Carl Reuter’s Design Guide gives a good, not too complex, overview of the components that make up a PV AE system and how it should all go together :

http://calsolarsolutions.com/rvandcabin.html

To summarise, you should know the following :

• Voltage is variable, it is like water pressure, devices can handle changes in voltage as long as it isn’t too much or to little.
• Amps are also variable, it is like the speed of the water flowing through a pipe.
• AmpHours is a rating of how long you can maintain that speed, it’s the bucket of water that will eventually get empty.
• Watts is the overall ‘usage’, Watts = Volts x Amps

Batteries

• Batteries are a 12V DC system, but they are really closer to 13V
• You need more than 17v or more to get a good charge into a battery
• Batteries do not like to be discharged below 12V, or 50% of their capacity
• A 50AH battery can give 1A for 50 hours, or 2A for 25 hours

Panels

• Panels are rated for their perfect conditions (midday, full sun, 25 deg C)
• Heat (aka the playa) reduces a panels’ output
• The angle to the sun reduces a panel’s output
• An 18V,75W panel really only puts out 15V,60A on average

Charge controllers

• 3-stage or PWM controllers are better
• controllers stop overcharging the battery
• controllers have a load (Amps) rating, if you panel has too many Amps, it will blow out the controller