If you have rooftop solar, PV surplus charging can divert excess generation to your EV instead of exporting it to the grid. With a go-e Charger, this can be handled by the go-e Controller or by a compatible third-party energy-management system (EMS) that already has access to household power-flow data.
The main difference is integration. The go-e Controller provides a dedicated go-e solution for measuring grid import and export and coordinating charging. A third-party EMS can be a better fit when suitable metering and automation are already installed.
How go-e PV Surplus Charging Works
PV surplus charging follows the power flowing between the property and the grid. When solar generation exceeds household demand, the charging system can increase the current supplied to the EV. When the surplus falls, it can reduce the charging current or pause the session. For a broader look at the underlying approach, see how surplus solar EV charging works across different home-energy setups.
Direct communication with the solar inverter is not necessarily required. The go-e Controller, for example, can use electrical measurements to determine whether the property is importing or exporting power. According to go-e, this allows PV optimisation to work with different inverter types without relying on a direct inverter connection.
Using the go-e Controller
The go-e Controller is go-e’s dedicated energy-management device for PV surplus charging, energy monitoring and dynamic load management. Installed in the electrical distribution system, it uses current sensors and voltage measurements to monitor power flows and coordinate charging with compatible go-e Chargers.
For the driver, the main advantage is that solar charging can be managed within the go-e ecosystem without building a separate automation system. The Controller can also reduce charging when other household loads increase, helping keep total demand within configured limits. This is the same principle behind dynamic load balancing with solar, where charging power is adjusted around both household demand and available generation.
- PV surplus control: adjusts charging according to available excess generation.
- Dynamic load management: reduces charging when other electrical loads require capacity.
- Energy monitoring: measures relevant power flows in the configured installation.
- Phase switching: compatible charger models can switch between single-phase and three-phase charging as available power changes.
The Controller also provides interfaces including HTTP API, MQTT and Modbus TCP, allowing it to participate in a broader home-energy setup where required.
Separate measurement of solar production is not required simply to determine whether surplus power is available. Where an AC-connected inverter is accessible at the appropriate point in the installation, additional measurement can be used to display PV production separately. DC-coupled storage behind a hybrid inverter is different because its individual battery flow may not be separately visible to the Controller. For most owners, the practical consequence is that homes combining an EV and stationary battery need their energy priorities configured carefully so one device does not consume energy intended for the other.
Compatibility note: go-e features vary by charger model and hardware generation. Before buying a Controller or designing a system around automatic phase switching or a particular interface, verify those features in the documentation for your exact charger.
Professional Installation Matters
The Controller is connected to the electrical distribution system, so installation and sensor placement should be handled by a qualified electrician in accordance with applicable requirements and go-e’s instructions. Incorrect sensor orientation or phase assignment can produce inaccurate import and export readings, which in turn prevents surplus charging and load management from working correctly. Correct EV charger CT installation is therefore important when power-flow measurements are used for solar charging and load balancing.
Using a Third-Party Energy Management System
A go-e Controller is not required when another compatible EMS can already measure household energy flows and control the charger.
Depending on charger generation, go-e documents interfaces including HTTP APIs, MQTT and Modbus TCP. Current go-e documentation also lists OCPP 1.6 JSON on supported chargers. For residential solar charging, the important question is not which protocol has the longest feature list, but whether both your charger and EMS support the same interface and the required charging controls.
An external EMS can use data from suitable meters, solar equipment or other energy-monitoring hardware to determine how much surplus is available and adjust the EV charging current accordingly. This can be especially useful in a home where one platform already coordinates solar generation, stationary storage, heat pumps, tariffs and other controllable loads.
OCPP is generally more relevant to charge-point management and backend systems, while local API, MQTT or Modbus integrations can be more practical for residential automation. The appropriate choice depends on what your specific charger and EMS support.
Low Solar Surplus: The 6-Amp Minimum and Phase Switching
The most important limitation in solar EV charging appears when only a small amount of surplus power is available. go-e specifies six amps as the relevant minimum charging current for PV surplus charging. At approximately 230 volts, that means about 1.4 kW when charging on one phase.
With three phases active at six amps per phase, the minimum is roughly 4.2 kW. This difference matters during mornings, evenings, cloudy periods and with smaller PV systems.
| Charging mode | Approximate minimum at 6 A | Practical effect |
|---|---|---|
| Single phase | 1.4 kW | Can make use of relatively modest PV surplus |
| Three phase | 4.2 kW | Needs considerably more surplus to maintain charging |
Automatic 1-/3-phase switching can therefore make a significant difference. On compatible go-e Chargers, the system can use single-phase charging when surplus is modest and switch to three phases when more solar power becomes available.
If the available surplus drops below the minimum required to continue charging, the system can pause the session. Depending on the chosen configuration, grid electricity can instead be allowed to supplement the available solar power. The better strategy depends on the driver’s priority: maximising solar self-consumption may mean accepting charging pauses, while ensuring the car reaches a required charge level may justify some grid consumption.
Solar Charging with a Home Battery
A stationary battery adds another destination for excess solar energy. Instead of deciding only between grid export and EV charging, the energy-management setup may also need to decide whether surplus should charge the home battery first.
How well individual battery flows can be measured depends on the electrical architecture. AC-connected storage can be easier to monitor separately at the AC side, while a DC-coupled battery behind a hybrid inverter may not expose its battery flow separately to the go-e Controller.
For the homeowner, the key issue is energy priority rather than the underlying wiring terminology. Configure the system so that EV charging, stationary-battery charging and any permitted battery discharge behave according to your goals rather than assuming the charger can infer those priorities automatically.
go-e Controller vs Third-Party EMS
| Consideration | go-e Controller | Third-party EMS |
|---|---|---|
| Best fit | Dedicated go-e energy management | Existing smart-home or energy-management installation |
| PV measurement requirement | Can control surplus without direct inverter communication | Depends on the EMS and available energy data |
| Configuration | Primarily through the go-e ecosystem | Depends on the selected platform |
| Custom automation | Additional integration possible through supported interfaces | Potentially extensive, depending on the EMS |
| Additional hardware | Requires the Controller and electrical installation | May require none if suitable metering already exists |
| Technical effort | Dedicated hardware followed by go-e configuration | Ranges from native integration to custom automation |
Which Setup Should You Choose?
Choose the go-e Controller if you want a dedicated go-e solution for measuring household power flows and coordinating a compatible charger. If your home already has reliable energy metering and an EMS that explicitly supports your go-e Charger, using that existing system can avoid adding another energy-management device. Owners using Home Assistant can also explore the dedicated go-e Home Assistant integration for charger control, WebSocket communication and solar-charging automation.
Whichever route you choose, automatic phase switching deserves particular attention if your solar system frequently produces modest surplus power. It can substantially widen the conditions in which surplus charging remains practical.
Bottom Line
For a dedicated go-e solar-charging installation, the go-e Controller offers the straightforward route; for a home that already has a compatible EMS and suitable metering, the existing system may be all you need. The key technical consideration is phase switching: a compatible charger that can move between single-phase and three-phase operation is better able to use lower and fluctuating solar surplus.
Source Transparency
This guide was checked against go-e product pages, PV surplus charging guidance and technical documentation available at the time of publication. Features can vary between charger models and hardware generations, so specifications for the exact charger should be verified before purchasing equipment or planning electrical work.
Primary references include the go-e Controller documentation, go-e PV surplus charging guidance and go-e technical documentation. Electrical installation work should follow local requirements and the manufacturer’s installation instructions.
