The Ultimate Guide to Modern Solar Pool Heaters
Article was written by Gregory Grochola (physicist)
So you're looking at heating options for your swimming pool and considering a solar pool heater - this comprehensive write up will help you get the low down on different types of options and all the things you'll want to consider, read on ...
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Solar thermal collectors (or panels, or array - these terms mean the same thing here) work on the very basic principle of passing cold water through warm sun exposed solar collectors typically mounted up on the roof. The warmed water simply comes back down directly into your pool. Solar thermal collectors differ from solar electric PV (PhotoVoltaic) collectors which collect energy via photons (light) hitting and exciting electrons creating a voltage across cells.
Solar thermal collectors are made as black as can be to turn all light hitting the surface into heat which is then conducted into and taken away by the flowing water. Water is a perfect heat transfer fluid as it has the highest heat capacity of any known liquid, which basically means it takes a great deal of thermal energy to warm water even 1°C.
Most systems use a digital controller which monitors the roof temperature, comparing it to the pools water temperature to see if there is any gain to be made by sending water up onto the roof. A digital controller also switches the system off it the set desired pool temperature is reached.
Most newer pools have dedicated suction and return ports installed to keep the solar plumbing separate from the main filter system. Older pools may not have solar suction ports installed and will need to draw water from the filter system.
These can be classed into two distinct groups, solar-based and utility-based. Solar-based means the energy is taken from the sun, while utility-based means the energy is taken from either gas or electric utilities. There are many types of solar pool heaters for sale to choose from.
2.1.1 Solar PVC Strips/Mat/Tube Roof Collectors
PVC strip collectors (also called solar mats or tubes) are made by extruding a strip of tubular water channels. They are typically mounted with strips going across the roof with their main header pipe (also called the manifold or feed pipe) going up/down the roof. The PVC material typically has a softening agent (a plasticizer) which makes the strips flexible. Individual tubes are joined to barbs on the manifold and are either glued in or held in place using mechanical clamping means. They are very popular here in Australia due to the fact that they can be laid and wrapped around a couple of different roof aspects.
2.1.2 Solar Pool Heating Roof Panels
Solar pool heater panels are one-piece construction blow-molded plastic panels with internal water channels. These are typically made from HDPE as are our solar pool heater panels. These panels have large internal water channels with a low pressure drop across them and turbulent water flow characteristics.
2.1.3 Hybrid Tube Roof "Panels"
These hybrid "panels" are typically made from extruded PP or PP blends with channels that are either made joined together or loose tube arrangements installed going up the roof, which are welded into the main header pipe going across the roof. They are very popular in America due to the larger roof space of American roofs, and are becoming more popular here in Australian.
2.1.4 Enclosed Solar Pool Roof Panels
Enclosed solar pool panels are basically polymer collectors that are covered with a glazing material (glass or transparent plastic). The glazing material increases the efficiency of the panels during adverse heating conditions like spring and autumn, which can have cold and windy but yet sunny days. These types of collectors are best reserved for heating premium indoor pools where the water temperature is substantially higher than the air temperature during winter.
2.1.5 Evacuated Glass Tubes Collectors
Evacuated tube collectors are typically used for solar hot water service systems, but have been adapted by some companies to heat swimming pools. They are made from air evacuated glass tubes with internal strips of black painted copper absorders. Heat is either conducted or transferred via copper tube water channels from the sheet absorbers to the main manifold heat sink. Again the glazing material and vacuum increase efficiency of these tubes during adverse heating conditions like spring and autumn, which can have cold and windy but sunny days. Again such collectors are best reserved for heating premium indoor pools where the water temperature is substantially higher than the air temperature during winter.
2.1.6 Combination PV Panels with Heat Pumps
The combination of solar electric panels (PV panels) and heat pumps can also be classed as solar-based heating systems. These systems work by firstly, harnessing electric energy via the solar electric panels, which is then used to run a heat pump to warm the pool. Modern PV panels are typically only 19% - 24% efficient, as compared to a modern solar thermal pool panel which are about 80-90% efficiency, however an efficient heat pump with SCOP (Seasonal Coefficient Of Performance) factor 6 can make these systems about 130% efficient, which now slightly better to thermal pool heating panels.
The main issue with these systems is the large upfront cost, of course the PV panels will produce electricity during non-pool heating times, unlike solar thermal collectors, which can off-set the price difference in installation, however the payback times will be substantial.
2.1.7 Solar Pool Covers
We can class a solar pool cover as a solar-based heating method as normally the surface of the pool itself forms the largest natural solar collector. A solar pool cover is typically transparent and works by letting light through into the pool while forming an insulating layer to keep the heat in by preventing evaporation.
2.1.8 Coiled Poly Pipe Collectors (no "Ultimate Guide" Would be Compete :)
Lastly, there are of course coiled poly pipe systems which people on tight budgets have used from time to time, for a good write-up of these see our blog article - Definitive Guide to DIY Poly Tube Solar Pool or Spa Heaters.2.2.1 Electric Heating Element
This is basically a bar heater or heating element, immersed in flowing water, electricity is used to heat the element and in turn the water. Typically, used to heat highly insulated spa pools, they are the least efficient means to heat a pool or spa. Their COP factor (energy in to energy out ratio) is 1.0 - meaning for every 1 kWh worth of electrical energy you put in you get 1 kWh worth of thermal heating.
2.2.2 Heat Pumps
Heat pumps work by using electricity to "pump" or transfer heat from the air into the pool water. They work on the same principle as air conditioners but in reverse. If you ever stood next to one you'd feel they exhaust cold air, much colder than the surrounding air. This means they are pulling heat from the surrounding air into the pool water. Unlike an electric element, since they are pulling thermal heat from the air they can have average SCOP factors as high as 6, meaning for every 1 kWh worth of electrical energy you put in you get 5 kWh worth of thermal heating. Just to compare however, a solar pool heater can easily have COP factors of 100.
2.2.3 Gas Heaters
Gas heater basically burns domestic gas to heat a heat exchanger with flowing water, in turn heating the water. They have typical efficiencies of 87%; meaning of the total energy obtained from burning gas, 87% will get transferred into the pool water, the rest will get blow out with the hot exhaust air.
Of course there is one more clever way you can warm a pool and that is to change its heat/loss equation by - firstly, removing any shading on the pool and secondly, sheltering it from the wind by planting windbreak shrubs (that don't grow tall so as to shade the pool) or building a windproof fence. Our pool water temperature simulator will help you decide whether this is worth it for your pool.
However, these two factors really can contribute significantly to a warmer pool. Note, for a light-colored pool about 85% of the sun's energy falling on the pool's surface is absorbed (90% for a dark pool) - considering that solar pool panels are on average about 80% efficient, then for every 1m² of pool that is shaded all day, this is equal to about 1 OKU solar pool heating panel! So for example, if you remove 16m² of shading on a pool that's like installing a 16 panel OKU solar pool heating system! Not bad for cutting down that tree.
There are certain pros and cons for solar pool heating systems. For a full set of advantages, see for example our blog article on the benefits of solar heaters, however briefly the main advantages are:
The main advantage of solar-based systems is the cost of ownership over 10 years, as this includes running costs. We'll talk more on running costs below, however since solar-based systems draw the bulk of the heating power from the sun, they are much less extensive to run. Although, utility-based heating systems do have reduced running cost if a pool cover is used, they are still much more expensive over the long run. So once you're made the initial outlay for your solar pool heater; the running costs are very low, especially if you are running a small pump on a fast flow, low-pressure drop collectors like OKU solar pool heating panels.
Conventional auxiliary pool heaters comprise of heat exchangers, combustion chambers, fans and compressors. The units are often situated in a corrosive environment like that around a pool, where corrosive chlorine vapour is ever-present in the air. While manufacturers often make efforts to prevent corrosion over the long term, conventional heaters simply don't last anywhere near as long as solar water heaters. The only moving part on a solar pool heater is an easily replaceable solar pump.
Of course lastly, solar pool heaters are the environmentally responsible choice. We are all living through an age where climate change has grown to become such a pressing issue that it's everyone responsibility to do their bit for the environment. Luckily, solar pool heating systems are such a no brainier that this choice actually benefits your hip pocket as opposed to costing you anything.
The main disadvantage of solar-based systems over utility-based systems is that they are not an "on-demand" type heating system, namely if the suns not shining over a few days the pool will get cooler.
This disadvantage is partly be offset in a couple of ways, firstly, a pool cover can stop the pool from getting too cool over cloudy, windy and or rainy days when combined with a solar pool heating system.
Secondly, most people don't realize but when the air temperature falls below a certain threshold people simply don't want to get into an outdoor pool no matter how warm the water due to the wind chill factor. It's partly why the Aus Stand doesn't recommend over-sizing a heating system past a certain collector size. A lot of people choose a heat pump or gas heater based on this "on demand" aspect - namely I can warm up the pool and swim whenever I like - technically yes, but keep in mind that fact; not many people want to get in a pool when it's cold and windy out. And when it's warm out, solar pool heating systems work great, even in party cloudy weather there is still significant solar radiation around as long as the roof air temperature is warm.
Solar collectors, of course, require a roof space and not every home has an ideal roof space available. Some homes have their optimal North facing roof aspects covered in solar PV panels and/or solar hot water panels. These days in Australia there is a trend to build compact two-story townhouses, where installations on smaller two-story roof are more difficult. In most cases however, the performance loss from an installation of pool collectors on less than idea aspects, like West or East facing aspect is small. See for example our write up on the optimal roof aspect angle for pool collectors.
It's also instructive to point out that solar PV and solar pool collector optimal tilt requirements don't actually overlap in most areas, for example see our study on idea North facing tilts for PV vs pool collectors, we show that the optimal pool collector tilt vs latitude of location actually follows a reverse relationship to that of PV panel tilt. To quote "... for low latitude areas like Darwin (latitude 12.4°) for example, you want a large (pool collector) tilt like 40°. While for high latitude areas like Hobart (latitude 42.8°) you want a low (pool collector) tilt 20-25°. "
So how much warmer can they make your pool? Well this depends on a lot of factors and heat loading computations are quite complex. We've done these calculations as we show in our blog article - How Warm Can a Pool Get With a Solar Heater and Cover.
The table below summarizes various heat loading scenarios for a pool heated using our OKU solar pool heating panels with a total collector area 67% that of the pool's water surface area (termed the coverage) or equivalently equal to approx. 100% coverage of an older style well spaced PVC tube system - used in conjunction with a transparent bubble type pool cover on 100% of the time.
Averaging the temperature boosts over shoulder pool heating months only (not including peak hot summer months) for all Australian capitals we get the following temperature boosts.
Light Walls
50% shaded
Light Walls
0% shaded
Light Walls
0% shaded
Light Walls
0% shaded
Dark Walls
0% shaded
Temperature boost from a 67% coverage OKU panel pool heating system using in conjunction with a transparent bubble pool cover on 100% of the time.
In the table: "Shade" means shading on a pool. "Windy/Exposed" or "Clam/Sheltered" specifies the pool is either fully exposed to a windy area or fully sheltered and situated in a wind clam area respectively (two extremes). "Light/DarkWalls" refers to the colour of the pool floor and walls.
So the first column shows the temperature boost if one was to install a solar pool heating system with a pool cover on an unsheltered, wind exposed pool, in a windy area (like a hill or beach front) with 50% shading on the pool. The last column shows the temperature boost for a wind-proofed pool, in a wind sheltered area (like a valley), with dark pool walls and floor, and no shading.
As can be seen you can get temperature boosts anywhere from 5°C to 18°C depending on the heat loading specifics and location. For an average pool you're looking at an average 11-14°C temperature boost depending on location. Remember though these are averages - averaged over night and day, cold and warm spells; most people tend to swim in the afternoons during a warm spell, so during those time, you're going to see larger boosts.
This depends on the state and the amount of solar collector coverage installed, the largest factor effecting your total season is whether or not you are going to use a solar pool cover, however to give you some idea of typical season swimming month in various states we've produced this table:
* Standard season without solar
As a general rule a solar pool heater and pool cover will easily double your season, if you have a specific set of heat loadings on your pool, try our online pool heating running cost calculator to see exactly how much a solar pool heating system can extend your season.
- Use of a pool cover - this has the greatest effect on the ability of a solar pool heater to increase pool temperatures substantially.
- The efficiency of solar collector system - the gap between the best and worst collector system is about 50% in output.
- The collector size - larger sizing's offer more heating at a diminishing return point.
- Flow rate of the system - has a large impact on collector efficiency. Faster flow rate strip heat from collectors better.
- The roof the collectors are mounted on - dark hot tin roofs are warmer than for example a car port roof.
- The wind exposure on the roof - wind has a large cooling effect on unglazed solar collectors.
- Suction ports or skimmer box water draw - drawing warm water from the skimmer box does not mix pool water as well as drawing cold water from the bottom.
- Use of an automatic controller - people can't be expected to baby sit manual systems every time it clouds over.
- Wind sheltering of the pool - i.e. fencing and shrubbery around a pool which shelters a pool reducing heat loss from the surface.
- Local wind strength terrain factors - i.e. are you in a built up sheltered suburban area or on a windy beach front.
- Shading on a pool - between the hours 10am to 4pm, this is a large factor and can substantially cool a pool.
- In ground or above ground - above ground pools loose substantial heat from exposed sides.
- Color of pool floor and walls - darker colors absorb more light.
- State and location the pool is in - determines air temperature, average wind and solar radiation available.
- Solar pool cover usage - pools with transparent pool covers are substantially warmer especially when used with solar.
- and of course the use of a solar pool heating system or auxiliary heater.
The first thing you'll want to consider, is of course: do you have the roof space to mount a large solar collector? (Note, some collectors require less roof space than others see next section below). For optimal aspects and tilts, see for example our write up on the optimal roof aspect angle for pool collectors. Even if you have to comprise on the ideal roof space, it may be that the loss factor is small and can easily be made up using a slightly larger area. See our online solar simulation calculator here, which will accurately assess the loss factor from mounting collectors on different roofs. This calculator even has a morning/evening, wind and air temperature correction for East and West facing aspects so it's very accurate. Now assuming you have a roof space, you'll want to consider the following:
Collector efficiency is an important factor when considering a solar pool heater system as some collectors are more efficiency than others and require less roof space. Let's have a look at all§ the design factors that actually impact collector efficiency. This will help you see through all the marketing fluff (written by Dr Gregory Grochola - thermodynamics physicist).
§ excluding glazing, back insulation and/or surface emissivity/absorptivity treatments - none of which is practical or economical for a pool heating panel.
0.11-0.22† for PP
0.42-0.51† for HDPE
And that's it! Forget all the marketing fluff, what you want in terms of efficiency is a collector with good polymer thermal conductance, moderate face thickness (considering durability), no hot spots, fast turbulent water flow and a flat collector face. You can now easily compare other collector designs and see which aspects they have. We estimate that the best collectors are about ~50% more efficient (in the shoulder months) than the worst collector designs, which corresponds to 33.3% less roof space requirements. But keep in mind, efficiency is only one aspect to consider; a low-efficiency collector can easily be as effective as a high-efficiency collector, you just need a larger area.
Apart from efficiency below is a comprehensive list of things you might like to consider when choosing a solar pool collector type.
So we've compared collector efficiencies and collector design aspects, what about actual system design aspects.
We always recommend Independent Systems, see definitions below. These systems run a small independent pump, typically for 8 hours per day and are actually more energy efficient than systems running through the main filter pump which have to run the large filter pump for 8 hours per day just to pump the solar side. Of course independent systems require separate solar suction and return lines, whereas for older pool these might not have been installed. If that's the case you'll need to go with a plumbing configuration that taps into your existing filter return line to divert water to your roof. There are a few configurations that can be chosen, see below or one of our pool heating manuals. Most people that do not have independent solar suction and return ports will choose a Manual/Timer System and place the main filter pump on a timer to run during the warmest part of the day. These manual systems can be automated down the track. We have three class of listings:
- "Automatic Kit" - can be used to set up an Independent System or Integrated-Independent System - includes a solar controller (pump sold separately)
- "Manual Kit" - runs through the filter lines, can be used to set up a Manual/Timer System with a 3-way and non-return PVC ball valve (can be motorized/automated later)
- or just collector "Replacement Kit" - for people that just need to replace their old PVC tube collectors on the roof
If you need to set up a specialized system like for a Booster/Retro Fit System (requires AquaSmart 5 FS or CD controller) or the Motorized Ball Valve System (requires AquaSmart 5 AV controller), please contact us at EcoOnline.
If you're considering installing an independent or retro/booster type system you'll need to consider solar pump sizing. If you're purchasing a new pump make sure it's specifically suited for solar pool heating systems, as pool filter pumps are geared differently. In terms of sizing, a grossly oversized pump could not only limit collector lifetimes, but will cost you more in electricity usage (literally thousands of dollars over a systems lifetime!). An undersized pump conversely will limit collector efficiencies and not turn the water over sufficiently, resulting in poor system performance. To help you size a pump, we've written quick table guides in our manuals, but if you really want to optimize your pump power saving you can use our panel system pump sizing calculator or our - PVC strip system pump calculator - these simulate various pump sizing choices and their respective effects on collector efficiencies and energy savings.
It's unfortunate however there are no solar pool heater reviews of specific systems or collector systems available to the Australian public today. This is most probably due to the complexity of the science required to evaluate the performance of any particular system. Prospective buyers need to look at reviews for individual solar pool heating companies and suppliers, as well as think critically about systems, their constructions and evaluate them against all the issues given above in section 6 of this article.
So you've decided on a specific solar pool heating system and now you want a cost estimate, here are the specifics you'll need to consider.
First and foremost, for a costing you'll need to figure out how much of a season extension you want which will determine the size of the system. If you want to do this yourself - we've developed a pool water temperature simulation calculator which will tell you the water temperatures you can expect with or without solar (and/or a pool cover) at certain times of the year. Keep in mind there will be times of the year where it'll get too cold to swim.
Generally regarding sizing, in the solar pool heating industry, we talk about "season extension" months. The Australian Pool Heating Standard recommends about a 3 month extension. What this means is that you'll get the same pool water temperature 1.5 months earlier in the season and 1.5 months later in the season with solar heating. The collector area is then sized accordingly to aim for the desired extension.
However, it's not set in stone nor is it one size fits all, it depends on what you desire and your budget and/or available roof space. Sizing can range from a minimum of 2 month extension; as some people really just want to swim in the summer months - to a 4 month extension for people that use the pool more frequently or want to swim at night, and hence want that almost "on demand" pool heating experience. As mentioned above it's important to understand the limitations of solar pool heating, as these systems are not an "on demand" type system, however if sized higher, and especially if a solar pool cover is used, it can come pretty close to an "on demand" system.
When sizing a new system there are several factors to consider. We provide an interactive sizing calculator that takes into consideration almost every imaginable factor, see below. This calculator is based on minimum Australian Standard pool heating sizing and will include weather, solar sunlight hours per postcode, combined with installation-specific factors to come up with the best possible sizing for your budget. It gives sizing advice for PVC strips and panels.
It's important to factor every aspect affecting a pool's temperature, as some pools can suffer from a number of cumulative cooling factors, for example our calculator instantly assess:
- Your postcode location
- Roof pitch angle of the installed collectors
- Roof facing compass direction
- Your pools total water surface area
- Whether or not the pool is sheltered from the wind
- Shading on the pool during the shoulder months
- Local / Regional weather factors
- Whether it's an indoor or outdoor pool
- Your roof type
- Manual or Automatic system
- Depth of solar suction ports
- Color of pools wall surfaces and floor
- Whether it's an in ground or above ground pool
- And finally your budget and expectations
To work out the surface water area of odd shaped pools use the following trick:
- Measure the pool's edge to edge length.
- Draw an imaginary horizontal line cutting the top edge of the pool so that the dark blue shaded areas above the line are approximately equal to the red areas below the line. You can eyeball this quite accurately, then mark it.
- Now do the same for the bottom side, then finally measure the width distance between these two eyeballed lines.
Possibly the largest cost consideration is going to be whether or not you DIY or get a pool heating company or installer to quote on an installed system. Due to the seasonal nature of the work this can get very expensive. Depending on system size and the amount of plumbing required you can budget about $1,000- to $3,000 just for labour and installer mark-ups on supplied components (and installers will push their components due to the marks ups they get). So is it worthwhile taking some time for a DIY project? We've seen and heard about a number of overpriced, shoddy, low quality component installs to say absolutely, if you are able to do it safely you should seriously consider DIY. You can source the best quality components from reputable suppliers (here we only sell the best) and you'll have full control over how the system is installed. Make sure a supplier has extensive manuals to guide you and many years of experience to answer any technical questions you may have during installations. You'll end up owning a higher quality more reliable pool heating system for less money sometimes than inferior competing kits AND you'll have better quality install that you'll know how to service.
7.4.1 Consider Quality of Work, Components and Roof Fixing Methods
It's understandable why shoddy installs happen sometime; pool heating installations are seasonal, full-time installers wait around all year then all of a sudden they get bombarded with more jobs requests than they can handle so they feel they can charge an arm and a leg and be picky with their jobs. Companies and installers then need to take on part-time workers that may not be well trained, and they are rushed and under pressure to finish the job fast. If there are complications, installers have no motivation to take their time and do it properly to make sure the system will last as they are not paid by the hour. Most of the shortcuts they may use appear many years down the track typically with no recourse for the consumer.
We've seen competitors use self-tappers or rivets as fixings on metal corrugated roofs as that's the easiest and fastest thing to do. In 5-10 years these superficial metal to metal fixings are likely to corrode drill holes and are likely to pull out in a strong wind storm. The only proper metal roof fixing method that we recommend (as stated in Solar PV Australian Wind Loading Standard) are long roofing screws, sunk deep into battens or rafters. We've seen other companies drill tile perforations for fixings that in time are likely to leak water down the screw onto the batten. We recommend non-peforating solar roof hooks as standard tried and tested tile fixings in the PV industry. In terms of other hold down fixings we see some competing products use glass filed plastic fixings which are subject to UV degradation - after 10 years of baking in the hot Australian sun what level of strength will these plastic fixings retain? The only plastic that has a proven long term pedigree in the sun is polyethylene. Our philosophy is that fixings must last the entire life of the system.
7.4.2 An Important Note on Safety
Having said all of that; you should only consider DIY if you're confident of performing the work safely. If you need to get up on a pitched two story roof and you are not 100% confident, best leave it to the professionals, as you should never underestimate the chance of a fall. If you can't DIY try to source a trusted installer - at the very least go with a company with good component and installation quality control standards.
As you can see EcoOnline has intimately considered all aspect of pool heaters and has chosen to sell particular systems not by accident, but by extensive research into them. We only sell, develop and support the best systems that are excellent value for money. In fact we won't be beaten on the cost of an equivalent system so just ask. We sell two types of pool heating systems: PVC tubes and OKU panels with an extensive history of longevity in the field. Check out our lists, or for an instant quote try our online size and quote calculator here.
Wikipedia on Solar Pool Heating
Australian and US Government Resource Pages
- SA government energy saving advice
- NSW gov aquatic center energy saving advice
- US FSEC on pool heating costs
- US FSEC on solar pool collector sizing
- US FSEC on solar pool heating installation
- US Energy.gov on solar pool heating
- US Energy.gov on pool heaters in general
Solar Pool Heating Testing Organizations
- ICC-SRCC organization ratings for solar collectors
- US FSEC on ratings for solar collectors
- IEA-SHC collector ratings organization on solar pool heating
Solar Pool Heating Standards
Solar Pool Heating Research Links
- ScienceDirect pool heating search page
- Google Scholar pool heating search page
- UCSUSA.org on solar water heating
- Stanford University on pool energy conservation
For a wealth of installation info, see our installation instruction download page, where you'll find PDFs for installing PVC tube or panel-type systems for both pools and spa pools. If you prefer online instructions, see here for instructions on how to install solar pool heater panels or here for instructions on how to install PVC solar pool heater mat systems.
Q. Will a solar pool heating system work in partly cloudy conditions?
A. Partly, yes, but only if the air temperature is sufficient and there is enough solar insolation. Keep in mind that pool heaters also heat the ground around the pool. Hence, a pool will not completely lose heat in one day of cold weather. Although it might be substantially cooler, it will get back to temperature quickly the next day if there is sun. Eventually, it's the overnight cold air losses that make it impractical to keep heating the pool, signaling the end of the season.
Q. Can I split the collectors and install them on two different roof aspects?
A. Collector arrays that face different compass directions are not recommended unless the roof pitch is less than ~15°. What will happen is—depending on the location of the roof sensor—the controller will turn the system ON with one bank of collectors in full shade, which can cool the water and be counter-productive.
Q. What size PVC piping do you recommend?
A. For panels, generally, we recommend 32mm on the roof, except for larger multiple-row arrays with a secondary header pipe feeding multiple rows of panels, for which you should use 40mm. Coming down the roof, the pipe size can then be adapted to the pipe size you have for your solar line ground run, i.e., 40mm or 50mm. For strips, we recommend 40mm as the manifold connections are 40mm.
Q. Should I paint the PVC pipe black for extra heat absorption?
A. We don't recommend this (unless perhaps on the ground where it will be filled with water constantly). The issue is that PVC will soften substantially at 70°C; hence in summer on really hot days during stagnation on a hot roof, we've observed black PVC pipe soften to such an extent that it loses structural integrity and collapses in on itself. The second issue is that PVC will expand more when it's black due to larger thermal temperature variations, hence care must be taken to ensure long lengths of PVC pipe runs have enough room to expand and contract without putting pressure on right-angle connections.
Q. I have a long run from the pool to the roof; do I need a larger pump?
A. Generally, no, your pump size will only be determined by the pump height. Having said this, keep in mind that it's very difficult to determine a pump height level across a long distance. If you have a long pipe run, we simply recommend using 50mm PVC to reduce the frictional losses.
Q. I have a long run from the pool to the roof; should I insulate the PVC piping?
A. Generally, no for outdoor pools, as the temperature difference between the air and the pool water is small, hence the loss in this pipe will be small. For spa pools and indoor pools where the water temperature can be substantially different from the air temperature, this can be of some benefit. However, if the PVC piping is exposed to a north-facing aspect and gets sun, then it's sufficient to simply paint the PVC pipe black, saving on insulation (note the caveat mentioned above).
Q. What collector plumbing arrangement do you recommend?
A. There are multiple plumbing arrangements available for both the panels and PVC strip systems, too many to mention here. We refer the interested reader to our download section where you can download the manuals and see each configuration.
Q. Do I still need a pool cover if I have solar heating?
A. Yes, we highly recommend solar pool heating systems be combined with a pool cover due to the synergistic effect between the two. See this article for a description.
Q. What if I already have a gas or a heat pump pool heater?
A. Solar systems can naturally be combined with auxiliary heating systems. In fact, not only will they lower the cost of heating your pool, but they'll also extend the life of the auxiliary heater by reducing the load on it.
Q. What kind of maintenance is required?
A. Solar pool heating systems require maintenance from time to time, depending on the system installed. We refer the interested reader to our download section where you can download the manuals and see each configuration.
Q. We live on a hill—can I install a pool heating system below the water level?
A. Generally, this is not recommended if the collector system is more than 1m below the water level. This is because panels and tubes will experience constant pressure from the force of the water. This is especially an issue in summer when the system is stagnating in the extreme heat. Such events will act to limit collector lifetimes as polymer longevity is sensitive to pressure and heat. Any breakage in the collector system can also drain the pool, potentially flooding lower areas, so this must be considered.
Q. How much do solar pool heating collectors weigh?
A. OKU pool heating panels weigh 6kg empty and 12kg full. PVC strips weigh 4kg empty per m² and about 7kg per m² when full.
Q. How many panels do I need?
A. Please use our interactive sizing calculator to accurately size your panel or strip needs. If you have any difficulty, please contact us. Note: we frown upon the practice of selling you more panels than you actually need for your heating goals. To back our smaller sizing recommendation, we provide a panel sizing guarantee.
Q. I was sized a much larger rubber mat system—why is your panel area recommendation smaller?
A.Besides the increased efficiency in cooler weather during critical season extension months, we strongly oppose the industry practice of selling you a larger system. The new Australian Standard 3634-2022 for sheltered pools recently increased sizing recommendations; however, we believe in a more tailored sizing solution based on proper heat loading circumstances. Over-sizing a system will result in polymer collectors stagnating at detrimental temperatures of up to 80°C for longer periods during hot days when the controller shuts the system down. As such, over-sizing reduces collector lifetimes, requires a larger pump, and incurs higher upfront costs—all for diminishing gains in water temperature. If you require higher temperatures beyond our maximum collector recommendation, we suggest using a solar blanket.
Q. Can I undersize my system and upgrade as needed later?
A. For panels, yes, but only to an extent, and we don't recommend it. You should not go below our minimum 2-month extension recommendation; see our interactive sizing calculator. No, we are not trying to sell you a larger system. There are very good reasons why a system should not be dramatically undersized. Effective heating requires a minimum daily turnover of typically 50% of your pool water volume. However, there are flow limitations on panels; hence an undersized system may not handle the flow required, which could over-pressurize panels, or if the flow is insufficient, will result in an unmixed stratified layer of warm water which will cool excessively overnight.
For PVC strip, we have to say no, it's difficult to slice in an extra manifold section into the main manifold pipe once it's all glued up; it's best to size your system right the first time.
Q. Can I use my existing controller and mains power pump?
A. You can use your existing controller if it’s in good working order. However, pressure pumps that power rubber mat systems are typically too strong for these panels. Over-sizing the pump not only uses more electricity but has the potential to limit panel lifetimes due to large pressure fluctuations in the panels. EcoOnline (and OKU) only recommend typically 0.25HP to 0.5HP pumps for small 8 to 30 panel systems.
Q. Can I use my filter pump and save electricity by not installing a second pump?
A. It is a false economy to use a large filter pump for solar applications—the pump still has to expend energy to pump water to the roof, putting back pressure on the pump and reducing filter flow, hence there is no free energy gained. Besides this, we don’t recommend running a high-power filter pump for 8 hours per day for the solar side (potentially over-pressurizing panels) if you don’t need to filter for that long. An independent system with a well-matched small pump will save you money in running costs and look after your panels in the long run.
Q. Can I use a low-energy usage variable speed pump?
A. No, after witnessing customers try such pumps and struggle with them, our advice now is not to use them, unless they can be set to run at a constant speed without a startup surge. We find variable pumps start at full power then taper back. This puts a lot of pressure fluctuations through the panels on startup which could limit panel lifetimes. We only recommend pumps that can pump at a constant set pressure.
Q. I don't have independent solar lines installed on my pool—can I tee into my main filter pump suction line?
A. Generally, we don't recommend this as you may have priming issues with your main filter pump during startup due to air being drawn in from the solar line tee you installed. Whether your filter pump will de-prime in this case will depend on how far below the waterline you installed the solar tee. Note, a non-return valve on the solar line will not help here as non-returns are not generally airtight over time. If you do not have independent solar lines and can't install the tee far below the waterline (minimum, say 1m below), then your options are a manual system, a booster system, or a motorized ball valve option. See the manual for plumbing diagrams.
Q. Do we have installers?
A. At present, unfortunately, no, we do not have installers as we ship around Australia. However, our manuals are very comprehensive and cover most situations and issues. There is also unlimited tech support available. Most handymen/tradespeople can install our systems. From what we hear, solar pool heating installs are very seasonal, hence most specialist pool heating installers are run off their feet during the install season. This means they charge an arm and a leg for poor, rushed installs. Our advice is if you can DIY safely or source a trusted installer that will take his/her time, you will save a great deal of money and headaches.
Q. Can I download your comprehensive manual before I purchase?
A. Yes, in fact, we highly recommend you check over the manual to get a good idea of installation requirements before you purchase. The manual can freely be downloaded from our EcoOnline download page.
Q. Is this system easy to install on tiles?
A. OKU panel installation on tiles is more difficult and should only be attempted by experienced DIYers or tradespersons. PVC strips are easier to install on tiles. (Please note the safety notice when climbing up on a roof.)