Solar domestic hot water

With the rising cost of the fuels traditionally used to heat water in your home (electricity, natural gas, propane, and oil), a solar domestic hot-water system can reduce dependence on your existing water heater by more than 60% annually in Southwestern Ontario – this is about 3000 kWh per year with a typical family of four using a solar system with two collectors. You will see real savings on your utility bills and also help reduce your carbon footprint.

Have a geothermal system, or thinking of installing one in the near future? Combining solar thermal and geothermal together gives a longer lifespan for both systems, getting you a better bang for your buck. Learn more about combining solar thermal and geothermal.

Solar energy delivered based on tilt angle and orientation angle

The chart below shows the average amount of solar energy (in kWhth) delivered over the course of a year for a family of four, at varying tilt and orientation angles. As you can see, an optimal angle is due south at 30° tilt, but moving to south-east or south-west results in only a 5% loss of annual energy; tilting up to 45° facing south results in a miniscule 0.2% loss of annual energy.

  orientation of solar collectors
tilt angle West South-West South South-East East
2472 2472 2472 2472 2472
15° 2468 2767 2879 2781 2488
30° 2440 2937 3105 2963 2482
45° 2344 2933 3099 2978 2414
60° 2156 2750 2869 2856 2220
75° 1881 2374 2438 2462 1942
90° 1543 1881 1883 1989 1587
solar energy numbers are displayed in kWhth


  • Family of four using 75 L of hot water per person per day
  • Typical meteorological data for London, Ontario
  • 2 collectors with 272 L storage tank


Frequently asked questions (download PDF version)

  1. Will a solar water-heating system replace my existing water heater?
    To ensure that hot water is available at any time of day year round, your existing water heater will act as a backup for times when solar energy is not available, such as at night. Systems are sized so that solar will deliver most of the energy for generating hot water.
  2. Where can the solar collectors be installed?
    Typically, solar collectors are placed on the roof of a building. If the roof can not be used, collectors can be mounted on a rack located on the ground, a wall, or on a fence. Shading throughout the year must also be taken into account.
  3. How long will an installation take?
    Installations can take between one and two days on a home.
  4. How does a solar water heater save me money?
    By offsetting the energy required by traditional sources (e.g. water heaters powered by electricity, natural gas, and other fossil fuels), you will reduce your utility bills. You also extend the life of your existing heater as it will work less.
  5. How do I optimize the amount of energy collected?
    The best orientation for collectors is due south; however, collectors can be positioned anywhere between south-west and south-east with negligible loss in performance. You can also get the most out of solar system by using hot water while the system is producing hot water.
  6. What is the expected lifetime of a solar water-heating system?
    Quality solar water-heating systems offered by SunTap are designed to last 20 years or more.
  7. What about the condition of my roof? Does it matter?
    If the roof needs replacing, it is highly recommended to have it replaced before installing solar collectors; otherwise the collectors will have to be removed and re-installed to accommodate a re-roofing.
  8. How will the collectors look when installed on my house?
    Most collectors are designed to blend in with the roof, having the appearance of skylights.
  9. Are there any other benefits to installing a solar water heater?
    If you are planning on selling your home, having a solar water heater already installed may improve the resale value of the property. You reduce pollution by offsetting energy consumption, as well.