This paper discusses the contribution of intermittent generation sources to power system adequacy for the Chilean Northern Interconnected System (SING) at different demand levels. Curves showing the system risk for different levels of demand are obtained using a Monte Carlo simulation approach that performs unit commitment and economic load dispatch, considering randomly generated outages and randomly selected synthetic wind and solar generation profiles created using a semi-parametric model. The simulation results are then used to estimate the probability of having energy not served for different demand levels. These curves can then be used to gain a better understanding of the contribution to adequacy of intermittent generators such as wind and solar (CPV and CSP), and the impact that thermal storage in CSP plants can make to improve their capacity value.