Solar Power works on the basic principle of photo-electric effect. The photo-voltaic panels ( the panels that produce the good stuff ) are made from semiconductor material, and there are different grades available - Monocrystalline, polycrystalline etc.
When photons ( light ) hit the panel, it imparts energy to the electrons in the valence band. When the electrons have enough energy to bridge the energy gap, they go to the conduction band where they are free to move and this movement produces current.
PV panels produce DC power, and this can be stored in batteries, but if you want to run any loads, then you need AC power. So most systems have an inverter that converts the available DC power to AC power. Batteries are one of the more expensive parts in the PV system, and their main function is energy storage. The idea is that whatever energy is created by the panels during the day, can be stored in the batteries and be accessed at night as well. It is optional to have a battery bank, because the system can be grid tied and you feedback the energy to the grid, saving on your electricity bill. However, if the idea is for a stand alone system, then you do need a battery bank. If you are using a battery bank, then you also need a charge controller. The main function of the charge controller is to prevent overcharging and under charging of the batteries.
If you are using 2 or more panels, you need a combiner box. The basic function of a combiner box is to combine all the different leads and feed one or more output to the inverter.
For safety reasons you need circuit breakers and fuses in the appropriate places in the circuit.
So to summarize, these are the different parts of a simple PV system
1. PV Panels
2. Combiner Box
3. Junction box / Fuses
4. Inverter
5. Charge controller
6. Battery Bank
7. Outlet
