Grid-Tied (or
Utility-Intertie) and Back-up power systems
Out of all the technology we use in renewable
energy systems, the battery is the least
environmentally friendly. Batteries require
periodic maintenance, are only 80% efficient at
best, contain toxic substances and have a high
failure rate (in comparison to the other equipment
used). If we were to eliminate the battery, it
would improve the system longevity and minimize
the system’s environmental effects.
It is possible for you to connect your renewable
energy system through an inverter directly to the
utility grid. Connected this way, there is no need
for the system to have batteries. Energy produced
and not used by the system is “stored” on the
utility grid. When energy use exceeds production,
the grid supplies the extra needed. In this way,
ordinary citizens can produce and supply renewable
energy to the utility grid.
These intertie systems can be any size. One 100 to
300 watt solar module can be connected through a
small intertie inverter. AC Modules like our
Sunsine and the Eversun are pre-assembled and
tested units that allow a homeowner to “plug in
the sun” and the utility grid easily. This
allows individuals to start with a very small
system and add modules as they wish. For 1000-1500
watts of solar modules and up, it is more cost
effective to use a single intertie inverter, (like
Trace Utility-tie inverters and the AEI CG-1000).
Intertie inverters have all the needed protective
electronics to synchronize with the utility grid
and to automatically disconnect from the grid in
the event of an outage. Intertie systems
utilitizing intertie inverters are installed and
working safely in every state in the United
States.
The intertie system/utility connection varies from
state to state and is rapidly changing. Some
states are encouraging intertie systems and have
passed laws to allow for net metering and
streamlined the connection of intertie systems.
Solar rebates and tax credits are also available
depending on the location of the system.
Under a net metering arrangement, homeowners who
use solar systems run their electric meter
backwards as they feed extra electricity back to
their utility. This means that the utility
“pays” the customer the retail rate for the
electricity produced. Not all utilities offer net
metering to their customers. Some require two
electric meters to be installed, one for measuring
the electricity used, one for electricity
produced. This allows them to pay a different
price for the produced electricity, often at a
lower rate that the consumer pays for electricity.
A lockable disconnect is also often required.
The systems offered here satisfy the requirements
for the California Buydown Program,( a solar rebate
in California), the RERP (a 6$ a watt up to
60% incentive program in Illinois
and other renewables incentives.
Check the DSIRE web site for information about
incentives in your area at: www-solar.mck.ncsu.edu |
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