Electromobility and solar power: operating charging stations with PV

The combination of electromobility and solar power will be particularly exciting for homeowners with their own roof space, for companies with a fleet of vehicles and for everyone who not only wants to feed in the PV power they generate themselves, but also wants to use it sensibly. While household electricity in Germany is still significantly more expensive than self-generated solar power, the attractiveness of pure feed-in often decreases compared to self-consumption. A PV-optimized charging solution can therefore be a real lever for returns.

PV charging stations at a glance

• PV surplus charging reduces travel costs: If you prefer to charge your electric car with your own solar power, you replace expensive grid electricity with self-generated energy from the roof.
• A normal wallbox is not always enough: For automatic PV charging, the wallbox should be able to communicate with an inverter, smart meter or energy management system.
• The driving profile is more important than the pure system size: Those who charge at home or at the company location during the day use solar power much more easily than commuters whose car only returns in the evening.
• A battery storage system increases flexibility: It can shift solar power, but should not automatically be oversized just so that the car can be charged at night.
• Funds must currently be checked: The former KfW grant 442 “Solar power for electric cars” can currently no longer be applied for. Regional programs may change.

How can I charge my electric car with solar power?

An electric car can be charged with solar power by connecting a photovoltaic system, a suitable wallbox and, ideally, an energy management system. The PV electricity generated first supplies the household. Surpluses then flow into the electric car. If the solar power is not enough, the wallbox can supplement mains power or reduce the charging power, depending on the setting.

There are three typical charging types in everyday life. The simplest variant is manual charging: you start the charging process when the sun is shining or the app shows a high PV yield. This works, but requires attention. Automatic PV surplus charging is much more convenient. Here, a smart meter measures how much electricity would currently flow into the grid. The system passes this power on to the wallbox. The wallbox then only charges with the excess or combines it with a minimum share from the network.

The third variant is a mixed strategy. It charges the car in the morning or evening with a minimum amount so that the necessary range is safely achieved. As soon as there is excess solar power during the day, the system automatically increases the charging power. For many households, this solution is the most practical because it combines comfort and self-consumption.

The internal guide to intelligent power storage and energy managers is also worth reading because it explains the role of the control system in the overall system in more detail.

What components does a PV charging solution need?

A PV-based charging solution does not just consist of solar modules and a socket for the car. It is a small energy system. The better the components communicate with each other, the greater the benefit.

Photovoltaic system

The photovoltaic system generates the electricity. For a single electric car, a system with around 5 kWp is technically usable, but it usually becomes more pleasant from 7 to 10 kWp. This is not a hard and fast law. An economical electric car, short commutes and frequent charging during the day can also cope with smaller systems. If you have two vehicles, a heat pump or high household consumption, you should plan bigger.

Inverters and smart meters

The inverter converts direct current from the modules into usable alternating current. For PV-optimized charging, the system requires additional measurement data. This is usually provided by a smart meter or an energy measuring device at the grid connection point. It detects whether electricity is being drawn from the grid or whether excess PV electricity is being fed in.

Wallbox

The wallbox charges the vehicle safely and in a much more controlled manner than a household socket. It should be controllable for charging with solar power. Functions such as dynamic charging power, phase switching, energy management interfaces and compatibility with the existing inverter are crucial. An 11 kW wallbox is sufficient for most private applications. 22 kW is not automatically better because higher connected loads may require approval and many vehicles do not charge faster at home anyway.

Energy management system

The energy management system is the conductor. It decides whether electricity flows into the household, into the storage system, into the car or into the grid. Good systems not only take into account the current PV yield, but also household consumption, battery level, charging target, electricity tariff and sometimes weather forecasts.

Battery storage

An electricity storage system can increase self-consumption because it postpones solar power over time. It is particularly interesting for electric cars if the vehicle is not parked at the house during the day. Nevertheless, the storage should be considered economically. A large home storage system that is purchased just to charge a car at night can be expensive. A moderate storage size that supports household use, evening consumption and occasional recharging is often more sensible.

What variants of PV charging are there?

Not every charging solution has to be extremely complex. The right variant depends on how regularly the car is at home, how large the PV system is and whether comfort or maximum savings are the priority.

How much does charging with solar power cost compared to grid power?

Economic viability is the point at which solar power and electromobility become particularly strong. The Federal Network Agency quotes an average price of 40.05 cents per kilowatt hour for household electricity on April 1, 2025. In many practical calculations, self-generated solar power is significantly lower, depending on investment costs, system performance, financing, self-consumption and service life.

For a simple rough calculation, you can expect an electric car consumption of 15 to 20 kWh per 100 kilometers. With mains electricity at around 40 cents/kWh, the electricity costs are around 6 to 8 euros per 100 kilometers. If the car is charged primarily with its own solar power, the calculated energy costs can be significantly lower. The exact value depends on whether you are counting on production costs, lost feed-in tariffs or the full costs of the PV system.

The decisive lever is self-consumption. Every kilowatt hour that does not flow into the grid for a comparatively low feed-in tariff, but instead charges the car, replaces more expensive electricity purchases. This is precisely why the combination of a PV system, wallbox and electric car is often economically stronger than a pure feed-in strategy. If you would like to evaluate your own system more precisely, you can use the internal amortization calculator for photovoltaic systems.

How big should the PV system be for an electric car?

The appropriate PV size depends on mileage, consumption, roof area and household electricity requirements. An example makes it tangible: If an electric car drives 12,000 kilometers per year and consumes 18 kWh per 100 kilometers, it requires around 2,160 kWh of traction current annually. A PV system with 8 to 10 kWp can often cover this energy requirement in terms of balance. However, balance sheet does not automatically mean simultaneous. In winter the PV yield is lower, in summer there is often a surplus.

That’s why it’s not just the annual amount that counts. What matters is when the car is at the charging point. A vehicle that is at work from 8 a.m. to 5 p.m. on weekdays can use less solar power directly at home. A company car that charges at the company location during the day, on the other hand, is an excellent fit for PV. The same applies to home offices, shift work, second cars or vehicles that are often parked during the day.

The rule of thumb is: A larger PV system increases the chance of usable surplus, but it does not replace intelligent control. Anyone who has roof space should not just plan “for the car”, but also consider the overall electricity requirements: household, heat pump, air conditioning, hot water, storage and future consumers. This is exactly where the best synergies arise.

What exactly does PV surplus charging mean?

PV surplus charging means that the electric car is preferably charged with the electricity that is left over from current household consumption. For example, if the PV system produces 6 kW while the house requires 1 kW, 5 kW are mathematically available for the wallbox. The wallbox then dynamically adjusts its charging power.

A technical peculiarity is the minimum charging power. Many electric cars only charge stably from around 1.4 kW in single-phase and only from around 4.1 kW in three-phase charging. If the PV surplus falls below this, charging pauses or the system supplements grid power. Modern wallboxes can switch between single-phase and three-phase charging. This makes PV surplus charging much more efficient because smaller solar surpluses are also used.

Good systems offer different modes. In pure solar mode, charging only occurs when there is enough PV power available. In Eco mode, mains power is allowed to provide proportional support. In fast charging mode, charging occurs at full power regardless of the PV yield. This selection is valuable in everyday life. Nobody wants to wait on Sunday for solar optimization if they have a longer trip on Monday morning.

When is battery storage worthwhile for charging electric cars?

Battery storage is not automatically worthwhile just because you have an electric car. It is worth it if you regularly shift electricity from the day to the evening and thereby replace expensive mains electricity. This can be very useful for households with high evening consumption, heat pumps, home offices or multiple consumers. For a car with a very large traction battery, however, the home storage is only a small buffer.

A typical error is double storage. Solar power is first loaded into the home storage system and later transferred from the home storage system to the car. This results in conversion losses. If the car is connected during the day, direct PV charging is usually better. If the car is only available in the evening, the storage can help, but should be sized with a sense of proportion.

Prioritization in energy management is practical. First the household needs. Then the car when it’s connected. Then the memory or vice versa, depending on the destination. If you need household electricity in the evening, you will prioritize storage. If you need range the next morning, you will prioritize the car. Good systems make this logic adjustable.

What technical requirements must be met?

The installation of a wallbox belongs in the hands of a specialist electrical company. This is particularly true with higher charging powers, existing PV systems, storage, multiple meters or multiple charging points. The specialist company checks the connected load, cable cross-section, fusing, residual current protection, mains connection and communication of the components.

It is also important to register with the network operator. Charging facilities up to and including 11 kW usually have to be registered. Higher performance charging facilities usually require a permit. For companies, apartment buildings or multiple charging points, load management is also relevant so that the house connection is not overloaded.

When selecting a product, these points should be clarified:

• Is the wallbox compatible with the existing inverter?
• Does it support PV surplus charging?
• Can it charge single-phase and three-phase or switch automatically?
• Are there interfaces such as Modbus, OCPP or manufacturer’s own APIs?
• Can a smart meter be integrated?
• Is dynamic load management possible?
• How is the charging current for company cars or multiple users billed?
• Are there regular software updates?

For planning the electrical side, the internal installation and planning area is a suitable further introduction.

What applies to companies, fleets and businesses?

The combination of PV and charging infrastructure is often even more interesting for companies than for private households. The reason is simple: vehicles are often parked on the company premises during the day. This is exactly when the PV system produces electricity. Delivery vehicles, pool vehicles, service fleets or employee cars can benefit directly from roof power.

If there are several charging points, load management is mandatory. Without control, several vehicles would be able to perform at high levels at the same time. This can overwhelm the grid connection and cause expensive power peaks. An intelligent system distributes the available power as needed: urgent vehicles first, long-term parkers slower, visitors limited and company vehicles based on departure time.

Billing is also becoming more important. Companies often need RFID cards, user management, export functions and separate evaluations. Anyone who sells solar power to employees or third parties should clarify tax and energy law issues with experts. The implementation is usually easier for pure personal consumption in the company than for public charging points.

What subsidies are there for wallbox, PV and storage?

Funding changes quickly. Therefore, no article should make a blanket promise that a specific wallbox-PV combination is currently subsidized. According to KfW, the well-known KfW grant 442 “Solar power for electric cars” can currently no longer be applied for. Anyone who has already made a commitment can continue to find information about implementation and submitting evidence there.

Nevertheless, the test is worth it. States, municipalities, municipal utilities or regional energy agencies can offer their own programs. Sometimes wallboxes, grid connections, energy management systems, battery storage or charging infrastructure for companies are funded. The order is important: Many programs require the application before placing the order. Anyone who orders first and then seeks funding often loses their claim.

The official KfW page for photovoltaic funding and the federal and state funding databases are therefore better starting points than outdated blog lists. The transmission system operators’ publications on network transparency are relevant for EEG remuneration rates and processing instructions.

Which errors occur particularly frequently with PV charging stations?

Many problems arise not from poor technology, but from false expectations. A PV system does not provide enough electricity to fully charge the battery every day. Yields may be low in December. In June there is often more electricity available at midday than the car needs to use. Those who understand this plan more relaxed.

• PV system too small: The car is being charged, but a large part comes from the grid.
• No suitable control: The wallbox charges rigidly, even though there is a surplus of PV.
• Wrong priorities in the storage: The house storage is discharged unnecessarily, even though grid power would be cheaper later or solar power would be directly available.
• Car is at the charging point at the wrong time: Without daily charging, the solar power share drops significantly.
• Planned too close to the maximum connection load: Several consumers can put a strain on the house connection.
• Funding checked too late: Some subsidies must be applied for before the order is placed
• No expandability considered: A second electric car will be added later, but the system and distribution are not prepared.

Step by step to your own PV charging solution

At the beginning the question is not about the most beautiful wallbox, but about the energy profile. How many kilometers does the car travel per year? When will it be at home? What charging power is really needed? Is there already a PV system or is a new one being planned? Will a heat pump be added later? These answers determine the interpretation.

This is followed by the technical inventory. The electrical specialist checks the meter cabinet, house connection, cable routes, fuses and existing PV components. When it comes to a new PV system, the wallbox should be taken into account. For an existing system, compatibility with the inverter and smart meter is particularly important.

The control logic is then defined. Should only excess PV be charged? Should a minimum range be guaranteed? Can mains power be supplemented? Should storage be prioritized? For companies, user management, billing and load management are also included.

After installation and commissioning, optimization begins. The first few weeks show whether loading times, priorities and app settings are correct. Many systems only become really good with small adjustments: changing the minimum charging power, entering departure times, setting a memory reserve or activating the eco mode for everyday use.

Conclusion: PV charging stations are worthwhile if planning and everyday life fit together

Operating charging stations with PV is not a gimmick, but one of the most sensible forms of self-consumption. The self-generated solar power replaces expensive grid power, increases the cost-effectiveness of the photovoltaic system and makes electric mobility cheaper in everyday life. Users whose car is regularly at the charging point during the day or whose energy management system neatly combines solar power, storage and grid power will benefit the most. If you just install a wallbox and hope for chance, you are wasting potential. On the other hand, if you plan the driving profile, PV size, control and installation together, you will get a robust system that will last for many years.

FAQ: Frequently asked questions about charging stations with PV

Can any wallbox be used with a PV system?

In principle, almost every wallbox can use electricity from a PV system because the electricity is provided in the house network. For real PV surplus charging, the wallbox must be controllable and receive measurement data from the energy system. Without this communication, it usually charges rigidly and only randomly uses solar power optimally.

How much PV capacity do I need for an electric car?

A PV system of around 5 kWp can already support one electric car, while 7 to 10 kWp is often more convenient. Annual mileage, vehicle consumption and charging times are decisive. Anyone who can charge during the day uses significantly more solar power directly.

Is a battery storage system worthwhile for charging an electric car?

A battery storage system can be useful if the car is usually charged in the evening and plenty of PV surplus is available during the day. Economically, however, it should not be oversized solely for the car. Direct charging from the PV system is generally more efficient because it involves fewer conversion losses.

Is a 22 kW wallbox better than an 11 kW wallbox?

Not necessarily. An 11 kW wallbox is sufficient for most private households. A 22 kW wallbox may require approval and only offers an advantage if the vehicle, grid connection and usage profile are suitable.

Is KfW funding currently available for PV, battery storage and a wallbox?

The well-known KfW grant 442 “Solar Power for Electric Cars” is currently closed to new applications. Anyone seeking funding should check regional programs, state-level support and the latest KfW information. Applications generally need to be submitted before placing an order.

Can I charge my electric car entirely with my own solar power?

In annual energy terms, a sufficiently large PV system can cover an electric car’s electricity demand. In practice, generation does not always coincide with charging times, so grid power is often still needed in winter and for evening charging.

Sources and further information

• European Commission: Electrification and smart charging
• European Commission JRC: Efficient and eco-friendly EV charging
• EU Publications Office: Smart and bidirectional charging