Environmental Engineering Reference
In-Depth Information
Figure 5.8
Photovoltaic island systems offer advantages for many applications compared to grid
connections.
industrialized countries there are towns that are very remote from the grid and where
any kind of cabling would be extremely expensive. There are alternatives to using
island networks to supply solar energy - such as diesel generators. A solar system
often compares favourably in terms of cost and supply reliability, specifi cally in
cases where demand for electricity is low. Nevertheless, the costs of photovoltaic
island systems are still relatively high. Therefore, they are currently used mostly for
small output requirements. For cost reasons, diesel generators and grid connections
are usually given preference when a high demand for electricity exists.
Solar island systems are comparatively straightforward and can even be installed by
people with limited technical skills (Figure 5.9). A battery ensures that supply is
available at night or during periods of bad weather. For reasons of cost, lead batteries
are normally used. In principle, 12-volt car batteries are also an option. Special-
purpose solar batteries have a considerably longer lifetime but are also more expen-
sive. As batteries can quickly be ruined as a result of leakage or overcharging, a
charge regulator protects the battery. The battery, the power consumer and the photo-
voltaic module are connected directly to the charge regulator. It is important to make
sure the plus and minus poles are not switched as this will cause a short circuit.
When the battery is nearly empty, the power consumer is switched off. Although
the lack of electricity is a nuisance, this is better than a defective battery. As
