Don't let yourself be overwhelmed! Tackle your understanding one bite sized piece at a time.
1) Get a meter. Learn how to use it.
a) www.ebay.com -- Fluke 87 or Fluke 336
b) Radio Shack meter
c) Home Depot meter
2) Draw a diagram of your system as you think it works. Be as specific as possible with the wattages, voltages and amperage identifications for each major piece of equipment. Draw the system from the point of view starting with the Sun and ending with a light bulb in your house.
3) Read the manual for the meter on your system; i.e. E-meter, Trimetric, Link or Trace meter. This meter is your window into understanding your system.
4) If you are troubleshooting a problem or error, consult the manual for that specific piece of equipment and look in the index for the troubleshooting reference.
5) Call for technical support (unlike other industries, the renewable energy industry is actually fairly responsive with regards to customer service, in some cases the person you are calling engineered the product you are calling about), as they more than likely have experienced your error or problem before.
6) Call the person you purchased the equipment from in the first place. The buck stops here, and they should be able to assist you with a repair, return or warranty issue.