Tesla 500 MWh Energy Storage Project Officially Commissioned in Texas

Another major energy storage milestone for Tesla — the Old 300 battery energy storage project, developed by Danish energy company Ørsted, has recently gone live and connected to the grid in Nedville, Texas. The project deploys Tesla's Megapack system, with a total capacity of 250 MW / 500 MWh, making it one of the key newly operational flexible resources on the ERCOT grid.

According to publicly available information, the Old 300 energy storage station is located southwest of Houston and is fully integrated into the Electric Reliability Council of Texas (ERCOT) grid. Capable of delivering full-rated 250 MW output for two hours, the battery system provides fast-response grid support functions including frequency regulation and voltage control — offering tangible benefits in alleviating power supply strain during Texas' summer peak demand and extreme weather events.

All Megapack units were manufactured at Tesla's Megafactory in Lathrop, California — currently the largest industrial-scale energy storage system factory in the U.S. Each Megapack ships pre-integrated with battery modules, inverters, thermal management systems, and control units, significantly reducing on-site installation effort. The current standard two-hour configuration delivers approximately 1.9 MW per unit and stores roughly 3.85 MWh.

Notably, the Old 300 energy storage station sits adjacent to Ørsted's 430 MW Old 300 solar farm — which entered operation in 2024 — but operates independently. This storage facility is not co-located or coupled with photovoltaic generation; instead, it draws power flexibly from the ERCOT grid and discharges during high-demand periods, enabling time-shifted energy dispatch and ancillary services.

Ørsted reports that the Old 300 solar farm alone generates enough electricity annually to serve approximately 80,000 Texas households and commercial customers. When paired with the new storage system, the combined assets are projected to generate around $110 million in property tax revenue for local school districts, infrastructure, and emergency services.

"Battery energy storage systems have consistently delivered critical power support during periods of tight supply-demand balance on the ERCOT grid," said Melissa Peterson, Ørsted Americas Onshore. The project also pushes Tesla's global operational industrial-scale energy storage capacity past 58 GWh across 65 countries and regions — while helping Ørsted expand its U.S. onshore renewable energy operating capacity to approximately 6 GW.