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Solar
Water Heating Overview "Hot water, the first step toward civilization." That’s
a line from a recent disaster movie, in which the things
we take for granted become frighteningly apparent as soon
as they’re unavailable. Disaster or not, hot water is something
we should always appreciate: we use it every day for cleaning
our clothes, dishes, bodies, and homes. It accounts for
20-30% of residential energy consumption in B.C. and for
another 50% in homes that use hot water for space heating.
Households with swimming pools consume even more energy
for water heating – it often doubles the annual heating
bill.
Solar water heating (or solar thermal) encompasses
a range of technologies that efficiently convert solar
energy into useable heat. These systems are safe, reliable,
and emission-free. Some pumping energy is often required,
but it is marginal compared to the solar energy generated.
Solar water heating taps into a tremendous resource that
is forever available all around the world. Contrary to
popular belief, it is not restricted to warm climates:
Austria and Germany are among the world leaders in the
use of solar hot water. There are hundreds of successful
installations all across Canada, including the territories
and B.C.’s "wet" coast.
Global Highlights
- Worldwide solar thermal capacity was 70,000 MWth
(megawatts thermal energy) in 2001 – more than wind
and PV combined.1
- China has over 32 million m2 of solar thermal
collector area installed. Europe had 14 million m2 by the
end of
2004, with an ambitious target of 100 million m2 by 2010.2
- Spain announced in November 2004 that all new homes must
have solar water heating collectors.3
- The technology is mature. Manufacturers
around the world are producing high quality solar heating
collectors that convert over 80% of the sunlight that
hits them into useable heat.4
- In a constrained carbon future, solar
water heating could contribute 131 petajoules to Canada’s
energy mix in 2030. This translates to approximately
22 million collectors.5
- Funding for REDI, Canada’s successful incentive
program for commercial water heating projects, has been
renewed.6
What’s happening in BC?
Lots! Here are some recent projects…
- Hyde Creek – solar domestic hot water
for a community centre in Coquitlam.
- Redfish Ranch – solar water heating at
a tilapia fish farm, one of the most sustainable species
for aquaculture.
- YVR – 100 glazed collectors installed
for hot water at Vancouver International Airport’s domestic
terminal building.
- Ocean Village – solar pool heating system
for a resort in Tofino. Yes, it even works on the edge
of a rainforest!
- Solar-Ready – new co-housing community
in Robert’s Creek is pre-plumbed for solar; retrofits
will be quick and easy.
- Residential swimming pools – countless
installations across B.C.
- Private homes – numerous installations
across B.C.
What does it cost?
There are many solar water heating products
on the market. Consumers are encouraged to do some research:
it is often worth paying a premium for quality, performance,
and system longevity. Solar pool heating systems in B.C.
typically cost $90-160 /m2 ($8-15 /sq.ft.) of pool surface
area, installed. Residential domestic hot water (DHW) systems
cost $800-$1,400 per person, installed. Systems for multi-unit
DHW and similar commercial-scale year-round applications
cost $100-200 per annual gigajoule offset. For solar aquaculture
systems, use pool heating figures.
Environmental matters
Solar water heating typically offsets fossil
fuel combustion, reducing greenhouse gas emissions and
other pollutants. Systems can help reduce peak loads, thereby
postponing or preventing the need for additional baseload
energy generation and distribution infrastructure.
Solar water heating systems fit well in the
built environment, adding little to our ecological footprint.
Collectors are usually installed on rooftops, occupying
otherwise unused space. Most equipment is made of locally
available and recyclable materials: glass, plastic, copper,
aluminum, wood, and steel. The full lifecycle impact is
small, considering the 20-50 years of service that a solar
hot water system will give, producing zero-emission energy.
Pool systems are typically plumbed with PVC
(polyvinyl chloride), a plastic whose manufacture and disposal
have environmental and health risks. The whole pool industry
should look to alternatives, such as ABS or HDPE plastic
piping.
Technical matters
You need the sun. Yes, Vancouver gets enough.
There are some site-specific factors to consider: try for
a sloped, south-facing collector orientation with minimal
shading from nearby trees and buildings. For storage, solar
DHW systems typically use an insulated tank in or near
the mechanical room. For pool systems the pool is often
the storage tank. A solar heating system typically operates
as a pre-heater in conjunction with a backup energy source
of any kind. In B.C. some seasonal heating loads can be
met by solar alone.
There are four main solar hot water technologies
that you can use:
- Glazed Flat Plate Collector . Metal absorber
in an insulated frame with glass covering. General purpose
solar collector suitable for domestic hot water and other
year-round, high temperature applications.
- Unglazed Collector. Plastic or rubber
absorber without glass covering. Suitable for swimming
pools, aquaculture, and other mid-temperature applications.
- Evacuated Tube Collector. Metal absorber
in a vacuum tube. Good for very high temperature applications
and/or harsh climates.
- Batch Heater. Collector and storage tank
in one. Good for small, seasonal applications.
For more information you can download these
brochures or order them from Natural Resources Canada:
Social, Economic, and Political
Matters
- There is no PST on solar products and
services in B.C.
- The Renewable Energy Deployment Initiative (REDI) is
a federal incentive program that offers 25% toward the
installed cost for commercial solar water heating systems,
40% in designated remote communities.
- Systems are cost-effective in many applications,
with a return-on-investment that is better than most
GICs.
- Solar heating is increasingly seen as
an important energy solution by policy-makers in B.C.
and across Canada, though more education and awareness
are needed to reach our full potential.
- Some people find it a challenge to budget
for long-term energy savings in return for the up-front
capital expense. Financing solutions are being developed:
low-rate loans are currently offered by some solar companies
and financial institutions in B.C.
These are some policies which will promote
the installation and use of solar hot water in B.C.:
- The federal government should eliminate
GST on solar products and services, to reflect solar
hot water’s reduced environmental costs
- The provincial government should establish
a low-interest revolving loan fund for solar installations.
- Banks
and credit unions should offer "prime
plus zero" loans for solar installations
- Municipal
governments should be required to undertake solar mapping,
so that every owner knows
their building’s solar suitability, as Perth, Ontario,
has done.
- Building codes should require the use
of solar hot water systems in all new buildings that
have a suitable roof orientation.
Can I do it at home?
Yes, but…
Collectors are large and awkward (4’ x 8’ or
larger). Installation involves plumbing, electrical, roof
work, physical labour, and sometimes carpentry or metal
work. You will generally save time and money by hiring
a professional installer. That said, do-it-yourself installations
can be quite successful, especially for standard residential
systems. Most companies will offer quotes and estimates,
and offer installation advice and support where needed.
Links
Footnotes
1. European Solar Thermal Industry: www.estif.org
2. International Energy Agency: www.iea.org
3. Energy Bulletin: http://www.energybulletin.net/3092.html
4.Trends in European Solar Thermal Market, 11 July 2003:
www.SolarAccess.com
5. Solar Energy Society of Canada: www.sesci.ca
6. Kyoto and Beyond: The Low-Emission Path to Innovation
and Efficiency, Sept 2002, by Torrie Smith Associates for
the David Suzuki Foundation and the Climate Action Network:
www.climateactionnetwork.ca/publications.html
6. REDI program at Natural Resources Canada: www.nrcan.gc.ca/redi
Credit
Written by Morgan McDonald for the BC Sustainable Energy
Association
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