How well does a roof-mounted solar thermal panel work when the outside temp. is below zero?
Glycol solar thermal systems are expected to perform throughout winter months if they are receiving radiation from the sun. Drain-back systems drain water into the house to prevent freezing in sub zero temperatures. Solar thermal systems are generally expected to cover 30% of water heating needs during winter months. Colder weather can improve the efficiency of PV systems compared to hot sunny days when panel components heat up.
