Thanks to energy storage, it is possible to reduce electricity costs and, among others, charging electric cars at the time when energy is the cheapest. In addition, as the analysis shows, effective energy management with the use of an energy storage will enable the construction of a charging system for electric vehicles in facilities with many parking spaces, both in buildings and in the area directly adjacent to them, and the fulfillment of the obligation to provide charging stations for these vehicles.

There are already over 12,000 vehicles on Polish roads. fully electric cars. Each of the car companies offers electric cars - from hybrids with a range of approx. 50 km, to fully electric cars with a range of approx. 400 km. When deciding to buy an electric car, we often wonder - where will we charge it?

In mid-2022, approx. 1.5 thousand were available in the country. public charging stations, of which only 33% were fast charging stations with a power of 40-50 kW, where we could charge a vehicle within 1-2 hours for cars with a range of up to 200 km and cars with a longer range, respectively. From the slow charging station, i.e. from 3.7 to 22 kW, we can charge the vehicle within 6-8 hours, which is the best for our car's batteries.

It is worth knowing that:

24% of charging stations are located in shopping malls. However, this requires a daily trip to the shopping mall and spending several hours there to charge the vehicle;

21% of charging stations are located on hotel premises, mainly for hotel guests. If they are open to the public, you have to pay for a few hours of parking.

Naturally, a particularly convenient solution is when we live in a single-family house with a garage and we can charge the car from the home installation, or we work in a company that has car chargers.

The law supports electric cars

You should also be aware that Directive (EU) 2018/844 of the European Parliament and of the Council of May 30, 2018 stipulates that EU Member States should ensure the development of electromobility, e.g. by building an easily accessible infrastructure that will reduce the costs of installing charging points for individual owners and will provide electric vehicle users with access to charging points.

In Polish legislation, in accordance with the Act of January 11, 2018 on electromobility and alternative fuels, non-residential buildings with more than 10 parking spaces are designed and built, ensuring the installation of at least one charging point and channels for cables and electric cables enabling the installation of charging points at each parking stand, if these parking stands:

are inside the building,

are adjacent to the building.

This requirement covers newly built and modernized facilities.

Problems with car charging places

The implementation of the directive in practice is presented in the analysis of the following case study carried out in a complex of multi-apartment houses, where cars are parked in an underground garage with 360 parking spaces.

It is planned to modernize the parking spaces with the possibility of making paid parking spaces available to other residents. Currently, 4 electric passenger cars are parked there, which are charged at a nearby petrol station with two stands. These positions are often occupied as they serve the entire estate. The construction of the charging station in the garage hall encountered difficulties due to the insufficient connection power of the building. The installation is prepared to power lighting, ventilation, etc. It was not intended to power the vehicle charging station, especially in the afternoon. In addition, the willingness to buy electric cars was expressed by some residents, if it will be possible to charge in the hall. The solution would be to limit the charging of vehicles only to night or morning hours. Due to the fact that residents often do not wait until 10 p.m., when there is a night load trough, and they connect to charging as they return from work, i.e. at approx. 17.00 - 18.00, i.e. at the peak of the load, this may cause the demand for power to exceed the value of the connected power.

Pursuant to the Act of 11 January 2018 on electromobility and alternative fuels, public utility buildings and multi-family residential buildings, as well as internal and external parking spaces related to them, are designed and built, ensuring the connection capacity that allows these stations to be equipped with charging points with not less than 3.7 kW. The Regulation of the Minister of Climate and Environment of May 7, 2021 on the method of determining the minimum connection power for indoor and outdoor parking spaces related to public utility buildings and multi-family residential buildings specifies that the minimum connection power is the product of 50% of the number of parking spaces and the power value equal to 3.7 kW. This means that the minimum connection power for a multi-family residential building with 360 parking spaces will be 666 kW. This is a value comparable to the consumption of energy by residents for household needs. Therefore, twice as much power supply infrastructure should be built.

If it is a newly designed housing estate, it is easier to design an installation of the appropriate size and additionally incur the already considerable construction costs, where the DSO will appropriately expand the network infrastructure, for which we will all pay in distribution fees. It is more difficult in the case of modernization of existing buildings or inserting the so-called seals between existing facilities. Here, we may not obtain connection conditions for such high connection capacities for technical reasons. Due to the existing historical, environmental or road infrastructure, increasing the network connection capacity may be very costly, long-term or even impossible. The solution may be a vehicle charging station from an energy storage that would be charged during lower demand, e.g. at night or during the hours of the morning valley.

Chargers with energy storage - case study

For the prepared case study, a solution of a charger with an energy storage of 250 kW and a capacity of 1000 kWh was proposed, which would enable simultaneous charging of 6 cars with full power or 37 cars with economic power, regardless of the time of day, with effective energy management. Cars are charged with full power at fast charging stations sporadically, as this significantly reduces battery life. It is best to charge them systematically with a power of 4 to 7 kW for several hours. The proposed power supply system for the vehicle charging station is shown in the figure.

According to the analysis, effective energy management with the use of an energy storage will enable the construction of a charging system for electric vehicles in facilities with many parking spaces, both in buildings and in the area directly adjacent to them, and the fulfillment of the obligation to provide charging stations for these vehicles.

The size of the warehouse must be matched to the demand. The energy storage, apart from the benefits related to the reduction of the demand for connection power and the actually consumed power, allows for savings in the form of reduced outlays for the extension of the connection and its operating costs.

The energy storage as a "power guardian" can ensure that the ordered power is not exceeded, for which the car park managers incur fees, and thus also avoid the costs of additional penalties in the form of fees for exceeding this power. In addition, by managing energy flows, it can reduce electricity costs, as it can be charged at the time when energy is the cheapest and deliver this energy to the chargers at the time when it is the most expensive.

According to the analysis, effective energy management with the use of an energy storage will enable the construction of a charging system for electric vehicles in facilities with many parking spaces, both in buildings and in the area directly adjacent to them, and the fulfillment of the obligation to provide charging stations for these vehicles.

The size of the warehouse must be matched to the demand. The energy storage, apart from the benefits related to the reduction of the demand for connection power and the actually consumed power, allows for savings in the form of reduced outlays for the extension of the connection and its operating costs.

The energy storage as a "power guardian" can ensure that the ordered power is not exceeded, for which the car park managers incur fees, and thus also avoid the costs of additional penalties in the form of fees for exceeding this power. In addition, by managing energy flows, it can reduce electricity costs, as it can be charged at the time when energy is the cheapest and deliver this energy to the chargers at the time when it is the most expensive.