We recommend that the batteries be placed indoors, especially if the system is used all year round. It is also possible to install outside or under the cottage in a place where the sun does not shine, as the function of the battery is also affected by the operating temperature. The AGM battery has a very long life, many times as long as a standard Freetime battery, but high temperatures significantly reduce the life of the battery. So an even cool temperature is best.
Make sure that the batteries are sufficiently charged during the winter.