Setting the Grid-tied ESS Mode
The grid-tied ESS has three main working modes: self-consumption, TOU (time-of-use), and excess fed to the grid.
Self-Consumption
- This mode applies to areas where the electricity price is high, or areas where the FIT subsidy is low or unavailable.
- Excess PV energy is stored in batteries. When PV power is insufficient or no PV power is generated at night, batteries discharge to supply power to the loads, improving the self-consumption rate of the PV system and the self-sufficiency rate of residential energy, and reducing electricity costs.
- In this mode, Maximum self-consumption is selected. By default, the charge cutoff capacity is 100% and the discharge cutoff capacity is 0% for Huawei LUNA2000 batteries. For details about how to change the charge or discharge cutoff capacity, see Battery Commissioning.
Parameter |
Description |
Value Range |
|---|---|---|
Working mode |
Set this parameter to the maximum self-consumption mode. |
|
Maximum charge power (kW) |
Retain this parameter to the maximum charge power. Additional configuration is not required.If only one battery expansion module is configured, the maximum charge power is 2.5 kW. |
[0, Maximum charge power] |
Maximum discharge power (kW) |
Retain this parameter to the maximum discharge power. Additional configuration is not required.If only one battery expansion module is configured, the maximum charge power is 2.5 kW. |
[0, Maximum discharge power] |
End-of-charge SOC (%) |
Set the charge cutoff capacity. |
90%–100% |
End-of-discharge SOC (%) |
Set the discharge cutoff capacity. |
0%–20% |
If no PV modules are installed or the system has not detected sunlight for at least 24 hours, the minimum end of discharge SOC is 15%.
Example of Self-Consumption
Examples of self-consumption:
(1) When the sunlight is sufficient, the PV module outputs 8 kW power, the loads consume 4 kW power, and the batteries charge 4 kW power.
(2) When the sunlight becomes weak, the PV module outputs 3 kW power, the loads consume 4 kW power, and the batteries discharge to supply 1 kW power to the loads.
TOU (time-of-use)
- This mode applies to scenarios where the price difference between peak and off-peak hours is large.
- In this mode, TOU (time-of-use) is selected. You can manually set the charge and discharge time segments. For example, you can allow the grid to charge batteries in low electricity price periods at night and discharge batteries during high electricity price periods, saving electricity fee. The charge from grid function must be enabled.
- A maximum of 14 time segments can be set. For details about how to set charge and discharge parameters, see Battery Commissioning.
- In some countries, the grid is not allowed to charge batteries. Therefore, this mode cannot be used.
- This mode requires at least one charging period and one discharging period,the grid charges batteries during the charge time and supplies power to loads during the discharge time. In other time segments that are not set, the batteries do not discharge, and the PV modules and grid supply power to loads. (In grid-tied and off-grid mode, if the grid is powered off, the batteries can discharge at any time.)
Parameter |
Description |
Value Range |
|---|---|---|
Priority of excess PV energy |
|
|
Allowed charge power of grid (kW) |
Indicates the maximum charge power allowed by the grid. The value is determined by the local grid company. If there is no requirement, the value is the maximum charge power of the ESS by default. |
|
Parameter |
Description |
Value Range |
|---|---|---|
Charge from grid |
If Charge from grid function is disabled by default, comply with the grid charge requirements stipulated in local laws and regulations when this function is enabled. |
|
Grid charge cutoff SOC |
Set the grid charge cutoff state of charge (SOC). |
[20%, 100%] |
Example of the TOU (time-of-use) electricity price
Examples of the TOU (time-of-use) electricity price:
Set power consumption peak hours (14:00 to 24:00) as the discharge time. During this time, the batteries discharge. During other periods, such as 03:00-14:00 , surplus PV energy can be used to charge the batteries, and the batteries do not discharge. When the load power supply is insufficient, the grid supplies power to the loads. For example, when the sunlight is insufficient, the PV module outputs 3 kW power, the loads consume 4 kW power, and the grid supplies 1 kW power to the loads.
Fully Fed to Grid
- This mode applies to the grid-tied scenario where PV energy is fully fed to the grid.
- This mode maximizes the PV energy for grid connection. When the generated PV energy in the daytime is greater than the maximum output capability of the inverter, the batteries are charged to store energy. When the PV energy is less than the maximum output capability of the inverter, batteries discharge to maximize the output energy of the inverter to the grid.
- In this mode, Fully fed to grid is selected. For details, see Battery Commissioning.
Example of fully fed to grid:
For example, when the PV modules generate 8 kW power, the SUN2000-5KTL inverter connects to the grid with the maximum output power of 5.5 kW, and the batteries charge 2.5 kW power. When the sunlight becomes weak, the PV modules generate 3 kW power, the batteries charge 2.5 kW power, and the inverter connects to the grid with the maximum output power of 5.5 kW.
