Solar Hot Water - How it Works
Technical information about Hills Esteem™
Solar Hot Water Systems
Evacuated Tube Technology
Evacuated tube technology delivers significantly better performance than traditional flat plate absorbers on the market today. The evacuated solar tube is a high performance solar absorber, the solar energy is captured efficiently even in low ambient temperature and cloudy conditions.
The advanced design incorporates tubes that consist of 2 layers of borosilicate glass the outer tube is transparent allowing solar energy to pass through it while the inner tube is coated with a special selective coating (Al-N/Al) which features excellent radiation absorption.
The top of the two layers of tubes are fused together and the air contained between the layers of glass is pumped out. This "evacuation" of the tube forms a vacuum. The vacuum acts like a thermos flask, retaining up to 97% of the thermal energy, resulting in increased efficiency.
Located in the centre of the evacuated glass tube is a copper heat pipe which has a small amount of evaporative liquid in each tube, this liquid is super heated by the captured sun's energy and forms into a gas. The gas rises to the top of each pipe and the thermal energy is then transferred to the manifold via the heat pipe located in each tube. Water is then pumped to and from the storage tank collecting the heated water ready for use in water heating applications.
Evacuated tubes have been used for many years in Germany, Canada, China and the UK. There are several types of evacuated tubes in use in the solar industry like the Heat pipe, water in glass and "U" tube. These systems are more efficient in cooler climates than standard flat plat technology. Hills have undertaken research to choose a quality system that will perform best in all conditions especially in winter when thermal energy is at its lowest therefore giving you the best possible performance all year. Even on cloudy and rainy days you may still achieve some solar gain.
Collector & Manifold
The collector manifold and lower rail is made from anodized aluminium and powder coated for maximum protection against corrosion, the collector system is assembled together using a custom stainless steel frame that is bolted together to form the base, at the bottom of the collector is the rail which houses the Evacuated tube locating cups.
The ideal location for the collector is facing due North, however 45° degrees North West or North East is acceptable with minimal effect. This performance is due to the collector tubes cylindrical design creating the tracking of the suns rays all day as shown in the diagram below.
Stainless Steel Tanks
All Hills ESTEEM™ Solar Systems use Stainless Steel tanks, which have a natural oxide barrier to corrosion, therefore removing the requirement for a sacrificial anode. Tank sizes available are 160 litres, 250 litres and 315 litres.
A UV stable polymer outer casing provides an attractive finish and eliminates the rust which can occur on the outer casing of vitreous enamel steel tanks.
Hills ESTEEM™ Solar Systems are available in either gas boosting or electric boosting for backup heating if required.
Stainless steel tanks are tough, durable and lighter than their equivalent vitreous enamel mild steel tanks.
The tanks are of a high quality and attract a 10-year warranty.
Frost & Hail
The Hills ESTEEM™ Solar Evacuated glass tubes are frost tolerant and have passed the AS/NZ 2712:2007 Standards for both hail and freeze resistance to below -15° C without the need for heat exchanger or glycol. Importantly, Hills ESTEEM Solar systems do not use the toxic glycol that needs to be regularly replaced in flat plate systems to prevent them freezing and bursting in cold climates.
The range of Hills Esteem Solar Hot Water systems have been approved by Australian Standards (AS/NZS 2712 & AS/NZS 4234) and carry the Australian Standards and Watermark seals of approval. (Australian Standards License No. SMKP20319)
How efficient is this technology?
The following chart demonstrates the efficiency of the Evacuated tubes compared to the flat plate technology. The Evacuated tubes are better at exchanging heat into water than flat plate technology at 75°C. As the temperature of the water increases in the exchanger, the ability for any system to exchange that heat decreases. Evacuated tubes perform much better at this then any other system as shown in the diagram below.
No ugly water tank on your roof
Hills ESTEEM Solar is a 'split system' using a sleek solar collector on your roof and a highly-insulated storage tank at ground level. The collector only weighs up to 108kg so there is no requirement for any strengthening of the roof structure, as is required by other heavier systems.
Now you can do the right thing for the environment and still have a great-looking house.
Freedom to make your house look good
With our system you are not limited to putting the collector on a north facing roof - it will work on east or west facing roofs with a small drop in efficiency. This gives you the flexibility to place it where it will look and function best - maintaining your home's value.
Superior quality means long system life
The use of high-grade stainless steel in our components makes them ideal for our harsh Australian condition: particularly in high-humidity areas or near the ocean.
Perfect for cold climates
Evacuated glass tubes do not carry the risk of freezing that can destroy other systems. Importantly, Hills ESTEEM Solar systems do not use the toxic glycol that needs to be regularly replaced in flat plate systems to prevent them freezing and bursting in cold climates.
System Schematics
Hills Solar offer electric boosted solar systems to sustain the water at an appropriate temperature when radiant heat is low and there is cloud cover and rain. The system comes with a standard 3.6kw bottom element however, can be changed to a 4.8kw element to conform with different State regulations. Positioning of the element ensures you will have a full tank of hot water available.
ESTEEM™ Gas Boosted Solar Hot Water Systems
Hills Solar offers a choice of gas boosting using the Bosch continuous flow gas booster, 21e or 26e to ensure a continual flow of hot water on low thermal days. When water below 60° C is drawn from the tank, the gas booster will boost the water temperature to 60° C ensuring that only the water drawn is heated, saving energy.
