A BP Plc. BP, +0.87% subsidiary has signed an agreement to buy and install a Tesla Inc. TSLA, -5.59% high-storage battery for its wind farm in South Dakota, the first of its kind for the U.S. wind business of the integrated oil and gas company, the company said Tuesday. The Tesla battery will be used to store electricity and meet demands when the wind is not blowing, the company said. No financial terms were disclosed. The battery-storage project is expected to launch in the second half of the year. BP operates 13 wind farms in the U.S., and its wind farms have a gross generating capacity of 2,259 megawatts, or enough electricity to power all homes in a city the size of Philadelphia, the company said. American Depositary Receipts of BP rose 2.5% in midday trading Tuesday, while Tesla shares gained 4%.