Energy can be derived from the sun by a number of means.
The now familiar solar hot water service uses a black surface that heats water
from the visible and infra red (heat) portion of sunlight.
Electricity can also be produced from sunlight using what are known as
Photo-Voltaic Cells. These cells are thin glass-like plates of silicon material
that produce electricity between the front and back surface when sunlight falls
on the front surface. The electricity is produced from the visible portion of
sunlight, not the heat part. The more intense the light the more electricity it
produces. Even under cloudy condition's electricity can be produced although in
lesser quantities.
The electricity that the solar panel produces is placed into storage
batteries for later use. During the night and during dense cloud cover
electricity is drawn from these storage batteries. The batteries are recharged
when bright sunlight reappears.
When using solar panels it is important not to allow shadows to fall over the
panel. A shadow covering as little as 5% of a panel can cause the output to drop
up to 90%. This is particularly important with smaller panels having a number of
cells. The solar panel should also be cleaned regularly to maximize the amount
of power received from the sun.
Types of panels
Their are two main types of solar panel:
Polycrystalline and amorphous. All Sureguard products use the
superior polycrystalline type. You can recognize the type of panel simply by
looking at it. Polycrystalline panels are constructed from a number of
individual silicon cells that are connected together and form the complete
panel. Amorphous panels are a glass surface with a uniform black deposit of
silicon on the back surface.
Comparison between polycrystalline and amorphous
panels
Polycrystalline panels have over double the efficiency of
amorphous panels, about 14% verses 6%. Moreover, the efficiency is stable over
10 to 20 years whereas amorphous panels drop to about 4% efficiency in just 6
months exposure to sunlight. Polycrystalline panels are substantially smaller
and lighter. They are always the panel of choice where long life is important.
Typical warranty on polycrystalline panels is 10 years.
Amorphous
panels are fabricated by depositing a thin film of silicon onto a glass surface.
An inexpensive solar panel can be produced this way but the glass is susceptible
to breakage and the thin film generally disappears from the edge of the panel
when it is subjected to moisture. You may have seen a similar effect when
moisture gets into the edge of a mirror. Large panel size and weight can be a
problem. Typical warranty on amorphous panels is 1 year.
