Resource complementarities carry significant benefit to the power grid due to their smoothing effect on the variable renewable resources output. In this paper, we show that complementarity significantly reduces energy storage requirement by using simulation results generated for Israel, Saudi Arabia, California and Finland. In a complementarity study performed using Israeli and Californian data sets (focusing on the electricity sector alone), the wind-solar complementarities were shown to significantly increase grid penetration as compared to stand-alone wind/solar systems even without the need of energy storage. At even higher grid penetration their complementarity carries significant multidimensional benefits to the power grid. The most important observation was the achievement of very high grid penetration at reduced energy storage and balancing requirements as compared to stand-alone systems. Using specific energy storage capacity (186 GWh/22 GW) and setting the solar share to 0%, 50% and 100% of the total VRE capacity, the 50-50 wind-solar capacity mix has led to significantly higher penetration as compared to the stand-alone systems. For instance, by allowing 15% energy curtailment, it was shown that grid penetration of 63%, 80% and 55% of the annual demand, respectively, can be achieved. This was because of storage being able to follow a flexible dispatch strategy, which makes it applicable for various services depending on the season of the year and the available resources. A study on a 100% renewable energy system of Finland shows that one of the best scenarios was related to a 43%-57% wind-solar capacity mix for a 70% VRE penetration by 2050. A similar study on Saudi Arabia shows that broader resource complementarity and higher level of flexibility obtained through sector coupling has reduced the required storage very significantly. The results indicate that the multiple benefits obtained from resource complementarity should be emphasized during the transition to systems of high renewable energy shares.