What is it?
The sun is an enormous and inexhaustible source of energy, both in the form
of heat and light.
Photovoltaic solar panels only make use of absorbed sunlight which they
convert into electricity. This is called thephotovoltaic conversion. This
process occurs without the emission of substances such as e.g. CO ².
The conversion is done according to the photo-effect, which was
discovered in 1839 by Alexander Becquerel. A solar cell consists of a thin
plate of semi-conducted material, usually pure silicon, which has gone
through a few chemical processes and as a result has a negative top layer
and a positive bottom layer. If we connect the two layers with, for
example, a light and we let (sun) light shine onto the solar cell, an
electric current will be created that will light the lamp.
Part of this light is converted into heat, and a small portion is
reflected. Another part will be converted by the cell into electricity. The
efficiency of a solar cell is the proportion of the incoming light
converted into electricity.
Currently there are 3 types of silicon solar cells industrially produced:
- Mono-crystalline silicon
- Poly-crystalline silicon
- Amorphous silicon
Each with their specific properties and output.
Individual solar
cells provide a current and voltage which are too small to use
separately. Moreover they are fragile and the metal contacts are moisture
sensitive. For these reasons they are mutually linked and placed together
in a so-calledPV-panel (abbreviation of
photovoltaic). The ability of a PV-panel is expressed in Wp (Watt-peak),
the peak capacity at standard solar radiation and solar cell temperature of
25°C.
In Belgium we obtain a maximum gain at an inclination of 35° and 2°
W from the South. There is also a fairly wide zone where the annual gain is
only 5% less, namely the orientations between southeast and southwest and
slope angles between 20° and 60 °.
The grid-connected PV-system:
In a grid-connected system the direct current supplied by the PV-panels is
converted into alternating current voltage by means of an alternating
converter, or, in short, converter. The alternating current
voltage can be supplied directly to the electricity network, or immediately
used by a household appliance.
We distinguish 2 groups of grid-connected installations: the centralised
and the decentralised systems. The centralised plants are the major
installations (from some 100
kWp to several MWp) that send supplied electricity directly onto the
network, while decentralised systems have a much smaller capacity (i.e.
roofs of houses, construction industry, etc.)
The panels and the converter are the 2 main
components of a PV system.panelen
The solar cells are manufactured by the Belgian, Tiens Company Photovoltech
