Any time of the year beside the dead of winter her DIY ones will boil the water in holding tank in a blink, so you have to have the valves and temperature controls setup properly to avoid that...
It's amazing what sunlight can do even in the winter for example Google up 'solar oven' with a roll of aluminum foil, a cardboard box and a glass window you could roast your entire turkey day feast, including the bird out in your driveway...
