Many factors determine if you are a good candidate for a solar system, and how the system will be designed. Gathering the proper information will save you time and enable the system to be designed properly.

Geographic Location

Every location has an average amount of daily full sun exposure. This is known as the insolation factor. Full sun supplies 1000 watts of radiation per sqare meter. A location with 5 hours of full sun exposure per day would have 5000A watts.

Most places have a very good solar resource. Germany, for example, is one of the leading solar markets in the world, and it has about the same insulation as the worst locations in the United States. If your location has a low insulation factor, a slightly larger collector area will provide the necessary additional energy demand.

Collector Sizing

Determining the location and size of your solar hot water system is a crucial step in the process of maximizing the efficiency of a system that is right for you. Use this diagram to accurately size your solar hot water system according to the number of people in your household.

Collector Orientation

Roof Orientation - In the Northern hemisphere, the sun arcs across the Southern sky. Because of this, the collectors should be tilted in a Southerly direction (latitude +/- 15°). Ideally they will be flush mounted on the roof when the roof pitch is tilted in that direction. Even if the roof slope is oriented within 15 degrees of south, there is very little loss in the production from optimal orientation. And perhaps most importantly, your collectors must not be place in a shady spot. They need direct contact with sunlight during all peak sunlight hours of the day.

Flush Mount

A type of mounting system in which the collectors are anchored directly against the surface of the roof structure.This method is ideal for roofs that have been built with an adequate pitch to allow for proper drainage of the water through the collector

Tilt Mount

This orientation method is used primarily for flat roofs. The collectors can be tilt mounted to a Southern orientation, which will allow for optimal sun contact with the collectors.

Ground Mount

When installing your collectors, if the building's roof doesn't have proper orientation to the sun, the collector array may be ground mounted.

When determining where to place your ground mounted collectors, it's best to pick a sunny location close to the structure - preferably on the South side of the building.

Shading Analysis

Shading is an important consideration, but some shading is allowable for near optimal performance. Ideally a solar installation will have full sun all day, but even a partially shaded location can produce close to the same yearly energy output.

Annual Shading - Most of the heat collected during the year occurs between April and September. If shading occurs during the winter months when the sun is low in the sky, only a small percent of the overall production will be lost. Another consideration is that deciduous trees lose their leaves in the fall. Approximately half of the solar radiation gets through a leafless tree.

Daily Shading - The lion’s share of the daily collected energy occurs between 10am and 3pm. If shading occurs in the morning or late afternoon, the system will still perform quite well. Additional collector area can overcome losses due to partial shading.

Tools - There are shading analysis tools available to very accurately calculate the percent of full sunlight for the location. An example is the Solar Panthfinder. A solar professional should have such a tool to determine the solar resources available.

Existing Hot-Water Systems

Locate the existing hot water system and take notes on these topics
· Is it a tank or tankless? How many gallons? Efficiency?
· What is the fuel? Natural gas, electric, propane, heating oil?
· What are the space constraints? Area? Ceiling Height?

Existing system
· What is the location with respect to the roof where the collectors will be mounted?
· Are there chases or closets where the solar lines can be run to the attic?
· If not, are there exterior walls where lines might be run to the roof?
· Gather as much information as possible!

Energy Demand

Determine your hot water demands -

Residential
· How many people for domestic use?
· What is the BTU demand for space heating?

Commercial
· What is the usage?
· Number of gallons? Temperatures?

Type of Energy Used & Energy Cost

Gather more information - Collect your recent fuel bills. Analyzing your monthly spending will help you to determine your potential savings with the installation of a solar system. Figure your cost per:

· KWHr for electricity
· Therm for natural gas
· Gallon for propane or heating oil

Incentives

· Federal Tax incentives provide a 30% income tax rebate for the cost of a solar installation
· Additional commercial depreciation will provide up to an additional 15% of the system cost
· Additional state, local and utility incentives are available throughout the country.
· To see details on the REAP Program which utilizes a host of available incentives and rebates in combination with SHEM financing, please click here.

 For a better view, please feel free to download this map here
 A complete lists of all solar incentives can be found at www.dsireusa.org

After reviewing this information, a quick and accurate determination can be made as to whether a solar hot water system would be a good fit for you. How can we help you go solar?

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