Quite interesting remark. However, I'm not saying the savings from producing more wind are not real. They are very real, because you avoided using other means of production, potentially fossil fuels. So that's good.

On the other hand, saying that you basically got your Macbook for free (saved all the money, i.e. ran exclusively on wind) can only work if you didn't spend anything else. Saving 999$ but spending 200 more (i.e. also having coal) and not counting it because you somehow earned more money somewhere else (i.e. exported it) is not what I call proper bookkeeping.