Indeed. It is all about averages. Any and all "energies" demand a resource of one kind or another. In your case Mr.Bartlett you want to utilize the Sun and Wind. Nothing new really. I mean humans beings have been doing this since, well since there has been humans! Just recently though for the purpose of generating electricity. Which I believe is what you wish to do. So with that in mind I'll get back to averages.
Average wind speed and average solar radiation for the purpose of generating electricity will obviously be higher or lower as determined by what region of the planet Earth we are referring to. Obviously the equator will have a greater average of solar radiation than say, the North or South poles. Like wise, a mountain top will have a greater average of high speed sustained winds than forrest floor would.
All common since, right? Right!
Even the amount of consumption of a resource is based on averages for a region. For example: Someone living near the North pole would have to rely on a greater average of energy for the purpose of heat, where as a person living near the equator might rely on a greater average of energy for the purpose of cooling or less for heat. Lets face it we humans adapt to warmer climates with much less effort than cold climates but it would seem that we prefer a place more "in between." Not to hot, not to cold, at least were averages over the seasons are concerned. With that in mind, here are some average wind speed and average solar radiation charts for the U.S.of A.
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/http://rredc.nrel.gov/wind/pubs/atlas/maps.htmlI believe what you will want to do is "predict" daily power production from Sun and Wind for your specific site on our Earth as averaged out over the year. This should give you something with which to compare with your electric utilities monthly bill.
In a "nutshell" one will spend an almost equal amount of money to harvest solar and wind energy and convert it into electricity as one would pay for a life time of electricity generated from any other source. We have commoddities brokers to blame for that. The reason for non-polluting renewable energies is precisely that. They are non-polluting and renewable. As opposed to other resources used for generating electricity such as burning coal.