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From July 2017 many swimming pool owners are experiencing an astonishing 30% or more increase in the price of electricity required to filter and chlorinate their pools and are now looking to adding solar PV panels to reduce these new costs.   Will solar PV panels help? Not necessarily. Adding solar panels to a home with pool, will certainly reduce the amount of energy you will need to purchase from the Grid, but it will also likely force you to use more expensive Grid energy, actually putting your bills up. The reason for this apparent contradiction is the weather. This blog explains why it happens, how you can avoid the problem and how you can save dollars.

Firstly, it is important to understand that you cannot run an average pool directly and entirely from PV panels, no matter how much you want to.  There are two reasons:

The first reason is that pools in Sydney generally need around 10 hours of filtration and chlorination a day to keep them clean and well sanitised in summer.  Unfortunately, adequate solar power is only available for about 6.5 hours a day in ideal locations.   This means that, even on sunny days, most pools will need to operate partially from solar panels and partially from the Grid.

The second reason is the weather.  In Sydney, there is an average of 109 sunny days a year with good solar PV generation, 129 days of rain and overcast with little generation, and 127 unsettled days with sunny and cloudy patches producing quite intermittent generation.  If you use time-clocks to run your pool equipment during daytime hours, it will run, rain or shine.   While you may get ‘free’ power on the sunny days that make up one-third of a year, you will almost certainly be running your pool and/or house using the most expensive grid power for much of the other two thirds of the year.  This will likely wipe out your sunny day savings two to three times over.  The detail is given below, but simply, unless you have weather control sensing and software, you will almost certainly put up your bills.

Pooled Energy has weather controlled solar PV operations for your pool.  This will save you both energy and dollars.

In Detail

If you have solar PV, you will almost certainly have a Net Meter so that you can get paid for solar power that you export to the web.  This also means that you will be purchasing power from your electricity retailer based on a Time-of-Use Electricity Tariff from the Grid.

Effective solar PV generation is available from about 9.00 a.m. to 3.30 p.m in summer. So, it would appear sensible to set your pool’s time clocks to run the filter and chlorinator from around 8:30 a.m. to 3.30 p.m, depending on panel orientation. Then, to set the high-power devices such as pressure cleaners or solar heaters to run during the strongest, sunshine period, from 11 a.m. till 2 p.m.  To get the full 10 or so hours of run-time that you need each day, you would also set the remaining 3 hours of operation to occur during the off-peak period from 10 p.m. to 7 a.m.

If you have solar heating, then it must run during the time when the strongest sunshine is available.

Of course, your solar PV panels need to be big enough to run the pool equipment as well as any background power consumption in the house, such as fridges or computers.  How big is that?

The pool consumption is typically 1.5 KW for the filter, 0.2 KW for the chlorinator, 1.7KW for the pressure cleaner and another 1.7 KW if you have a solar heater as well.   Since solar PV typically produces about 70% of the nameplate power at peak, this means that you need a minimum 5 KW system operating at full capacity just to operate the filter, chlorinator and pool sweep.  You will need a 7.5KW system operating at full capacity if you have solar heating.

This can work for a suitably sized solar PV array reasonably well on the 109 sunny days that are the yearly average for Sydney.  Your operating cost on these days is then equal to the capital cost of your panels amortised over their useful life…plus the approximately 6c/KWh Feed-In-Tariff that you would have received if you had exported the energy rather than used it yourself.  You also have to pay for any night-time supplemental electricity usage.

On the 129 average days of rain and overcast however, you will be buying energy from the Grid at shoulder rates from 8:30 a.m. to 2.pm., and peak rates from 2 p.m. till 3.30 p.m. in the Ausgrid area.  Endeavour peak rates start earlier at 1 p.m.  The electricity at these times costs about 3 times (Ausgrid) what it would have cost if you had purchased (used) the energy off-peak and not used the solar PV at all.  You have therefore removed your savings on the 109 sunny days, approximately 3x over.

On the 127 spotty days, the same thing happens but less severely, and it all depends on the relative amounts of cloud and sunshine.  However, it is probable that you will wind up paying about 1.5-2 times what it would have cost you to buy the same energy off-peak.

Overall, you have saved energy but paid quite a lot more for it.  For an average Sydney pool of 45,000 litres with typical equipment and operating hours, the extra cost is probably in the vicinity of $500 over simply using off-peak power.   In addition, you have to pay for the solar PV panels in the first place.

Some pool owners may also consider adding batteries to store electricity from sunny days, for rainy days. You will need some more solar panels to provide the energy to charge the batteries and cover their losses, and lots of batteries to deal with more than a single day of rain or overcast.  Batteries are therefore likely to add many thousands of dollars to your costs when used this way. You can reduce your electricity bill by using batteries but you need a big investment that to do so.  It is unlikely that you will recover this investment during the operational life of the batteries at this stage of the technology.

The good news is that Pooled Energy offers a solution using weather control software.  In addition, it reduces the energy required by the pool, often by 70% and reduces the instantaneous power used by the filter and chlorinator by about the same amount.  This means you need fewer/smaller solar panels.

Overall, the Pooled Energy automation system reduces the amount of electricity used by your pool in the average house by up to 30% of total household use.  In addition, the weather adaptive software in the Pooled Energy system uses weather forecasts to decide whether to run your pool from PV panels or scheduled to use off-peak electricity.

On sunny days the Pooled Energy system will run the pool from panels as much as practical.  On rainy and overcast days it will schedule the pool equipment to operate using off-peak power, and, on unsettled days, it will schedule opportunistically.  This approach will use energy more effectively.

The Pooled Energy system is the most effective solution available for energy and chemistry minimisation and optimisation. Pooled Energy is an electricity retailer that decreases your energy consumption as well as helping you manage when you use electricity better.

We’re here to help! For more information contact us at info@pooledenergy.com or 1300 364 703.

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