The brutal winter weather boosted revenue for many PJM companies in the first quarter, even while some were absorbing huge costs from strategy shifts.

Here’s an overview of the results from the major companies doing business in PJM.

NRG

NRG Energy, which closed on three acquisitions in the quarter, reported a loss of $56 million despite record earnings before interest, taxes, depreciation and amortization (EBITDA) of $816 million, more than double the $383 million cash flow it reported for 2013. More than half a billion of its earnings — $525 million — were from sales in the Northeast.

Duke

Duke Energy, while showing a $97 million loss from its pending sales of 13 coal-fired plants in the Midwest, still posted earnings of $1.17 per share, a 15-cent jump over the same period last year – primarily from winter energy sales.

Pepco

Pepco Holdings Inc. also showed its investors some love, turning a profit of $75 million, or 30 cents a share, compared with a year-earlier loss of $430 million, or $1.82 a share, on increased sales of electricity and gas.

Exelon

The same day Exelon reported an agreement to acquire Pepco parent PHI, for $6.8 billion, Exelon reported earnings of $90 million, or 10 cents a share, compared to a loss of $4 million, or 1 cent a share, for the same period last year. CEO Christopher Crane credited cold-weather sales at its PECO and Commonwealth Edison units for an extra bump in revenue.

Revenue shot up to $7.24 billion, from $6.08 billion last year.

“Our nuclear assets in particular contributed to grid reliability during the polar vortex, while our strategy of matching generation to load allowed us to capitalize on the increasing volatility in power markets,” Crane said.

Earnings would have been higher but for increased storm restoration costs, especially in the PECO service territory, and increased PJM capacity prices, Exelon said. These factors were partially offset by rate increases at BGE and ComEd and cold weather-related revenue in both the PECO and ComEd territories.

FirstEnergy

Cold weather drove FirstEnergy’s numbers, too. The company reported earnings of $208 million, or 50 cents per share, for the first quarter of 2014, compared with $196 million, or 47 cents a share, for the same period last year. Revenue was $4.2 billion, up 13.5%, compared with $3.7 billion for the first quarter of last year. Sales to residential customers increased 11% over 2013 while deliveries to commercial customers increased 6%. Industrial customers increased by 1%.

“The strong performance of our distribution and transmission businesses … partially offset the impact of extremely challenging market conditions on our competitive business,” CEO Anthony J. Alexander said.

American Electric Power

American Electric Power reported first-quarter earnings of $560 million, or $1.15 per share, up from $363 million, or 75 cents a share, for the same period last year, an increase of about 55%.

“We experienced the coldest temperatures in 35 years during the first quarter, which led to strong residential and commercial demand for the period,” CEO Nicholas K. Akins said. “Even when this demand is adjusted for weather, we saw improvement across residential and commercial customer classes for the second consecutive quarter.”

Dominion Resources

Dominion Resources, which sold its unregulated retail business to NRG Energy last month for $165 million, said its first-quarter earnings fell 23%, from 86 cents a share a year ago on $495 million to 65 cents a share on earnings of $379 million.

It said much of the slide was attributable to its exit from its unregulated business and its “repositioning” in the regulated market.

Mark F. McGettrick, Dominion’s chief financial officer, credited the winter weather for an additional 5 cents per share in earnings, however. At regulated Dominion Virginia Power, EBITA for the first quarter was $269 million.

PSEG

Public Service Enterprise Group reported a 21% increase in first-quarter earnings, with a profit of $386 million, or 76 cents a share, compared to $320 million, or 63 cents a share, for the same period last year.

The company’s 2013 results were hurt by restoration costs following Superstorm Sandy.

“We delivered on many fronts during the quarter,” CEO Ralph Izzo said. “I don’t need to tell you how cold it was this winter. The record low temperatures challenged our employees, our equipment and our markets.”

PPL

PPL Corp.’s first-quarter earnings slipped 24% compared to the same period in 2013, dropping from $413 million, or 65 cents a share, for 2013 to $316 million, or 49 cents a share. The results reflect $207 million in “special item charges,” most resulting from “adjusted energy-related economic activity.”

Operating results were rosier, with earnings from ongoing operations totaling $523 million, or 80 cents a share, a 15% increase over 2013 ($454 million, 71 cents a share).

“The unusually cold winter weather resulted in increased sales to customers in Pennsylvania and Kentucky, and our competitive generating plants in the PJM Interconnection operated well during the periods of high electricity demand,” CEO William H. Spence said.

AES

The weather hurt earnings at AES Corp., parent company of Ohio’s Dayton Power and Light Co. The company reported earnings per share of 24 cents on revenue of $4.26 billion, a drop of 3 cents from the year before on revenues of $4.15 billion. AES pointed to a 3-cents-per-share “negative impact from forced outages and lack of gas availability during the extremely cold weather in January at DPL.”

Earnings also suffered from a drought in South America, where the company has significant hydropower holdings.

The company recorded a $307 million charge ($0.41/share) for goodwill impairment at DPL in the fourth quarter of 2013, citing “lower than expected PJM cleared capacity prices for 2016/2017, lower expectations of future PJM capacity prices and lower projected energy margins.” AES bought DPL in 2011 for $3.5 billion.

Like many other utilities, AES has said it is going to concentrate on regulated business, and it is looking to sell generation assets. The company, which derives 75% of its earnings from outside the U.S., announced late last year that it was shedding assets in Cameroon, India and Poland. It also announced earlier this year that it will sell DPL’s generation fleet rather than spinning it off into an unregulated subsidiary.