Anyone have a formula for cost-benefit analysis of buying a windmill for power generation?

1.8kW wind generator... running at 25% load produces 1.8kW * 0.25 * 24hours/day * 365days = 3942kWh/year.

Let's make that 4000kWh. You can probably sell that electricity for $0.07/kWh. Makes a total income of $280/year.

5% annual interest on $13000 is $650. Yep, you are going to lose roughly $370 per year... not counting running cost for repairs etc.

Sounds like a great business proposition? I don't think so.

If you are just offsetting your own consumption and electricity prices are around $0.15/kWh, you might just brake even. Barely...

In general I would not think that wind below 250kW is a good investment. Try 10MW+ wind parks and you are probably talking about a sound business model.

And some people simply want to do their share to improve global warming. They don't need to be concerned about the financial downside. If you are one of them, go for it. It will make you feel a lot better.

First you need to know what you annual electrical consumption is. You also need to know what you pay per kilowatt for that power.

Next you need to know the total installed cost for the windmill with its accessories, batteries, etc.

Finally how much interest can you make on your $13,000 if you put it in the bank. Unless you save more on electricity than you can make investing the same $13,000 then you shouldn't buy the windmill.