Solar Water Heating
Through specially designed systems, energy from the sun can be used to heat water for your home. Depending on climate and water use, a properly designed, installed, and maintained solar water heater can meet from half to nearly all of a home’s hot water demand. If your location has a southern facing roof or wall with little obstruction to the sun you may have a good location for a Solar hot water system. Almost as important is the slope of your roof. Ideally you want your collector to be mounted at an angle equal to your latitude plus 15 degrees more if to be optimized for winter heat.
Two primary components, a collector and a storage tank, characterize most solar water heaters. Beyond these common features, solar water-heating systems vary in design.
Two popular designs can be classified as passive or active, and as direct (also called open loop) or indirect (also called closed loop).
Evacuated tube solar hot water heating is one of the most efficient and cost effective energy capture systems available today follow our Collectors link at the left side of this page.
Solar Heating may not be enough for your Hot Water
Although you may be able to heat water to between 100 and 1200F during cloudy fall days and to much more during sunny days in even if winter. Both active and passive solar water-heating systems often require more “conventional” water heaters as backups, or the solar systems function as pre-heaters for conventional units.
Solar heating of your water will take the chill out and even warm your water to 600 degrees C or to as high as 1400 F but this may not be enough for the dishwasher or that scalding hot shower. ...and then there are those cloudy cold rainy and snowy days. For this reason solar water heaters are frequently used to pre-heat the water before it is fed into a demand or traditional hot water heater.
Choosing a solar water heater with good ratings is not enough. Proper design, sizing, installation, and maintenance are critical to ensure efficient system performance. Although the purchase and installation prices of solar water heaters are usually higher than those of conventional types, operating costs are considerably lower.
Supplemental Heat, On-Demand Hot Water
Why invest additional fuel to heat water to that extra hot temperature long before it is needed? Heat will leak away through tank insulation over time. A propane or NG fuelled demand hot water heater is the perfect compliment to your solar heated hot water. If and only when it is needed the demand hot water heater will boost the heat to the temperature you have set the system to. On-demand hot water systems are rated and sized by the amount of water flow they can heat. Theses on-demand hot water heaters are not new. They have been extremely popular in Europe for 50 years!
Determining Capacity - Conventional / Standard Hot Water Tanks
When both purchase and operating costs are taken into account, conventional electric hot water storage, the least expensive system to buy, is one of the most costly to operate over a 13-year period. An electric heat pump water heater, though expensive to purchase, has a much lower cost over the long term. A solar water heating system, which costs the most to purchase, has the lowest annual operating cost among water heating systems. At current electrical rates a solar water heat system can pay for itself in as little as three and a half years.
Although most people base their purchase of conventional heat storage hot water tanks on the size of the storage tank, the peak hour demand capacity, referred to as the first-hour rating (FHR) on the EnergyGuide label, is actually the more important figure. The FHR is a measure of how much hot water the heater will deliver during a busy hour, and it is required to appear on the unit’s EnergyGuide label. Therefore, before you shop, estimate your household’s peak hour demand and look for a unit with an FHR in that range.
Conventional Hot water storage fuelled by Gas have higher FHRs than electric water heaters of the same storage capacity. Therefore, it may be possible to meet your water-heating needs with a gas unit that has a smaller storage tank than an electric unit with the same FHR. More efficient gas water heaters use various non-conventional arrangements for combustion air intake and exhaust. These features, however, can increase installation costs.
Units with longer warranties usually have higher price tags. Often, the least expensive water heater to purchase, the electric hot water tank, is the most expensive to operate.
From Natural Resources Canada: An Introduction to Solar Water heating Systems (PDF)
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