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Solar Pool Pumps in Ontario

The impact of swimming pool pumps on the electrical grid in Ontario.

Swimming pools are a standard backyard accessory in central-Canadian middle-class homes. With over 700,000[1] residential pools in Canada (600,000[2] of those in Ontario & Quebec) based upon pool permits issued in large municipal areas. The numbers are probably notably higher as pools in small communities & rural pools are not captured by the surveys done by Pool & Spa Marketing.

All of these pools need a pump to circulate the water through a filter to keep them clean. Historically these pumps were run continuously, every day, for the whole season to prevent water problems such as algae and to keep sanitation systems, heaters and water features functioning. Recently, as the cost of running a pool pump have increased along with the rising cost of electricity, some pool owners have installed timers to reduce the number of hours the pool pump actually operates. Typically the running hours are cut in half to 12 hours a day. Now with “Time of Use” electrical rates being applied, some pool owners are shifting their pool pumping to off-peak times of the day.

In Ontario, the (conservatively) estimated number of pools is 311,000[3]. The average size of pool pumps installed over the past 10 years is one horsepower. Given that the life expectancy of a pool pump is 7 to 9 years, it is reasonable to expect that the vast majority of the pool pumps in service are at least one horsepower. A standard efficiency one horsepower pool pump consumes 1725[4] watts of power when running. It does draw a higher current when starting, but this is not being considered in this report.

311,000 times 1725 watts equals 536.5 Megawatts of power. More than the output of one nuclear reactor at the Pickering power station[5] – even before taking into account transmission losses between the power station and the pool pumps it powers.

If this massive consumption of power were only during off-peak hours, it might not be an issue for the peak loading of the grid. Unfortunately, there are several good reasons why pool pumps need to run during the day (and coincidentally, at peak times), and that running pool pumps only at night does not work for pools or their owners.

Swimming pools, unlike spas & hot tubs, are used primarily during the day. In the Summer they are used throughout the week as children are home from school & people are vacationing.

When a pool pump shuts off, it disables equipment dependent upon pool water flow, such as; the pool filter, the pool sanitation system and the pool heater (solar, fossil fuel or electric). When people use a pool they introduce a large variety of contaminants into the pool water. Sweat, sun-burn/tan/block lotions, dirt and several bodily fluids. Pets and the wind add to the variety of other contaminants. These are materials the pool sanitation system is designed to neutralize and the pool filter to remove.

The Ontario Health Protection and Promotion Act[6] requires that public pools circulate and filter the water in the pool a minimum number of times a day. The entire contents of a Class A pool must filtered a minimum of 4 times a day. Class B pools must have their water filtered a minimum of 3 times a day. It is recommended that private (residential) pools filter their water at least once to twice a day. To achieve this volume of filtering most residential pool pumps will have to operate for 10 to 12 hours.

Chlorine is a typical pool sanitizer, and is supposed to be maintained at 1 to 3 parts per million in a residential pool with a chlorine sanitizer and around ½ part per million in a “salt-sanitized” pool. The chorine is consumed in the process of sanitizing and must be constantly refreshed to maintain a sanitary pool. Chlorine is also actively destroyed by sunlight. In pools with salt water sanitation the low level of residual chlorine disappears very rapidly when the pump is turned off during the day, quickly leaving the pool un-sanitized. What are the potential consequences of there being no chlorine in the pool water?

  • Rapid algae growth – especially in areas where there is not normally a lot of water flow, if the pool is warm and it is a sunny day
  • Survival and transmission of viruses and germs through the water between swimmers (children with colds, flu, etc.)
  • No sanitation to combat urine & fecal contamination (or worse) in the pool.

Without the pump running, the pool filter cannot remove debris from the pool. Bugs, leaves, dust and other matter will not be automatically removed from the pool. Fine materials that cloud the water, including algae (both alive & dead) will not be removed. Pool chemicals that depend upon being dispersed and circulated around with the pool water will not function properly.

Without the pump running pool heaters cannot function. This is especially true for solar pool heating systems that must run during the day to gather solar energy to heat the pool. Solar pool heating systems also have a direct environmental benefit by eliminating the substantial amount of carbon dioxide generated by natural gas heaters that can be run at any time. Solar systems also save the pool owner money by reducing or eliminating the use of the gas heater. Also, if the pool pump does not run during the day, the pool water temperatures will tend to stratify – leaving the top of the pool warm and the bottom noticeably cooler.

Without the pool pump running, water features such as pool waterfalls & water slides obviously can’t function.

Although some of these issues may seem trivial, pool owners recognize that that there can be significant costs in chemicals, time and service calls if the pool water gets fouled-up. Also, pools cost a lot to install and the owners want to get the most enjoyment they can during a short season. The electricity-cost saved by only running the pool pump at night is not worth the risks, inconvenience or the potential loss of pool use.

Pool pumps are the second largest electrical load a home with a swimming pool – right after air-conditioning. This large electrical load will not shift to off-peak hours because pools do not work well if they are not filtered during the day. The reality is also that the dollar savings achieved by running only off-peak compared to running only on-peak, amounts to only $85 for an entire 5 month season. This is less than the cost of one pool service call to address a bad-pool-water condition, let alone the chemicals and effort to correct it.

High-efficiency pool pumps are beginning to be available. They have the potential, if properly used, to reduce a pump’s electrical demand by about 50%. However they are expensive and the first generation of pumps has had some durability issues. Originally designed and built for the California market, the pump’s marketing in Ontario typically grossly overstates the potential savings and benefits because they use California data: pools operated for 12 months of the year, California electrical rates & California energy subsidies.

An ironic thing frequently happens when people get a high-efficiency pool pump – they start to run their pump more –typically 24/7. This can significantly negate the energy and cost savings achievable with the high efficiency pump.

Smaller, lower horse-power, pool pumps can reduce the power consumption – but – they may not be capable of providing the minimum level of water circulation required for proper filtering & sanitation. If they are operated for more hours to achieve the necessary amount of filtering, all energy and cost savings will be lost.

Another, new, option has become available: high-efficiency, permanent-magnet, brushless - DC, solar powered pool pumps. These new pumps are capable of providing all of the pumping required for proper filtering and effective sanitation during daylight hours. They are typically run directly from a modest solar electric array (700 – 900 watts) and are not connected to the electrical grid. (Backup grid power supplies are available.) Pools are used during the day when the solar powered pumps are working – maintaining the operation of the necessary filtering, sanitation and water feature systems. At night the solar pumps don’t run. Filtering and sanitation systems don’t operate – however with little or no bather load and no sunshine to destroy the chlorine or grow the algae, there is very little need to run a pump. If absolutely necessary there are backup power supplies to run the high efficiency solar pumps from grid connected AC power.

Solar powered pool pumps run for free. The can displace the entire electrical load that a conventional pool pump places on the electrical grid. This displacement can reduce local grid capacity issues and larger system-wide peak loading issues.

Pool water pumping is entirely forgiving of the wide swings and frequent variability of daily PV power generation – unlike the electrical grid that PV power generating systems are tied to.

PV pool pumps will enhance the pool owner’s enjoyment of their pool. Operating the pool can now become (energy) guilt-free and (energy) cost free, meaning they will likely use their pools more and run them earlier and later in the season.