Hoku Corp.’s net loss widened sharply in the quarter ending June 30 as the company continued to run up expenses at its polysilicon plant under construction in Idaho.

Hoku lost $10.2 million, or 19 cents a share, in the quarter compared with a loss of $2.7 million, or 5 cents a share in the same period a year earlier, the Honolulu-based company reported.

Earnings also were weighed down by a decline in revenue, which the company generates primarily from the installation of photovoltaic electricity generating systems through its Hoku Solar subsidiary. Revenue dropped to $485,000 in the latest quater from $930,000 a year earlier.

Hoku is on track to deliver the first commercial shipment from its Pocatello polysilicon plant by year’s end, said CEO Scott Paul.

He said the company’s single-biggest expense last quarter was the $5.3 million it paid Idaho Power as part of an agreement to buy electricity from the utility for the plant.

The electric service agreement, signed in 2008 and amended in 2009, provides for certain minimum payments to Idaho Power each month regardless of whether the company is consuming any power. Hoku said the minimum payments were agreed to by both sides to guarantee that Idaho Power could service Hoku’s large power demand.