The following five items are important considerations when selecting a solar heater:
1. Flat Plate vs. Evacuated Tube Collector
There is a lot of debate over which collector is better, flat plate or evacuated tube. While we do offer flat plate collectors we generally recommend evacuated tube collectors for the following reasons:
· Evacuated tube collector are more efficient in cold climates than flat plate collectors
· Evacuated tube collectors can be tilted up without catching the wind
· Snow does not accumulate on evacuated tube collectors
· Evacuated tube collectors absorb more heat over a longer period of the day
· Evacuated tube collectors do not provide a direct target for hail stones
2. Collector location and angle
For the best performance the collector should face south, although evacuated tube collectors will operate at 95% efficiency when facing 45 degrees off south. Energy collected is directly related to the sunlight intensity so the collector should not be shaded by other buildings, trees or natural obstacles. If at all possible the collector should be angled so as to catch the winter sun. A horizontal collector absorbs very little energy in winter when the demand is high and lots in summer when the demand is low. A collector between 45 and 75 degrees absorbs substantial energy year round. A vertical collector gives maximum winter energy and a little less in the summer months which is ideal for space heating applications.
3. Reliance on grid electricity
A solar heating system that consumes grid electricity adds to your electrical bill while saving on your fuel bill. A draw of just 50 watts during the day for a year is close to $100 per year and contributes to the environmental damage associated with grid electricity. These systems do not work when the power is out and during such instances are prone to damage from overheating. A technician may also be required to restart the system when the power is restored. Simple Solar water heaters do not use grid electricity and so save you money on your electricity bill and reduce your environmental impact. They work when the power is out and will not overheat or be damaged by a power failure.
4. What Kind of Heat Exchanger and Tank
An external heat exchanger is only 60% to 80% efficient and so it loses at least 20% of its solar energy. Simple Solar uses a heat exchanger that is inside the tank so all the solar energy is used to heat the tank. The size of the tank is an important consideration as is the quality of the construction. The tanks Simple Solar uses are designed for solar heating and have internal heat exchangers. They are also insulated with 2” of foam insulation to reduce heat loss. Watch out for tanks designed for electric heating that do not have proper piping connections and are poorly insulated.
5. How to Deal with Excess Heat
Most solar heating systems are not able to handle the excess heat which can occur when there is a lot of solar energy and low hot water demand, such as when the homeowner is away for a long weekend or vacation. One solution common with flat plates is to size systems smaller than required to heat the tank in the winter so that they don’t overheat in the summer. Other suppliers include ‘vacation’ settings or complex ‘drain back’ systems to avoid overheating. All Simple Solar systems include an automatic heat dissipater that returns excess heat to the atmosphere safely, automatically and only when your solar tank is full of hot water.
Please compare us to other systems and find out for yourself that Simple Solar makes simply the best solar heaters!