Solar panels (photovoltaic cells ) simply convert sunlight to electricity. Pv cells are generally made up of silicone. They are not that efficient (current estimates around 12-18%) and as such quite a few panels are required to provide the electricity required for a house of developmentment. The electricity produced is very rarely used straight from the panels as sunlight determines power produced. The power comes of the solar panels normally in 36.5v dc. Typically in an off grid system this power from the panels typically goes to charge a battery bank so the stored energy can be used at the discression of the users.
To charge batteries from a solar array you need to have a charge controller this mentains the charge in the batteries and helps maintain the batteries for the longest time possible.
With almost all renewable energy the energy production is dependant on the elements which obviously have peaks and troughts of production so it is important to create a battery bank to allow yourselves to have power when there is no sun and wind outside.
Types of Batteries
Car Batteries Car batteries are designed to give a large power over a very short time. A brand new car battery will have a charging cycle of between 40-200 (dependant on quality) which means if you keep running a new battery flat everyday it will only last 1 1/2 -7 months.
Leisure Batteries Leisure batteries are similar to car batteries but have 500 charging cycles and only halve the discharge rate. Great for solar systems as dont lose capacity when under 10.8v
Lead Gel Batteries These have a similar cycle rate and discharge rate to leisure batteries. Are very sensitive to overcharging and will be destroyed if allowed to totally discharge to 0v. If used in a hot country please be very careful as the gel can dry out destroying battery.
Deep Cycle Batteries These are normally used in fork lifts and milk floats but are being used increasing in solar system. They are huge, heavy and robust, they carry huge capacities and also have up to 1,000 charging cycles.
great walk through of a global model solar install from http://www.offthegridbuild.com/