Portable diesel generators keep power flowing when the grid can’t, from remote jobsites to stormy nights at home. They’re valued for sturdy torque, fuel efficiency, and long runtime, yet choosing one isn’t as simple as picking a wattage sticker. This guide breaks down how they work, what sizes fit common loads, and how diesel stacks up against gasoline, propane, and battery options. You’ll also learn safe setup, maintenance habits, and real-world costs so you can buy with confidence.