Form #602300A
Determining the size of a renewable
energy generation system
Glossary
The information in the table below is intended to give you a
rough indication of what to expect in terms of cost and energy
production for a small wind generator.
Capacity of wind turbine
generator (kW)
Estimated installed cost
($)
Estimated annual energy
production (kWh)
3
15,000
5,000
5
10
25,000
50,000
11,000
22,000
Capacity
In the electric utility industry, this word has two meanings:
1. Power; i.e. the rate of delivery of energy. For example, to say
that a generator is producing 15 kW of power means that it
is delivering energy at the rate of 15 kWh per hour.
2. The maximum amount of power that a piece of equipment
is capable of producing.
Government’s intent in introducing net metering is to assist
customers who want to supply a portion or all of their annual
electricity load from a small capacity renewable energy
generation system. Thus the starting point is to determine how
much electricity you use during a year. (Your monthly bill from
Maritime Electric has a section on the lower left hand side that
shows your electricity usage for the most recent 14 months.)
Kilowatt (kW)
A measure of electrical power, equal to 1,000 Watts. A kilowatt
is approximately equal to 1.33 horsepower.
The following are some suggested sources for further
information:
Net metering system
A metering system that is part of the interconnection facilities
between a customer-owned generator and the utility’s
distribution system and that makes separate measurements of
the electricity supplied by the customer to the utility’s system
and the electricity delivered by the utility to the customer’s
load.
• Yellow pages under Engineers - Electrical
• Yellow pages under Energy Consultants & Management
• PEI Department of Environment, Energy & Forestry
Getting started
Kilowatt-hour (kWh)
A measure of electrical energy. For example, operating ten 100
Watt light bulbs for one hour will use one kilowatt-hour.
The Renewable Energy Act lays out the process to follow for
customers who are interested in installing and operating a
small capacity renewable energy generation system in parallel
with the utility’s system.
Small capacity renewable energy generator
In the context of the Renewable Energy Act, this is a person
that owns or operates a renewable energy generation facility
with a name plate capacity equal to or less than 100 kW.
Copies of the Renewable Energy Act and associated Regulations
can be obtained from the PEI Department of Environment,
Energy and Forestry, or by going to the PEI Government website
(www.gov.pe.ca).
Voltage
The electrical potential or force that causes a current to flow in
an electrical circuit. In the water-in-pipe analogy for electricity,
the water pressure corresponds to the voltage. Voltage is measured
in Volts (V) or kilovolts (kV).
Note: Customers who are considering a small capacity renewable
energy generation system should be aware that installing a
wind turbine is a regulated activity which may require a building
permit. People should check with their community’s bylaws if
they live in an incorporated community or with Community
& Cultural Affairs if they live in an unincorporated part of the
Province.
Net Metering
Helping our Customers
Understand Net Metering
For Renewable
Energy Generators
up to 100 kW in size
NOVEMBER 2007
Form #602300A
Background
What is net metering?
How does net metering work?
In December 2005 The Renewable
Energy Act and associated Regulations
came into effect. A Government policy
objective incorporated in the Act was
the introduction of net metering for
small capacity renewable energy
generators up to 100 kW in size (see
Glossary at end for definitions of
technical terms).
Net metering is a way of encouraging customers to generate their
own electricity from renewables by subsidizing the payment that
the customer receives for electricity supplied to the grid. The
diagram below shows the relationship between the metering and
the customer’s generator in a net metering installation.
Shown below are examples of the month end calculations. The
examples are based on a Residential customer who uses 1,000
kWh per month and who has a 5 kW wind turbine generator.
The average Residential customer in PEI uses about 550 kWh
per month, so this example is based on a customer whose usage
is almost twice the average.
For over 25 years Maritime Electric has
been working with customers to allow
the connection of small generators
powered by renewable energy sources
to its system. The introduction of net
metering has resulted in three main
changes to this past practice.
1. The utility is required to compensate the customer for
kWh supplied to its system at the same cents per kWh rate
that it charges for kWh delivered to the customer. For a
Residential customer this rate is approximately 12 cents per
kWh. (In the past Maritime Electric paid for the electricity
supplied to its system at a price per kWh based on its avoided
cost; i.e. the price that Maritime Electric would have had to
pay to purchase elsewhere or generate itself the energy supplied
by the customer. Maritime Electric’s avoided cost is normally
less than 12 cents per kWh. Under net metering, the difference
is recovered from all customers through rates.)
2. The utility is required to pay for the extra costs associated
with the customer having two meters. (The Renewable Energy
Act provides for the costs that the utility incurs in complying
with the provisions of the Act to be passed on to all customers
through rates.)
When a customer connects a small generator to the utility’s system,
a second kWh meter is installed. One meter measures the energy
that is supplied to the utility’s system during periods when the
customer’s generator is producing more electricity than is being
used by the customer’s loads (“out” meter). The other meter
measures the electricity that the utility delivers to the customer
during times when the customer’s loads are using more electricity
than the customer’s generator is producing (“in” meter).
The meters are read once a month. To calculate the monthly bill,
the number of kWh supplied by the customer to the utility is
subtracted from the number of kWh delivered by the utility to
the customer. This results in the customer being billed for his net
usage during the month (hence the “net” in net metering).
Note: The customer still pays for only one monthly service charge,
even though there are two meters.
Example 1:
Usage by customer during month: 1,000 kWh
Production by customer’s generator during a lower wind
month: 800 kWh
Supplied by customer to utility during month (measured by
“out” meter): 300 kWh
Delivered by utility to customer during month (measured by
“in” meter): 500 kWh
Net energy billed to customer at month end = 500 kWh – 300
kWh = 200 kWh
Example 2:
If the number of kWh supplied by the customer to the utility
during the month is greater than the number of kWh delivered
by the utility to the customer, then the extra kWh are credited
to the customer’s account for possible use in a future month.
Usage by customer’s loads during month: 1,000 kWh
Production by customer’s generator during a higher wind
month: 1,200 kWh
Supplied by customer to utility during month (measured by
“out” meter): 500 kWh
3. The relationship between the utility and the customer is now
to be formalized by a standardized agreement.
Delivered by utility to customer during month (measured by
“in” meter): 300 kWh
Government’s intent in introducing net metering is to assist
customers who want to supply a portion of or all of their annual
electricity load from a small capacity renewable energy
generation system.
Net energy billed to customer at month end = 300 kWh – 500
kWh = -200 kWh
Since the number is negative, the 200 kWh would be credited
to the customer’s account for use during a future month. (Note:
The credits do not accumulate indefinitely. On October 31, or
another month end if the customer so chooses at the time of
applying for net metering service, of each year any outstanding
credits from the preceding year are eliminated.)