Hybrid Power Plants: Status of Operating and Proposed Plants, 2024 Edition

Improving battery technology and the growth of variable renewable generation are driving a surge of interest in “hybrid” power plants that combine, for example, wind or solar generating capacity with co-located batteries. While most of the current interest involves pairing photovoltaic (PV) plants with batteries, other types of hybrid or co-located plants with wide-ranging configurations have been part of the U.S. electricity mix for decades.

This annually updated briefing tracks and maps existing hybrid or co-located plants across the United States while also synthesizing data from power purchase agreements (PPAs) and generation interconnection queues to shed light on near- and long-term development pipelines. The scope includes “co-located hybrids” that pair two or more resources (e.g., multiple types of generation and/or generation with storage) that are operated largely independently behind a single point of interconnection, and “full hybrids” that also feature coordinated operations of the co-located resources. The focus is on plants with one megawatt (MW) or more of capacity; smaller (often behind-the-meter) projects are also increasingly common, but are not included in this data synthesis.

Key findings from the latest briefing include:

• At the end of 2023, there were 469 hybrid plants (>1 MW) operating across the United States (+21% compared to the end of 2022), totaling nearly 49 GW of generating capacity (+19%) and 3.6 GW/11.1 GWh of energy storage (+59%/+67%). PV+storage plants are by far the most common, dominating in terms of plant number (288), storage capacity (7.8 GW/24.2 GWh), storage:generator capacity ratio (54%), and storage duration (3.1 hours).  But there are nearly twenty other hybrid plant configurations as well, including several different fossil hybrid categories (each dominated by the fossil component) as well as wind+storage, wind+PV, wind+PV+storage, geothermal+PV, and others.
• Last year was another strong year for PV+storage hybrids in particular: 66 of the 80 hybrids added in 2023 were PV+storage. As of the end of 2023, there was roughly as much storage capacity operating within PV+storage hybrid plants as in standalone storage plants (~7.5 GW each). In storage energy terms, however, PV+storage edged out standalone storage by ~7 GWh (24.2 GWh vs. 17.5 GWh, respectively).
• Interconnection queue data show continued strong developer interest in hybridization. At the close of 2023, there were 18% more hybrid plants—representing 33% more generating capacity—in interconnection queues across the United States than there were at the end of 2022. Solar dominates these proposed plants as well: at the close of 2023, there were 599 GW of solar capacity proposed as a hybrid (representing ~55% of all solar capacity in the queues), most typically pairing PV with battery storage. At the same time, there were 51 GW of wind capacity proposed as a hybrid (representing ~14% of all wind capacity in the queues), again most-often pairing wind with storage. Meanwhile, more than half of all storage in the queues is estimated to be part of a hybrid plant. While many of the plants proposed in the queues will not ultimately reach commercial operations, the depth of interest in hybrid plants—especially PV+storage—is notable, particularly in certain regions. For example, in CAISO, 98% of all solar capacity and 34% of all wind capacity in the queues is proposed as a hybrid.
• The report also surveys power purchase agreement (PPA) price data from a sample of operating and proposed PV+storage plants. PV+storage PPA prices have begun to increase, and “levelized storage adders” have recently increased as well to ~$10000/MW-month, ~$80/MWh-stored (assuming one full cycle per day), or ~$35/MWh-PV. Some of the recent price increase could simply reflect a trend towards higher battery:PV capacity ratios on the mainland over time (whereas this ratio is typically pegged at 1 to 1 in Hawaii), which will increase costs, all else being equal. The well-publicized impact of inflationary and supply chain pressures on prices in 2022 could also be a short-term contributor, though battery prices have more recently hit all-time lows.

For further details on these and other findings, please refer to the short PowerPoint-style briefing, which can be downloaded here. The briefing is accompanied by two data visualizations, one focused on online plants and the other on those in interconnection queues, as well as an Excel data file with details on individual plants.