* H1 underlying NPAT A$375 mln vs A$336 mln expected by analysts
* H1 net loss A$449 mln vs A$308 mln net profit previous year
* Makes $20 mln investment in U.S.-based Sunverge Energy
* Origin, Telstra and others are also in batteries business (Recasts; adds analyst quote and market context)
By Byron Kaye
SYDNEY, Feb 10 (Reuters) - A week after quitting a gas business hammered by depressed oil prices, Australia's AGL Energy AGL.AX fast-tracked on Wednesday a shift into another competitive market by buying a stake in U.S. solar battery maker Sunverge Energy.
The move, announced by AGL as it posted a A$449 million ($317 million) half-yearly loss on its exit from gas exploration, intensifies the rivalry between the country's No. 2 energy retailer and larger Origin Energy ORG.AX , which in 2015 began selling the batteries of Tesla Motors Inc TSLA.O . telecoms giant Telstra Corp Ltd TLS.AX has also said it is starting a renewable energy unit focusing on solar and battery technology, while smaller manufacturers like Sydney-listed RedFlow Ltd RFX.AX and indigenous-owned AllGrid Energy have developed battery products.
"We could have built a capability internally and maybe in three years we would have had an OK technology. We decided to go out and view the market and invest in somebody who's the best globally in it," AGL Chief Executive Officer Andy Vesey told Reuters in a telephone interview.
Vesey added that AGL's $20 million investment in Sunverge would give it exclusive distribution rights in Australia. AGL did not specify how much of Sunverge it now holds but said it was a minority stake.
San Francisco-based Sunverge has been supplying products for a Queensland government renewable energy trial and its financial backers include Australia's Southern Cross Venture Partners.
"AGL has a lot of customers and has planned its entry into that market quite carefully so it has reasonable prospects," said UBS utilities analyst David Leitch, referring to the company's 3.7 million customers.
AGL also said it would start a renewable energy development fund with an initial investment of A$200 million. The company will tap Australia's A$2 trillion pension fund industry for investments with a target of raising up to A$3 billion.
The company's net loss for the six months to end-December compared with a A$308 million profit a year ago. Without writedowns associated with its now-aborted gas projects, underlying earnings rose 24.2 percent to A$375 million, better than analysts' expectations of A$336 million.
It also declared an interim dividend of 32 Australian cents per share, up two cents per share from a year ago, and said it expected full-year underlying profit towards the top of a A$650 million to A$720 million range.
AGL shares were down 0.2 percent in afternoon trading, better than a broader market's .AXJO 1 percent decline. ($1 = 1.4184 Australian dollars)