This chapter presents three different methods concerning how to analyze systems with large shares of solar and wind power. The methods are applied to a Swedish case with close to 100 percent renewable power based on hydro, solar, wind and biofueled combined heat and power (CHP). The chapter shows that there are limited balancing costs for this case. The costs for curtailment of surplus as well as to keep enough capacity to cover a high load combined with low solar and low wind is comparatively small, below 0.3 Eurocent/kWh. There are several challenges regarding the handling of large amounts of wind and solar power in power systems. The overall general challenge is to maintain a continuous balance in an economical and reliable way with minimum environmental effects. The challenge for the continuous balancing process is that controllable production and consumption have to maintain the balance on all time scales.
