How to prevent solar water heater pipes from freezing? If anyone knows, please tell me.

There are four ways:

1. Cover the pipe with a thick insulating PET pipe

2. When not in use at night, let the faucet drain slowly to prevent dripping. frost;

3. Attach a solar companion (heating tape) to the pipe and plug it in

4. You can ask the manufacturer to do this. install a drain valve.