Solar Thermal Sizing Guidelines
Our sizing professionals will work with you to design a solar system that meets your exact needs. We offer prepackaged systems that meet most needs for domestic hot water heating in the US. Our interactive
map will give you an idea of the performance a Thermomax solar system can offer you.
For domestic hot water systems, we size a system to meet around 75% of your family’s yearly hot water needs. There are more hours of daylight in the summer and therefore a system will output a higher percentage of your family’s needs than in the winter. If the system is oversized, once the water tank reaches temperature, the extra energy must be dumped somewhere. Since this is wasting energy, we don’t like to do this unless we have to. Even 75% of your family’s hot water needs will save you a significant amount money over the lifetime of the system.
When sizing a system for InFloor heating, we size the system to handle your domestic hot needs first and then switch over to heat your house. Domestic hot water is a more efficient use for the solar thermal collectors than heating and will provide you with greater energy savings. Systems designed for InFloor heating will provide almost all of your family’s hot water (sometimes cloudy, cold days in December will still need a back up). The system is then carefully designed to meet a portion of the heating needs of your house. Usually a system will provide 20-30% of the heat required in December and January and then increase from there. The size of the system depends heavily on your location and the heating requirements for your house. Please contact us for more information on heating with solar thermal and a performance quotation based on your house. Visit our map to get output from collectors in your area.
Swimming pools are an excellent and efficient use for solar thermal collectors. Properly sizing a solar thermal system for a pool is more difficult than most applications, based on location and specific operating parameters of the pool. We have software to help analyze your pool and determine how to properly size the solar system. Please contact us for more information on this.
Explanation of the Data:
The data is calculated using NREL’s (National Renewable Energy Laboratory) TMY3 (Typical Metrological Year, data set 3). This data provides solar radiation and weather data for over 1000 sites in the US. We then take testing performance data from the SRCC, or Solar Keymark for the solar collector and are able to calculate performance of the solar collector. This takes into effect the length of the days, the weather conditions and the temperatures at the location the data was taken at.Domestic Hot Water Percentage: In the United States, a typical person uses about 15 gallons of hot water per day. These charts are created for a family of four, using 60 gallons of hot water per day. The colored bar represents the hot water that is provided by the solar system and the grey bar the water that will have to be made up by another source, usually an electric element in the solar tank.
Average Daily Solar Output: This plot shows the average BTUs (amount of heat) one collector will produce in a day for the given location. This information is computed for an InFloor type application. The orientation of the collector affects the daily output. What is shown in the optimal orientation with the collector tilted at the latitude of the location. For heating applications, typically the panels are tilted a little steeper to allow them to collect more energy in the winter months. Please contact us for a custom solar thermal performance estimation in your area.
Savings: The table at the bottom estimates the savings from a Thermomax collector over its 25 year lifetime as compared to conventional water heaters. The efficiencies for conventional hot water heaters are based on ACEEE (American Council for an Energy Efficient Economy) for typical hot water heaters installed today in the US. The costs for energy are based on current market rates ($0.11/kWh for electricity, $2.00/gallon for propane, $2.50/gallon for fuel oil and $1.67/therm for natural gas) in February 2009. The energy inflation rate is assumed at 7.5% per year. For CO2 savings EPA data is used. This is a best guess at providing an estimate of what energy costs will do in the future. Clearly the price is quite volatile for all energy in the world today.
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