en.Wedoany.com Reported - Freen has launched a hybrid energy storage solution combining small vertical axis wind turbines and sodium batteries to address the generation shortfalls of solar self-consumption systems during winter and cloudy days.
One year after the major blackout in Spain in April 2025, the country's energy storage industry has developed rapidly. According to data from Red Eléctrica, Spain had only 28 MW of battery installed capacity in April 2025, reaching 193 MW by April 2026, a 589% increase in one year, with the combined capacity of projects under development also growing by 464% year-on-year. In the self-consumption sector, according to the Spanish Renewable Energy Association (APPA Renovables), residential storage capacity grew by 155% in 2025, while the commercial and industrial sectors saw a 95% increase. Freen believes that wind energy can serve as a complement when solar power cannot generate due to consecutive cloudy days and the local grid is saturated.
Photovoltaic solar is the most competitive distributed generation technology in Spain, with an average annual generation of approximately 1350 kWh per kWp installed. However, its weakness lies in generation being concentrated during daytime and warmer months, with low output on cloudy days and no generation at night. Studies on the Iberian Peninsula show that in most regions, the correlation between wind and solar energy is negative, meaning that wind tends to strengthen when solar radiation weakens. In the northwestern zone of the peninsula, nighttime wind power can account for approximately 35% of the annual generation of a hybrid system.
The Freen-9 is a vertical axis wind turbine (VAWT) with a rated power of 9 kW, featuring a three-blade Darrieus aluminum rotor with a diameter of 6 meters and a swept area of 24 m². Its cut-in wind speed is 3.5 m/s, rated wind speed is 14 m/s, cut-out wind speed is 17 m/s, and survival wind speed is 36 m/s. The vertical axis design allows it to capture wind from any direction without active yaw, with a sound level of 45 dB at 100 meters, and it can be installed on towers ranging from 4 to 18 meters. The generator is a permanent magnet direct drive with no gearbox, and is equipped with remote monitoring and an electromagnetic braking system. Under the Spanish regulatory framework, the 9 kW power rating qualifies as a low-power installation subject to simplified procedures; self-consumption installations with no surplus electricity or with surplus electricity not exceeding 100 kW do not require end-users to proactively handle formalities.
According to the Wind Atlas of the Institute for Energy Diversification and Saving (IDAE), at a height of 30 meters, the Canary Islands have the greatest wind energy potential, with a capacity factor of approximately 14-18%, followed by Cantabria, Andalusia (the Tarifa and Almería corridors), Galicia, and the Balearic Islands. In regions such as Navarre, Catalonia, Castile and León, or Aragon, values range between 12% and 14%. At a height of 10 meters, even in the best areas, the capacity factor is typically below 10%. The most stable wind corridors include the Ebro Valley (Cierzo wind) and the Strait of Gibraltar (Levante and Poniente winds).
Freen's energy storage system uses sodium batteries, offering two configurations: the Freen-BSL 7.6 kWh (low voltage, 48 V nominal) and the Freen-BSH 10 kWh (high voltage, 288 V nominal). Both use layered sodium oxide chemistry, claiming a lifespan of over 10,000 cycles (at 60% capacity) with a 10-year warranty. The BSL battery can charge and discharge at a maximum current of 100 A, with a power of 4.8 kW; the BSH offers a maximum power of 5 kW, a voltage range of 144-379 V, a discharge temperature range of -40 to +60 °C, and an efficiency exceeding 97%. The system is designed for indoor installation (IP20).
Freen's solution connects the Freen-9, photovoltaic panels, and batteries to a hybrid inverter, whether in grid-tied or off-grid configurations. The operating logic is: during the day and warmer months, solar energy meets consumption and charges the batteries; at night, on cloudy days, and in winter, wind energy takes over. Freen is a European manufacturer of small wind turbines and energy storage systems, with its headquarters and production base located in Estonia, primarily developing vertical axis turbines and sodium batteries for residential, agricultural, and commercial applications.
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