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EV Charger Solar Charging

Automatically adjust your EV charge current based on real-time solar surplus, so the car charges from free energy instead of the grid.

The Problem

Without Hanergy, an EV charger draws power at a fixed rate regardless of what the solar panels are producing. Surplus energy that could charge the car is exported to the grid at a low feed-in tariff, while the car charges from expensive grid power overnight or whenever it is plugged in.

The Solution

Hanergy configures the EV charger as a dynamic load. On every evaluation cycle, the engine reads the available surplus and adjusts the charger's current setpoint to match. When the sun comes out, charge amps go up. When a cloud passes, amps go down. The car absorbs exactly as much solar energy as is available, minimizing grid import.

Device Configuration

Add the EV charger as a dynamic load in Settings > Devices.

Field Value Notes
Name EV Charger Display name
Type Dynamic Adjustable setpoint
Switch entity switch.ev_charger On/off control in HA
Parameter entity number.ev_charger_amps Charge current setpoint in HA
Parameter min 6 IEC 61851 minimum (6 A)
Parameter max 32 Maximum amps your charger supports
Parameter unit A Amperes
Watts per unit 230 Approximately 230 W per amp (single-phase)
Rated power 7360 Maximum draw at 32 A
Minimum power 1380 Draw at 6 A
Ramp time 5 Seconds for charger-to-car negotiation
Feedback entity sensor.ev_battery_soc Car battery state of charge (optional)

Finding your watts_per_unit

A practical way to calibrate: set the charger to minimum amps, note the power draw. Set it to maximum, note again. Divide the watt difference by the amp difference. For a typical single-phase charger: (7360 - 1380) / (32 - 6) = 230 W/A.

Priority Configuration

Create a priority entry in Settings > Priorities.

Field Value Notes
Load EV Charger Select the device created above
Minimum surplus 1500 Watts required before charging starts
Threshold 80 Stop charging at 80% SOC
Enabled Yes

With a minimum surplus of 1500 W and a surplus buffer of 100 W (default), the engine requires at least 1600 W of raw surplus before activating the charger. This ensures the car starts charging at a stable rate rather than flickering on and off at the edge of viability.

Single-Phase vs Three-Phase

The watts_per_unit value depends on the number of phases:

Phases Voltage Watts per amp Max power at 32 A
1 ~230 V ~230 W/A ~7,360 W
3 ~400 V ~690 W/A ~22,080 W

For a three-phase charger, set watts_per_unit to approximately 690, rated_power_w to 22080, and min_power_w to 4140 (6 A x 690 W/A).

Tips

  • Minimum charge amps. Most EVs refuse to charge below 6 A (IEC 61851 standard). Setting param_min below 6 will cause the car to reject the charge session. Some vehicles require 8 A minimum -- check your car's documentation.

  • Ramp time. The charger and car negotiate via a pilot signal when the session starts. A ramp_time_sec of 5-10 seconds gives them time to agree before Hanergy begins adjusting the current.

  • Feedback entity. If your EV integration exposes a battery SOC sensor, use it as the feedback entity. This lets Hanergy stop charging at a target percentage (e.g., 80%) and free up surplus for other loads.

  • Multiple priority levels. For advanced use, place the same charger at two priority positions: a high-priority entry to charge to 60% at moderate amps, and a lower-priority entry to top up to 80% only when surplus is abundant. See the Multi-Level Priorities guide.

Compatible Chargers

Hanergy works with any EV charger that exposes a controllable current setpoint in Home Assistant:

  • OpenEVSE -- native HA integration with number entity for amps
  • Wallbox -- via Wallbox integration
  • go-e Charger -- via go-e integration
  • Easee -- via Easee integration
  • Any OCPP charger -- via OCPP integration

If your charger appears as a switch and a number entity in Home Assistant, it will work with Hanergy.