According to their website, an Albany NY based company called AWS True Power has released open source wind farm design software that is free to download and use. The free software is called AWS Openwind, and anyone is free to join the community of users and make improvements to the software. You can download the software, watch instructional videos and view tutorials on the AWS Openwind website. You can also see screen shots of the software here.
If you need advanced features like deep array wake models, grid layout, or optimization for cost of energy, AWS has an enterprise version of the software available for sale...but I'm thinking that for my first backyard windmill, the free version will do the trick.
If you have used the openwind software and have any comments about it, I'd love to hear them.
I want to develop a free tool with a friendly user interface that will allow casual users to optimize windmill airfoils, siting, and generator parts for construction and use at their homes. I have used CNC rapid prototyping technology for custom airfoils. If you are interested in any aspect of optimizing home wind power generation I would love to hear from you.
The Open Source Tech Revolution wind power resource page is here.