The primary reason to act sooner rather than later is the looming cut to the federal investment tax credit for solar, which is equal to 30% of the project’s cost. Only projects that are online prior to December 31, 2016, are eligible to receive this credit. Projects brought online after this date will receive a significantly lower credit (10% of project cost). From the perspective a project developer, the end of 2016 is right around the corner. Large solar projects need to be in late-stage planning by mid-2015 in order to get online in 2016. Projects that don’t capture the federal tax credit will need to price their energy at a higher rate, making them less competitive against traditional energy markets.

Second, is energy market volatility. In most regions of the U.S. today, wholesale energy prices are down due to the low price of natural gas (which fuels many power plants). Large solar projects must compete in that space. If a deal makes sense in today's market, it is very likely to make sense for the foreseeable future. But if wholesale energy prices go up, don't expect the offered price of solar energy to stay low. Like any business, solar companies will sell their power for what it's worth.

Last, in some markets, incentives are structured to encourage faster action. New York is a great example. With a new program starting May 2015, the solar incentives will decline in value as more and more solar is built. To capture the highest (earliest) incentives, projects need to be ready to build soon.