There are situations where you would want your panels facing in another direction than the south (given that you are in the US or at least in the northern hemisphere). While a system gives maximum power output when it is turned to the south, sometimes solar energy is needed at a certain time of day. If you turn your panels slightly to the west, you get more energy in the evening, when people come back home from work and turn on lights and devices. If you turn your panels to the south-east, they absorb the light of the rising sun in the morning, which can be handy for reheating the house in the first hours of the day. In theory, by choosing southeast or southwest you lose around 7-8% of daily amount of energy but it's better used.
There are two other situations that are even more specific, but nevertheless seem interesting. The overall power output of solar panels drops slightly when it gets over 77 degrees Fahrenheit. In the hottest states of America, like Arizona or Nevada, it may be wise to turn panels slightly to the east so they would get more energy in the morning when it's still cold and panels function better. In some places certain times of day get cloudy — morning fog at San Francisco can be set as an example. Efficiency of solar panels drops by 15-25% in these conditions, so it would be smart to focus your panels on the time when they would have the most amount of sun. Of course, this last example differs from state to state. If you want to know more about solar panels efficiency in cloudy conditions, read our article on the effect of bad weather on solar energy production. " How solar panels perform on cloudy days and why electricity prices matter more than the weather