Just as a solar power system in your home would need deep cycle batteries to store energy for later use so would a wind turbine or windmill. The draw back with the batteries is their expense, finding a way to save on these would be a great benefit to the homeowner. You need them or you will not have any standby electricity for extended cloudy conditions.
You may be paying up to $250 per battery for some batteries, you can get those nice sealed batteries that do not have to be vented outside. Otherwise you can get deep cycle batteries like used in golf carts. These are cheaper but when you need a bank of them the cost adds up.
A better alternative if you are short of cash is to check around at the golf course maintenance facilities, boat yards or anywhere golf carts may be in use. They may have some old batteries laying around that they would be glad to get rid of. There may be nothing wrong with them, they may need to be reconditioned to get them back in shape.
There are a few methods to recondition batteries that you can do at home. One is to replace the fluid in the batteries cells with EDTA which is ethylene diamine tetra acetic. This can be added to the batteries cells that show a weak reading on a electrolyte Hydrometer.
There are other methods that work also depending on the condition of the battery and what type of battery you have. All that is required is some inexpensive tools and a manual to teach you the procedures.