The Tauranga-based electricity generator and retailer has been monitoring a site at Otaraia, in eastern Southland, for nine months.
Spokesman Graeme Purches said the location, about 15km south-east of Gore and between Mataura and Clinton, had good potential and plenty of wind.
TrustPower had secured agreements with landowners to build the wind farm if it was shown to be viable.
Resource consents for the wind farm, which crosses several properties, would be lodged soon, and the first power could be generated in two years.
It was likely the wind farm would generate at least 100 megawatts (MW) of power, otherwise it was hardly worth building, Purches said.
Monitoring would continue for two more months but initial analysis showed it was a good prospect.
"The wind's looking to be excellent. What we'll do is get to the end of the monitoring period, sit down and see exactly what we've got," Purches said.
"We'd certainly expect to have lodged a resource consent in the first half of this year. It could even happen towards the end of the first quarter."
Landowners were given an indicative contract if they wanted to have a wind farm on their property, he said. TrustPower paid them a fee to put a mast on their property and in return got the first option to build a wind farm there.
"With this project, the only people who are going to see the turbines are already on the sites," he said.
TrustPower is also working on its 200MW Mahinerangi wind farm about 40km west of Dunedin.
Purches said he expected the resource consents for that would be publicly notified in a couple of weeks, and a hearing would take place probably in May or June.
If that went well, TrustPower would aim to sign contracts for turbines by the end of the year.
While international demand for turbines was exceeding supply at present, the major manufacturers were building extra factories around the world and customers were hoping the waiting time for turbines would soon reduce to about a year.
State-owned electricity company Meridian Energy is the other major player preparing to generate wind power in Otago and Southland.
Its controversial $2 billion Project Hayes plan would see it install 176 turbines in the Maniatoto, 50km south of Ranfurly, in what would be New Zealand's largest wind farm, and one of the world's largest, generating up to 630MW.
Opposition to the proposal has come from farmers, residents, conservationists and artists, who believe the number and size of turbines would ruin the Central Otago landscape.
Just before Christmas, the Central Otago District Council received 1067 submissions on the project - 531 in support, including one from Environment Minister David Benson-Pope, 520 against and 16 neutral.