September 07, 2010
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Solar Hot Water for Commercial Applications

Technology Name:
Solar Hot Water (SHW) for commercial applications

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: large volume of hot water

Typical applications:
To supply hot water for industrial, commercial, agricultural, food processing purposes.
To clean or sterilize food and animal processing equipment
To heat water for aquaculture
In combination with radiant hydronic space heating
To reduce the use and dependency on gas and electricity for water heating for commercial uses.
Anywhere large volumes of hot water are required.

Expected Pay-Back:
Solar water heating for the aquaculture of salmon, trout, and tilapia has been investigated, each fish having different water temperature requirements. Simple payback terms as low as 5 years have been found.
Commercial and institutional applications can have paybacks of 3 to 7 years.

Range of possible dimensions and sizing considerations for the system:
Whereas domestic solar hot water systems may be 2-6 solar hot water panels, commercial systems may have 40 to 400 collectors, with a collector area of 120 to 1,200 m². Multiple storage tanks can be used and are sized depending on the volume of water required. Additional considerations in designing a Solar Hot Water system include the cold water intake temperature, desired hot water temperature, pattern of hot water use. Depending on the application and temperature required, a commercial solar hot water system may be designed to meet half to all hot water needs. For year round use a closed loop system with an anti-freeze heat exchange fluid used to prevent freezing. Where hot water is only required when temperatures are above freezing a drain back system can be used.

Collectors:
Collector sizes vary, however a common panel size is 4 x 8 feet. Commercial systems may have 40 to 400 collectors. The collector array size should be determined based on the size of the storage tanks chosen to meet hot water needs as well as the solar exposure and climate. As a rough guide, the solar system should have one square metre of collector area for every 50 l/day of hot water usage.

Storage Tanks:
Multiple storage tanks can be used and are sized depending on the volume of water required. As a rough guide, the storage tank should have 50 l/m2 of collector.

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):
The installed cost of commercial systems is about $500/m2. Maintenance contracts may be purchased as part of installed cost or as required. Expect to pay local hourly plumbing rates.

Design, Installation, Maintenance & Operation of SHW:
Design of a SHW:
Expertise/knowledge required can include: sizing the SDHW system, plumbing, electrical, mechanical, general construction.

Installation of a SHW:
Skills required can include: plumbing, electrical, mechanical, general construction skills, roofing.

Maintenance of a SHW:
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 a SHW:
Can be monitored and operated by owner or maintenance staff with instruction from contractor/installer.

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 SDHW 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.

Range of Operational & Maintenance requirements (ex: how much labour time per week for how many people):
Requires only periodic monitoring and maintenance to ensure proper functioning.
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 hot water use.
Ensure southern exposure clear of obstructions between the hours of 10 AM and 3 PM or longer.

Permitting:
Many jurisdictions in Canada are still unfamiliar with solar hot water systems. New CSA system certification should help build confidence with decision makers and ease the permitting process. Contact your local permitting office early in project development to find out what permits may be required. Work with your local system retailers to provide decision makers in your area with information about solar hot water systems.

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.

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).

Potential combination with other energy systems (hybrids and combination systems):
Water Heating and Space Heating:
SHW is often combined with solar hot water space heating. The capacity of the system can be increased to provide space heating (through radiant floor/wall or baseboard hot water heaters) in addition to hot water.

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 federal, provincial and municipal incentive programs.
Applications for solar water heating in aquaculture may be eligible for a 25% cost incentive from the federal government through the REDI program. There are currently only a couple of these systems in Canada.
It is recommended that systems be designed by an engineer who is experience in the field of solar water heating.

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