I am just a little confused by your question so, please, bear with me.
At first I thought you wanted to know how to figure the area of an equilateral triangle, but then I thought, no, everybody that has graduated high school or its equivalent knows how to do that. The simplest being; half the base times the height. For those that may not have graduated high school yet or perhaps were out sick that week -
http://www.clarku.edu/~djoyce/trig/area.htmlI then remembered seeing a photovoltaic modules that was actually built in the shape of a triangle.
http://www.renewableenergyworld.com/rea/partner/products/view?id=22184But now we need some dimensions. Now that we know there is such a product I am reasonably sure that Sharp builds corresponding square PV modules to mate up to the triangular PV modules and it would be reasonable to assume that Sharp would have an area calculator for there triangular PV modules systems. Wow! I think I know now what your are looking for and its not easy. So far I have not been able to find the corresponding module or anything except dimensions. My best guess would be to contact
www.sharpusa.com with your specific diemensions and ask them. Evidently its a big secret they want to keep for themselves.