Quick answer
The battery should keep a safe local plan if the internet goes down. If the on-site controller can still talk to the meter and inverter, it may keep following its saved schedule. If that local link also fails, the inverter should move to an agreed fallback setting after a set timeout.
If the site loses internet access, the battery should still have a local control plan. The on-site EMS controller may continue controlling it, or the inverter may move to its own fallback setting.
An internet outage does not necessarily break the local connection between the energy management system, or EMS, controller, meter, and inverter. If the controller can still read the meter and send instructions to the inverter, local control may continue.
If the controller can no longer read the meter or send instructions to the inverter, the inverter needs its own fallback setting. During commissioning, agree how long the inverter will wait for a new EMS instruction and which fallback setting it will use when that time runs out.
What should continue at the site
The battery management system, or BMS, and inverter should continue to apply their safety and operating limits. They do not need an internet connection to do this.
If the on-site EMS controller still has a local connection to the meter and inverter, it may also continue to:
- Read the site meter
- Communicate with the inverter
- Follow the last schedule it downloaded
- Keep the agreed minimum battery reserve
- Limit site imports or exports against a fixed limit, provided that it can still read the site meter
- Store operating data and upload it later
The controller can only continue local control while it can read the information it needs and send instructions to the inverter.
What might stop until the connection comes back
Functions that rely on cloud data or remote instructions may stop temporarily. These may include:
- Updated forecasts of the client’s electricity use and solar generation
- Revised schedules based on tariff prices
- Battery trading instructions
- Remote dashboards and alerts
- Software updates
- Remote setting changes from the EMS provider
If new EMS instructions stop arriving, the inverter should only continue following the previous instruction until the agreed timeout expires. It should then follow a stored local schedule or move to the agreed fallback setting.
What should you check before handover?
Before handover, ask the relevant supplier or contractor to test two separate faults:
- An internet outage
- A loss of local communications between the controller, meter, and inverter
Record:
- How long the inverter waits for a new EMS instruction
- Which fallback setting it follows
- Which battery reserve remains protected and which device or controller protects it
- How long the controller stores operating data
- What the client or supplier needs to check when the connection returns
Also confirm whether the controller needs a cellular backup connection or a separate power supply.
If the internet fails, the battery should continue following a stored local schedule or move to the agreed fallback setting. It should not continue following an old charging or discharging instruction after the agreed timeout expires, and it should not stop without an agreed fallback.
Related questions
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