To give a best answer, you want to give complete information. The coldest temperature in your part of the country and the construction of the panels are important clues.
Panels that accept water directly from the water heater are the most frequent cause of failure and dissatisfaction. Systems that use solenoid valves to drain water out of the panels in freezing weather fail most frequently. Systems with direct city water pressure fail.
To prevent these and other health problems, use a heat exchanger near the water heater between the panels and the water heater. Weil McLain boiler company supplies heat exchangers at reasonable cost to plumbing suppliers. A bronze or stainless-steel pump moves water through the heat exchanger from the cold to the hot of the water tank. Another pump moves water through the panels. In this way, the panels can work at low pressure and a break spills little antifreeze-protected water. Many of my Lennox-Honeywell solar systems are still in operation after 20 years.