Mammoth Solar

Mammoth Solar is a 1,600 megawatt (MWDC) solar photovoltaic power project in Pulaski and Starke Counties, Indiana, United States. The plant is being contructed in three phases and will be the largest solar project in the United States and western hemisphere when complete. The first section of 400 MW came online in July 2024. The project is being developed by Doral Renewables, a subsidiary of Israeli company Doral Energy, and is expected to cost $1.5 billion. It will produce enough electricity to power 250,000 homes.

Project
Doral has contracts with about 60 landowners to use approximately 13,000 acres of land for the project, though excluding setbacks, forests, and wetlands, the 2.85 million solar panels will cover only about 2,500 acres. Most of the farmland is used for corn ethanol production; powering gasoline cars with bioethanol consumes around 70 times more land than powering electric vehicles with solar power. Doral is working with landowners to support dual uses of the project land as agrivoltaics to allow for sheep grazing and crop farming around the solar panels, including reseach on plant growth under panels.

The phases will use three points of interconnection on a 345 kV power line to deliver power into the PJM Interconnection. American Electric Power has power purchase agreements for electricity produced in phases one and two and half of phase three. Constellation Energy has a PPA for the other half of the power in phase three, passed on to four corporations

Pulaski and Starke Counties will see $1 to 2 million per year in additional property tax revenue for the life of the project, about a fifth of their budgets. Pulaski County also designated the project an Economic Revitalization Area, granting it a tax abatement; the Indiana Court of Appeals rejected a lawsuit challenging the designation. Local landowners are paid about $600–1000 per acre leased.

The project's name references mastodon fossils that were unearthed in the region of the solar project, now on display at the National Museum of Natural History.

NIMBY groups have organized against the project and filed suit against Pulaski County's zoning approval.

Phases and construction
SOLV Energy is the project's EPC contractor.

The Mammoth North phase in Starke County had a groundbreaking ceremony in October 2021. Construction began in March 2022 and it was completed in July 2024 with a capacity of 480 MWDC/400 MWAC. The project uses 540-watt modules from Trina Solar.

The second phase, Mammoth South in Pulaski County, had a groundbreaking ceremony in November 2022. Construction is expected to begin in 2024, and it will have a capacity of 300 MWAC.

Indiana governor Eric Holcomb attended groundbreaking ceremonies for both phases.

Work on the 600 MWAC third phase, Mammoth Central in Pulaski County, may begin in 2025.