Technical - Solar Dryers Australia

34 Coronation Street
Bellingen NSW 2454
Phone: 61 2 6655 2100
Mobile: 61 427 256 140
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Solar Collectors on SG 100 Kilns
An array of solar hot water collectors is mounted on the roof of the solar kiln or on an adjacent building. Water is pumped in a closed circuit between the collectors and the heat exchanger inside the kiln. Heat is extracted from the water which then returns to the collector array for re-heating.

4 x SG 50 Kilns
The circuit involves a "Day" and "Night" loop with a diverter valve controlling the direction of the water flow according to the commands of the Differential Temperature Controller. An auxiliary water heater is incorporated in the circuit to "top up" the temperature if required. In the standard format this is the indirect fired gas unit, but any external heat source could be used. Most operators use gas to bring the kiln to temperature where it is maintained by the solar circuit with occasional top ups from the gas auxiliary.
Kilns can also be run using Solar heating alone if required.
An automatic PLC controller allows a full range of schedule options where any kiln climate can be achieved.
Humidity control is maintained by a balance between venting and fogging.


Our kilns are fully engineered structures of thermal panel, with aluminium and stainless components for maximum life, they are designed to suit specific site conditions.
Thermal efficiency and air sealing has been a major design objective with all our kilns as we require them to be capable of operating on solar heating alone if necessary.
Auxiliary Heating

We have developed a safe and economical system with minimal compliance cost and easy accessibility. Our gas unit is externally mounted and flued, feeding hot water to the heat exchanger inside the chamber.
The heat exchanger is designed to be coupled to a waste wood hot water system if desired, replacing or supplementing the gas unit.

Operating Costs

These vary according the timber charge and the kiln temperature required, but drying 25 mm air dry hardwood from 25% to 10% MC costs $4 - $7 per m3  for gas in Australia at 2018 prices

International Conversions

Economic And Environmental Benefits

Greenhouse Gas

Current world concern with energy use and greenhouse gas emissions brings us to examine energy costs involved in drying lumber.
The most important difference between Solar Dryers Australia and other kiln manufacturers is that up to 80% of the heating energy to dry the timber in the kiln is derived from the sun.
This single factor represents a huge saving not only the running costs for the kiln but also a very significant saving in the amount of greenhouse gas produced to dry the timber.
The savings are so significant that with our SG100 kiln the savings in the gas heating costs alone can pay for the outright cost of the kiln within 7 years  under favourable weather conditions.
Currently Solar Dryers Australia has around 150 solar kilns installed, representing the saving of over 5000 tonnes of CO2 per year and saving its customers an average of AUD$1.8 million in gas costs per year.   
This is equivalent to taking 1100 cars off the road or 800 family houses off the electricity grid.
These figures of course will grow with the number kiln sales.
A solar kiln will lock in operating costs for drying timber and reduce exposure to ever rising fuel costs.
Below is a graph showing the gas cost savings for one of our customers with 13 kilns with respect to rising LPG gas costs.

© 2008 Solar Dryers Australia Pty Ltd
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