Shares of Power-One Inc. fell nearly 10 percent Thursday after the Camarillo solar power equipment maker announced it expects to lose up to $15 million in the fourth quarter. The company said lower-than-expected product demand in European markets led to the loss. Analysts had predicted a profit of $11.2 million. The company makes equipment that converts solar power from direct current to alternating current that is usable by customers. “Greater than anticipated weakness in key European markets was the chief contributor to revenue being below our expectations,” said Chief Executive Richard Thompson, in a statement. “We continue to believe that Europe will be a major market for solar power over the long-term. However, near-term demand will be more volatile as the market adjusts to the recent changes in the PV incentives.” The company will announce its fourth quarter financial results Jan. 31 after market close. Power-One said the loss could range from $13 million to $15 million. Shares of Power-One lost 42 cents to close at $3.92 on the Nasdaq.