Swimming Pool Blog
by Rob Cox, October 10, 2010
Solar Pool Heater FAQ
Solar pool heaters are more popular than ever these days, with the rising costs of gas and electricity. Solar heat also gives the pool owner the added benefit of being "green" in the operation of their pool. Definite conversation starter.
We've had a lot of questions over the years related to the purchase, installation, use, care and repair of solar pool heater panels. We've put together a bit of a summary below, in old school Frequently Asked Questions (FAQ) format.
If you have other questions not answered here, feel free to post a comment on the blog below, or contact me through the link under the Pool Blog logo - above left.
Q. What's the difference between in ground and above ground solar pool heaters?
A: As most equipment for the pool, solar heaters are sold for above ground pools and for in ground pools. In fact, they could be interchangeable. The main difference is that most in ground solar pool heaters are installed on the roof, and you need an in ground pool pump, with enough power vertical lift to pump the water up to the roof. Another large difference is the price point. Above ground solar heaters are usually made from polypropylene, instead of the more expensive neoprene like rubber of our In ground solar pool heater by Enersol.
Q: Can I use an In ground solar system on an above ground pool - or vice versa?
A: In ground pools typically have a larger volume of water than above ground pools, which builds the requirement for solar heaters with greater heat transfer. In ground solar heaters can be used on above ground pools, but the panels will probably need to be located on the ground or ground level rack. Above ground solar heaters can be used with most in ground pool pumps, if careful not to over-pressurize the panels, which are made to withstand the pressure from smaller, above ground pool pumps.
Q: What does a solar controller do?
A: A solar controller is a wall mounted box with a thermostat dial and an on/off switch. Two temperature sensors are connected to the controller, one mounted next to the solar panels, and one clamped over a hole drilled in the pipe, to measure water temperature. A third wire runs to a valve actuator, mounted atop a standard 3 way Jandy type valve. When there is a call for heat, the controller will signal the valve actuator to turn the 3 way valve, sending water to the panels. When the water temp reaches the thermostat setting, the valve returns to it's previous position, bypassing the solar panels. Solar Controllers optimize the sunny part of the day, turning on when optimal and bypassing the solar panels when solar conditions are poor. Solar controllers can also be used to cool the pool if the water temperature gets too warm, by sending water to the solar panels at night, or during a rainstorm.
Q: Do I have to buy a solar controller for my solar pool heater?
A: Not necessarily, but it does make it convenient and provides better use of the sun. Without it, a passing shower or heavy clouds or winds could begin to cool your pool water. Or you could forget and leave it on overnight, which also will cool the pool water. Most above ground pools do not have a solar controller installed, and pool owners manually open and close a valve to send water through the solar panels.
Q: What options are there for mounting pool solar panels?
A: The better question is: What areas, near your pool equipment, allow for at least 4-6 hours of direct sun per day? A southern exposure is best, and mounting panels at a 45 degreen angle to the sun is better than having them horizontal or even vertical. As shown in the image above, panels can be mounted to the roof, or to a home built rack, or they can even be laid on the ground. Having the panels as close to the equipment as possible cuts the work load and cost of piping.
Q: How much heat can I expect from a solar pool heater?
A: That depends on how much sun your panels receive, and how much square footage of panels you install. Using a pool cover or solar blanket can keep the pool much warmer, especially at night. Cloudy, rainy weather will also limit the amount of heat transfer, although solar pool heaters will still produce heat on overcast days. On average, a solar pool heater will deliver 10-30 degrees of temperature rise to a pool. I have installed an Enersol system that was used to heat a spa up to 105 degrees!
Q: I live in Northern Michigan, will solar heating work for me?
A: Absolutely, solar pool heating is very popular in Canada, and works well wherever the sun shines. Generally, most North American solar pool heater installations add another month onto each end of the pool season - opening a month earlier and closing a month later, with water temperature from 78-88 degrees.
Q: How is a solar pool heater installed?
A: Basically, we cut the return pipe in between the filter and pool, and re-route the water to go in and out of the solar panels. Use of a 3 way valve makes the operation simpler, although it can be done with two 2 way valves. A check valve is placed in line, to prevent water from doing "a loop". In practice, most of the water should bypass the solar panels, and use a diverter valve to "divert" 10-20% of the water volume in and out of the solar panels. Installing on a roof or on a rack made at a 45 degree angle allows for better heat absorption. Installing solar panels on a roof can be dangerous, so use precautions to keep yourself safe. Installation next to a pool, or on a rack mounted onto a fence or free standing is a simpler affair and should take only a few hours.
Q: Do I need to install a larger pump to push water through the solar panels?
A: Generally, no. I have never had to increase the horsepower of a pump when installing solar panels, even if pumping 30 feet up to the roof. Remember that aboveground pumps may not have the power to pump up too far, but most inground pumps of 1hp or greater can do it without a problem. Usually, we see about a 3psi increase in the filter pressure after installing a new solar pool heater system.
Q: What maintenance or repairs are needed with solar panels?
A: One of the things I like best about solar heaters is that they are virtually maintenance free. Unlike gas heaters, solar pool heaters have no moving parts, no maintenance schedule, no failing componenents. If a hole were to develop in one of the heater tubes, a small insert or stint can be put in this tube or the tube can be abandoned. The only other repair I have ever done is to replace temperature sensors or valve actuators (automatic valve turners, used with a solar controller). Solar pool heaters are very low maintenance items.
Q: How long does a solar pool heater last?
A: Longer than a gas pool heater. Enersol has a 15 year warranty, and I have seen them last longer. The polypropylene type of panel, made by Sungrabber or Sunheater will last almost as long, but somewhere between 12-15 years, they will begin to become brittle. This can be accelerated with year round use, or strong sun. I once did a replacement solar pool heater installation in Jamaica, where the sun had broken down the polypropylene panels in 10 years.