* Weak economy hits sales, but solar demand stays strong
* To continue pursuit of acquisitions, joint ventures
* Stock down 5 pct after tumbling nearly 10 pct
OTTAWA, Oct 8 (Reuters) - 5N Plus Inc VNP.TO shares fell as much as 9.7 percent on Thursday after the maker of specialty metals and solar power products said the tough economy hurt quarterly sales and earnings, which lagged analyst forecasts.
5N said late on Wednesday that demand for its solar products remained strong in the first quarter, but sales for all other products weakened. The company's other markets include radiation, thermoelectric and optical storage.
The company produces specialty metals for electronic applications and is one of the world's biggest manufacturers of cadmium telluride, used in solar power panels.
5N said earnings fell to C$3 million ($2.8 million), or 7 Canadian cents a share, from C$4.1 million, or 9 Canadian cents a share, a year earlier.
Analysts had expected a profit of 10 Canadian cents a share on revenue of C$18.7 million, according to Thomson Reuters I/B/E/S.
Revenue rose 14 percent to C$16 million from the same period last year, but it represented an 11 percent decline from the fourth quarter.
"In spite of this weakness, its backlog did increase to C$57 million from C$52.2 million, due to increased contractual commitments from First Solar," said Jennings Capital analyst Marc Charbin in a note.
Solar panel maker First Solar Inc (FSLR.O) accounted for about 85 percent of first-quarter sales, up from 78 percent in the fourth quarter, said Dundee Capital Markets analyst Ian Tharp.
Montreal-based 5N closed the quarter with C$65 million in cash and said it will continue to "aggressively pursue" acquisitions and joint ventures to spur growth.
The company announced in late August a joint venture with Amerigon Inc ARGN.O to develop and manufacture advanced thermoelectric materials used in heating, cooling and power generation applications.
5N shares fell as low as C$5.50 on the Toronto Stock Exchange on Thursday before edging up to C$5.80, for a decline of 29 Canadian cents, or 4.8 percent. The stock has gained about 29 percent in the last 12 months.
$1=$1.05 Canadian Reporting by Susan Taylor; editing by Rob Wilson