Solar Thermal Hot Water

A solar hot water system will cost about $5,000 to install, providing upwards of half a typical family's hot water supply and paying for itself, in energy savings, in 10-15 years.	It's a significant investment, requiring a fair bit of planning.	It will reduce a homeowner's greenhouse gas emissions by an average of 0.8 tonnes per year over its 20-year-plus lifespan.

Solar thermal hot water is one of the most cost-effective uses of solar energy in Alberta. Considering hot water accounts for about 20 per cent of the natural gas consumed in a typical Alberta home, replacing half that gas use with clean, renewable energy can make quite a difference.

What is solar thermal hot water?

Simply put, it is water heated by the sun and stored for normal household uses such as showers and running dishwashers and washing machines. In a typical installation, the sun's rays heat water or glycol that circulates, in a closed loop, through rooftop solar collectors. This heated liquid is then pumped through pipes to a heat exchanger, which transfers the heat to water in a tank (in many cases, the heat exchanger is inside this tank). The pump can be solar powered or run on a small amount of electricity.

Can a solar system provide all the hot water I need in my home?

Probably not. If you're a typical Alberta family of four, it should meet about 50 to 60 per cent of your hot water needs. You'll need a conventional natural gas-fired hot water tank (or a tankless gas-fired heater) to supply the rest.

Does the sun have to be shining for the system to work?

The system will still work when it is cloudy but will produce considerably less hot water than under full sunlight. Solar hot water systems work well in Alberta because of the amount of sunshine we receive, which in many locations is greater than much warmer places like Miami.

Will a solar hot water system work during our cold winters?

Yes. It will produce hot water at temperatures well below freezing, though not as efficiently as in summer because the sun is lower and the days are shorter. As well, many systems have freeze-protection mechanisms, which allow the water in the pipes to drain back into the house when the system is shut down. This mechanism also keeps the system from overheating during hot summer days.

Do I need to change my hot water use habits with a solar system?

If you want to maximize the use of your solar system and save the most money on your energy bill, you should learn a few management tricks. For example, if you can take shorter showers and avoid running, say, three showers in a row, you're less likely to deplete your solar-supplied tank and be forced to use your natural gas backup. Similarly, if you can run your dishwasher during the morning, rather than at night, your solar hot water system should have sufficient daylight hours to recharge itself for necessary evening uses.

Is much maintenance required?

No. The technology is well established and systems should run well with little maintenance. You should check the system once a month, when the sun is shining, to make sure the pump is running and the pipes are warm. Carry out maintenance according to the manufacturer's recommendations and have the system inspected every year or two.

Can I get a rebate if I purchase a solar hot water system?

Yes. Natural Resources Canada (NRCan) is offering a $500 rebate to homeowners who install solar hot water systems that meet CAN/CSA standards. The federal rebate - available until 2011 - requires an energy audit from an NRCan-licensed advisor. Click here to visit the website for the ecoENERGY Retrofit Program.

What size of system do I need?

It depends on the amount of hot water you use. You can reduce the system's size, and its cost, if you first reduce your hot water demand. This involves taking such steps as installing low-flow showerheads and low-flow faucet aerators and buying an energy-efficient dishwasher and a front-loading washing machine. The system's size also depends on the sun's energy intensity where you live. For example, the energy intensity in Lethbridge is 20 per cent higher than in Fort McMurray. A qualified contractor can tell you what size your system should be.

Where can I find a qualified contractor to install a solar hot water system?

Check with the Canadian Solar Industries Association for a directory of qualified contractors: www.cansia.ca. Ask potential contractors how much experience they have in designing and installing solar hot water systems and ask for references from previous customers.

Where will the solar collectors, for my system, be installed?

You'll need an unshaded, south-facing roof or wall. The solar collectors can also be mounted on a sturdy, nearby frame or on the roof of a storage shed or unattached garage. Most installations need one or two solar collectors, each requiring a flat mounting area of about three square metres.

Is it difficult to integrate solar hot water into my existing hot water system?

No. You'll need enough room beside your existing hot water tank to accommodate the storage tank for your solar system and for a heat exchanger, if it is outside the tank. Your contractor will also have to install piping that connects the solar collectors to the storage tanks. This can usually be run through a closet, cold air return or wall cavity or along an outside wall. Note: If you're planning on replacing your roof shingles soon, it makes economic sense to do so before installing your solar collectors.

What about installing a solar hot water system in a new home?

Compared to retrofitting an existing home, it's considerably easier and less expensive to integrate a solar system into the design of a new home. If you think you might add a system later, it will be relatively easy to do so if your builder can make it "solar ready" when building the house.