the Opportunity of Solar Distributed Generation
36 May 2012 SOLAR TODAY solartoday.org
For more than 100 years, our elec- tric distribution systems have been designed for stable energy flowing in one direction, from the power plant to the customer.
Now, with solar and wind technology on customer properties, energy travels in two directions, from the utility to customers and from
customers back to the grid.
Meanwhile, both solar and wind fluctuate
as the weather changes. In small amounts, solar
and wind variability has negligible impact on
today’s distribution system. Large variations,
as expected with future growth of wind and
solar sources, will be a challenge to manage.
And, as we know, every few years customers
add a new technology — like HDTVs or cell
phone chargers or soon, electric vehicles — to
the overall load.
In Arizona, the public utility APS is planning to grow its renewable energy portfolio.
A decade ago, our grid drew less than one
percent from renewable sources. By 2025,
we expect to have 15 percent of the total
energy provided to customers from renewable
resources. A large percentage of this renewable energy expansion will include distributed
resources located at or near the customer. For
this reason, APS is implementing a strategic,
targeted and integrated set of studies to better
understand how these intermittent resources
impact the current energy-delivery system.
The goal is to make sure APS can continue to
provide reliable, affordable and high-quality
electricity to customers while maximizing the
amount of clean energy on the system.
Nationwide, an increasing number of industry groups is looking at a complex set of tools
and issues to help find value in these resources.
Unlike traditional energy sources that you can
rely on to meet your energy needs 24 hours
a day, solar energy is only available when the
sun is shining, and can drop off quickly during
cloud and storm movements.
As the electric utility, you want to provide
reliable power — after all, customers are used
to flipping the switch and the lights coming
on — so we must plan to build the system as
if the resources don’t exist or will not be there
The APS Community Power Project is a
unique high-penetration distributed energy
(DE) demonstration being built on a tar-
geted segment of the APS system in the
Doney Park neighborhood of Flagstaff, Ariz.
The pilot program brings solar panels to
Flagstaff rooftops with no upfront cost to
customers, in effect creating an intercon-
nected renewable power plant. The project
is the culmination of significant research by
the company into ways to develop viable
renewable energy generation alternatives to
meet the company’s commitment under the
Arizona Corporation Commission renewable
energy standards (RES).
APS has completed residential installations on 125 homes, with 2- to- 4-kilowatt solar systems producing power directly to the grid. APS contracts with local solar installers to design, implement and maintain the systems at no cost to the homeowner. The hom- eowner grants a rooftop easement to APS and in return receives the Community Power rate, a fixed rate for 20 years.