The company's operating earnings for the year were $330.7 million, up 19% on the $227 millon in the previous corresponding period.
Underlying earnings, which many companies are now using as a more accurate measure of their profit, were $122.9 million compared with $108.5 million in the previous corresponding period (pcp), a rise of 13%.
Revenue for the period was $993.5 million compared with $811.7 million in the pcp.
A final dividend of 21c per share would be imputed to 14 cps. Together with the interim dividend of 20cps, the total payout of 41cps was a 2.5% increase on the pcp.
However, chairman Bruce Harker said in a statement the earnings, while well ahead of those in the 2014 financial year, were at the lower end of expectations.
He named the impact of the strong New Zealand Australian dollar exchange rate on Australian earnings as a factor as Australian earnings contributed a larger proportion of group earnings following the completion of Snowtown Stage 2.
Also, poor wind generation in the second half of the financial year at the Snowtown and Tararua wind farms hurt earnings, along with weak North Island hydro generation as the result of low inflows due to drought conditions during the fourth quarter.
Trustpower's key strategic priorities were to increase value in its retail business through the roll out of its multi product offering to a wider customer base and to position itself in Australia to develop further wind generation projects, Dr Harker said.
Over the next 12 months, Trustpower was targeting further customer growth as well as increased conversion of existing customers to multiple utility services.
Trustpower now had three wind projects in South Australia, Victoria and New South Wales at various stages of development approval processes.
The company continued to assess other renewable development opportunities in Australia with the aim of increasing the scale of its developments, where possible. That included considering the potential of grid connected solar as both a competing and complementary technology to wind generation.
''Pleasingly, structural risk for the energy industry in New Zealand appears to have stabilised following the 2014 general election.''
The outlook for Trustpower remained positive, he said. The 2016 financial year would be the first full year of earnings contribution from Snowtown Stage 2.
Trustpower expected to increase its retail customer base at a similar rate to the 2015 financial year and continue to increase the number of multi product customers, improving retail profitability.
The ongoing high level of the NZ Australian dollar exchange rate was expected to continue to provide a partial negative effect to earnings in the coming year, Dr Harker said.
