Earning as much as possible through remuneration by feeding in electrical energy into the public grid is not what Klar Folien GmbH wants to achieve with their PV system. The medium-sized company based the German region of Westerwald furthermore wants to achieve a high degree of self-sufficiency with its PV system, i.e. to be as independent as possible from a power supplier. And for most of the year this works to well over 90 percent. The crucial element is an intelligent lithium storage system by Sonnenbatterie.
On a typical month Klar Folien GmbH reaches an average energy self-sufficiency rate of 90 to 100 percent. This means that the company generates almost all consumed electricity with its PV system itself. The company, based in the small town of Dernbach in the Westerwald region reaches this high degree of self-sufficiency almost throughout the entire year between late February and the end of October, when the weather is good even till November. Only in December and January the company must obtain small amounts of energy from the grid.
REACHING FOR COMPLETE SELF SUFFICIENCY
THE KEY DATA
The key to this high degree of self-sufficiency is a 41-kWh Sonnenbatterie energy storage system that the company has owned since the end of 2012. With the Sonnenbatterie system the company is able to use more electricity from its PV plant. At a depth of discharge (DoD) of 70 percent 29 kWh of capacity are available for use. The storage system is integrated in a PV system with an output power of 100 kWp.
CASE STUDY: SONNENBATTERIE
The total power consumption of the company is at around 25,000 kWh throughout the year, which is about 2,000 kWh per month. In summer, when the days are long and the nights are short, the storage system is normally fully charged by the end of the morning, as it was not fully discharged during the night. Even on cloudy days, the PV system is able to cover the daily energy requirements, in this case the storage system is then loaded until the evening.
Screenshot from the Sonnenbatterie online platform. The yellow peaks is the produced pv energy while the red curve means discharging during the night. The green curve is charging the battery.
The intelligent storage system with a capacity of 40 kWh and a maximum output power of 18 kW.