After comparing [this solar cell sold by Sparkfun and [this panel by Brunton, it seems to me that the solar cell sold by Sparkfun delivers about twice the power output given that 0.280mAh x 8V = 2.24 Watts hence 2.24W x 4= 8.96 ~ 9 Watts. That is almost twice the stated 5W of the Brunton.
Did I get that right?](All Products – Brunton)](http://www.sparkfun.com/commerce/product_info.php?products_id=7840)