Solar swimming pool suggests using the sun's energy to drive the pump and chlorinator; and using rainwater to top it up. Building eco friendly homes has become a passion in Bernard Preston's twilight years.
To build, or not to build a swimming pool many years ago was for me a vexed question. Constructed during an era when our children had already graduated beyond the too small home edition, and when our backs weren't needing the gentle exercise, it turned out to be an expensive and time consuming hole in the ground.
If you have very young children, and a back that needs exercise, then by all means build a pool, but do first count the cost beyond the initial installation of your pool.
Apart from the cost in time spent, much of the electrical cost of cleaning and chlorinating the pool can be balanced by building a solar powered generator. An inverter energised by the sun's light and captured by your PV panels will produce ample watts during the day when you usually have an excess.
The pool can be filtered just as readily when the sun is shining, though in theory chlorination is more effective at night.
Our experience is that daylight chlorination of a saltwater pool appears to be as effective, or nearly so, as at night.
In fact, perhaps more effective; our pool is often described as the cleanest and clearest many people have ever seen; after all the bugs are proliferating when the water is warmer during the day.
Firstly, do you have at least an hour or two per week to commit to the cleaning and general upkeep of your pool? Swimming pools are dirt traps and one shouldn't underestimate the time needed to maintain your pool in a pristine condition.
Secondly, a pool must be chlorinated, or it becomes a haven for pathogens and algae causing ear infections.
There are few more ugly things in the home than an unkempt, green pool. The cost of chlorine is unlikely to be less than ten dollars per month for much of the year.
Thirdly, don't underestimate how long it takes to remove and replace the safety net if you have small children about. Tragedies happen on a regular basis. Double protection of a fence plus a net is advisable.
This may all seem totally negative. With so many people with problem backs and circulatory systems, swimming provides the perfect exercise, with your weight borne by the water. There's plenty of research showing the aquacise of one form or another is hugely beneficial to arthritic joints and tired hearts.
One of the great virtues of a solar swimming pool is that the grandchildren love to visit in the hot summer months. Having your children learn to become competent swimmers should be on every parent's agenda. What better way to do it than to visit granny and grandpa twice a week, and leave to them the cost and effort of maintaining the pool?
Back to counting the cost of a pool.
Fourth, periodically you will have to test the pH of the pool water and add either hydrochloric acid or a base; more time and money.
Fifthly, a pool pump must run for about eight hours a day depending on the season. My pump uses 0.75 kilowatts, totaling about six kilowatt hours per day, or 180 per month; that's a lot of energy.
This is where a solar swimming pool comes into its own; during the day when you may have a surplus of energy from your generator powered by the sun you can divert that excess to driving the filtration pump.
A swimming pool in your own garden has much to do with your philosophy of life, and the upbringing of your children. Are you committed to starting the next generation on a culture of exercise and physical fitness? Then this is certainly one way to achieve that.
Then, do you want your child playing in your own home environment where you have a measure of control?
One doesn't want to be overly controlling but in a society of junk food, hours playing computer games and the dangers of unsupervised trolling of the net, perhaps you would prefer your neighbour's and children's friends at your own home.
Scarily, unsupervised children begin experimenting with drugs and sex at an astonishingly young age. A solar swimming pool is one way to help keep your children fit and out of doors.
Rather the dangers of too much sunshine than those of a sedentary lifestyle and all that goes with it. In fact, learning the importance of a hat and block out becomes part of the equation.
One way to reduce the schlep of maintaining a pool is to use a salt water chlorinator. The steady supply of disinfectant to the pool as the pump is running not only reduces the cost of HTH tablets but more important reduces the need to be vigilant about caring for your solar swimming pool every evening. Power it of course from your solar generator.
Swimming pools, of course, need water; whether it's due to the splashing of children or evaporation on a hot day, they need to be topped up periodically. Here enters your rainwater harvesting model.
Rainwater harvesting certainly takes some planning, considerable cost and effort to build your own reservoir and pump. It does mean in times of severe drought, when pools may not be filled from the municipal supply, that you are not up a creek without the proverbial paddle.
There's ample rainwater falling on your roof for home, garden and pool; if you can store it.
The upside too is that you have a far higher quality of water than any municipality can provide.
And you don't have to accept the toxic effects of added chlorine and fluoride to your drinking water.
Plus you can enjoy a totally indulgent shower every day, without guilt. We don't use water; it simply takes a detour from the roof to the earth, via our toilets and showers; and via your solar swimming pool.
Philosophically it takes us back to our hunter gatherer days; only now we are collecting photons of sunlight, and harvesting the rainwater.
If you go away on holiday, you don't come back to a green pool; no toxic algaecides are necessary with this setup.
But again that's where a solar generator pays its way by supplying that energy during the day when you have a surplus of free electricity. When the weather is cool the pool needs less chlorine, so that's not a problem.
The chlorinator is a heavy user of electrical power, drawing 2-3 amps at 220 volts, or a little over a kilowatt together with the pump. So, altogether we are looking at 200 kWh per month. In my country that would mean about three to four hundred rands; say 50 dollars.
By supplying energy from the sun, your solar powered generator will make a significant contribution to reducing your electricity bill.
This is what a chlorinator might look like. A box producing a high amperage current to the cell in the background where electrolysis produces chlorine from the salt water.
Salt of course is sodium chloride; it takes considerable energy to split the ions and produce chlorine gas.
That salt water chlorinator can easily be powered by electricity from your solar powered generator; it's a natural adjunct to the solar swimming pool.
A solar powered swimming pool is just one of the many options that you can choose if you have a sufficient PV panels and an inverter to produce high voltage alternating current.
Although it's generally recommended that you add HTH at night, we have found that the salt water chlorinator works perfectly well during the day when there's free surplus energy.
The device is at least 15 years old and has given trouble free service. The platinum electrodes are now old and weathered and it seems wise to upgrade to a new machine with solid plates that is self cleaning.
A pool blanket is an important addition to your solar swimming pool, reducing evaporation and heat loss at night, and trapping the warmth of the sun during the day.
I haven't yet considered heating our solar swimming pool for a longer season at the beginning and end of winter; that's in the pipeline.
One other huge advantage to a salt water chlorinator is that there's zero troubles from ear infections, if with lots of kids swimming.
Change over switch enables you to easily move from a solar powered generator to the utility for your electricity. Then one flick of the button will move all your circuits from sunshine to Eskom or vice versa; but we use the solar swimming pool pump and chlorinator only on sunny days.
Our solar swimming pool is only pumped and chlorinated on sunny days; only very occasionally, if we have a five day rain, is there a problem and we need to add extra chlorine.
Friends have complimented us on the crystal clear water.
Residential solar panels in and around the home can provide power for other uses. See how we used solar panels to power our electrical gate; the saving in installation costs of an armoured 220V line by a qualified electrician alone made the exercise worth while.
Fairy lights in the garden, boundary LED lights and of course the PV panels on your roof or better still next to your home to power a solar generator; the possibilities are endless.
Going off the grid is a romantic but impractical notion unless you have pots of money for batteries. It won't affect your solar swimming pool either way; simply aad some chlorine once or twice a year when extended inclement weather sets in.
In short building eco friendly homes has become one helluva ride; unless you passionate about something, anything, after retirement, you probably won't live too long.
Bernard Preston has a fascination for all things electrical; even as a young boy he was fiddling with changing plugs, once getting nearly fatally electrocuted. Then it was a science degree majoring in physics and now turning to matters such as solar swimming pools, salt water chlorinators, change over switches and installing PV panels on his roof.
In his spare time, he is the author of six successful books, and busy with his seventh. Have you read the Bernard Preston series of chiropractic anecdotes? They are dirt cheap on your Kindle.Bernard Preston » Day in the life of solar geek Bernard Preston » Solar swimming pool