NZ Windfarms has reported a loss of almost $9 million for the 12 months to the end of June, but it's an improvement on the $25 million loss it made last year.

The company said the result is disappointing and reflects a lack of wind during the year, as well as weaker spot market wholesale electricity prices.

It generated 31% less power than budgeted, due to the lack of wind and this is the main reason for its poor performance in the last financial year.