Quick answer
The installer or electrical contractor usually fits and wires the controller. The EMS supplier normally sets up the software and leads commissioning, while the battery or inverter maker handles faults inside its own equipment. After handover, the contract should clearly say who deals with each type of fault.
On a commercial battery EMS project, different companies usually handle the physical installation, EMS setup, commissioning, and fault handling.
The usual split looks like this:
- Physical installation: The solar installer, EPC contractor, or electrical contractor fits the controller, connects its power supply, and runs the site wiring
- EMS setup: The EMS supplier sets up the software, schedules, and communications between the controller, inverter, meter, and EMS platform
- Commissioning: The EMS supplier or an approved controls engineer tests the controller and checks that the battery charges and discharges when the EMS sends an instruction
- Battery and inverter faults: The battery or inverter manufacturer handles faults inside the battery, battery management system, inverter, or manufacturer firmware
- Other faults: The contract or handover agreement should state who the client contacts first when a fault affects the controller, cabling, meter, network, or internet connection
Who installs and commissions the controller?
The solar installer, EPC contractor, electrical contractor, or battery installer normally completes the physical work.
This may include:
- Fitting the controller and enclosure
- Connecting the controller’s power supply
- Running Ethernet or RS485 wiring to the inverter
- Connecting any meter or current transformer clamps that the EMS needs
- Connecting the controller to the site network
The contractor needs to understand both the electrical work and the site network. This includes IP addresses, communications cables, and connections between devices.
The EMS supplier or its approved controls engineer should lead the commissioning work. They normally:
- Check which readings come from the inverter, battery, and meter
- Check that the import, export, charging, and discharging values show the correct direction, units, and scale
- Load the agreed schedules and EMS control limits
- Send controlled charging and discharging instructions
- Check which controller the inverter follows when more than one controller sends instructions
- Test what the equipment does if the controller loses power, the site network fails, or the internet connection drops out
- Record the final settings
The battery or inverter manufacturer may need to provide the register map or API guide so that the EMS supplier can confirm which readings and control instructions the EMS can use.
The manufacturer may also need to enable external-control mode on the inverter. In some cases, the manufacturer may need to confirm the final power limits, state-of-charge limits, or export-limit settings.
Who maintains the system after handover?
After handover, responsibility for fixing a fault depends on what caused the problem.
- EMS supplier: Controller software, schedules, device drivers, cloud connection, data mapping, and remote diagnostics
- Local contractor: Power to the controller, damaged cables, network switches, meter faults, and replacement of the on-site controller
- Battery or inverter manufacturer: Faults inside the battery, battery management system, inverter, or manufacturer firmware
- Site IT team: Router, firewall, network permissions, and internet access
The EMS supplier may spot an inverter fault through the EMS platform before anyone else. However, that does not always make the EMS supplier responsible for fixing it.
For example, the inverter may have tripped, stopped responding, or refused a charging or discharging instruction. The battery or inverter manufacturer may then need to repair the inverter, update its firmware, or change a manufacturer setting.
The contract or handover pack should state:
- Who the client contacts first
- What each company is responsible for
- How quickly each company will respond
- When a site visit is chargeable
- Who pays when equipment supplied by another company caused the fault
Without this information, the client may not know who to contact when the battery stops following EMS instructions. Each company may say that another supplier must deal with the fault.
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