6.
Net Metering System
The net metering system is also used in a grid-connected house, but instead
of storing power in batteries, it is sold to the utility company.
The net metering
system employs a special type of inverter, which inverts DC power from
the PV array into low distortion full sine wave AC power, acceptable
for purchase by the local utility power company. Batteries are not required
for storage. The power is delivered through a kilowatt-hour (kWh) meter
to the utility grid as the PV modules produce it. A second kWh meter
is sometimes used to measure the power consumed.
The user of this
system will notice no difference from any utility run system, except
lower utility bills or possibly payments from the power company for
the excess electricity that is generated.
Until recently,
the net metering system requires a PV array of 1000 watts or more (12
or more PV modules) to be cost effective since the smallest inverters
were 1000 watts (1 kW). Recently, a new, smaller utility inverter has
become available, allowing systems as small as 100 watts to feed power
back into the grid. Any electricity fed into the grid must be compatible
with the power generated by the utility or problems might arise.
Net metering system
requires utility power to operate, so a house of this type will have
no electricity during a power outage. Adding a battery bank to the PV
system would provide power during outages.
