Quick answer
Often, yes. You can usually keep the battery and inverter if the inverter can share the live data the EMS needs and accept charge and discharge instructions from it. The EMS supplier should check the exact model and firmware first, then test the controls, metering and what happens if communications fail.
In many cases, yes. The client can keep the existing battery and inverter and add a controller that reads site and battery data before sending charge or discharge instructions to the inverter.
Whether the retrofit will work depends on:
- The exact inverter model
- The firmware version running on it
- The control connection that the manufacturer provides
Access to monitoring data alone does not make the retrofit possible. The inverter must also support the commands that the EMS needs to change the charging power, discharging power, or operating mode.
What does the existing inverter need to allow?
The inverter must support two-way control. It must let the EMS read live operating data and send charge or discharge instructions back.
The optimisation software normally communicates through an on-site controller or communications gateway. The controller can read information such as:
- The amount of charge in the battery
- The charging and discharging power available
- The inverter’s operating status and alarms
- The amount of electricity the client imports and exports
- The amount of electricity the solar panels produce
- The battery’s operating limits
The optimisation software calculates the required charging or discharging instruction and sends it to the inverter through the controller or communications gateway.
Many manufacturers use Modbus TCP or Modbus RTU to let the EMS exchange data and instructions with the inverter.
However, Modbus support does not prove that the retrofit will work. Some manufacturers let external software read monitoring data but block or leave out the controls needed to change how the battery operates.
Some manufacturers provide their own control connection instead. The EMS supplier needs to check the technical documents for the exact inverter model and firmware version. You do not need to interpret register maps, API guides, or individual control commands yourself.
What do we need to send the EMS supplier before we can price a retrofit?
Before pricing the retrofit, send the EMS supplier:
- The model numbers for the battery, inverter, and controller
- The firmware versions running on them, where available
- Details of the existing meter and current transformer clamps
- The current controller or operating mode
- The single-line diagram
- The battery warranty details or maintenance contact
The EMS supplier can then check:
- Whether the inverter gives the EMS the required access to data and controls
- Whether the retrofit requires extra metering or communications equipment
- How the inverter will respond if the controller or internet connection fails
During commissioning, the EMS supplier will also test:
- Charging and discharging instructions
- Battery operating limits
- Alarms
- Loss of communications
These checks matter because inverters respond differently when the EMS stops sending instructions. The inverter may stop charging or discharging, continue following the previous instruction, or switch to a preset value.
You should also check the original grid connection agreement if the new control method could change the client’s maximum import, maximum export, or export-limitation arrangement.
When the EMS supplier confirms that the inverter and battery are compatible with the retrofit, you can use GridVolt’s simulator to compare the battery under two control setups:
- The inverter manufacturer’s best available controls
- The same battery with Energy Manager, GridVolt’s separate EMS
For the proposal, show how much extra the client could save with Energy Manager after deducting all EMS costs, rather than the total saving from the whole battery project.
Related questions
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