DETROIT (AP) — After more than a decade of making cars and SUVs — and, more recently, solar panels — Tesla Inc. wants to electrify a new type of vehicle: big trucks.

The company unveiled its new electric semitractor-trailer Thursday night near its design center in Hawthorne, California.

CEO Elon Musk said the semi is capable of traveling 500 miles (804 kilometers) on an electric charge — even with a full 80,000-pound (36,287-kilogram) load — and will cost less than a diesel semi considering fuel savings, lower maintenance and other factors. Musk said customers can put down a $5,000 deposit for...