DIY windmill will certainly help you save. The associated costs are very marginal in terms of fuel consumption and system maintenance. Many articles have been written about windmills and according to experts, the amount of energy we can get from the wind is a lot greater than what the world is currently consuming. Truly, there is a significant cost reduction in using a DIY windmill than the ones that are commercially available.
This also means that aside from cost saving, the availability of wind power is out of the question; it will never run out. The problem is that there might be an impact to the atmosphere if wind power is harnessed in a global and massive scale. There might be repercussion that we are unaware of but right now, there are no facts that will show what damages could happen but studies are in progress.
The biggest challenge or disadvantage of using DIY windmill is battery maintenance. Although it was mentioned earlier that maintenance is not costly, it is a challenge to rewire batteries of wind turbines. The hassle is that you need to take the battery to a shop or person who specializes in battery rewiring. For now, the alternative you can have is to have two batteries so you have a spare if the other one conks out.
As a DIY windmill enthusiast, you need to know that an average battery can produce 300 volts. This should give you an idea what kind of power you can generate and for how long. Many DIY windmill apparatus uses 23-24 volts at an average. Although there are batteries that can contain more energy, these are also more costly than the ordinary ones. This is a choice you have to make depending on the energy you consume and depending on the energy your windmill can produce.