|Current PV systems
comprise a series of panels consisting of silicon-based elements,
and an inverter and power electronics which convert the DC power
produced to useable 230 volt AC power for use in the home. The PV panels are
extremely expensive to produce both in economic and carbon terms and
paybacks for both are poor. However, a number of advanced,
so-called "third generation" technologies are under development
which may radically reduce the cost of PV and eventually make it competitive
with conventional generation sources.
PV is claimed to deliver "zero carbon" electricity. Whilst it
is true that, once installed, PV does generate electricity without
any additional CO2emissions, the CO2 emitted
during the manufacture of PV is substantial. The CO2"payback"
is estimated at between 3-9 years and the specific CO2emissions
in a typical UK installation are around 0.25kgCO2/kWh
electricity produced, more than fossil fuelled micro CHP and around
half the current (2008) average UK generation mix.
Although the electricity produced is "free" once
you have paid for the installation, if you consider the investment
and divide by the amount of electricity produced during the typical
(30 year) life of a system, the effective cost is around 20p/kWh
ignoring interest charges (50p/kWh including interest); compared
with current electricity costs of 10p/kWh this is not a good
investment, but maybe better than buying a new Porsche if you want
to impress the neighbours.