Since MPPT controllers make use of the excessive voltage of panels which builds up, for example, in cold sunny weather, it would be fair to say that these regulators pay for themselves best in winter. They let you use around 30% more energy from solar panels at that time of year, so you can be sure your house will be well-heated. Obviously, since MPPT controllers have more energy at their disposal during those days, they can charge an empty battery faster. They are the least efficient in summer when it's hot and bring you around 10% more energy than PWM-regulators. Judging by that, it makes sense to use MPPT-controllers in cold and cloudy states especially. If you're wondering how exactly weather affects the performance of solar panels, check out our article on
how solar panels perform on cloudy days.