However there are a few drain back systems that only use water.
Antifreeze solar panels.
Using an antifreeze solution.
Solar thermal panels collect solar heat and transfer it to hot water tanks.
Solar water heating systems that use an antifreeze solution propylene glycol or ethylene glycol as a heat transfer fluid have effective freeze protection as long as the proper antifreeze concentration is maintained.
The photovoltaic solar panels or pv solar panels convert the sun s energy into electricity which then can be used to heat water.
Antifreeze fluids degrade over time and normally should be changed every 3 5 years.
The industry standard for solar fluid is a mix of propylene glycol and water.
Garrison advised that electrical hot water tanks work the best for solar hot water use.
A special water heater tank incorporating a heat exchanger works in conjunction with one or more flat plate roof mounted collectors.
However you should always mix as much water as possible with your choice of glycol product as simple water is the ideal solar fluid.
Most new solar homes feature a variation of one kind or another.
Recommended dilution 40 providing total volume of 12 litres for use in solar systems.
It has a long track record over many decades in this application and is widely available from a number of sources.
The antifreeze is normally non toxic propylene glycol as opposed to toxic ethylene glycol.
Closed loop active antifreeze systems are the most versatile and failsafe of all the solar supplemental water heating systems.
Glycol or some equivalent antifreeze fluid fills.
What type of solar system do you have is it sealed or drainback a correctly installed drainback system should not require antifreeze sealed systems require a good quality antifreeze that will not break down with the high temperatures of solar it should also be a premixed antifreeze it is no good injecting a small quantity of antifreeze into the system as it will not mix and so will not.
Solar thermal panels are a closed system of tubes that contain a solution similar to antifreeze.
5 litres solar antifreeze.
This is not automotive antifreeze which is a different substance ethylene glycol and is.
Most solar thermal systems use antifreeze as the liquid to transport heat from the solar panel to the cylinder.
Propylene glycol pg has become the most common heat transfer fluid used in closed loop solar heating systems that contain antifreeze.
Solar panels can also directly heat water by heating water filled pipes within the solar panels or by heating a transfer fluid such as antifreeze usually propylene glycol.