7. Multiphase regulation
In a system with more than one phase, the way power is balanced across the phases affects both the capacity available to the loads and what the utility meter records. This chapter explains the two regulation options, then works through the two arrangements in which the difference matters: a single-phase system on a three-phase grid connection, and a three-phase system.
7.1. Introduction
Use the multiphase regulation setting in systems with a three-phase connection to the utility grid. The setting defines how the system interacts with the individual phases.
By default, Total of all phases is selected. All phases are adjusted to convert the same power to and from DC, dividing the work equally across the phases. This makes the full system capacity available and is optimal for billing.
Note
The setting has no effect on single-phase systems and can be ignored. It also has no effect when Mode is set to Keep batteries charged.
The two options behave differently depending on whether the system itself is single-phase or three-phase:
In a single-phase system connected to a three-phase grid, Total of all phases regulates the combined power of L1, L2 and L3 to zero, while Individual phase regulates only the power of L1 to zero. See Single-phase system with a three-phase grid connection.
In a three-phase system, Total of all phases loads the inverters symmetrically and keeps the combined power of all phases to zero, while Individual phase regulates each phase to zero independently. See Three-phase system.
7.2. Single-phase system with a three-phase grid connection
A single-phase system uses a single inverter/charger. In an installation with a three-phase connection to the utility grid, the two multiphase regulation options behave as follows:
Total of all phases : the system uses the battery to balance the combined power of all phases to 0 W.
Individual phase : the system uses the battery to balance only L1 to 0 W. L2 and L3 are visible on the GX device, but are not used in any way.
In the following example the inverter/charger is connected to L1. By compensating for phases L2 and L3 as well, it regulates the total power at the distribution panel to 0 W.
L1 | L2 | L3 | Total | |
|---|---|---|---|---|
Load | 100 W | 400 W | 200 W | 700 W |
System | -700 W | 0 W | 0 W | -700 W |
Distribution box | -600 W | 400 W | 200 W | 0 W |
Note
Install the inverter/charger on L1. If it is installed on another phase, the visualisation will be wrong and the function impaired.
7.3. Three-phase system
A three-phase system has at least one inverter/charger installed on each phase. Leave the multiphase regulation setting at its default, Total of all phases.
Total of all phases (default and recommended)
The system balances the total power of all phases (L1 + L2 + L3) to a net 0 W at the meter, loading the inverters symmetrically.
In the example below the loads on L1 are 6000 W, exceeding the capacity of the inverter on that phase, while L2 and L3 have no load. Taking the sum of all three phases, the system provides surplus from L2 and L3 to displace the load on L1. This is optimal for billing efficiency.
Load | System | On the meter | |
|---|---|---|---|
L1 | 6000 W | 2000 W | 4000 W |
L2 | 0 W | 2000 W | -2000 W |
L3 | 0 W | 2000 W | -2000 W |
Sum | 6000 W | 6000 W | 0 W |
Similarly, in a situation with both PV and load: if there is 6 kW of excess PV on L1 with the same inverter/charger configuration, all inverter/chargers charge at approximately equal power.
PV + Load | System | On the meter | |
|---|---|---|---|
L1 | -6000 W | 1800 W | -4200 W |
L2 | 600 W | 1800 W | 2400 W |
L3 | 0 W | 1800 W | 1800 W |
Sum | -5400 W | 5400 W | 0 W |
Excess PV power from solar chargers is not actively made symmetrical across the phases.
PV + Load | System | On the meter | |
|---|---|---|---|
L1 | -6000 W | 0 W | -6000 W |
L2 | 0 W | 0 W | 0 W |
L3 | 0 W | 0 W | 0 W |
Sum | -6000 W | 0 W | -6000 W |
Individual phase
The system balances the power of each separate phase to 0 W. Using the system this way causes significant losses, as power flows from one AC phase to another through the DC connection. This incurs the losses of converting from AC to DC on one phase and back from DC to AC on the other.
Maximum charge current
In a multiphase system, the charge current is configured per phase, rather than for the whole system. A limitation of this arrangement arises, for example, where a relatively small battery bank is installed and a significant over-supply of AC-coupled PV power is available on L1 but not on the other phases: only part of that excess PV power on L1 is then used to charge the battery.