Forecasting solar energy generation is difficult due to the variety of solar power systems and weather regimes encountered. This report presents a suite of generally applicable and value based metrics for solar forecasting for a comprehensive set of scenarios (i.e., different time horizons, geographic locations and applications). In addition, a comprehensive framework is developed to analyze the sensitivity of the proposed metrics to three types of solar forecasting improvements using a design of experiments methodology, in conjunction with response surface and sensitivity analysis methods. The results show that the developed metrics can efficiently evaluate the quality of solar forecasts and assess the economic and reliability impact of improved solar forecasting.