NEW YORK — Shares of Hoku Scientific Inc. surged yesterday after the company announced a new agreement to supply Solarfun Power Holdings Co. with polysilicon, a material used in making solar cells.

The deal is worth as much as $306 million, with the first shipments set for the second half of 2009. Since June, Hoku has signed polysilicon supply contracts that could be worth more than $1.5 billion through 2019, including an agreement with Suntech Power Holdings Co. Ltd. that could reach $678 million.

Hoku, which is building a polysilicon plant in Idaho, also has contracts with Solar-Fabrik AG and Sanyo Electric Co. Ltd. Shipments to each will begin in 2009.

Hoku shares jumped $2.30, or 38.9 percent, to close at $8.22 on the Nasdaq Stock Market.

Cowen & Co. analyst Rob Stone said buyers are gaining confidence in Hoku, which is already planning to expand the capacity of the Idaho plant.

"The fact that Hoku was able to secure an expansion-phase contract, in addition to deals already in place with Sanyo, Suntech, Solar-Fabrik, suggests that customers view the Hoku plant as a credible source of future poly supply," he said.