We live in a frost prone area, how do these cope?

Exceptionally well.

Evacuated tube solar hot water systems are perfectly suited to frost prone areas as they are not effected by ambient temperature.

We have systems in alpine regions of Victoria including Mansfield, as well as Mount Macedon. We have done ‘Real’ testing at Mount Buller in midst of winter.

We have tested the tubes at Mt Buller in temperatures between 0 to -10 over 3 nights. The tubes were not effected by the temperature and held water temperature between 19degC>61degC>16degC.
The tubes were not part of a tank system. This was done to increase the vulnerability of the tubes and integrity of the tests.

So frost is not an issue in our systems.

In every test and with every install our results have been well above expectations.

We have clients who have put glycol in the systems at a ratio of 40L/200L, but we do not have any research based evidence that this has any real benefit.