Quick answer
A third-party EMS normally needs an on-site controller, power, a connection to the inverter, whole-site meter readings and internet access. Some sites can reuse their existing meter, CT clamps and network. Others may need extra metering, cabling, a gateway, network equipment or a mobile-data connection before the EMS can work properly.
A third-party energy management system, or EMS, normally needs:
- An on-site controller or communications gateway
- An enclosure and power supply
- A connection to the inverter
- A connection to the site meter and current transformer, or CT, clamps
- Internet access
On some sites, the client can keep the existing meter, CT clamps, and network connection if they already provide the readings and communications that the EMS needs.
You may need to include a new meter, gateway, extra cabling, network switch, or cellular router in the proposal if the existing metering, inverter connection, or site network cannot provide those readings and communications.
What equipment is normally needed on site?
The controller normally needs:
- An electrical enclosure and suitable power supply
- Ethernet or RS485 wiring to the inverter
- Access to whole-site import and export readings, either through the inverter or directly from the site meter
- Internet, remote, and network access under security rules that the EMS supplier and the client’s IT team agree
RS485 is a common wired connection that electrical equipment uses to exchange data and instructions.
The on-site controller or gateway connects the battery equipment to the EMS software. It reads data from the inverter and meter, receives the latest battery schedule, and sends charging or discharging instructions to the inverter.
The EMS may receive the whole-site import and export readings through the inverter if the inverter already receives them from its own grid meter. On other sites, the EMS may need a direct connection to the site meter or separate CT clamps.
Make sure the EMS receives readings for the whole premises rather than only the amount of electricity entering or leaving the inverter. Also check for:
- CT clamps on the wrong side of the main load, solar, or battery connection
- CT clamps facing the wrong direction
- The wrong CT ratio
- A meter that sends new readings too slowly for battery control
Before pricing the work, confirm whether the EMS will receive the whole-site import and export readings through the inverter, a direct meter connection, or separate CT clamps.
The EMS needs reliable readings for whole-site imports and exports before it can control the battery correctly.
What extra equipment might the site need?
The client may need little more than the controller, enclosure, and communications wiring when the existing setup can:
- Share the readings that the EMS needs
- Accept instructions from the EMS
- Provide the EMS with whole-site import and export readings
- Connect to the site network
Other clients may also need:
- A replacement meter or new CT clamps
- A protocol converter when the inverter and controller cannot communicate directly
- A network switch or extra Ethernet cabling
- A cellular or mobile-data router when the client cannot provide internet access
- Separate meters for solar panels, electric vehicle chargers, or other large electrical loads
- Digital input or output modules for signals from relays, alarms, or other equipment
- An uninterruptible power supply, or UPS, or a second controller power supply if the controller must remain powered during short power cuts
Before pricing the EMS work, check who will supply, install, connect, and commission each item.
GridVolt normally includes an on-site controller as part of the EMS deployment. The client can usually keep compatible batteries and inverters. Any extra equipment will depend on the meters, communications equipment, and network connections already at the premises.
Related questions
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