This week's Question: The US now has 1 million solar power installations, and some industry experts expect the number of solar-power systems to increase dramatically in the span of two years. “By the end of 2020, the amount of installed solar capacity will be 300 percent higher than today,” said Dan Whitten, vice president of communications at the Solar Energy Industries Association, noting that the nationwide number grew 10 times between 2008 and 2015. This month, the Swedish furniture giant Ikea also recently announced the opening of its “Solar Shop,” which will sell panels and setup services. Two major challenges for the solar panel industry have been cost and capacity; compared to fossil fuel costs, solar panel installations can be time-consuming and expensive. What do you think? Will solar power supplant fossil fuels as a primary energy source?