50 kVA / 130 kWh Commercial Solar Battery Storage Project in Poland

GSL ENERGY installed a GSL-BESS-50K130 commercial battery energy storage system alongside a ground-mounted solar array in Poland. The outdoor cabinet contains 13 lithium iron phosphate (LFP) battery modules with a combined nominal capacity of 133.12 kWh. The system is designed to store surplus solar generation for later use and discharge when the site needs to limit how much power it draws from the grid.

The battery cabinet and its 50 kVA platform

The installation record shows the cabinet beside the PV array. With both doors open, two battery stacks are visible. Six modules sit beneath the high-voltage control box on the left, with seven on the right. Each GSL-HV51200 module is rated at 51.2 V and 200 Ah, equivalent to 10.24 kWh. Connected in series, the 13 modules provide a nominal battery voltage of 665.6 V and a total nominal capacity of 133.12 kWh. The catalogue designation for this configuration is 130 kWh.

Using midday solar to manage later demand

When the solar array produces more electricity than the site is using, the battery can store some of the surplus. As solar output falls or site demand rises, the battery can discharge to supply part of the load. For peak shaving, the energy management system (EMS) can use grid meter readings to trigger discharge as grid import approaches a configured threshold.

Sizing the battery for that job depends on both the size and duration of the peak. If a site needs to cut grid import by 20 kW for two hours, the battery system must deliver 40 kWh on the AC side. A shorter peak may need less energy but a higher discharge power. The 50 kVA figure is the platform's apparent-power rating. Available active power in kW and usable battery energy determine how long the cabinet can sustain a given reduction in grid import.

What to measure on the Polish electricity bill

Contracted capacity (moc umowna) and the capacity-market charge (opłata mocowa) call for different measurements. For contracted capacity, track the site's highest grid import against its agreed limit. For the capacity-market charge, review how much electricity the site imports during the applicable billing periods and how the tariff treats that consumption. A short discharge may trim the highest peak, while a longer discharge may shift more grid purchases away from a billed period.

The project's financial outcome depends on its load profile and tariff. Measured savings have yet to be published.

Two checks before commissioning a similar installation

Winter charging. The product specification lists a charging temperature range of 0 to 55 °C and a discharge range of −20 to 55 °C. If a site relies on early-morning or overnight charging in winter, check how the cabinet maintains battery temperature and when the battery management system permits charging.

Grid connection. Verify the installed inverter model and applicable documentation with the local distribution system operator. Where the Polish NC RfG certification procedure applies, check the equipment entry and certificate acceptance dates in the PTPiREE register.

Frequently asked questions

How much energy does the GSL-BESS-50K130 store?

Its 13 battery modules provide 133.12 kWh of nominal energy. Usable energy depends on the configured state-of-charge limits. Conversion losses also affect how much electricity reaches the AC loads.

Can the 50K Series work with an existing solar inverter?

The platform supports AC and DC coupling. An AC-coupled design can retain the existing solar inverter and connect the battery system on the AC side. A DC-coupled design can connect suitable PV strings to the platform's solar inputs.