.g., 208 / 120 Vac (USA), e.g., three phase applications).

[0013] Figure 1 is a block diagram of a system 100 (e.g., energy management system -renewable energy system) in accordance with one or more embodiments of the present disclosure. The diagram of Figure 1 only portrays one variation of the myriad of possible system configurations. The present disclosure can function in a variety of environments and systems.

[0014] The system 100 comprises a structure 102 (e.g., a user’s structure), such as a residential home or commercial building, having an associated DER 118 (distributed energy resource). The DER 118 is situated external to the structure 102. For example, the DER 118 may be located on the roof of the structure 102 or can be part of a solar farm. The structure 102 comprises one or more loads and / or energy storage devices 114 (e.g., appliances, electric hot water heaters, thermostats / detectors, electric vehicles (EV), electric vehicle system equipment (EVSE), portable energy systems (PES), boilers, water pumps, and the like), which can be located within or outside the structure 102, and a DER controller 116, each coupled to a load center 1 12. Although the energy storage devices 114, the DER controller 116, and the load center 112 are depicted as being located within the structure 102, one or more of these may be located external to the structure 102.

[0015] The load center 112 is coupled to the DER 118 by an AC bus 104 and is further coupled, via a meter 152 and a MID 150 (microgrid interconnect device), to a grid 124 (e.g., a commercial / utility power grid). The structure 102, the energy storage devices 1 14, DER controller 116, DER 118, load center 112, generation meter 154, meter 152, and MID 150 are part of a microgrid 180. It should be noted that one or more additional devices not shown in Figure 1 may be part of the microgrid 180. For example, a power meter or similar device may be coupled to the load center 112.1733371 v1 4PATENTAttorney Docket No.: EE395P

[0016] The DER 1 18 comprises at least one renewable energy source (RES) coupled to power conditioners 122 (e.g., power converter such as an AC battery microinverter). For example, the DER 118 may comprise a plurality of RESs 120 coupled to a plurality of power conditioners 122 in a one-to-one correspondence (or two-to-one). In embodiments described herein, each RES of the plurality of RESs 120 is a photovoltaic module (PV module), although in other embodiments the plurality of RESs 120 may be any type of system for generating DC power from a renewable form of energy, such as wind, hydro, and the like. The DER 118 may further comprise one or more batteries (or other types of energy storage / delivery devices) coupled to the power conditioners 122 in a one-to-one correspondence, where each pair of power conditioner 122 and a corresponding battery may be referred to as an AC battery 130.

[0017] The power conditioners 122 invert the generated DC power from the plurality of RESs 120 and / or the battery 141 to AC power that is grid-compliant and couple the generated AC power to the grid 124 via the load center 1 12. The generated AC power may be additionally or alternatively coupled via the load center 112 to the one or more loads and / or the energy storage devices 114. In addition, the power conditioners 122 that are coupled to the batteries 141 convert AC power from the AC bus 104 to DC powerfor charging the batteries 141 . A generation meter 154 is coupled at the output of the power conditioners 122 that are coupled to the plurality of RESs 120 in order to measure generated power.

[0018] In some alternative embodiments, the power conditioners 122 may be AC- AC converters that receive AC input and convert one type of AC power to another type of AC power. In other alternative embodiments, the power conditioners 122 may be DC-DC converters that convert one type of DC power to another type of DC power. In some of embodiments, the DC-DC converters may be coupled to a main DC-AC inverter for inverting the generated DC output to an AC output.

[0019] The power conditioners 122 may communicate with one another and with the DER controller 1 16 using power line communication (PLC), although additionally and / or alternatively other types of wired and / or wireless communication may be used. The DER controller 116 may provide operative control of the DER 118 and / or receive data or information from the DER 118. For example, the DER controller 116 may be a gateway that receives data (e.g., alarms, messages, operating data, performance data, and the like) from the power conditioners 122 and communicates the data and / or1733371 v1 5PATENTAttorney Docket No.: EE395P other information via the communications network 126 to a cloud-based computing platform 128, which can be configured to execute one or more application software, e.g., a grid connectivity control application, to a remote device or system such as a master controller (not shown), and the like. The DER controller 1 16 may also send control signals to the power conditioners 122, such as control signals generated by the DER controller 116 or received from a remote device or the cloud-based computing platform 128. The DER controller 1 16 may be communicably coupled to the communications network 126 via wired and / or wireless techniques. For example, the DER controller 116 may be wirelessly coupled to the communications network 126 via a commercially available router. In one or more embodiments, the DER controller 116 comprises an application-specific integrated circuit (ASIC) or microprocessor along with suitable software (e.g., a grid connectivity control application) for performing one or more of the functions described herein. For example, the DER controller 116 can include a memory (e.g., a non-transitory computer readable storage medium) having stored thereon instructions that when executed by a processor perform a method for grid connectivity control, as described in greater detail below.

[0020] The generation meter 154 (which may also be referred to as a production meter) may be any suitable energy meter that measures the energy generated by the DER 118 (e.g., by the power conditioners 122 coupled to the plurality of RESs 120). The generation meter 154 measures real power flow (kWh) and, in some embodiments, reactive power flow (kVAR). The generation meter 154 may communicate the measured values to the DER controller 116, for example using PLC, other types of wired communications, or wireless communication. Additionally, battery charge / discharge values are received through other networking protocols from the AC battery 130 itself.

[0021] The meter 152 may be any suitable energy meter that measures the energy consumed by the microgrid 180, such as a net-metering meter, a bi-directional meter that measures energy imported from the grid 124 and well as energy exported to the grid 124, a dual meter comprising two separate meters for measuring energy ingress and egress, and the like. In some embodiments, the meter 152 comprises the MID 150 or a portion thereof. The meter 152 measures one or more of real power flow (kWh), reactive power flow (kVAR), grid frequency, and grid voltage.1733371 v1 6PATENTAttorney Docket No.: EE395P

[0022] The MID 150, which may also be referred to as an island interconnect device (HD), connects / disconnects the microgrid 180 to / from the grid 124. The MID 150 comprises a disconnect component (e.g., a contactor or the like) for physically connecting / disconnecting the microgrid 180 to / from the grid 124. For example, the DER controller 116 receives information regarding the present state of the system from the power conditioners 122, and also receives the energy consumption values of the microgrid 180 from the meter 152 (for example via one or more of PLC, other types of wired communication, and wireless communication), and based on the received information (inputs), the DER controller 116 determines when to go on-grid or off-grid and instructs the MID 150 accordingly. In some alternative embodiments, the MID 150 comprises an ASIC or CPU, along with suitable software (e.g., an islanding module) for determining when to disconnect from / connect to the grid 124. For example, the MID 150 may monitor the grid 124 and detect a grid fluctuation, disturbance or outage and, as a result, disconnect the microgrid 180 from the grid 124. Once disconnected from the grid 124, the microgrid 180 can continue to generate power as an intentional island without imposing safety risks, for example on any line workers that may be working on the grid 124.

[0023] In some alternative embodiments, the MID 150 or a portion of the MID 150 is part of the DER controller 116. For example, the DER controller 116 may comprise a CPU and an islanding module for monitoring the grid 124, detecting grid failures and disturbances, determining when to disconnect from / connect to the grid 124, and driving a disconnect component accordingly, where the disconnect component may be part of the DER controller 116 or, alternatively, separate from the DER controller 116. In some embodiments, the MID 150 may communicate with the DER controller 116 (e.g., using wired techniques such as power line communications, or using wireless communication) for coordinating connection / disconnection to the grid 124.

[0024] A user 140 can use one or more computing devices, such as a mobile device 142 (e.g., a smart phone, tablet, or the like) communicably coupled by wireless means to the communications network 126. The mobile device 142 has a CPU, support circuits, and memory, and has one or more applications, such as an application 146 (e.g., a grid connectivity control application) installed thereon for controlling the connectivity with the grid 124 as described herein. The application 1461733371 v1 7PATENTAttorney Docket No.: EE395P may run on commercially available operating systems, such as IOS, ANDROID, and the like.

[0025] In order to control connectivity with the grid 124, the user 140 interacts with an icon displayed on the mobile device 142, for example a grid on-off toggle control or slide, which is referred to herein as a toggle button. The toggle button may be presented on one or more status screens pertaining to the microgrid 180, such as a live status screen (not shown), for various validations, checks and alerts. The first time the user 140 interacts with the toggle button, the user 140 is taken to a consent page, such as a grid connectivity consent page, under setting and will be allowed to interact with toggle button only after he / she gives consent.

[0026] Once consent is received, the scenarios below, listed in order of priority, will be handled differently. Based on the desired action as entered by the user 140, the corresponding instructions are communicated to the DER controller 116 via the communications network 126 using any suitable protocol, such as HTTP(S), MQTT(S), WebSockets, and the like. The DER controller 116, which may store the received instructions as needed, instructs the MID 150 to connect to or disconnect from the grid 124 as appropriate.

[0027] Figure 2 is a schematic diagram of a power conversion system 200 comprising a converter 202 (e.g., a switched mode power converter), in accordance with embodiments of the present disclosure.

[0028] The power conversion system 200 comprises the DC component 220 coupled to a DC side of the converter 202. The converter 202 comprises a capacitor 222 coupled across a DC component 220 and H-bridge 204 The output of the H-bridge 204 is coupled across a series combination of a capacitor Cr and an inductor Lr, which form a resonant tank, and the primary winding of transformer 208. In other embodiments, the resonant tank may be formed by a different configuration of the capacitor Cr and the inductor Lr (e.g., the capacitor Cr and the inductor L may be coupled in parallel). In some embodiments, Lr may represent a leakage inductance of the transformer 208 rather than a physical inductor.

[0029] A series combination of the secondary winding of the transformer 208 and the inductor L can be coupled across a bridge. For example, the secondary winding of the transformer 208 and the inductor L can be coupled across a cycloconverter 210 which produces a single-phase AC output (e.g., N and L1 , to the AC bus 104). For1733371 v1 8PATENTAttorney Docket No.: EE395P example, the cycloconverter 210 comprises two bi-directional switches Q-1 and Q-2, (collectively referred to as switches Q) respectively in a first leg and a second leg coupled in parallel to one another. In accordance with embodiments of the present disclosure, each of the switches Q-1 and Q-2 is a native four quadrant bi-directional switch comprising one ormore of the aforementioned semiconductor (or vacuum tube) devices. Alternatively or additionally, the cycloconverter 210 can comprise two monolithically formed switches (e.g., a Monolithic Bi-Directional Switch (MBDS)) - Gallium-Nitride (GaN) based on a HEMT structure, as described in greater detail below. In at least some embodiments, each of the switches Q-1 and Q-2 comprises a pair of Gallium-Nitride (GaN) High Electron Mobility Transistors. In at least some embodiments, each of the switches Q-1 and Q-2 comprises a first pair of Gallium- Nitride (GaN) High Electron Mobility Transistors and a second pair of Gallium-Nitride (GaN) High Electron Mobility Transistors connected in series.

[0030] The first cycloconverter leg comprises the 4Q switch Q-1 coupled to the capacitor C1 , and the second cycloconverter leg comprises the 4Q switch Q-2 coupled to the capacitor C2. A first AC output phase line (N) is coupled between the switch Q-1 and the capacitor C1 , and a second AC output phase line (Li) is coupled between the switch Q-2 and the capacitor C2. The converter 202 may also include additional circuitry not shown, such as voltage and / or current monitors, for obtaining data for power conversion, data reporting, and the like.

[0031] The converter 202 additionally comprises a controller 206 coupled to the H- bridge switches (S-1 , S-2, S-3, and S-4), and the cycloconverter switches (Q-1 and Q-2) for operatively controlling the switches to generate the desired output power. In some embodiments, the converter 202 may function as a bi-directional converter.

[0032] The controller 206 comprises a CPU 284 coupled to each of support circuits283 and a memory 286. The CPU 284 may comprise one or more conventionally available microprocessors or microcontrollers. Additionally or alternatively, the CPU284 may include one or more application specific integrated circuits (ASICs). The support circuits 283 are well known circuits used to promote functionality of the CPU 284. Such circuits include, but are not limited to, a cache, power supplies, clock circuits, buses, input / output (I / O) circuits, and the like. The controller 206 may be implemented using a general purpose computer that, when executing particular1733371 v1 9PATENTAttorney Docket No.: EE395P software, becomes a specific purpose computer for performing various embodiments of the present disclosure.

[0033] The memory 286 is a non-transitory computer readable medium such as random access memory, read only memory, removable disk memory, flash memory, and various combinations of these types of memory. The memory 286 is sometimes referred to as main memory and may, in part, be used as cache memory or buffer memory. The memory 286 generally stores the OS 287 (operating system), if necessary, of the controller 206 that can be supported by the CPU capabilities. In some embodiments, the OS 287 may be one of a number of commercially available operating systems such as, but not limited to, LINUX, Real-Time Operating System (RTOS), and the like.

[0034] The memory 286 may store various forms of application software, such as a conversion control module 289 for controlling power conversion by the converter 202, for example maximum power point tracking (MPPT), switching, and the like. The memory 286 may further store a database 299 for storing various data. The controller 206 further processes inputs and outputs to external communications 294 (i.e., gateway, the DER controller 116) and a grid interface 288 (e.g., the meter 152 and the MID 150).

[0035] As noted above, it may prove advantageous to connect a single-phase microinverter to a three-phase system connection. For example, the system 100 can be configured for three-phase operation, while the power conversion system 200 can be configured for single-phase operation.

[0036] For example, Figure 3 is a diagram of a three-phase system connection comprising a PLC filter for connecting to three single-phase microinverters (e.g., three converters, multiple single-phase microinverters), in accordance with one or more embodiments of the present disclosure.

[0037] For example, a PLC filter 300 (a local PLC filter) can be configured to couple / decouple PLC signal wires 302 (e.g., a, b, and c, three signal wires that are configured to provide PLC signals to the multiple single-phase microinverters) that are disposed in a system connection cable 304 (e.g., operably connected to the AC bus 104) from the power production wires 305 (e.g., A, B, and C) also disposed in the system connection cable 304. For example, the PLC filter 300 can comprise one or more inductors and capacitors that are connected between the PLC signal wires 3021733371 v1 10PATENTAttorney Docket No.: EE395P and the power production wires 305. For example, in at least some embodiments, an inductor / capacitor (two capacitors) pair 306, inductor / capacitor pair 308, and an inductor / capacitor pair 310 can be coupled between the PLC signal wires 302 and the power production wires 305. The PLC signal is generated (e.g., common mode) between the PLC signal wires 302 and the system neutral conductor (N). In doing so, during operation, the PLC filter 300 prevents the power production wires 305 from shorting out the PLC signal wires 302 (e.g., PLC signals). In at least some embodiments, the PLC signal wires 302 can be biased to respective voltages of the power production wires 305, which allows the microinverter to measure the bias voltage and use the bias voltage to obtain the phase voltage, e.g., using a power control unit (PCU), the controller 206. That is, making each of the microinverters sequence aware.

[0038] The system connection cable 304 features a multiple 4-way connector that mates with a 4-way AC connector (not shown) on the AC output of the converter 202. In at least some embodiments, the system connection cable 304 is configured to transpose (rotate) between each microinverter of the multiple single-phase microinverters. For example, the power production wires 305 can be rotated between each microinverter. For example, the power production wires 305 in the system connection cable 304 can be transposed (rotated) between each of the AC outputs pin Li and L2, and the PLC signal wires 302 can be rotated between each microinverter (e.g., pin L3). Thus, the multiple single-phase microinverters are equally distributed over the system connection cable 304. Additionally, the power production neutral conductor (N) can be connected to the neutral of each microinverter. For example, the power production neutral conductor (N) can connect to the same pin (e.g., N) on each microinverter.

[0039] Figure 4 is a diagram 400 of a three-phase system connection comprising a PLC filter 300 for connecting to three delta connection single-phase microinverters (LHS) and three wye connection single-phase microinverters (RHS), in accordance with one or more embodiments of the present disclosure. For example, unlike Figure 3 where the PLC signal is generated between the PLC signal wires 302 (a, b, and c) and the power production neutral conductor (N), the PLC signal is generated over the power production neutral conductor (N) directly to the neutral pin (N) on the microinverter. Additionally, the system connection cable 304 is configured to1733371 v1 11PATENTAttorney Docket No.: EE395P transpose (rotate) between each microinverter of the multiple single-phase microinverters. For example, the power production wires 305 in the system connection cable 304 can be transposed (rotated) between each of the AC outputs pin Li, L2, and Ls, and the PLC signal wire (e.g., the power production neutral conductor (N)) can be rotated between each microinverter (e.g., the neutral pin (N)). Thus, the multiple single-phase microinverters are equally distributed over the system connection cable 304. In at least some embodiments, the PLC filter 300 (inductor) can be rated for full power output current. Additionally, each of the microinverters on the LHS and the RHS can be sequence aware._For example, the concept of sequence aware relates to being able to determine the three-phase voltage (phase) rotation direction at the AC grid connection to the microinverter. Accordingly, in at least some embodiments, each of the microinverters on the LHS and the RHS can directly monitor / measure each of the three phases. In at least some embodiments, it may prove advantageous to identify the three individual phases based on, for example, the use of one or more colors, e.g., three colors such as red, yellow, and blue. With normal (or positive rotation direction), the voltage phase rotates in a R, Y, B, R, Y, B, ... order., and with reversed (or negative rotation direction), the phase voltage rotates in a B, Y, R, B, Y, R, ... order. If a microinverter can only connect to two of the phases, then the microinverter cannot differentiate between positive and negative voltage phase rotation.

[0040] While the embodiments of the connector and cable configurations have been described in terms of use with AC battery microinverters, the present disclosure is not so limited. For example, in at least some embodiments, the connectors and cable configurations can also be configured for use with PV microinverters.

[0041] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.1733371 v1 12

Claims

PATENTAttorney Docket No.: EE395PClaims:

1. An apparatus configured for use with an energy management system, comprising: a three-phase system connection comprising three power production wires and a neutral wire, the three-phase system connection configured to transpose the three power production wires so that multiple single-phase microinverters are equally distributed over the three-phase system connection; and a power line communication (PLC) filter connected to the three-phase system connection and PLC signal wires which are transposed via the three-phase system connection and connected to the multiple single-phase microinverters, the PLC filter is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation.

2. The apparatus of claim 1 , wherein the PLC signal wires comprise three signal wires that are configured to provide PLC signals to the multiple single-phase microinverters.

3. The apparatus of claim 1 , wherein the PLC signal wires are biased to respective voltages of the three power production wires so that each of the multiple single-phase microinverters measures the respective voltages to obtain a phase voltage.

4. The apparatus of claim 1 , wherein the neutral wire is connected to a neutral of each of the multiple single-phase microinverters.

5. The apparatus of claim 1 , wherein the three-phase system connection is a delta connection to a 208 Vac.

6. The apparatus as in any of claims 1 to 5, wherein the three-phase system connection is a wye connection to a 230 / 400 Vac.1733371 v1 13PATENTAttorney Docket No.: EE395P7. An energy management system comprising: a distributed energy resource comprising a renewable energy source coupled to a first microinverter and an AC battery; a three-phase system connection comprising three power production wires and a neutral wire, the three-phase system connection configured to transpose the three power production wires so that multiple single-phase microinverters of the AC battery are equally distributed over the three-phase system connection; and a power line communication (PLC) filter connected to the three-phase system connection and PLC signal wires which are transposed via the three-phase system connection and connected to the multiple single-phase microinverters, the PLC filter is configured to couple / decouple the PLC signal wires to / from the three power production wires to prevent shorting of the PLC signal wires during operation.

8. The energy management system of claim 7, wherein the PLC signal wires comprise three signal wires that are configured to provide PLC signals to the multiple single-phase micro in verters.

9. The energy management system of claim 7, wherein the PLC signal wires are biased to respective voltages of the three power production wires so that each of the multiple single-phase microinverters measures the respective voltages to obtain a phase voltage.

10. The energy management system of claim 7, wherein the neutral wire is connected to a neutral of each of the multiple single-phase microinverters.

11. The energy management system of claim 7, wherein the three-phase system connection is a delta connection to a 208 Vac.

12. The energy management system as in any of claims 7 to 11 , wherein the three- phase system connection is a wye connection to a 230 / 400 Vac.1733371 v1 14

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