The majority of the electricity your solar array will generate will be stored in batteries. 

Electricity as Water Pressure

Batteries are your reservoir of energy for future use.  It might help to compare this to water stored in a dam.  Both have potential that can used for various purposes. Batteries are used to even out the power that your panels generate.  They provide a constant load and give you power when the sun is down without drawing on your utility company. As mentioned earlier, your battery array will need to be hooked up to a controller, and probably an inverter if you want to use power for AC appliances.

Battery choices are fairly standardized, much the same way solar panels are. You'll want to make sure that you maintain your batteries carefully. For the most part, you're going to be using deep cycle (also known as "marine" batteries). These have lower peak yields per battery cell, but store the same amount of power. Their primary benefit is that they last longer under constant use.

You'll want as many batteries in a battery bank as you can get.  The less your battery has to work, the longer it will last, and the best way to do this (even with deep cycle batteries) is to spread the work out.

See the list to the right for complete information about how to build your own solar-powered system.