Annual Technology Baseline Provides Updated Foundational Solar Model Input Data for Electric Grid Studies

2021 Update of Annual Technology Baseline Includes Robust Data of Current Status, Market Trends, and Technology Improvement for Solar Photovoltaics and Concentrating Solar Power

Aug. 26, 2021

Photo of solar panels in the foreground with a large illuminated power tower in the background. The facility in Nevada represents the future of concentrating solar power.
Over 10,000 tracking heliostats focus solar energy at the receiver on the 640-foot power tower at the Crescent Dunes Solar Thermal Facility in Nevada. The facility is representative of concentrating solar power modeled in the Annual Technology Baseline. Photo by Dennis Schroeder, NREL

One of the challenges of aggregating energy data from different sources into studies is knowing whether the data uses consistent assumptions. The Annual Technology Baseline (ATB) resolves this challenge by creating consistent assumptions across all electric generation technology cost and performance data.

The ATB integrates current and projected data for electricity-generation technologies into one user-friendly tool. It is led by the National Renewable Energy Laboratory (NREL), assembled by a team of analysts from the U.S. Department of Energy's national laboratories and sponsored by the U.S. Department of Energy (DOE). Each year, new data are released, and the 2021 update of the electricity-sector ATB came out in July.

All renewable energy technologies are represented in the ATB. In this Q&A, solar power technology leads and NREL analysts—David Feldman, Chad Augustine, Parthiv Kurup, and Craig Turchi—share their insight on why the ATB is unique and what is new in terms of solar photovoltaics (PV) and concentrating solar power (CSP) in the 2021 update, including new technologies, expanded financial data, and better interoperability with other models.

Does any other resource like the ATB exist?

The ATB was created because there was no existing database with the level of nuance on technology innovation that energy analysts need. As a national laboratory dedicated specifically to renewable energy, NREL partners with Oak Ridge National Laboratory to dive into those nuances for renewable generation technologies. Without the ATB, analysts would have to seek out data in many places and are likely to have inconsistent assumptions.

How does NREL build the data each year?

We compile data from literature and expert surveys, studies, and industry partnerships.

Who are the primary ATB users?

The ATB is for any analyst out there who is trying to model the electric grid, or individual technologies, in the United States or internationally. We get questions from analysts all over the country and the world who want to use this data.

What cost and performance metrics are offered for solar technologies in the ATB?

We report upfront costs, operating costs, system performance, and financing costs for most technologies over a 30-year period. These values are used to calculate a levelized cost of energy (LCOE). Note that, while LCOE is an important metric of comparison between electricity generation technologies, there are other factors, such as the value of the energy, which must also be considered.

Today's representative CSP technology for the ATB is the molten salt power tower with two-tank thermal energy storage, which drives a Rankine steam cycle. This utilizes molten sodium and potassium nitrate as the heat transfer fluid and the storage media.

How is solar data in the ATB used at NREL?

The solar data goes into NREL's Standard Scenarios—a suite of forward-looking scenarios of the U.S. power sector to 2050 that are updated annually to support and inform energy analysis—but also any analysis done with the Regional Energy Deployment System (ReEDS) model, as well as many other NREL models.

ReEDS is NREL's capacity deployment model that is used in many high-impact studies across the laboratory, currently including the Storage Futures Study and upcoming Solar Futures Study.

In the past, solar ATB data has been used in the SunShot 2030, Geothermal Vision Study, and Wind Vision Study. Truly, any sort of big study that NREL does with ReEDS uses ATB as the foundational model input for PV, CSP, and all technologies.

In additional to NREL use, have you seen it used outside of the lab?

Absolutely. Recently, the California Energy Commission and Cal ISO [California System Operator] commissioned modelers to look at the future of their grid. They utilized the ATB for their model inputs to understand impacts of policy with high renewables deployment.

Internationally, organizations like the energy department in Chile have utilized the ATB costs in their scenarios and come to us asking about costs in the market as a validation.

Are there any new features or developments related to solar in the 2021 update?

This year we made the exciting linkage between the ATB and NREL's System Advisor Model (SAM) so that the costs of the representative CSP plant at the starting point of the projections, or the baseline, are reflected in the SAM model. With this development, people can now dive deep into our assumptions for how we came up with that assessment, down to the number of heliostats. From there, users can change the assumption as they think it should be or customize for their systems like longer storage times or more efficient technologies.

For both PV and CSP, we've expanded our resource classes so we have larger representation of how these systems will perform throughout the United States. We also do a better job this year of representing the ongoing operating costs of PV systems, including five new cost categories. That's a big improvement.

We also added cost and performance metrics for PV-plus-battery storage. Previously, we only had separate PV and battery storage costs, but there is an ever-growing number of PV systems that are coupled with battery storage in the United States. We're excited to include costs for those systems this year.

What are some trends that you've seen over the years in the ATB in terms of cost and performance of solar technologies?

Generally, performance has increased, and cost has decreased, dramatically for PV and overall in CSP. The ATB has shown us there are several paths forward for continued price reduction. In the Standard Scenarios studies, you can see that when price decreases, renewable energy can become a significantly larger share of U.S. electricity generation. When that happens, there is also a lot of opportunity for greater deployment of storage technologies.

Moving forward, how will you continue to improve the ATB?

The DOE recently made a down-selection of what they believe to be the next generation of CSP technologies as part of their Gen3 program, so going forward we would like to see those captured in the ATB with the same fidelity of modeling as the current technologies.

We'd also like to continue to watch the market for PV-plus-battery storage and how those systems are designed and operated to accurately reflect them in the ATB.

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