DIY Solar Pool Heater: 4 Ways to Use the Sun to Heat Your Water
Swimming in a warm pool is a summertime favorite for many, but the cost of heating a pool can swiftly curb the excitement. A DIY pool heater is a cost-effective and environmentally friendly solution that utilizes the sun’s power to warm your pool water. With just a few simple materials and some basic DIY skills, you can save money on your energy bills and enjoy a warm pool all summer long.
How Does a Solar Pool Heater Work?
Most solar pool heaters take the water from your pool with a pump and send it through a solar collector to heat your pool water. In other words, the solar collector can capture heat from the sun’s rays. As the water goes through the collector, it retains the heat as it goes back to your pool. The solar pool heater continues to recirculate your pool water through the solar collector and back.
Solar collectors are typically tubes or plates consisting of a variety of materials that attract the sun. It can be as simple as black tubing because the color black absorbs more heat than it reflects. Other materials include copper tubing, aluminum plates, or glass coverings.
Take a dip on a cool, sunny day with a solar pool cover
How Much Does It Cost to Install a Pool Heater?
The cost to install a pool heater depends on the type of heater. A gas or propane pool heater will cost anywhere from 450,500 to 6,000. Similarly, an electric pool heater costs 450,000 to 6,000 but has much higher operating costs than gas heaters.
For a more energy-efficient pool heater option, choose a heat pump pool heater for 5000,500 to 7,500 or a solar-powered pool heater for 5000,500 to 9,500. While the initial cost of a solar heater is a bit higher than other options, it will pay for itself in the long term since they harness solar energy from the sun.
Unlike the DIY solar pool heaters described below in this guide, a standard solar-powered pool heater uses a factory-made solar collector and more advanced equipment, including a pump, strainer, filter, flow valves, and a separate pool heater unit. Generally speaking, solar-powered pool heaters from a manufacturer will last longer and be more effective at heating your pool, hence the much higher price point.
You will save anywhere from 300 to 450,000 on labor if you install a pool heater yourself; however, most installations require modifying electrical or gas, which are tasks you need a pro to take care of. Contact a pool heater installer near you for pricing.
Prepping to Build Your DIY Pool Heater
Before building a solar pool water heater, it’s important to know which direction and angle will capture the most sunlight in your area. In the Northern hemisphere, facing solar panels toward the south is typically the best choice, along with angling them between 30 and 45 degrees. The exact formula will vary depending on where you live and the time of year.
Compost Hot Water
When we first installed the composting hot water it was revolutionary in its simplicity: one uses the heat of a decomposing compost pile to heat water. This is generally achieved by having a long tube coiled inside the compost mound. As you create the pile you slowly coil the tube amongst all the to be decomposed additions. This must be a hot, or thermophilic, compost system. When I first constructed this system it was fantastic. The water heats up within 24 hours and it stays hot night and day.
The really hot water lasts around two to four weeks, depending on the size of the pile, but over the next six weeks it does start to slowly cool down. At this point you have to build another pile for it to heat up again. At first this was easy, we would collect all of the trimmings from the occasional chopping of the soccer field to make the next pile. This would last about the same amount of time as the field took to overgrow and be cut again. It was good timing.
DIY Solar Pool Heater Build. Water over 90 Degrees After A Week. Watch Newest Video for Issues
Once the community bought a lawn mower though, this abundant supply of nitrogen for the pile dried up. Instead of waiting six to eight weeks between cuttings, the field began to get mowed regularly and now there are no longer large amounts of grass clippings available for a hot compost pile. There were other challenges; the tubing often became twisted and was an absolute pain to dismantle and re-use with each new pile. The hot water didn’t last long per shower, about five minutes, as it was limited to the amount of water held in the total length of tubing. All of this added up to a trip back to the drawing board!
Solar Hot Water
We have had several different solar hot water systems at the ranch. They all work really well as long as it is hot and sunny while you are taking a shower. Of course this is exactly the time when you don’t need a hot shower, usually a cold water shower feels most refreshing. I want a hot shower when it is cold and rainy!
Until now, none of our solar hot water showers would produce hot water when I wanted hot water. This was for two main reasons. The first was that the tanks were never insulated. Even though the water in the tank would heat up, it would not stay warm into the night without insulation. The second was the lack of a functioning thermosiphon system.
A thermosiphon is created when a manifold exposed to the sun heats up, this then hats the water inside, the water expands and becomes less dense than the cool water in the system. This creates a cycle of the cooler water in the tank sinking into the manifold (area exposed to the sun) below it whilst the water in the manifold travels up into the tank. This creates a continuous cycling of hot water through the system.
But if the height differential between the tank and the manifold is not large enough or there is not a one way valve the same thing can happen in reverse, this is known as reverse thermosiphoning. This meant that the passive thermosiphon process which heats the water up while it was sunny would then reverse once it cooled down and the tank would quickly cool. This occurred in our systems because of a missing one-way valve.
Improved Hot Water Batch System
In our new solar hot water system we have made some important changes from our past systems.
- We increased the surface area of water in the pipe to increase speed of water heating up. By using 3/4 PVC pipe in the form seen in the pictures we are creating a larger surface area to heat water up in the sun. There is also a relatively short distance for each amount of heated water to travel in order to rise to the tank. In old systems we have had one long continuous tube.
- We insulated the tank to keep the water hotter for a longer period of time. By insulating the tank with about 6-7 of sawdust insulation we can now keep the water hot for a minimum of 24 hours (enough time until the sun comes out to continue heating the water again).
- We installed a one way valve leading to the manifold to prevent a reverse thermosiphon.
In its current form the solar hot water works as a batch heater, meaning that as you use the hot water one must manually refill the tank by opening and closing the cold water input to the tank. The overflow on the tank tells you when it is full. We do not have access to tanks that can control the very high water mains pressure that we have, therefore we use this manual system.
To improve this for a pressurized system you would want a tank that can handle the mains pressure as well as installing a heat exchanger. Instead of the sun heating the water directly, it heats an intermediary fluid that then heats the water via an exchanger in a tank. This way you can heat the water without the pressurized system affecting the thermosiphon. If you don’t live so close to the equator you will also need to consider protection from freezing in the winter.
There are many forms and variations of solar hot water systems which can be designed and built. I like this system because it is passive, simple, cheap, uses easy to source materials and involves very little maintenance.
To learn more about systems like these, keep an eye out for upcoming workshops on renewable energy and appropriate technology.
STEP 2 : INSTALLING THE INLET AND OUTLET PIPES AND COATING WITH BLACK PAINT
To ensure proper functioning of the solar thermal water heater, two holes are drilled into the sides of the sturdy 4 x 4 plywood frame. These holes serve as the inlet and outlet ends of the pex pipes.
Cold water enters through the inlet and travels through the pex pipes, where it gets heated by the sun’s rays, and exits through the outlet as hot water.
To optimize the heating process, the interior and exterior surfaces of the plywood box are painted with flat black Rust-Oleum high heat paint.
This paint is specifically designed to absorb and retain heat, which helps to maximize the effectiveness of the solar thermal water heater.
STEP 3 : INSTALLING THE PEX TUBES
To start building the passive solar thermal water heater, the first step is to secure the pipes inside the heater box. You can use either half inch pex tubes or irrigation pipes for this project.
Whichever type of pipe you choose, ensure that they are strong and durable enough to withstand the pressure and heat.
To secure the pipes, start by installing the first layer of pipes using half inch pex talon clamps. These clamps are designed to hold the pipes securely in place and prevent them from shifting or moving around.
Install the clamps on all four sides of the box, securing each loop of the pipe to the box.
After installing the first layer of pipes, it’s time to add the second or upper layer. For this layer, you can use zip ties to secure the pipes to the box.
Make sure that the pipes are evenly spaced and arranged in a way that allows for maximum exposure to sunlight.
The total length of the pipe used in this project is 200ft, which is sufficient to absorb a significant amount of solar heat and transfer it to the water passing through the pipes.
Once inside, the pipe goes through the top layer and runs all the way to the outside before exiting through the outlet hole.
It is important to note that the bottom layer of pipes will not be exposed to the sun as much as the top layer, but they will still be warmed up because the entire box is covered with Lexan polycarbonate sheet.
The top layer of the pipe, which goes outside through the outlet hole, will have the highest thermal BTU. This means that the water running through this pipe will be heated the most and will be the hottest.
The two layers of pipes work together to ensure maximum heat transfer to the water, resulting in a highly efficient solar water heater.
STEP 4 : COVERING THE BOX WITH POLYCARBONATE SHEET
To ensure that the solar heater is functioning optimally, it is important to have a way of measuring the temperature inside the box.
This is achieved by installing a reed thermometer on the side of the heater. This thermometer has a 4-inch stem and is very affordable, making it a cost-effective way to monitor the temperature inside the heater.
To install the thermometer, a half-inch to three-eighths bushing reducer is used to attach it to the side of the box. The thermometer is carefully placed at a spot where it can accurately reflect the temperature inside the box.
To protect the pipes and ensure that the solar heater is efficient in capturing the sun’s energy, a 4 X 8 Makrolon Polycarbonate Sheet is placed on top of the heater box.
This sheet is secured in place using No 8 One and one fourth sheet metal screws, finishing washers, and rubber grommets.
Silicone adhesive is then used to seal any gaps that may exist between the sheet and the box frame. This ensures that the heat generated inside the box
Solar Water Heaters
Solar water heaters.- sometimes called solar domestic hot water systems.- can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use.- sunshine.- is free.
How They Work
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t.
Active Solar Water Heating Systems
There are two types of active solar water heating systems:
- Direct circulation systemsPumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
- Indirect circulation systemsPumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.
Passive Solar Water Heating Systems
Passive solar water heating systems are typically less expensive than active systems, but they’re usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems:
- Integral collector-storage passive systemsThese consist of a storage tank covered with a transparent material to allow the sun to heat the water. Water from the tank then flows into the plumbing system. These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.
- Thermosyphon systemsWater is heated in a collector on the roof and then flows through the plumbing system when a hot water faucet is opened. The majority of these systems have a 40 gallon capacity.
Storage Tanks and Solar Collectors
Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.
Three types of solar collectors are used for residential applications:
- Flat-plate collectorGlazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors.- typically used for solar pool heating.- have a dark absorber plate, made of metal or polymer, without a cover or enclosure.
- Integral collector-storage systemsAlso known as ICS or batch systems, they feature one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water. The water then continues on to the conventional backup water heater, providing a reliable source of hot water. They should be installed only in mild-freeze climates because the outdoor pipes could freeze in severe, cold weather.
- Evacuated-tube solar collectorsThey feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin’s coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for U.S. commercial applications.
Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a tankless or demand-type water heater for backup.
Installing and Maintaining the System
The proper installation of solar water heaters depends on many factors. These factors include solar resource, climate, local building code requirements, and safety issues; therefore, it’s best to have a qualified solar thermal systems contractor install your system.
After installation, properly maintaining your system will keep it running smoothly. Passive systems don’t require much maintenance. For active systems, discuss the maintenance requirements with your system provider, and consult the system’s owner’s manual. Plumbing and other conventional water heating components require the same maintenance as conventional systems. Glazing may need to be cleaned in dry climates where rainwater doesn’t provide a natural rinse.
Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part or two after 10 years. Learn more about solar water heating system maintenance and repair.
When screening potential contractors for installation and/or maintenance, ask the following questions:
Improved Solar Pool Heater. Full build
- Does your company have experience installing and maintaining solar water heating systems?Choose a company that has experience installing the type of system you want and servicing the applications you select.
- How many years of experience does your company have with solar heating installation and maintenance?The more experience the better. Request a list of past customers who can provide references.
- Is your company licensed or certified?Having a valid plumber’s and/or solar contractor’s license is required in some states. Contact your city and county for more information. Confirm licensing with your state’s contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.