The Voerde smelter, which produces 115kt/y of aluminium, declared insolvency on May 4.
Germany's metals industry association said the Voerde case illustrates the danger to German metal output from the country's high electricity prices.
Agreement has been reached with power utilities about continued electricity supplies to Voerde without the financial guarantees previously requested, provisional administrator Frank Kebekus said in a statement.
Continued power supplies were a fundamental requirement for continued operations, he said. The plant's main aluminium production units, the anode and electrolysis sections, are continuing full operations, he said.
Kebekus said he hoped to find a buyer for the main plant, based in the central German state of North Rhine-Westphalia, in the near future.