Why do wind generators need a constant power draw?

Question

I was researching wind generators, and I kept reading something about wind generators needing a big battery bank (300-400 Ah) or a charge controller with a dump or power diversion mode to maintain a draw on the generator at all times.

Answer 1

Some wind generators will overspeed if they don't have a load.  Even if they don't, using a charge controller with a dump load lets you use energy that would otherwise be wasted; even if the use doesn't gain you much, it's better than not having the energy at all and you didn't have to pay extra to get it.

Answer 2

It's not constant power draw.  The voltage is that of the battery bank, the current is variable, depending on wind speed.  You don't even need batteries if you use a grid-tied inverter, which I design.

Answer 3

The generator doesn't care whether you  draw power or not.  The issue with most wind generators is that when it has the  most power to generate, there is very little demand from  the owner, and so the power must either be stored, sold to the utility  company, or lost.  So, if you've spent all that money, you'd not want to waste all that generated power.  You can store it in batteries, but there are substantial losses, and you'd need lots of batteries, which are expensive and have limited lifetime.  Therefore, if you can, you want to sell the generate power to the electric utility company.  Then, when you  need to use electricity, you've  essentially paid for it through the  power that you sold from the generator.  In general, you'll come out slightly  ahead, since the power sold is usually during the day, at higher prices, than when you buy, which is usually at night, at lower prices.