Energy storage plays an important role in the process of energy transition , due to their application, the level of independence from the distribution system operator increases. Proportionally to the development of storage system technologies , the variety of offered systems and the level of complexity of applied solutions are growing . Optimizing a solution tailored to the individual needs and preferences of end users can be challenging . This article provides practical tips and suggestions to help you make the right choice .

Battery capacity is defined as the ability of a cell to store and return an electrical charge . It is expressed in watt-hours [Wh] . The value of capacity depends on the operating environment and the voltage at the battery terminals . Using the concept of capacity, it is possible to determine the length of time a battery can supply an electrical circuit with a specific current .

Power, expressed in kilowatts [kW] , is the amount of current a battery can deliver or draw at one time . Having the information on Voltage [V] and cell capacity [Ah] following the multiplication of the two values, we can determine the power that the battery will deliver to the device in a certain unit of time .

 

To determine the right capacity and power of an energy storage system, we need to match the solution to the customer’s needs and preferences . Here are some questions to consider:

How much energy does the customer currently consume, and what is the capacity of the electrical equipment to be powered by the energy storage?

How does the end customer currently manage its electricity, what is its self-consumption coefficient?

It is also necessary to take into consideration the customer’s future plans, such as the installation of electric car charging stations , heat pumps , air conditioners , and other energy-saving solutions . Also, of course, an important aspect in the overall calculation is the alignment of the energy storage installation with the existing or planned photovoltaic installation .

 

After obtaining answers to the above questions, you can proceed to calculate the appropriate energy storage capacity . It is assumed that 1 to 1.5 kWh for each kilowatt peak power of the photovoltaic installation (kWp) can be taken as a starting value for calculating the capacity . This means that for a 6 kWp photovoltaic installation, the recommended energy storage capacity is 6 to 9 kWh . Of course, it all depends on the demand and use of energy at particular times of the day .