These systems have many advantages:

• They are the only type that can handle freezing conditions.
• They're the go-to choice in locations with hard winters or any kind of severe cold weather.
• They work well with hard water supplies.
• They work in any climate where the heating load is reliable and consistent.
• The collectors can be mounted in a huge variety of ways.
• The collectors can be situated at quite large horizontal distances from the heat exchanger.
• They can use low-head, slow-starting DC pumps which can run on power from a PV array.

It's also important to consider these disadvantages:

• The solar fluid can degrade at high temperatures and become corrosive.
• The system must include measures to prevent overheating, to protect the solar fluid.
• The degradable solar fluid requires regular maintenance.
• The insulation must be able to resist extremely high temperatures.
• The collectors need to be accessible and adjustable in locations with regular snowfall.
• The system needs a shunt load if it will be inactive for extended periods.