it makes use of the ambient environmental temperature differences and works a clever engineering exploit which a crafty fellow like you may appreciate. [and may keep the cockles warm with when it gets nippy]
here is a snippet that describes the process:
Working like a refrigerator in reverse, an eco-friendly refrigerant with good thermodynamic properties, such as a R-407 mix, is pumped through the thermal absorber, called a collector, as a cold pressurized liquid. As it circulates inside the collector it absorbs heat energy from the surrounding atmosphere that has warmed the collector plate and as the temperature of the refrigerant liquid increases, it vaporizes changing the refrigerant fluid into a gas.
When the gas leaves the collector plate it is very warm but the gas passes through a compressor and is heated further by the action of the compressor, just like in a heat pump. As it circulates around the system, the now hot gas flows through a heat exchanger coil, called a thermodynamic block, inside the water cylinder were the heat is transferred into the water via the heat exchanger.
As the gas transfers its heat to the water, it cools reverting back to a liquid state and flows back to the solar panel were the process is repeated. So the cycle of the refrigerant is to enter the solar collector as a cold liquid and exit as a gas, pass through a compressor to concentrate the heat and pressure in the gas, just like in a heat pump, and then pass it through a heat exchanger which extracts the heat to heat water as the refrigerant returns back to a liquid.
Generally the refrigerant is continually circulated with the aid of the compressor pump and an external electrical source to keep the temperature difference almost constant during both the heat absorption (evaporation) and release (condensation) process helping to improve system efficiency.
Using a refrigerant gas in the solar collectors instead of water is the secret to the success of the solar thermodynamic heating system. The theory is that this makes it more efficient than traditional solar thermal panels, particularly when there is no direct sunlight allowing for a far higher efficiency at a much lower ambient temperature than conventional water filled solar panels.
But the biggest advantage of a solar thermodynamic heating system is that unlike traditional solar collectors which must be mounted on a roof in direct line of sight of the suns energy, thermodynamic solar collectors can be mounted anywhere, vertically or horizontally, in or out of the shade as its the surrounding ambient temperature they need and not direct sunlight. Also, as the thermodynamic solar collectors are full of a refrigerant gas and not water, they also weigh a lot less too.
As well as being able to produce hot water at up to 50oC in the shade with a very high efficiency and low energy consumption, solar hydrodynamic heating systems are now being used for underfloor heating and radiator systems in many new homes as they are capable of extracting sufficient warmth from the atmosphere to heat a building to a comfortable temperature even on the coldest of winter days. Thermodynamic solar panels can even be used to heat your swimming pool all year around.
Solar thermodynamic heating is a new and exciting way of producing free and clean hot water without the need of large, bulky or heavy roof mounted flat plate solar panels which may freeze in winter. Solar thermodynamic heating panels are gaining popularity today since many people are making a concerted effort to go “green” in order to save money and the environment.
These solar thermal heating systems are an important use of solar energy and the installation of this type of heating system allows people living in colder northern climates to benefit from the energy contained within the outside ambient air all year around. Then an energy revolution is under way in how we heat our water and solar thermodynamic heating is becoming a major player thanks to its special heat pump and simple system design.
