It is almost common knowledge that solar panels should face South as it maximizes the amount of energy the panels can produce. However a study from Pecan Street Research Institute show some interest in pointing solar panels west.
Solar panels facing in this direction produce more electricity when demand peaks, thus reducing the need for coal and other dirty fossil fuels at a key moment. So if you don’t have roofs pointing South, this could be a good idea to point them west.
But given how doing so reduces the total amount of energy produced, it is not sure this will maximize the investment for private persons.
Here is a graph showing the average daily generation profile of solar panels, whether they point south (blue) or west (green) :