The new company will have a combined track record of 463MW of battery storage projects across 48 projects in 13 countries, AES said.
It will be based in Washington DC, US, with offices in Germany. The joint venture is expected to launch by the end of 2017, subject to regulatory approvals.
"As the energy storage market expands, customers face the challenge of finding a trusted technology partner with an appropriate portfolio and a profound knowledge of the power sector. Fluence will fill this major gap in the market," said Ralf Christian, CEO of Siemens' energy management division.
The joint venture will offer Siemens' Siestorage battery system and AES' Advancion lithium-ion solution.
AES claimed to have deployed the largest lithium-ion storage system in the world at a site in Califonia, for San Diego Gas and Electric company. The 30MW project is set to be surpassed by Tesla's recently awarded South Australia project.