Solar pool heater has 3- to 5-year payback
April 27, 2003 - Clark County Public Utilities
Dear Energy Adviser: I attended your recent evening
presentation on solar options in Clark County. You didn't
touch much on solar pool heaters. I heat my swimming
pool with an electric heater. Would converting to a
solar pool heater decrease my pool heating costs? How
expensive is a solar pool heater?
Answer: Swimming pools are a lot of fun, providing
you and your family with exercise, entertainment and
possibly even some therapeutic benefits. Unfortunately,
in Clark County the outdoor swimming season is pretty
short unless you heat your pool. As you have discovered,
that can get expensive, even if you're only doing it
during the normal summer season, June through August.
Using a solar water heating system is very cost-effective.
In the case of your electric heater, payback on a solar
pool heating system should be between three and five
years at today's electricity rates, depending on the
temperature and how long you heat your pool. Since the
sun's heat is free, after the initial investment in
the solar system it really costs nothing to heat your
Solar pool heating systems are very simple. Instead
of diverting pool water through a standard heater, the
pool's existing filtration system pumps water through
solar collectors, and the collected heat is transferred
to the pool. Because solar pool-heating collectors operate
just slightly warmer than the surrounding air temperature,
these systems typically use inexpensive, high-flow,
low-temperature collectors made from specially formulated
The only moving part of the system is a diverting valve.
This valve determines whether water circulates through
the collector loop. When the collector temperature is
sufficiently higher than the pool temperature - generally
about six degrees - water is pumped through the collector
loop. When the sun goes down or cloudy weather keeps
the temperature in the collectors low, the water bypasses
The diverting valves can be controlled manually, with
timers, or more commonly by electronic sensors and controls.
To heat your pool most efficiency, the solar collectors
should face south. If you have only western exposure,
you can gain enough solar energy during the summer to
heat your pool, but the system will require 10-20 percent
more collector area.
"I size my systems between 60 and 75 percent of
the pool's surface area to get maximum performance,"
says Andrew Koyaanisqatsi of SOLAR ENERGY SOLUTIONS, INC.
(503-238-4502) in Portland. "Some companies will
size at 40 percent of the pool size, which is cheaper
initially, but doesn't keep the pool as warm or heat
it for as long as a larger system. My customers are
pretty happy with their systems. Once they've used a
solar pool heater, they never go back to their old heater."
Koyaanisqatsi recommends that pool owners use floating
blankets on their pools at night to retain heat.
A solar pool heating system for an average pool (16
by 20 feet or 20 by 40 feet) will cost $3,000 to $5,000
Clark Public Utilities offers a loan program for customers
who want to convert from electric to solar heating.
"For customers with an electric pool heater, converting
to a solar pool heater is one of the most cost-effective
things they can do to reduce their electricity bill
during the summer," says Bob West, an energy counselor
with Clark Public Utilities. "Not only do you reduce
your electricity bill, but you lower your maintenance
costs as well. Solar pool heaters are one of the best
kept secrets in Clark County."