Grid-connected PV systems
GRID CONNECTED SOLAR POWER
Grid connect systems use a photovoltaic array to generate
electricity, which is then fed to the mains grid via a grid
interactive inverter.
When the solar array
generates more power than is being used in the building,
the surplus is exported to the grid. When the solar array
generates less power than is being used in the building,
the difference is imported from the grid.
A Typical House
The average mains power consumption for dwellings in Far
North Queensland is 20kWh/day to 25kWh/day. Most of this
is used for cooking and heating, particularly water heating
and if these are replaced by gas and/or solar
hot water, typical consumptions range from 5kWh/day
to 15kWh/day depending on size of the family, lifestyle
and attention paid to choice of efficient appliances.
The government rebates available
for grid connected solar
systems are geared to provide maximum benefit for solar
arrays sized between 450W and 1,000W for residential systems
and between 450W and 2000W for community buildings. It is
unlikely that a grid connect system will have an array much
smaller than these values. However, it may be much bigger
- in 2002 Planetary Power installed a 3.8kW array
at a residence in Cairns.
The output of an array is influenced by many factors which
are touched on later in these notes, however approximately,
a solar array will on average deliver between 4kWh/day and
5kWh/day to the grid for every 1,000W of capacity.
Most grid connect systems generate less power than is consumed
by the building, making the home or community a net consumer
of power from the grid. However, this need not be the case
and installations that are net exporters of power to the
grid are permitted.
The cost of a grid connect solar installation depends on
the size of the solar array,
type of solar panels used
and the inverter.
A typical figure for the net installed cost of a system
in Cairns is between $2,600 and $3,000 for every kWh/day
on average delivered to the grid.
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