Solar forecasting is a domain of energy forecasting. Other domains of energy forecasting, primarily electric load forecasting, wind forecasting, and electricity price forecasting, were already fairly well developed by the year 2010, the time when modern solar forecasting first began. The relevant question is therefore: What does it take for this “new member of the band” to blend in and get along with the rest, to shine her character, and eventually, to flourish together with the rest? This chapter is concerned with contrasting theories and practices of various energy forecasting domains, and examining what can be shared across to and what is unique for solar forecasting. The closing section of this chapter inquires the common issues in energy forecasting, and makes a series of recommendations as to facilitate effective energy forecasting research.