Solar Heated Pools
It’s every child’s dream to have a backyard pool. It’s also the dream of electric and gas companies! Depending on your climate and the size of the pool, the cost of conventional heating can be $200 or more per month. Would you be interested to know that you could make an investment in a heating system that pays for itself in five years and then operates for free for the next 15 years? Solar heating for pools is one of the best applications of solar power for home use and is simple to install and maintain.
If you have ever left a black watering hose out in the sun, you know how hot the water inside becomes. The sun shines on the hose and heats up the water inside it. Solar collectors work on the same principle although they use materials which are more efficient and durable than a simple hose. There are several types of solar collector systems to choose from and most will last 15 to 20 years.
In regions where temperatures remain above freezing all year such as in the southern United States, solar collectors can be made with lower cost materials such as thermoplastic rubber or polypropylene. Collectors that operate in colder climates like Canada’s generally have copper absorber plates with low iron tempered glass as a covering. These systems often also require transfer fluid and heat exchangers. This allows the collector to maintain most of its efficiency even during cooler periods. As long as the sun is shining, it will collect some solar heat.
Most solar heating systems include the pool pump and two heat sensors connected to a solar controller. One sensor measures the temperature at the collector surface; the other measures the pool temperature. If the difference between the two is sufficient, the controller sends a signal to a motorized valve that closes and directs the pool water through the solar collectors.
Two important considerations when installing a solar system are the number of solar collectors to use and their placement. Most homeowners install their collectors on the roof since an average system will require 200 square feet of space. As a general guideline, the solar collection area should be a minimum of 50 percent of the pool area. For example, if your pool is 10 metres (30 feet) by 3 metres (9 feet), which is equal to 30 square metres or 270 square feet, you should allow an area of 15 square metres (135 square feet) for the solar collectors. This amount will vary depending on how warm you like your water, local temperatures, the latitude, wind conditions, shading of the pool, and the desired length of the swimming season. In Canada, it is not uncommon to have 100 percent solar collector coverage.
Your home’s latitude and the angle of the solar collectors are very important factors in how well your solar heating system will function. The ideal angle will vary based on latitude, and whether you plan to use your pool only in the summer or all year. For summer-only heating, use latitude minus 10 to 15 degrees. For example, if you live in Toronto, which is located at approximately 43 degrees North latitude, that would mean the ideal angle for the collectors would be 28 to 33 degrees (where zero degrees is flat against the roof). For year-round heating, install the collectors at a latitude which, in this example, would be 43 degrees. This allows the collector to capture light when the sun is at a low angle in the sky. Variations from these angles can be compensated for by installing additional collectors/expanding the collector area.
Most homeowners install their solar collectors on the roof because it frees up lawn space and is largely out of view. If you don’t wish to install collectors on your home’s roof, you can install them on a shed or garage roof or set up banks of collectors on the ground using a stand to achieve the proper angle.
Comparing the cost of gas, electric and solar heating systems, solar power is the hands-down winner in the long run. Although a gas heat pump requires a low initial investment of approximately $1400, it is expensive to operate especially with the recent increases in the cost of fossil fuels. Electric heat pumps require a smaller initial invest of approximately $1,000 and are relatively efficient except during cooler days and evening hours when the heater works harder. Solar heating systems require an initial investment of approximately $4,000 but the operating costs are almost zero. Even on a cool but partly sunny day, efficient solar collectors will continue to pump warm water into the pool.
Another benefit of a solar heating system is its durability. With no moving parts other than valves, solar systems can last 15 to 20 years. Most come with a 10-year warranty. Conversely, gas and electric heaters last less than 10 years, require regular maintenance, and have shorter warranties.
Regardless of the system you ultimately choose, it is wise to use a pool cover to make your system as efficient as possible. A cover stops evaporation and significantly reduces heat loss into the atmosphere. Because the cover reduces the amount of debris that falls into the pool, owners can reduce the amount of cleaning and chemicals required to keep the water clean—that’s particularly good news for anyone who has the job of cleaning a pool!
Solar pool heating for your home is the most economical solar application in Canada today. According to Natural Resources Canada, 10 percent of people who purchase new pool-heating equipment now select solar heaters. Why not discover for yourself the joys of jumping into a pool that’s as easy on the environment as it is on your pocketbook!