You get the most out of your solar panels by orienting them appropriately. In North America and other hemispheres, south-oriented roofs are best because they maximize exposure to sunlight. The sun rises in the east and sets in the west, so solar panels that face east or west will receive morning or afternoon sunlight, respectively.
Solar panel orientation is as important today as it was when choosing an orientation was a new concept in the 70s. For example, solar power production can be optimized by orienting panels to maximize exposure to the sun's light. Otherwise known as the position of sunrise and sunset, this orientation most significantly impacts energy production over time.