* Second-quarter loss $0.59/shr vs profit $0.16/shr year-earlier
* Second-quarter revenue down 28 pct to $348.2 mln
* Sees third-quarter gross margin between 2 pct and 5 pct
Aug 15 (Reuters) - Canadian Solar Inc reported a wider-than-expected loss on lower margins and said gross margin would continue to decline in the current quarter, sending its shares down 15 percent before the bell.
Solar companies have been stung by a sharp drop in panel prices over the last 18 months, which has shrunk their profit margins and forced many to close factories.
Canadian Solar, which makes solar wafers, cells and panels, reported a net loss of $25.5 million, or 59 cents per share, for the second quarter, compared with a profit of $7.1 million, or 16 cents per share, a year earlier.
Net revenue fell to $348.2 million from $481.8 million.
Analysts on average had expected a net loss of 30 cents per share on revenue of $393.9 million, according to Thomson Reuters I/B/E/S.
The operating margin was negative 0.9 percent in the second quarter, compared to positive 5.2 percent a year earlier. Gross margin slightly fell to 12.4 percent.
The company expects shipments of between 390 megawatt (MW) and 420 MW for the current quarter, with gross margin between 2 percent and 5 percent. The company had shipped 412 MW in the second quarter.
Shares of the Ontario-based company, which closed at $3.04 on Tuesday on Nasdaq, were down at $2.60 in premarket trading on Wednesday. They have fallen 62 percent in the last one year.