A rooftop solar power system is turning out to be cheaper than the grid in 42 of the 50 biggest U.S. cities. A new study from the North Carolina Clean Energy Technology Center claims that money spent on a residential solar system earns a better return than investing in Standard and Poor’s 500 index fund. The cost of solar installation is decreasing, due in large part to reductions in the cost of solar panels. And utility rate increases over time are fairly predictable, making the initial upfront investment in solar power worthwhile. Design professionals should take stock of this new reality when working with clients; beyond the obvious environmental benefits of solar energy, going solar can offer clear financial savings which any client will appreciate.