Small wind energy systems
can be connected to the electricity distribution system and are called
gridconnected systems. A grid-connected wind turbine can reduce your
consumption of utility-supplied electricity for lighting, appliances,
and electric heat. If the turbine cannot deliver the amount of energy
you need, the utility makes up the difference.
When the wind system produces more electricity than the household requires, the excess is sent or sold to the utility.
Grid-connected systems can be practical if the following conditions exist:
- You live in an area with average annual wind speed of at least 10 mph (4.5 m/s).
- Utility-supplied electricity is expensive in your area (about 10 to 15 cents per kilowatt-hour).
- The utility’s requirements for connecting your system to its grid are not prohibitively expensive.
- There are good incentives for the sale of excess electricity or for the purchase of wind turbines.
Federal
regulations (specifically, the Public Utility Regulatory Policies Act
of 1978, or PURPA) require utilities to connect with and purchase power
from small wind energy systems. However, you should contact your utility
before connecting to their distribution lines
to address any power quality and safety concerns. Your utility can
provide you with a list of requirements for connecting your system to
the grid. The American Wind Energy Association is another good source for information on utility interconnection requirements.
The following information about utility grid connection requirements was taken from AWEA’s Web site.
Net Metering
The
concept of net metering programs is to allow the electric meters of
customers with generating facilities to turn backwards when their
generators are producing more energy than the customers’ demand.
Net
metering allows customers to use their generation to offset their
consumption over the entire billing period, not just instantaneously.
This offset would enable customers with generating facilities to receive
retail prices for more of the electricity they generate. Net metering
varies by state and by utility company, depending on whether net
metering was legislated or directed by the Public Utility Commission.
Net
metering programs all specify a way to handle the net excess generation
(NEG) in terms of payment for electricity and/or length of time allowed
for NEG credit. If the net metering requirements define NEG on a
monthly basis, the consumer can only get credit for their excess that
month. But if the net metering rules allow for annual NEG, the NEG
credit can be carried for up to a year.
Most of North America gets
more wind in the winter than in the summer. For people using wind
energy to displace a large load in the summer like air-conditioning or
irrigation water pumping, having an annual NEG credit allows them to
produce NEG in the winter and be credited in the summer.
Safety Requirements
Whether
or not your wind turbine is connected to the utility grid, the
installation and operation of the wind turbine is probably subject to
the electrical codes that your local government (city or county) or in
some instances your state government has in place.
The
government’s principal concern is with the safety of the facility, so
these code requirements emphasize proper wiring and installation, and
the use of components that have been certified for fire and electrical
safety by approved testing laboratories, such as Underwriters
Laboratories. Most local electrical codes requirements are based on the National Electrical Code (NEC),
which is published by the National Fire Protection Association. As of
1999, the latest version of the NEC did not have any sections specific
to the installation of wind energy facilities, consequently wind energy
installations are governed by the generic provisions of the NEC.
If
your wind turbine is connected to the local utility grid so that any of
the power produced by your wind turbine is delivered to the grid, then
your utility also has legitimate concerns about safety and power quality
that need to be addressed.
The utility’s principal concern is
that your wind turbine automatically stops delivering any electricity to
its power lines during a power outage. Otherwise line workers and the
public, thinking that the line is “dead,” might not take normal
precautions and might be hurt or even killed by the power from your
turbine. Another concern among utilities is that the power from your
facility synchronize properly with the utility grid, and that it match
the utility’s own power in terms of voltage, frequency, and power
quality.
A few years ago, some state governments started
developing new standardized interconnection requirements for small
renewable energy generating facilities (including wind turbines).
In
most cases the new requirements have been based on consensus- based
standards and testing procedures developed by independent third-party
authorities, such as the Institute of Electrical and Electronic
Engineers and Underwriters Laboratories.
Interconnection Requirements
Most
utilities and other electricity providers require you to enter into a
formal agreement with them before you interconnect your wind turbine
with the utility grid. In states that have retail competition for
electricity service (e.g., your utility operates the local wires, but
you have a choice of electricity provider) you may have to sign a
separate agreement with each company.
Usually these agreements are
written by the utility or the electricity provider. In the case of
private (investor-owned) utilities, the terms and conditions in these
agreements must be reviewed and approved by state regulatory
authorities.
Insurance
Some
utilities require small wind turbine owners to maintain liability
insurance in amounts of $1 million or more. Utilities consider these
requirements are necessary to protect them from liability for facilities
they do not own and have no control over. Others consider the insurance
requirements excessive and unduly burdensome, making wind energy
uneconomic. In the 21 years since utilities have been required to allow
small wind systems to interconnect with the grid there has never been a
liability claim, let alone a monetary award, relating to electrical
safety. In six states (California, Maryland, Nevada, Oklahoma, Oregon,
and Washington), laws or regulatory authorities prohibit utilities from
imposing any insurance requirements on small wind systems that qualify
for “net metering.”
In at least three other states (Idaho, New
York, Virginia) regulatory authorities have allowed utilities to impose
insurance requirements, but have reduced the required coverage amounts
to levels consistent with conventional residential or commercial
insurance policies (e.g., $100,000 to $300,000).
If your insurance
amounts seem excessive, you can ask for a reconsideration from
regulatory authorities (in the case of private investor-owned utilities)
or to the utility’s governing board (in the case of publicly-owned
utilities).
Indemnification
An
indemnity is an agreement between two parties where one agrees to
secure the other against loss or damage arising from some act or some
assumed responsibility. In the context of customer-owned generating
facilities, utilities often want customers to indemnify them for any
potential liability arising from the operation of the customer’s
generating facility.
Although the basic principle is
sound-utilities should not be held responsible for property damage or
personal injury attributable to someone else-indemnity provisions should
not favor the utility but should be fair to both parties.
Look
for language that says, “each party shall indemnify the other…” rather
than “the customer shall indemnify the utility . . .”
Customer Charges
Customer
charges can take a variety of forms, including interconnection charges,
metering charges, and standby charges, among others. You should not
hesitate to question any charges that seem inappropriate to you.
Federal
law (Public Utility Regulatory Policies Act of 1978, or PURPA, Section
210) prohibits utilities from assessing discriminatory charges to
customers who have their own generation facilities.
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