Purchasing Tips — Solar Water Heaters

child bathing in a tub

If you are interested in an ENERGY STAR qualified solar water heater for your home, consider the following before you buy.

  1. Determine if your site is suitable. Most solar water heating systems are installed on the roof. For best results, you roof should:

    • Receive direct sunlight between the hours of 10 AM and 4 PM year round
    • Face South (within 15°)
    • Be sturdy with the shingles in good condition

    If your roof isn't appropriate for a solar water heater, but you have suitable unshaded land next to your home, you may want to consider a ground-mounted system instead.

  2. Decide what type of system meets your needs and lifestyle. A solar water heater contractor will help you determine what type and size system best suits your needs. Take the following steps so you can have informed discussions with contractors during the purchasing process:

    • Use the Product List to find qualified models for consideration.
    • Understand how solar water heaters work so you can discuss which collector type and circulation system makes the most sense for you.
    • Protect against freezing in colder climates. Some solar systems are appropriate for freezing climates, while others are not. As a general rule, if there is a good chance that temperatures will fall below 42°F, choose either a closed-loop system with antifreeze as the heat transfer fluid, or a system that automatically drains back when temperatures fall too low for comfort. Steer clear of batch systems if you live in a climate with distinct winters. Learn more about freeze protection.
    • Estimate the capacity you'll need. Use the gallon capacity of your current water heater as a starting point. You can find your current water heater's capacity or volume on its nameplate or yellow Energy Guide sticker. This should help you discuss the sizing of your solar system with contractors. If you have recently added or are planning to add more occupants to your household or a new shower, faucet, dishwasher or washer that will be in frequent use, take that into account in your discussions.
  3. Contact a Solar Contractor or Manufacturer. Ideally, you will find a local contractor who can assess your site, provide recommendations, install a system, and then perform periodic maintenance. Installing a solar water heater on an existing home requires careful installation, which often includes running pipes through walls. Use a contractor certified by the North American Board of Certified Energy Practitioners (NABCEP) if possible. When choosing a contractor you should also:

    • Request cost estimates in writing.
    • Ask for references.
    • Check the company with your local Better Business Bureau.
    • See if the company will obtain a local permit if necessary and understands local residential building codes and other regulations.
  4. Search for rebates and utilize tax credits. You may be able to reduce your costs by taking advantage of rebates or tax credits. Be sure to review the eligibility rules before you make your purchase.

    • Use the Special Deals Finder
      Determine whether there are rebates available for ENERGY STAR qualified water heaters in your zip code.
    • Utilize the Federal tax credits
      Every ENERGY STAR qualified solar water heater will qualify for a Federal tax credit equal to 30% of the system's installed cost — up to a maximum of $2,000.
  5. Don't forget about maintenance. After installing a solar system, it is important to perform periodic maintenance to ensure efficient operation. In addition to hiring a qualified contractor for annual maintenance inspections, you should periodically check the following:
    • On the roof or ground, depending on installation:
      • Collector is clean and not shaded
      • Collector is sound, sealing and glazing are not cracked or yellowing
      • Fasteners connecting collector to roof are sound
      • Piping and wiring are well-connected, well-insulated, and without damage
      • Roof penetrations are well-sealed
    • In the home:
      • Pressure relief valve is not stuck completely open or closed
      • Pumps (in active systems) activate when the sun is shining
      • Pipes are free of mineral build-up.
    If you live in an area with hard water, you may need to add de-scaling agents to the water every few years. For example, you can run a vinegar solution through the collector or hot water loop every three to five years. Learn more about how to avoid scaling and corrosion.