Page 253 - Alternative Energy Systems in Building Design

PASSIVE SOLAR WATER HEATING 229

HELICOL SOLAR COLLECTOR SIZING

To determine the number of solar panels needed, divide the solar collector area needed
by the total square footage of individual collectors. The following example demon-
strates the use of an insolation chart.
Calculate the solar panel requirement for a 14 ft × 28 ft pool located in Las Vegas,
Nevada.

2
Pool surface = 14 ft × 28 ft = 392 ft .
Las Vegas is located in zone 5, which has a multiplier of 0.52.
2
Collector area = 392 ft × 0.52 ft = 203.8 ft .
Approximate number of panels required using Heliocol HC-40 panels = 5.1, or
5 panels.

Sizing is an art as well as a science. There are so many factors that affect swimming
pool heat loss that no one has yet come up with the “perfect” model or sizing calcula-
tion. Your company already may have a sizing guide or sizing method that works well
for installations in your particular area, and you may not want to use the sizing method
outlined in this chapter. Be sure to find out from your sales manager what sizing method
or calculation you should use to determine the proper sizing for your systems.
This next section outlines a sizing method that can be applied to any geographic
area. If you follow the guidelines detailed herein and have a thorough grasp of your
geographic factors, you should be able to size all your solar system proposals properly
with a reasonable degree of accuracy and confidence.
Average pool water temperatures, ranging from 75 to 85°F, are usually considered
comfortable. In northern states, however, 72°F is considered warm, and in the south,
swimmers usually want the temperature to be approximately 82°F.

SOLAR WATER-HEATING-SYSTEM SIZING GUIDE
The following guideline addresses all factors that must be taken into account when
designing a solar water-heating system for a pool. It is assumed that the pool will be
covered when nighttime temperatures drop below 60°F. If you heat a pool, you should
use a solar blanket. Not to do so is much like heating a house without a roof; the heat
just goes right out the top! A cover retains more than two-thirds of the collected heat
needed to maintain a comfortable swimming temperature.
The key to sizing a system properly is taking into account all the environmental
and physical factors that pertain to your area in general and the prospect’s home
in particular. There are 10 questions that you need to have answered to size a system.
They are as follows:

1 How many months of the year do the owners swim in the pool?
2 How long can you reasonably extend their season, taking into account the geo-
graphic location?