The revisions sent the company's shares to their lowest level in a year and a quarter, trading down 11 percent at 24.65 euros by 1212 GMT.
SMA had already warned in August that the top end of its profit guidance was ambitious amid pricing pressure from Chinese rivals that seek to dump their products outside their collapsing home market.
SMA said third-quarter sales were above 220 million euros ($240 million), but that was down from 270 million euros in the year-earlier quarter, while its order backlog shrank 6.5 percent from a year earlier to 588 million euros.
The group now expects to post 2016 sales of 900 million to 950 million euros and earnings before interest and tax (EBIT) of 60 to 70 million euros.
That is below its previous guidance for sales of 950 million to 1.05 billion euros and EBIT of 80 to 120 million euros. It also fell short of analyst consensus for 1.02 billion and 95 million euros, respectively.
German peer SolarWorld also warned last week it would not achieve its 2016 sales and profit goals due to a collapse in demand in China.
SMA is due to publish full third-quarter financial results on Nov. 10.