Solar Fact Guide

 

Solar Air Heating
A solar air heating system’s primary objective is to supplement traditional home heating. As energy prices continue to rise, solar air heating becomes an increasingly attractive option.

Solar collectors are usually mounted on south facing wall, but can be mounted on the roof if the angle is suitable. In either case the collector needs to be in direct sunlight for most of the day to maximize the collected solar energy. Solar air heating systems are capable of increasing indoor air temperatures by as much as 10 – 15°C, provided they are sized properly and are being used in a sealed and well-insulated space.

How a Solar Air Heating System Works

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A well-insulated and airtight home will significantly reduce the amount of energy required to keep it feeling warm and comfortable.

  1. Solar radiation falls on the collector and the dark colored plate absorbs the energy.
  2. As the collector continues to absorb the solar radiation, the temperature of the air inside the collector begins to rise.
  3. A number of sensors measure and compare the difference in temperature between the air in the house, and the air in the collector(s).
  4. When the room thermostat calls for heat and the temperature inside the solar collector is higher than the temperature of the air in the room, a small fan is turned on.
  5. The fan pushes hot air from the top of the collector into the living space through a small duct, and draws cold inside air near the floor to be drawn into the collector.

Solar Air Heating Success Story (Cole Harbour, Nova Scotia)
Background:

  • Family of two
  • Home is 12 – 15 years old
  • Solar system heats living room

Technical Details:

  • Two collectors
  • Wall mounted system (angle 90°)
  • Faces 4° east of due south
  • Partial shading in December

Savings & Results*:

  • Initial Cost: $4,200 (tax included)
  • Rebate received: $750**
  • Raises indoor air temperature by 15°C during heating months
  • Excellent supplement source of heat

* Individual results will vary.
**Rebate amounts subject to change. Please visit efficiencyns.ca for up to date information on rebates and financing options.

Maintenance of Your Solar Air Heating Collector
[] Clean filter at least once a year
[] Ensure damper is functioning correctly
[] Check incoming air temperature for maximum gain
[] Check collector for signs of significant air/moisture leakage
[] Check exterior caulking for good seal

Solar hot air systems require a minimum amount of maintenance.
Homeowners should discuss potential maintenance/warranty issues with their contractor before installation.


Solar Domestic Water
Solar thermal technology has been in existence for hundreds of years. The idea has remained constant, however developments in technology have improved the efficiency of solar water heating systems.

With an increased focus on minimizing dependence on other fuel types, converting the sun’s power into usable energy can be cost effective while preserving the environment. There is ongoing debate about which collector type is more efficient. Under specific circumstances, flat plate collectors outperform evacuated tube collectors and vice versa, therefore neither is “more efficient” than the other.

  • Flat Plate Collectors
    • Build within a solid, sealed case and covered with tempered glass for protection from the elements; the air space in the case can lead to conduction and heat losses on cold and windy days
    • Better suited for low-temperature applications such as pool heating, domestic water heating and radiant floor space heating
    • Must be installed as one solid unit. If a portion of the collector fails, the collector must be shut down and retrofitted or replaced
    • Flat plate collectors can remain covered in snow during cloudy weather; however, when the sun comes out, the collector will warm up slightly creating a film of water between the glass and the snow. The snow will slide off due to gravity
    • Better suited to milder climates
    • Less sensitive to overheating
    • Typically less expensive than evacuated tube collectors
    • Many Canadian and US manufacturers
  • Evacuate Tube Collectors
    • Composed of multiple glass tubes that are completely sealed within a vacuum. The vacuum that surrounds the outside of the tube reduces convection and conduction heat loss. Vacuum leakage can occur over their lifetime.
    • Better suited to cold, cloudy climates
    • Better suited for higher temperature applications such as space heating using hot water baseboard heaters and industrial process hot water or steam
    • Can be carried in pieces for lighter, easier installation. If one tube is damaged, only that tube needs to be replaced
    • The gaps between the tubes may allow for snow to fall through the collector, minimizing the loss of production in some snowy conditions, though the lack of radiated heat from the tubes can also prevent melting of accumulated snow
    • The high temperatures that can occur may require special system design to prevent overheating
    • Can be more expensive than flat plate collectors
    • No North American manufacturers at this time

How A Solar Domestic Water Heating System Works

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Well-insulated pipes and properly sized solar storage tanks are important factors that affect the availability of solar hot water.

  1. Collectors can be mounted on the roof, on a wall, or on the ground. The two most common types of solar hot water collectors are evacuated tube and flat plate.
  2. In the most common type of system, a mixture of distilled water and food-grade glycol flows through the collectors and absorbs heat. This type of system is called a closed loop, active-indirect system.
  3. The sun’s energy warms the water-glycol mixture in the collector.
  4. Once the water-glycol mixture has reached a specified temperature, a pump begins to circulate it through the collector and down to a heat exchanger.
  5. The heat exchanger transfers the energy from the water-glycol mixture to the water in a solar storage tank. When the home has a need for hot water, the stored energy in the solar tank can be used for domestic hot water (i.e. bathing, laundry and dishwashing, and/or space heating.
  • Maintenance of Your Domestic Water Heating System
    • Ensure collectors are free of debris
    • Insulate hot water tank
    • Check and replace heat transfer fluid based on manufacturer’s recommendation
    • Ensure circulating pump is operating when solar gain available; no unusual noise
    • Maintain piping insulation
    • No signs of overheating or wear on electrical
    • Watch for fluid leakage in plumbing

In our climate, care must be taken when using an “active-direct” solar system, where only water (no glycol mix) flows directly through the solar collectors. Most often used for pool heating, active-direct systems are susceptible to freezing when the temperature drops, and therefore should be drained after the swimming season. If this preventative maintenance function is ignored, damage can occur to both the solar collectors and piping.

This does not apply to active-indirect systems used for solar domestic water and/or space heating.


 

Solar Photovoltaic (PV)
Installing a residential solar photovoltaic (PV) panel array has the potential to greatly reduce your home’s dependence on grid-based electricity. The systems are sized to produce some or all of the home’s electrical energy, which is measured in kilowatt-hours (kWh).

A properly sized system will be based on your home’s normal electrical consumption. Solar PV systems come in a variety of sizes, which include small residential arrays to large commercial installations. PV systems are defined by the number of panels, the type of panel, and the rated power output of panels. In all cases the orientation of the PV system is key to the long term performance of the system. Having a proper site assessment done by a qualified installer will ensure that your system’s performance doesn’t suffer from unplanned shading issues.

How a Solar PV System Works

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Use Energy Better
Adopting a more energy efficient lifestyle along with the installation of a properly designed solar PV system allows you to experience greater energy savings.

  1. PV panels convert incoming solar radiation to electricity. The panels absorb energy from the sun and produce direct current (DC) electricity.
  2. Most household appliances use alternating current (AC) electricity so PV systems must be equipped with an inverter. The inverter is a device that converts DC power into usable AC power.
  3. Electricity generated by the PV panels can be used for any of your home’s electric needs, including lighting, appliances, hot water, an even space heating. In some systems the PV panels can provide backup electricity to the home when the utility lines are down.
  4. Net metering allows customers to offset their power bill by connecting the PV system to the home’s power meter. If the PV system produces more electricity than is being used in the house, the extra energy is put onto the main electrical grid and a credit is counted by the utility. Consult your local utility provider to see if net metering is possible.

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Solar Photovoltaic (PV) Success Story (Antigonish, Nova Scotia)

Background:

  • Family of three
  • Home 1,600 square feet
  • Home was built in 2004
  • Space heat supplied by electricity and wood pellets
  • Water heated with electricity

Technical Details:

  • 36 panels installed (total 8 kW)
  • Faces true south
  • Home has net meter and time of day rate

Savings & Results*:

  • System cost was $35,975 + tax
  • Home consumes about 15,000 kWh
  • First year savings totaled 9,600 kWh
  • EnerGuide rating achieved: 91

*Individual results may vary.

Maintenance of Your PV Panel
[] Ensure inverter is functioning
[] Ensure no chafed or burnt electrical wires
[] Ensure panels are free of debris

If maintenance is required, homeowners should first contact the installer or manufacturer so that any warranty is not compromised. Minimal maintenance is required for most PV systems. Any abnormal readings or feedback from the system should be checked immediately.


 

Tilt Angle
All solar installations will be more effective when the sun’s rays are perpendicular to the surface of the collector.

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Therefore, all solar installations are angled towards the winter sun to maximize the amount and intensity of light exposure. As the sun’s angle changes throughout the year (higher in the sky during summer and lower in the sky during winter), the amount of light falling director on the collector changes, as does the energy output. For optimal performance, solar air heating should be installed at 90° while solar water heating and PV installed at 45°. A successful solar installation will be designed to minimize shading and maximize the amount of light that hits the collector.


 

General Information
Installation Considerations

Codes

  • Air Heating: Heating/Ventilation requirements must be followed.*
  • Water Heating: Hire a certified and experienced solar contractor.
  • PV: Hire a licensed Electrician.

Structural

  • Air Heating: Building framework and wiring must be located prior to installation.
  • Water Heating & PV: Consult a Professional Engineer.

Permits

  • Consult local zoning and utility requirements.

Installation

  • Follow manufacturer’s instructions.

Tilt Angle

  • Air Heating: The ideal angle is 90° (vertical).
  • Water Heating & PV: A tilt angle of 30 – 45° is ideal.**

Direction

  • Collectors should be facing as close to true south as possible.

* Check National, Provincial, and local building code requirements for your area
** To maximize efficiency, systems can be fixed or adjustable to allow for optimal efficiency and should be sized according to site-specific details.

 

Tips to Maximize System Performance

Energy Conservation

  • Draft proof and insulate your home and around water pipes first to maximize efficiency. Water heating systems should also have low flow shower heads and faucet aerators installed.

Shading

  • Use the best available location to minimize shading and maximize solar gain.

Maintenance

  • Keep the collector free of debris, dust, pollen, snow and shading.

Efficiency

  • Air heating: Long stretches of duct work increase cost and heat losses, so try to make duct runs short.
  • Water Heating: Adequately design and size the system based on the number of people in the home and the daily water consumption.
  • PV: An average home in NS with electric space and water consumes approximately 28,000 kWh/yr. Determine your electricity consumption and size the system to meet your needs.