Any business or large residence that uses significant quantities of hot water or could benefit from supplemental low-grade heat (40-60C) can potentially benefit from a solar thermal energy system. Whenever the sun shines, the 70% of the energy which it carries can be captured and applied to offset fossil fuels or electricity. Many systems can be sized so that up to 50% of a business's energy consumption for these uses (typically domestic hot water) can be provided by the sun. Similarly, many businesses requiring make-up air can profitably install solar air heating systems.

Solar water systems must be facing as close to directly south as possible (15-20 degrees off south is generally not a problem), at an angle that is optimized to their intended use (normally a 40-45 degree slope). Shading from trees and buildings must be avoided unless reduced production and higher energy costs are acceptable.

Installations on flat roofs require racking to provide the necessary slope, and a structural engineering assessment of the roof is essential in order to ensure that both the downward forces (system weight, snow and ice) and the upward forces (lift from wind) can be safely accommodated.

Conventional systems are retained for periods when the sun does not shine sufficiently,

Solar air systems have traditionally required a south-facing wall, but are now being designed to integrate solar PV panels over top of roof-mounted ducting, so both options are available.

Current system costs (fully installed and commissioned) involve relatively substantial up-front costs, which can be reduced by up to 50% (25% from the federal eco-Energy grant, matched equally in Ontario and Saskatchewan). The result is a payback of approximately 10 years at current energy prices.

When calculating payback, it is important to consider that:

1. Natural gas prices are at significant lows and do not yet reflect carbon pricing
2. Electricity prices in all jurisdictions are set to rise
3. Replacing conventional energy with solar energy provides known energy costs for that portion and reduces the impact of energy price volatility on business planning

These systems have durability that is comparable with any other plumbing system, without the negative impact of high-grade heat upon boilers. Solar systems may enhance the durability of existing water heating systems by reducing the amount they are used.

These are quite low maintenance systems. The glycol should be tested at least every 3 years to ensure that it has not overheated (which can damage it), but larger systems are going to have electronic monitoring built in which will indicate whether that has happened or not. Solar panels or wall-mounted solar air systems are self-cleaning.

• Federal Grant Program (Eco-Energy for Renewable Heat) Note–This program is set to end October 1, 2010; the specific final dates are indicated on the top right corner of the web site
• Ontario Solar Thermal Heating Incentive Program
• Saskatchewan Solar Heat Initiative for Today
• SolarBC Institutional Incentive
• List of Installers and Resellers for Solar Thermal Water and PV in south-eastern Ontario; Note that this list does not include many of the larger commercial installers; please call SWITCH for more information.