Vattenfall's net loss came in at 19.8 billion kronor (2.1 billion euros, $2.3 billion), compared to an 8.3-billion-kronor loss the previous year, while sales eased one percent to 165 billion kronor.
“The major challenge in 2015 continued to be the impact that today's very low electricity prices have on Vattenfall's profitability and on the valuation of our assets,” Vattenfall chief Magnus Hall said in a statement.
“Continued falling prices and a nuclear tax corresponding to SEK 0.07 per kilowatt-hour have put Swedish nuclear power in a critical situation,” he said.
Vattenfall has had to write down over 36 billion kronor due to the early closure of two nuclear reactors in Sweden, which became unprofitable because of stringent safety requirements.
It has also experienced the depreciation of coal assets in Germany in 2015 as a consequence of the German government's target to curtail energy production with high CO2 emissions.
The firm has already said it will shed 1000 jobs in northern Europe.
The closure of the brown coal plants in Germany ignited hot political debates in both Sweden and the northern European nation amid shift towards more non-renewable energy sources in both countries.
Sweden's Green Party called on the previous centre-right Swedish government to avoid allowing Vattenfall to sell on the sites, arguing that the move amounted to encouraging other firms to continue producing emissions that harm the environment.