Here's a shield calculator that should come in handy.

There's two actions;
calculating the Power and Parameter
calculating the desired Capacity and Charge rate (Total time from 0 to max in seconds)
In the attachment below The link, because I can't get it any lower than 800kb
No idea why as it's nothing but script, no graphics.
http://www.mediafire.com/?mygye3dnnwy
Yes I know I spelled it Steller instead of Stellar, the piece of shit wouldn't let me change the name after I uploaded it or let me upload it more than once.