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How well an active solar energy system performs depends on effective siting, system design and installation.
Sunlight strikes and heats an "absorber" surface within a "solar collector.” Either a heat-transfer fluid or potable water flowing through tubes attached to copper "fin tube" absorbers pick up the heat energy converted from the sun's radiant energy on the absorber.
The solar heated water is stored in a storage tank until needed. If additional heat is needed, it is provided by electricity or fossil fuel energy by the conventional “backup” water-heating system.
Good Collector Tilt
The collector angle is known as "tilt." While a typical roof angle is 22 to 32 degrees, the tilt should be at least 15 degrees up from horizontal. Additional tilt usually has little effect on total year-round performance unless you are in an area with very sunny winters like Colorado.
A tilt angle equal to latitude is considered ideal for space heating. Because the winter sun is so low in the sky, great results have been obtained by having collectors flush on a vertical wall for space heating, which also prevents summer overheating.
Storage
You need at least 1 gallon of storage for each square foot of collector area. It is desirable that your storage tank be at least 50 gallons of storage for up to 40 square feet of collector area, although a 40 gallon water heater can work well with up to 30 square feet of collector area. Generally, the larger the water heater the better, up to 2.5 gallons per square foot of collector area in sunny areas.
FREEZE PROTECTED SYSTEMS: Systems 4 and 5 use an excellent Rheem / Rudd or Richmond (all the same manufacturer) 80 Gallon Storage tank with a very efficient 120 foot "wrap around" heat exchanger. For a closed loop using an existing tank or added standard tank, an optional system 4 "POWER ROD" external heat exchanger uses a second pump for the domestic water loop and a "Quick Connect," similar to those used on the open loop systems, for the tank connection.
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Southern Orientation
Since the sun rises in the East, crosses over the horizon on the South and sets in the West, you want your collector to face as much to True South on your roof as possible. This is especially true for space heating where you need to be within 15 degrees of True South.
Up to 45 degrees East or West of true South has very little effect on year round domestic water heating. While less desirable, a West or even an East facing water heating system can work well, especially with an additional collector. Orientations over 45 degrees, such as a home with a North-South ridgeline can tilt the collectors South with a SolarRoofs.com tilt kit.
While most collectors are mounted on the roof, many have been mounted on the ground, or like an awning on the side of the house. Verticle mounting of collectors on the South roof is great for space heating. Naturally, it is important that there not be any shading where the collectors will go!
You Need Space for Solar Collectors
SolarRoofs.com's Skyline® collectors are rugged and powerful yet light weight. The Skyline® 10-01 collector weighs 19 pounds and measures 6' long x 20" wide by 3" thick. The Skyline® 20-01 collector weighs 38 pounds and measures 12' long x 20" wide by 3" thick.
Sizing Your System
A small system providing as little as 30% of your hot water can be very efficient and cost effective! If the budget is tight, consider getting a smaller system. More panels can be added later. The important thing is to take that important first step to go solar!
For 60 to 70% coverage in areas subject to hard freeze and a lot of clouds, start with four 10-01 or two 20-01 collectors for the first two people and then two 10-01 collectors or one 20-01 collector for every additional two people. For example, a family of 4 should have six 10-01 collectors or three 20-01 collector (60 square feet). |
