Environmental Engineering Reference
In-Depth Information
which is ideal for small appliances, but can be converted into alternating current
for larger equipment.
Historically, photovoltaic power was applied in niches and special applications,
such as isolated communities, electronic equipment (calculators, watches, and
communication technology), satellites, remote sensing, and sign lighting along
roads. The problem with niche applications is that it is done on a small scale and
at a high cost. Large-scale production is required for cost reduction. In places with
high insolation, 5,000 kWh of power a day could be produced over a hectare of
land covered with photocells with 10% efficiency. Some commercial cells have an
efficiency of 15%. The installation of PV panels is rapidly growing and the power
generation potential of photovoltaic panels is promising. One idea is that power
from buildings with solar roofs could be “fed-in” to the electricity grid. PVs may
be one of the main technologies for future decentralized energy systems.
By the end of 2010 there were 40 GW of installed PV systems. Germany is the
present market leader, leading Japan and the US. Previously, Japan was the group
leader in PV modules technology, concentrating on the consumer market niche
of electronic products (such as calculators and watches). The North American in-
dustry traditionally concentrates on large-scale applications. Other important sup-
pliers are China, Spain, and Italy. The limiting factors of photovoltaic power are its
cost, the limited power produced per unit, and the lack of available silicon in the
market. Photovoltaic panel manufacturing requires large amounts of polycrystal-
line silicon and there is now a supply bottleneck, which constrains the technology
expansion. Each Wp (watt peak) consumes 14 g of silicon. Still, the present in-
stalled cost for photovoltaic systems connected to the grid is lower than US$2,000/
kW.
In remote rural areas, which cannot be connected to the grid, PV modules are
used together with batteries, charge controllers, and inverters. Despite being small,
the power produced is enough to refrigerate medicines; preserve food and fishing
products; light houses, schools, and medical centers; extract and pump water from
wells; and support communication and entertainment. The disposal of batteries and
panels is a problem, as they contain lead and other dangerous heavy metals such as
cadmium. Another severe problem is lack of maintenance; this frequently occurs in
demonstration projects focused only on installation of a system, with no adequate
technical assistance or spare parts.
