There are two basic types of solar panels: the type widely known as the PV
or photovoltaic panel and the solar thermal collector.

Photovoltaic panels change the sun’s light into electricity. A single solar
cell which can be an inch to a few inches in size can generate about half a
volt of electricity. To provide power to operate a 12 volt appliance like a
hand mixer, you would need a module composed of 24 solar cells. Modules
connected together form a solar array, and the array with the additional
items needed to supply the electricity in a regulated manner make up a
system. This additional equipment includes mounting materials, an invertor
for changing DC power into AC power, and a storage battery.

PV panels are monocrystalline, polycrystalline, or amorphous. The prefix
mono- means one, and monocrystalline solar panels are made up of big single
silicon crystals. These types of solar panels are best in locations with low
amounts of light. The installation cost tends to be lower than that of
amorphous panels and they have the greatest efficiency of the three types.
The solar cells have a slightly rounded shape and a monocrystalline panel
takes up less room than an amorphous panel.

The prefix poly- means many and each polycrystalline panel is composed of
several small silicon crystals molded into blocks. The solar cells look like
several bits of broken glass melded together. Polycrystalline panels are
very common but slightly less efficient than monocrystalline panels. Like
monocrystalline panels, polycrystalline panels are installed at lower cost
and take up less space than amorphous panels.

Amorphous panels are big plates of stainless steel or flexible material to
which silicon is applied in a thin film. These highly durable panels are the
cheapest to make. They cost more to install and must be rather large to
achieve the efficiency of monocrystalline or polycrystalline panels.

Solar thermal collectors are used for heating water or spaces and are
usually mounted on rooftops. They are composed of a number of tubes through
which fluid flows. These are mounted on a metal sheet, usually of copper or
aluminum, and housed in an insulated box which keeps the heat from escaping.