TOKYO—Panasonic Corp. said the acquisition of a majority stake in Sanyo Electric Co. will weigh on its full-year results and change its future investment priorities from flat-panel televisions to energy-related products like electric car batteries and solar panels.

In December, Panasonic completed its 400 billion yen ($4.5 billion) acquisition of a 50.2% stake in Sanyo, the world's largest maker of rechargeable batteries by market share and a major manufacturer of solar panels, elevating its energy business as a main pillar of future revenue alongside its traditional consumer electronics business.

The unprofitable Sanyo initially will drag on its earnings. For the current fiscal year ending March 31, Panasonic said the Sanyo will add 10 billion yen in net loss even though it will boost revenue by 375 billion yen. Panasonic kept its full-year net loss outlook unchanged at 140 billion yen, although it said it would have narrowed the loss to 130 billion yen if not for the Sanyo deal.

"Up until now, we've focused on investing in flat-panel TVs, but we're going to shift somewhat to energy and environmental products going forward," said Makoto Uenoyama, Panasonic's chief financial officer.

One part of its existing energy business is a car battery joint venture with Toyota Motor Corp. Panasonic holds a 20% stake in Panasonic EV Energy, which makes car batteries for Toyota's hybrid vehicles. Mr. Uenoyama said Toyota's recent troubles could spill over to Panasonic's results in the next fiscal year if the problems linger, but he didn't elaborate further.

Panasonic's main electronics business has been mired in a slump, forcing it to shutter plants and cut jobs to reduce costs. Panasonic said it now expects to cut its annual fixed costs by 370 billion yen in the current fiscal year, an increase of 42% from a prior target.

Aided by cost-cutting, Panasonic returned to the black in its fiscal third quarter ended in December, with a net profit of 32.26 billion yen compared to a loss of 63.12 billion yen in the same period a year earlier. On an operating basis, profit nearly quadrupled to 101 billion yen. Revenue was up 0.4% at 1.887 trillion yen in the quarter.

Panasonic's net profit was worse than a mean estimate for a profit of 46.5 billion yen by analysts polled by Thomson Reuters. On an operating level, Panasonic beat analysts' estimates for a profit of 92.38 billion yen.

Panasonic's earnings rebound comes on the heels of improving results from across the electronics industry. Samsung Electronics Co. and Sharp Corp. posted a return to profit in the last three months of 2009, while Sony Corp. reported an eight-fold increase in net profit and a better full-year outlook.

For the full year ending March 31, Panasonic raised its operating profit outlook to 150 billion yen from the October forecast of 120 billion yen while raising its revenue outlook 5% to 7.35 trillion yen.

Like its competitors, Panasonic has slashed procurement costs and cut expenses across the company to cope with relentless declines in prices for televisions and other consumer electronics. While the global economy has shown some signs of improvement, Panasonic has yet to see overseas demand return to pre-downturn levels.

In Japan, where Panasonic gets more than half of its revenue, it has been helped in part by the government's Eco-Points stimulus program which has encouraged consumers to buy new TVs as well as home appliances with lower energy consumption.

Panasonic's core electronics business posted a 5% increase in sales, boosted by a 23% jump in television sales and surge in demand for Blu-ray players. Appliance sales were led by brisk demand for refrigerators and air conditioners.

—Juro Osawa in Tokyo contributed to this article.

Write to Daisuke Wakabayashi at Daisuke.Wakabayashi@wsj.com