Quick Summary (TL;DR)
The most reliable solar-surplus EV charging system puts a certified, correctly commissioned EV charger in charge of electrical safety and lets Home Assistant make slower, optional decisions about energy preferences. At minimum you need a bidirectional meter at the grid connection, a charger with a documented way to pause charging or change its permitted AC current, reliable communications, and a policy for battery priority and loss of data. Solar production alone does not tell you what is available to charge a car.
For a new installation, a solar-aware charger with its own supported meter is usually the lowest-risk choice. Home Assistant can select solar mode, set charging windows and show energy use without trying to replace the charger’s protective functions. If you already own a charger with a supported local interface, build a supervisory controller using measured net grid power, the charger’s actual current and an appropriately slow adjustment loop. Test the calculations in read-only mode before sending commands.
The central trade-off is the EV’s minimum AC charging current. A typical minimum of 6 A needs roughly 1.38 kW on one 230 V phase, but about 4.14 kW across three 230 V phases. If the household usually exports less than that, a charger capable of manufacturer-approved automatic single/three-phase switching can change the economics; a conventional three-phase-only arrangement may spend much of the day paused. Never attempt phase switching by DIY contactor control or bypass EVSE interlocks.
What solar-surplus charging actually measures
A rooftop PV inverter can produce 5 kW while the building needs 3 kW: only about 2 kW is available at the grid boundary. If the home has a battery, its charging or discharging can change that balance again. The quantity a solar-diverting controller needs is net power at the utility connection, measured with a known sign convention and including all household loads and the EV.
For this guide, positive grid watts = import and negative grid watts = export. A three-phase installation may expose summed active power and individual phase powers. Do not assume the inverter’s power value, a positive-only import counter or the absolute value of a CT reading is equivalent to signed net grid power.
| Measurement | Typical source | Why it matters | Common mistake |
|---|---|---|---|
| PV generation (W) | Inverter | Shows solar production | Treating it all as available EV surplus |
| Net grid power (signed W) | Correctly installed bidirectional grid meter/CT system | Direct indication of current import or export | Reversing the sign or monitoring only one phase |
| EV charging power/current | EVSE meter or API | Captures power already absorbed by the car | Adding current to the EV without accounting for its existing draw |
| Home battery power and state of charge | Battery gateway | Prevents solar charging from unexpectedly draining storage | Calling battery discharge ‘solar surplus’ |
| Charger limits and state | EVSE or approved controller | Sets feasible min/max current and pause capability | Assuming an EVSE supports arbitrary current or zero-amp commands |
| Energy import/export (kWh) | Cumulative utility meter | Audits the result over hours and days | Using cumulative kWh as an instantaneous control signal |
The accounting is straightforward if every reading refers to the same boundary and time: PV + battery discharge + grid import = household loads + EV load + battery charging + grid export, with consistent signs and measured losses included where relevant. But a mixed collection of inverter-side AC, DC battery and utility meter measurements can be inconsistent because conversion losses and sampling times differ. Align the measurement boundaries before writing automation rules.
See our published guide on solar import/export metering and avoiding double counting for dashboard accounting. A correct Energy dashboard is not by itself proof that its sensors update quickly enough for live charge regulation.
The three practical architectures
| Architecture | What controls charging | Required hardware | Strength | Main limitation |
|---|---|---|---|---|
| Solar-aware charger, manufacturer meter | Charger or its matched gateway | Approved CT/DIN meter, supported EVSE, installer configuration | Purpose-built, generally simplest support path | Brand-specific accessories; mode and firmware compatibility matter |
| Charger with documented local API + Home Assistant | Charger enforces limits; HA supervises user preferences/current requests | Signed grid meter, controllable EVSE, reliable LAN | Flexible automation and transparent local data | More software testing, updates and failure policies |
| Charger with OCPP + supported management platform | EVSE plus OCPP controller | Exact OCPP version/profile, communications, site meter and control software | Potentially vendor-neutral across chargers | ‘Supports OCPP’ alone does not guarantee pause/resume or smart charging works |
Buying route: Start with a charger supporting its own PV excess mode if you value predictable operation more than scripting. myenergi zappi ECO/ECO+ and Wallbox Solar Charging are examples of manufacturer-managed approaches; consult the product’s current installation guide for supported model, CT/meter, firmware, installer options, and feature interaction. Wallbox explicitly requires a compatible Wallbox meter for Solar Charging and lists restrictions on concurrent energy-management modes. These are not universal capabilities of every Wallbox model.
Home Assistant route: OpenEVSE with official Wi-Fi firmware has a built-in local Home Assistant integration exposing charger state, charge rate and a solar-divert switch. Enabling solar divert in Home Assistant does not feed PV or grid measurements to the charger: OpenEVSE must itself have a supported live import/export input configured. NRGkick Gen2 has a built-in Home Assistant local integration with power/current, charging enable and supported phase controls, subject to device firmware and regional hardware. The built-in Wallbox integration is cloud-polling, not a substitute for a low-latency on-site protection controller.
Protocol route: OCPP 1.6J or 2.0.1 may expose transaction control and current-limit profiles through a compatible backend. Actual control messages, enabled smart-charging profiles, CSMS permissions and response latency must be tested for the exact charger. OCPP and a grid meter are not electrical safety certification. See our smart EV charger integration comparison before buying solely on an API promise.
Hardware checklist: what to buy and why
A typical system needs a grid meter, a suitable EVSE, and optionally a Home Assistant host, network equipment and a battery gateway. The installer must size and protect the EV circuit and commission the charger’s hardware limit independently of software automation. Every proposed communication interface should be confirmed against the exact charger model and current firmware—not inferred from a similar-looking device.
| Component | Minimum requirement | Useful upgrade | Avoid purchasing until |
|---|---|---|---|
| Grid meter / CT kit | Signed bidirectional active power at utility boundary | Phase-resolved data, local wired polling, documented accuracy | Charger-maker’s compatibility and CT position are confirmed |
| EVSE | Correct electrical rating, certified protections, supported pause/current command | Local API, manufacturer PV mode, one/three-phase switching | Installer confirms supply, earthing, PEN/RCD arrangements and local rules |
| Charge power feedback | Real EV charging watts/amps and connected status | Local push updates, cumulative session energy | You know whether reported current is requested or actually measured |
| Local network | Stable Wi-Fi or Ethernet for optional supervisory controls | UPS for automation/network monitoring | You have a defined response to network/data failure |
| Solar/battery gateway | Read-only monitoring of power and state of charge when available | Local Modbus/approved integration | Readings are aligned with the grid meter boundary |
| Home Assistant server | Reliable host with backups | History, time-series dashboards and safe manual override | The charger’s standalone safety settings already work |
A whole-house CT clampAliExpress price is not interchangeable with every smart charger. Some require a particular phase order, CT ratio, gateway, RS485 protocol, energy-meter firmware or installer registration. For three-phase systems, have the electrician identify and label each phase and verify readings against independent measurements. Incorrect CT orientation can make import look like export—and drive the controller in precisely the wrong direction.
Ask for an itemised installed quotation: charger, manufacturer-approved meter/CTs, any wireless bridge, cable route, enclosure, earthing/protection, commissioning, travel, load-survey work and subscriptions. Prices vary markedly by property and country; there is no defensible single ‘complete solar EV charging cost’ without a site survey.
Why 6 A matters and when phase switching helps
For IEC-style AC charging, approximately 6 A is a common lower current requested via the control pilot, subject to the vehicle and EVSE. At 230 V and near-unit power factor, single-phase power is approximately 230 × 6 / 1,000 = 1.38 kW; on three phases it is roughly 3 × 230 × 6 / 1,000 = 4.14 kW. Actual voltage, phase load, charger losses and vehicle behaviour vary. Some cars stop or sleep after repeated interruptions, while others take time to respond to a change in advertised current.
| Verified surplus at the connection | Single-phase 6 A charging | Three-phase 6 A charging | Sensible response |
|---|---|---|---|
| 0.6 kW | Below typical minimum | Below minimum | Wait, or explicitly permit measured grid top-up |
| 1.6 kW | Approximately feasible | Below minimum | Single-phase mode with margin, if installed and supported |
| 3.2 kW | Up to roughly 13 A theoretical | Below minimum | Single-phase current modulation |
| 4.8 kW | Can exceed 16 A on one phase | Approximately feasible | Three-phase possible where EVSE and car support it |
| 7 kW | Near 30 A on one phase | About 10 A per phase | Respect installation and vehicle limits; do not assume phase switching |
Values are idealised steady-state estimates, not commands or a guarantee of zero import. A charger may have a hard 16 A rating, dynamic site limits or a vehicle that accepts a lower rate. Manufacturer-approved one/three-phase switching generally requires a controlled charging interruption and compatible vehicle/charger behaviour: do not create external phase switching with a general-purpose smart relayAliExpress price.
Some manufacturers provide explicit modes that allow a defined amount of grid supplementation when solar is below the minimum. Wallbox, for example, distinguishes Eco mode (permitting some grid contribution) from Full green mode (waiting for sufficient surplus). That is a user policy choice—not a claim that the electricity can be traced as physically solar-only over every moment of a session.
Control architecture: keep the safety boundary separate
Treat the charger as the authority for EVSE electrical limits. Home Assistant should only request charging enabled/disabled, supported modes or allowed current values. The qualified installer configures maximum circuit current, dynamic load curtailment, RCD/earth-fault provisions, cable ratings and any site limit within the charger or its approved controller; those must continue to operate with Home Assistant powered off.
A robust supervisory controller has five stages: (1) acquire fresh grid, EV and optional battery measurements; (2) validate sign, units, phase count and age; (3) decide whether solar-only, solar-plus-grid, scheduled tariff or manual override has priority; (4) calculate a conservative requested charge current or pause; (5) confirm the EVSE actually changed state and back off if it did not. A lost reading, stale timestamp, unavailable API or inconsistent phase report must not be interpreted as unlimited solar surplus.
| Responsibility | Charger / supported hardware | Home Assistant |
|---|---|---|
| Electrical maximum and protective functions | Mandatory, independent of internet and automations | Never replace or override |
| Dynamic supply limiting | Installer-commissioned charger/controller | May ask for lower current, never bypass limits |
| Surplus/tariff policy | May provide built-in mode | Choose preference or make bounded requests |
| PV and battery history | Optional | Useful for energy dashboards and rules |
| Handling network outage | Remain electrically safe with a documented local policy | Alert, inhibit automation or stop issuing requests |
| Manual override and departure requirement | EVSE/vehicle native controls remain operable | Show clear mode selection and expiry |
A practical automation should never compete with a charger in its own solar mode. Use one active surplus regulator: either the manufacturer’s divert function or Home Assistant/other dedicated energy-management software. Two controllers adjusting the same limit can oscillate, cause excessive start/stops, and ignore each other’s battery-priority assumptions.
Calculate requested current correctly while the car is already charging
An often-copied but flawed rule is new_current = exported_watts / 230. That is only approximately sensible before charging begins. Once the car is charging, the grid meter sees the remaining export after the EV load: its reading is feedback from the existing setting. If the car draws 10 A (about 2.3 kW) while the grid still exports 0.7 kW, setting the current to just 0.7/230 = 3 A would overreact and force a stop. The available request is closer to 10 A + 700/230 ≈ 13 A, before safety margins and limits.
For a single-phase illustrative controller with positive signed grid import, a near-steady-state correction can be estimated as:
candidate_A = measured_EV_current_A - grid_power_W / (voltage_V × active_EV_phases)
If the grid exports 700 W, the second term is negative and the controller increases the current. If 500 W is being imported, it decreases it. This requires a measurement of EV current and correctly identified active phases. Do not use the advertised maximum current as a substitute for measured current without accepting lag and error. Clamp to the charger’s installer-configured limits and introduce damping so that one passing cloud does not generate another command every second.
| Instantaneous observation | Existing EV charge | Grid reading | Illustrative corrected target before margin |
|---|---|---|---|
| Car off; 2.0 kW exporting | 0 A | -2,000 W | About 8.7 A single phase; start only after delay |
| Car at 10 A; 700 W exporting | 10 A | -700 W | About 13.0 A single phase |
| Car at 13 A; 460 W importing | 13 A | +460 W | About 11.0 A single phase |
| Car at 6 A; 900 W importing | 6 A | +900 W | About 2.1 A: below minimum, so pause or use approved grid top-up mode |
These examples assume roughly 230 V, near-unity power factor and a single active phase; they are calculation illustrations, not field-tested control parameters. Three-phase systems require correct phase-aware treatment, the vehicle’s onboard charging capability and a meter with reliable import/export behaviour on each phase. Never allow this arithmetic to bypass a charger-enforced load-balancing limit.
Start/stop hysteresis and cloud response
Solar production changes quickly, while charging start/stop imposes delays and mechanical/electrical cycling. The aim is not to eliminate every watt of export each second. It is to avoid repeated toggling, stay within site limits, and preserve a useful charging session. The following are conservative initial tuning examples, not universal manufacturer requirements:
| Setting | Starting point for one-phase 6 A system | Why |
|---|---|---|
| Start threshold | About 1.6–1.8 kW verified export | Allows margin above 1.38 kW minimum |
| Start dwell time | 2–3 continuous minutes | Ignores brief sunny spikes |
| Stop condition | Insufficient surplus/import beyond explicit policy | Prevents draining home battery unintentionally |
| Stop dwell time | 2–5 minutes, if site capacity remains safe | Avoids stopping for a short cloud; site safety is separate |
| Current adjustment | Recompute every 15–60 seconds with max step/change guard | Gives EV and meter time to respond |
| Recovery after manual override | Clear explicit mode or next scheduled boundary | Prevents silent takeover of driver’s intention |
| Data freshness | Use the device’s documented update rate and local outage detection | Distinguishes stale readings from actual zero grid power |
A site-limit event must not wait for a three-minute solar hysteresis timer: the charger’s independent protective load-limiting function must act according to its design. The slow timers above are for economic preference, not for circuit protection. evcc documents start/stop delays and battery-priority settings for exactly this sort of solar-charging behaviour, and warns some vehicles do not tolerate repeated charging interruptions well.
Home Assistant configuration: dry-run before commands
This example deliberately creates a read-only suggested-current sensor. It does not alter a charger, turn on charging or affect electrical protection. It assumes the grid sensor is signed in watts (positive import, negative export), the EV sensor is actual measured amperes, and the EV is confirmed to be on one phase at approximately 230 V. Replace the sample entity IDs with your actual integration entities. Verify the sensor states in Developer Tools before relying on the result.
# Illustrative configuration.yaml template; monitoring only.
template:
- sensor:
- name: "EV Solar Suggested Current (Dry Run)"
unique_id: ev_solar_suggested_current_dry_run
unit_of_measurement: "A"
state_class: measurement
availability: >-
{{ is_number(states('sensor.grid_net_power_w'))
and is_number(states('sensor.ev_measured_current_a')) }}
state: >-
{% set grid_w = states('sensor.grid_net_power_w') | float(0) %}
{% set ev_a = states('sensor.ev_measured_current_a') | float(0) %}
{% set raw_a = ev_a - grid_w / 230 %}
{% if raw_a < 6 %}
0
{% else %}
{{ [16, raw_a | round(0, 'floor')] | min }}
{% endif %}
The 0 A output is only a suggested paused state for display; do not send 0 A into an EVSE number entity whose valid range starts at 6 A. A real controller must use the charger’s separately documented pause/enable action, check whether the vehicle is connected, validate freshness/timestamps, and implement start/stop hysteresis and a manual override policy. The 16 A ceiling is an illustration, not the allowed installed maximum; consult the charger entity attributes and electrician’s configuration. It is safer to test for days with a history chart showing suggested current, measured EV current, net grid power and battery current before enabling any commands.
A simple notification-only trial can use a numeric-state trigger, with a sustained-export period, to tell the user when solar charging might be viable:
alias: "EV surplus available - notify only"
triggers:
- trigger: numeric_state
entity_id: sensor.grid_net_power_w
below: -1700
for: "00:03:00"
actions:
- action: persistent_notification.create
data:
title: "Solar charging opportunity"
message: "Grid export has exceeded 1.7 kW for three minutes. Check battery priority and EV charger status."
mode: single
This alert cannot provide electrical protection, and it should not be relied on as an emergency notification. Home Assistant’s for: timer is reset by an automation reload or restart, which is another reason not to use it as a safety interlock. When the dry run is stable, map commands only to documented charger-specific entities, checking the valid range and response. Examples of manufacturer-supported controls appear in the official OpenEVSE, NRGkick and Wallbox documentation. Do not mix those entities or assume names match on another system.
Solar and home-battery priority: choose a policy, not a guess
A battery can make the grid meter show almost zero export while a car is charging, because the storage inverter supplies some of the difference. ‘Zero grid import’ is not proof that the EV is using current solar surplus. This matters for battery cycling costs, backup reserves and the headline claim of solar-only charging.
| Policy | Typical rule | Benefit | Trade-off |
|---|---|---|---|
| Battery-first | Charge home battery to chosen SoC before inviting EV load | Preserves evening/backup capacity | Less midday time for EV |
| EV-first | Give some surplus to EV before home battery reaches full | Useful for a car departing soon | May reduce backup reserve |
| Reserve-aware | Allow EV only while home battery SoC above reserve and discharging power under agreed threshold | Balances resilience and charging | Requires dependable BMS data and correctly chosen hysteresis |
| Cheapest-energy | Blend solar opportunity with tariff and departure time | Often improves real household economics | Not equivalent to solar-only |
For a home with a battery, consult the inverter’s official energy-management modes before attempting to override them from Home Assistant. Some gateways report battery power only every several seconds; SoC may be delayed or rounded. A safe supervisory strategy can require the battery to be not discharging, above a chosen reserve and charging behaviour stable before requesting more EV power. A fixed SoC target is a user preference, not a replacement for the BMS low-voltage cut-offs.
See our published solar forecasting comparison for forecast inputs. Forecasts are useful for deciding whether to wait until noon; real-time measurements still decide what is available at the grid connection now.
Three-phase metering, netting and vehicle behaviour
Some three-phase utilities net simultaneous imports and exports across phases for billing; other meters or chargers may implement different logic for local control. Even when a total-sum power sensor reports −2 kW export, one phase may be importing substantially while another exports. A site controller must respect per-phase current, cable limits and the charger’s own phase-specific behaviour—not just a single summed watt value.
The actual charge current is limited by the vehicle’s onboard AC charger and its thermal/SoC management, not only by the wallbox rating. A 22 kW capable EVSE connected to an 11 kW limited car does not produce 22 kW. Automatic phase switching requires a supported EVSE/vehicle combination and correct vendor procedures. Ask the installer to test at minimum-current charging, at maximum permissible current, on a cloud transition and after a charger restart.
Economics: surplus is not automatically free
The money saved by diverting solar to an EV depends on your avoided import price minus the export payment you would otherwise receive, adjusted for charging efficiency, battery involvement and whether the car could have used cheap overnight electricity instead. Do not use the full retail tariff as ‘free saving’ if solar export has material value.
Suppose an illustrative 8 kWh AC charging session could be bought from the grid at 24p/kWh, or charged from solar that would otherwise earn 8p/kWh export. The simple opportunity benefit of moving 8 kWh from export to EV is 8 × (24p − 8p) = £1.28 before equipment cost and other differences. If the car could instead charge overnight at 9p/kWh, the same solar diversion beats that alternative by only 8 × (9p − 8p) = 8p under this simplified comparison. Real import/export tariffs, EV charging losses, taxes, contractual rules and battery interactions must be checked; these amounts are examples, not current tariffs.
| Consideration | Low-cost system advantage | Potential hidden cost |
|---|---|---|
| Manufacturer integrated PV mode | Few extra controllers required | Approved CT/meter accessory and labour |
| Home Assistant local supervisory setup | Reuses existing server and compatible local API | Time spent testing, maintaining and recovering from software changes |
| Cloud-only integration | Simple for some branded chargers | Dependency on internet, service and allowed poll rate |
| Automated phase switching | Captures weaker midday surplus | More specialised EVSE and commissioning |
| Battery-priority coordination | Protects reserve and avoids unwanted cycling | Misconfigured rules may discharge battery at poor value |
The cheapest apparent setup is not always the cheapest installed and maintained system. An off-the-shelf charger with a supported meter may beat a collection of unrelated CTs, Wi-Fi relays and cloud bridges once electrical installation and troubleshooting are included.
Commissioning tests before trusting an automation
Perform these tests with a qualified installer responsible for the EV installation. Home Assistant tests should verify observability and policy, never substitute for electrical protection tests.
| Test | Expected observation | Investigate if |
|---|---|---|
| Sign convention | Turning on a known household load moves signed grid power towards import | Export increases instead: reversed CT/sign |
| PV variation | Grid import/export changes plausibly with a cloud or known load | Sensor freezes or lags several minutes |
| Charger starts | Net export declines as EV power rises | Export appears to increase with charging |
| Existing-load feedback | A current adjustment uses EV power already being drawn | Current oscillates 6–16 A every refresh |
| Minimum charge | Charger pauses rather than accepting invalid 0–5 A requests | Automation floods service errors or restarts EV repeatedly |
| Home battery priority | EV behaviour matches reserve and discharge policy | Battery drains while controller says ‘solar only’ |
| Internet/LAN outage | Charger remains safe and follows manufacturer-configured local policy | Site limit protection depended on cloud or Home Assistant |
| Home Assistant restart | No unrequested charging and a deliberate recovery mode | Old desired-state values silently override EVSE mode |
| Manual override | Driver can force an explicit timed exception without defeating electrical limits | Automation immediately overrides user choice |
| Three-phase operation | Relevant phase currents stay within commissioned limits | Aggregate watts look fine but an individual phase overloads |
Never use Home Assistant or a generic ESP32AliExpress price relay to interrupt an EV pilot line, switch live charging conductors, defeat charger RCD/DC detection, or change the EVSE’s maximum circuit-current commissioning. Those are professional installation and certified equipment responsibilities.
Common faults and fixes
| Symptom | Likely explanation | Appropriate next check |
|---|---|---|
| Charging starts with little/no sun | Wrong sign, minimum grid-top-up mode enabled, or automation interpreting PV production as surplus | Inspect signed grid watts and chosen EVSE mode |
| Charger never starts | Less than roughly 1.4 kW one-phase/4.1 kW three-phase surplus, minimum threshold or vehicle asleep | Check active phases, minimum current and sustained export |
| Charger cycles repeatedly | No start/stop delay, too frequent feedback changes, car response latency | Use hysteresis, longer dwell and bounded updates |
| Home battery drains into EV | Battery inverter regulating grid at zero; SoC reserve policy absent | Review gateway battery power and inverter settings |
| HA shows 0 W when charger is active | Stale entity, wrong integration capability or delayed cloud polling | Compare charger native display and meter timestamp |
| Charging current cannot change | Installer-configured limit, unavailable API permission, incompatible firmware or conflicting native solar mode | Review official charger documentation and integration entities |
| Grid import rises despite surplus mode | Clouds, update latency, house loads, car minimum current or cloud polling | Audit one-minute import data and control update rate |
| Three-phase site behaves oddly | Phases reversed, energy summation conventions or unsupported phase switching | Qualified installer phase-resolved metering verification |
Which approach should you use?
New charger, minimal maintenance: Prefer an EVSE with a documented solar-divert mode and its compatible grid meter. Let Home Assistant observe energy and change a supported high-level mode only if the manufacturer documents it. This is often a better purchase than chasing a generic ‘works with Home Assistant’ label.
Existing local controllable EVSE: Use Home Assistant first for read-only data, then introduce a single bounded supervisory regulator with slower feedback, hysteresis, offline checks and a clear manual override. OpenEVSE and supported NRGkick devices are concrete examples of official integrations, though their capabilities and prerequisites differ.
Multiple chargers or complex batteries and tariffs: Consider an approved site-management system or a maintained EV energy controller such as evcc after verifying the exact devices and supported interfaces. Home Assistant remains useful for dashboards, preference inputs and alerts; avoid running two simultaneous controllers for the same charger.
No documented pause/current interface: Do not improvise by cycling a smart plug or contactor upstream of the charger. Buy an EVSE supporting the required controls or use its native smart charging functionality.
Frequently asked questions
Can I use an ESP32 CT clamp as the grid meter?
An ESP32AliExpress price energy-monitoring project can be useful for diagnostics, but charger vendors may require a specific certified meter, CT orientation, isolation or local communications path for their dynamic safety functions. An unsupported ESP32AliExpress price sensor must not become the only protection against service overload. For general energy-monitoring background, see the site’s Home Assistant energy dashboard troubleshooting guide.
Can I charge from solar without importing any grid electricity?
You can attempt to minimise import, but meter latency, house-load changes, minimum EV current, voltage variation and charging losses mean a perfect zero-import claim is not realistic for every second. A manufacturer ‘full green’ mode is still governed by its stated tolerances and integration limits.
Is an OCPP charger automatically better for Home Assistant?
No. The controller needs a tested OCPP version and working smart-charging features, while solar-divert accuracy still depends on a good grid measurement. Local manufacturer APIs may be simpler; a cloud-only OCPP backend may introduce latency. Confirm the actual firmware and supported current/pause commands.
Why does solar charging stop after a few clouds?
Some cars cannot sustain AC charging below the advertised minimum current. Below that threshold, a solar-only policy must pause rather than command an unsupported current. Configure conservative dwell times, and consider whether your EVSE and vehicle officially support phase switching or an intentional small grid supplement.
Do solar forecasts replace live measurements?
No. A forecast helps decide when to plan charging; signed grid power and actual charger feedback decide whether surplus is available at this instant. Forecast error and moving household loads must be expected.
Official documentation and further reading
- Home Assistant: OpenEVSE integration — local EVSE monitoring, current controls and limits of the solar-divert switch.
- Home Assistant: NRGkick integration — local API prerequisites, current/phase entities and a solar charging automation blueprint.
- Home Assistant: Wallbox integration — cloud polling and available charger controls.
- Wallbox Solar Charging help — compatible meter requirements, full-green/eco modes and interactions with other site features.
- evcc: Solar Surplus Charging — PV mode, starting/stopping behaviour and home-battery priority.
- Home Assistant: Automation triggers — dwell-time behaviour and restart limitations.
- myenergi zappi manual — grid CT configuration and export-margin concepts; confirm the latest manual for your hardware.
Editorial note: hardware/firmware capabilities, local wiring rules, tariffs and manufacturer integrations change. Always verify the actual model, country, supplier and electrical installation with the current official documentation before ordering or commissioning. Worked calculations are illustrative rather than on-site test results.