# Solar Surplus Charging

> Explains how solar surplus charging works in Smart mode, at which power charging starts, pauses or switches phases and how the solar share slider helps.

Use excess solar energy to charge the electric car. This is the core function of evcc.

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## Smart Mode

Solar surplus charging is activated at the charging point via **Smart** mode.

![Screenshot of a charging point. Cursor clicks on the Smart mode.](/_astro/smart-mode-en-light-1x.Buim3hhh.webp)

Screenshot of a charging point. Cursor clicks on the Smart mode.

In this mode, charging starts automatically as soon as the solar system delivers **enough power**. The charging power is continuously adjusted so that **no power is drawn from the grid** if possible. If the solar system no longer delivers enough power or if household consumption increases, charging is paused and continued later.

Besides solar surplus, **Smart** mode also covers charging in the cheap hours of a [dynamic tariff](/en/features/dynamic-prices) and [charging plans](/en/features/plans). All strategies can be combined. An overview of all modes is on the [modes page](/en/features/modes).

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### When does charging start?

All electric cars have a **minimum charging power**. This is determined by the minimum current of 6 A specified in the charging standard [IEC 61851](https://en.wikipedia.org/wiki/IEC_61851). The minimum charging power depends on the number of phases that the car and wallbox use for charging.

| Phases    | Minimum charging power (6 A)   | Maximum charging power (16 A / 32 A)                      |
| :-------- | :----------------------------- | :-------------------------------------------------------- |
| 1-phase   | **1,4 kW** (1 x 6 A x 230 V)   | **3,7 kW** (1 x 16 A x 230 V)                             |
| 2-phase   | **2,8 kW** (2 x 6 A x 230 V)   | **7,4 kW** (2 x 16 A x 230 V)                             |
| 3-phase   | **4,1 kW** (3 x 6 A x 230 V)   | **11 kW** (3 x 16 A x 230 V) **22 kW** (3 x 32 A x 230 V) |

Most wallboxes today are connected three-phase (11 kW or 22 kW). This means that the minimum charging power is 4.1 kW. For [wallboxes with automatic phase switching](/en/chargers#features) (1P/3P), evcc can switch between single-phase and three-phase as required and start charging at just 1.4 kW.

The feed-in power is shown in the **energy flow diagram**. If the surplus is above the minimum charging power for a certain period of time, charging starts.

![Energy flow diagram shows 3.4 kW feed-in.](/_astro/energyflow-surplus-en-light-1x.BSNT053R.webp)

Energy flow diagram shows 3.4 kW feed-in.

Note: The value on the grid meter is the decisive factor. Solar surplus charging does not work for systems with regulated grid feed-in (“zero feed-in”).

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### Not enough surplus?

By default, charging only starts once the surplus covers the full minimum charging power. For small solar systems or in the winter months this can be rare. With the **Solar Share** slider you allow a share of grid power so that at least part of your charging needs is covered by solar energy. You find it in the settings of the charging point under **Solar Surplus**.

![Solar share slider in the charging point settings, set to 50%.](/_astro/solar-share-en-light-1x.exbgn4Lh.webp)

Solar share slider in the charging point settings, set to 50%.

The slider defines how much of the minimum charging power must come from solar. At 100% charging only starts when the surplus covers the whole minimum charging power. At 50% charging starts as soon as solar covers half of it and the rest is drawn from the grid or the home battery. At 0% charging starts as soon as some surplus is available. Charging stops when the solar share drops below the set value for a while.

If you have a home battery, the missing power may come from the battery instead of the grid. Under [battery priority](/en/features/battery#priority) you control to what extent the home battery may be used for charging the vehicle.

The delays before charging starts or stops can be adjusted under **Configuration → Charging points & Heaters → \[My Charging Point]** in the **Behaviour** section. Choose them so that charging is not switched on and off too often. Some vehicles refuse to charge if it is interrupted too often and must be made to charge again, for example by unlocking or plugging/unplugging the charging cable. For these vehicles, [Always charge](/en/features/modes#always-charge) keeps the charging session running without interruptions.

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### Interaction with the home battery

Battery systems have their own, fast regulation. In the standard case, the home battery has priority. In **Smart** mode, vehicle charging only starts when the home battery can no longer absorb any power.

You can find out how to adjust this behavior under [Home battery](/en/features/battery).