Utility-Scale Fixed-Tilt PV vs. Single-Axis Tracker PV: Nems Projections to 2050
The main purpose of this National Energy Modeling System (NEMS) project was to investigate the cost and performance tradeoffs of utility-scale solar PV through modeling variations in fixed-tilt and single-axis tracker technologies. This objective was accomplished by using capital costs and capacity factors as inputs into NEMS to produce outputs for utility-scale crystalline silicon (c-Si) fixed-tilt solar PV. Yearly capital costs, cumulative unplanned capacity additions, and levelized cost of electricity (LCOE) were the projected outputs at the regional and national level from the year 2019 to 2050. These outputs were also produced in the same manner for utility-scale c-Si single-axis tracker solar PV. Expected modeling results for the three NEMS outputs were determined prior to running the models. Due to the technology learning curve, fixed-tilt and single-axis tracker capital costs will continue to decline from 2019 to 2050. The LCOE for single-axis tracker PV in many cases will be lower than that for fixed-tilt PV, depending on resource quality and financial assumptions. Furthermore, the national LCOE for single-axis tracker projects will decrease at a larger percentage than the national LCOE for fixed-tilt projects. If the cost gap between single-axis tracker and fixed-tilt widens, growth rates and total yearly capacity additions for fixed-tilt PV will become greater than those for single-axis tracker PV at the national level. A similar result will be observed, in some instances, if the capacity factors for fixed-tilt improve. The results of this modeling project matched closely with the predicted outcomes. Capital costs for both fixed-tilt and single-axis tracker did in fact decline as expected, but the capital costs decreased by approximately 33% between 2019 and 2050 for both technologies. This result indicates that the learning rate for fixed-tilt PV is equivalent to that of single-axis tracker PV. As was predicted, the single-axis tracker LCOE for the baseline run decreased at a greater percentage than the fixed-tilt LCOE for the baseline run – 18% compared to 14%. Single-axis tracker LCOE was in fact lower than fixed-tilt LCOE in many regions and at the national level, and only at 25% and 50% input capital cost decreases was fixed-tilt LCOE competitive with single-axis tracker LCOE at the national level. Based on the output results for the cumulative unplanned capacity additions, new project development in the utility-scale solar PV market will be dominated by single-axis tracker projects over fixed-tilt projects. At the baseline input price of $2.53/W-AC for single-axis tracker projects and $2.36/W-AC for fixed-tilt projects, single-axis tracker capacity growth vastly outnumbered capacity growth for fixed-tilt projects with 143.29 GW built by 2050, whereas capacity growth for fixed-tilt projects only reached 0.04 GW built by 2050. In conclusion, even though the capital costs for fixed-tilt PV and single-axis tracker PV declined at the same percentage, the capacity addition growth rates and totals from single-axis tracker were greater than those for fixed-tilt in the baseline capital cost scenarios, due in large part to the lower single-axis tracker LCOE compared to fixed-tilt.