On each of the subcomponents of a power generation system, we've harped on making sure you use the proper wiring weight. Consider those warnings repeated. While you're at it, look up the local electrical codes, and seriously consider having a professional electrician do the installation. It will go faster, and while you're studying the electrical contracting codes, he knows them by heart for your local area.
If your time is less valuable to you than your money is, all of the components involved are simple to install and maintain, if you follow the manufacturer's recommendations and your local codes. Any home owner who can do a moderate amount of home repair and use tools safely should be able to do this.
If you do this yourself, remember, as voltage decreases (from 120 volts alternating current to 12 volts direct current) the amperage (current) increases. Amps x Volts = Watts . When the current increases, the size of your wire must also increase to handle the additional resistance and heat. Resistance means loss of power from the source to the load. Overheating can be very dangerous. When in doubt, go to the next largest size of wire. The increased efficiency and safety factors are well worth the added cost.
Wire comes with varying insulation qualities, depending upon your requirements. Temperature ratings and resistance to water and sunlight are also factors to consider. Indoor and outdoor wiring are different. Let your supplier know what your application is.
Lastly, keep in mind the need for circuit breakers. Ratings for fuses, breakers and switches are not the same for alternating current as they are for direct current. When purchasing, be sure your supplier is aware of the application. Short circuit protection must be provided for all units connected to the battery. Manual shutdown switches should be provided between all components and the power source. It is necessary when maintaining or replacing components to isolate them from the power source.