September 10, 2010
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Solar Hot Water - Domestic & Hydronic Space Heating

Technology Name:
Solar Hot Water - Domestic - space heating (various radiator systems - floor/baseboard)

Date Introduced in the market:
1890s

Maturity of the technology:
Established industry with continuous growth over 5+ years.

Type of energy that can be produced (i.e. thermal, electrical):
Thermal: hot water for domestic uses and space heating

Typical applications:
To supply hot water for home, farm, business or commercial space heating. Hot water can be circulated through a variety of hydronic (water) heating systems such as baseboard radiators, under floor piping or in wall piping systems. Solar water heating systems can also be used to heat air for circulation through a water to air heat exchanger.

Some specific beneficial agricultural applications for solar systems with radiant floor heating include heating the creep area of the furrowing pens, concrete floors in chicken farms, warming shop space.

Expected Pay-Back:
Commercial applications of solar hot water systems for space and water heating can pay for themselves in 3-7 years. Smaller, domestic heating and hot water systems will take longer. Factors such as incentives, rising energy costs and favourable financing arrangements will affect the cost effectiveness of a system.

Range of possible dimensions and sizing considerations for the system:
The main components of a SHW system for heating are the collectors and the storage tanks. Radiant floor heating systems used with solar hot water consist of radiant floor tubing integrated into the floor (usually 16mm PEC plastic piping), distribution manifolds, thermostats, valves and circulation pumps. These components are sized depending on the heating needs of the household, climate and solar exposure. Often, systems are combined with a SHW system for domestic hot water use (see SDHW). When designing a system for winter space heating, the greater the summer hot water demand the greater the efficiency of the system. While domestic hot water systems can be cost effective when designed to meet 60-80% of solar hot water needs in Canada, a SDHW system designed to provide the majority of space heating needs in the winter will usually have excess energy to meet summer hot water needs. A significant summer hot water demand, such as pool heating, will improve the cost effectiveness of the system. Demonstration projects are utilizing summer storage of solar heat to be used in the winter for space heating.

Other considerations in designing a SDHW system for space heating include the cold water intake temperature, design of the space heating system and heating load, type of back up system, available space for storage and collectors.

Collectors:
Collector sizes vary, however a common panel size is 4 x 8 feet. Collector array size should be determined based on the size of the storage tank chosen as well as the solar exposure and climate.
-A rule of thumb to size collectors: 1 square foot of collector plate per 1 gallon of hot water storage.

Storage Tanks:
Solar storage tanks can double as the household hot water storage tank (with 2 heat exchangers, one for the solar system and one for the back up heating system) or be a separate pre-heat tank to a back up tank. For domestic water and space heating, about 70 litres per square metre of collector surface will be needed. The amount of hot water storage required will depend on the type of heating system used, area to be heated, heating load, climate and solar exposure.

Range of performance of the technology per unit installed:
In Canada, Approx 500-1000 Kwh/m²/year or approx 1.8 - 3.6 GJ/m2/year

Range of costs per unit of energy and per system (installed, and maintenance costs):
A household system for 2-4 people may cost from approx. $4,500 to $6,400. Cost of a radiant floor heating system is approximately $2.50 - $3.50/ square foot. Retrofit installations are possible but more difficult and expensive than incorporating a radiant heating system into new construction.
Maintenance contracts may be purchased as part of installed cost or as required. Expect to pay local hourly plumbing rates. A solar hydronic heating system in cold climates to heat a house of approx 2000 sq ft. will typically require 6-10 solar collectors and cost from $6,000 - $10,000...

Design, Installation, Maintenance & Operation of a Solar Hot Water Space Heating System:
Design of Solar Hot Water Space Heating System:
Expertise/knowledge required can include: sizing the solar heating system, HVACR (Heating Ventilation Air Conditioning Refrigeration), plumbing, electrical, mechanical, general construction.

Installation of Solar Hot Water Space Heating System:
Skills required can include: plumbing, electrical, mechanical, HVACR, general construction skills, roofing.

Maintenance of Solar Hot Water Space Heating System:
Maintenance depends on type of system.
Skills required can include plumbing, electrical, mechanical.
Tasks to be done can include:
  • Monitoring system pressure.
  • Replacement of anti-freeze solution after approx 7-10 years (for closed loop pressurized systems).
  • Repair or replacement of circulation pumps.

Operation of Solar Hot Water Space Heating System:
Can be monitored and operated by homeowner with instruction from contractor/installer. Operator of a commercial hot water system should be knowledgeable of the system's flow rates, pressure drop and other technical specifications.

Training for designers and installers:
CanSIA is working with colleges to implement training programs for designers and installers of SHW systems, based on the North American Board of Certified Energy Professionals SHW certification. A wide variety of training opportunities exist from online courses and free information to hands on workshops and college courses. See www.cansia.ca for more information. For heating training see www.hrai.org, the Heating, Refrigeration and Air Conditioning Institute of Canada.

Range of Operational & Maintenance requirements (ex: how much labour time per week for how many people):
A solar heating system requires only periodic monitoring and maintenance to ensure proper functioning.
Pumps and valves of radiant heating system require routine maintenance.
Monitoring and Operation: ?.? hr/month - ? hr/year, ? person
Maintenance: ?-? hr/year, ?-? person

Potential problems or challenges:
To ensure system performance:
Investigate certification of collectors or evacuative tubes. Two rating and certification systems are: The Solar Rating and Certification committee (SRCC) and Florida solar Energy center collector approval (FSEC)
A new program is in place to provide Canadian Standards Association certification (CSA F379-5) for solar hot water systems and systems in Canada are now able to apply for CSA certification.
Other considerations:
Investigate Maintenance contracts or warrantees.
Ensure system is designed for climate and heating loads.
Ensure southern exposure clear of obstructions between the hours of 10 AM and 3 PM or longer.

Permitting:
Permitting is inconsistent across Canada. Local permitting offices and decision makers may not be familiar with solar hot water applications and their requirements and may need to be informed. Be sure to investigate potential permitting requirements before beginning any project.

Range of warranties and life expectancy of the systems:
Warranties: 10 years
Life Expectancy: 20 - 30 years

Solar Resources Assessment:
Site specific solar resources can be measured by visual techniques and inspection or through commercially available solar site analysis tools. The U.S. National Renewable Energy Laboratory has extensive solar radiation resource information at http://rredc.nrel.gov/solar/. Links to Canadian solar radiation data can be found at http://www.canren.gc.ca/resou_asse/index.asp?CaId=55&PgId=452

Canadian Solar Resource maps are available at: http://atlas.nrcan.gc.ca/ and https://glfc.cfsnet.nfis.org

Inputs and outputs for the technology:
Outputs:
Solar Thermal collectors directly convert energy from the sun to useable heat energy. Heat produced by the SDHW is used for space heating in a radiant system, usually in addition to hot water use (See SDHW)

Inputs:
Sun:
A southern exposure unobstructed from the hours of 10 AM to 3 PM is preferred.

Anti-freeze solution and heat exchanger:
Many systems use an Anti-Freeze liquid (usually propylene glycol) and a heat exchanger to convert energy from the sun to useable heat energy. The anti-freeze solution usually lasts many years before having to be replaced.

Electricity:
Most systems have electric pumps that circulate propylene glycol through a pressurized closed loop. The amount of electricity required is minimal. It could be provided by the grid or by other sources such as a PV panel (see under "Potential combination …" for more detail).
The radiant heating floor or baseboard will have circulation pumps to control the flow of heat exchange liquid through the pipes.

Potential combination with other energy systems (hybrids and combination systems):
Water Heating and Space Heating:
Solar radiant space heating systems are usually most efficient when designed to meet both a space heating and a year round hot water load.

Photovoltaic (solar electric):
Most systems have electric pumps that circulate propylene glycol through a pressurized closed loop. The amount of electricity required is minimal. These electric pumps can be DC and run by a PV panel ensuring hot water production when there is no electrical grid.

Roofing Material and PV:
Some Solar Hot Water collectors are specifically designed to double as roofing material. If you need a new roof, this is a good time to consider solar hot water roofing collectors (or any solar roof mounted system). Some roofing solar hot water collectors integrate with Photovoltaic (solar electric) roofing materials and can be installed together to perform the function of shingles or other roofing materials. Offsetting the cost of roofing materials helps improve the cost effectiveness of the solar system.

Links to other sources of information:

Sources of supply (in Canada):
Check CanSIA's website for contact information for suppliers and installers in your area. www.cansia.ca
Énergie Solaire Québec sells for a small fee (free with membership) a list of renewable energy suppliers and businesses in Quebec. http://www.esq.qc.ca/

Recommendations on how to proceed with a project development:
Contact CanSIA: check their database for a local installer.
Finding a contractor: As when hiring any contractor, ask for references from other clients or examples of their work and past experience.
Contact your local building inspector and municipal permitting office.
Ensure you have the necessary permits and the inspector is familiar with your plans before construction.
Check the links above for more information.
Investigate potential government incentives, supportive financing opportunities. Check with CanSIA, NRCan, and your provincial and municipal energy offices.

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Created: 02-13-2008
Modified: 03-31-2008