Nice work.  A different airfoil with thicker profile might help - there are several with Cl/Cd ratios similar to or better than the 4412 IMO.  The 4415 is one choice that might be considered a standard.

I have found the tricky thing to do is compensate for flat bits on a constantly changing airfoil, especially if it has a cusp as many of the really modern wind turbines do. I now have a stratigy and am working on larger blades.

If you would like to discuss this further, my user name -at- yahoo.com will get an e-mail to me.