System-cost-minimizing deployment of PV-wind hybrids in low-carbon U.S. power systems

Hybridization of solar photovoltaic (PV) and wind installations has the potential to reduce transmission costs through sharing of spur-line capacity and other interconnection cost components. Many studies have assessed hybridization opportunities on a site-by-site basis but have not captured the impact of PV-wind hybridization on overall power system evolution and system costs. Here, we use a high-resolution national-scale capacity-expansion model to explore electricity-system-cost-minimizing deployment of PV-wind hybrid systems across the United States (U.S.) in scenarios that achieve a zero-carbon electricity mix in 2040. While overall system cost savings resulting from hybridization are relatively small—roughly 0.8% for baseline interconnection cost assumptions and <2% for sensitivity cases with high interconnection costs—there are notable shifts in deployment patterns when hybridization is allowed. PV capacity is often relocated to sites where wind capacity and associated interconnection capacity is already deployed, and "overbuilding" of nameplate PV and wind capacity relative to point-of-interconnection capacity is observed to increase with rising interconnection costs. Roughly 300 gigawatts (GW) of point-of-interconnection capacity (over 500 GW of nameplate PV and wind capacity) are deployed at hybrid installations with PV:wind capacity ratios between 1:3 and 3:1 in modeled zero-carbon power systems across the U.S.