Choosing the Right Electric Generator Set
If you're in the market for an electric generator set — also called a genset — you have a lot of options. There are small portable generators, big standby generators, diesel generators, gas generators, and more. How do you choose the right one? Here's a step-by-step guide to picking the right generator for your needs.
Step 1: Know What You Need to Power
The first question is: what are you going to power with the generator? That determines everything — the size, the type, the features. Make a list of all the things you want to run, and add up the wattage:
- Essential loads: What do you absolutely need to keep running, when the power goes out? Refrigerator, lights, furnace, well pump, phone charger, medical equipment?
- Nice-to-have loads: What would you like to run, if you have enough power? TV, computer, air conditioner, electric stove, water heater?
- Starting watts vs. running watts: Remember, electric motors need more power to start up than they do to keep running. A motor that uses 1,000 watts to run might need 3,000 watts to start. Always account for starting wattage, when you're sizing a generator.
Add up all the running watts, then add an extra 20-30% for starting watts and future expansion. That's the minimum size generator you need.
Step 2: Choose the Right Type of Generator
There are two main types of generators:
Portable Generators. These are small, movable generators, on wheels. They're good for occasional use — camping, tailgating, power tools on a job site, or temporary backup power. Advantages: cheap, portable, easy to move around. Disadvantages: noisy, not automatic, you have to run extension cords, they don't have enough power for a whole house.
Standby Generators. These are big, permanent generators, installed next to your house or business. They run automatically, when the power goes out. Advantages: automatic, quiet, enough power for a whole house, you don't have to do anything when the power goes out. Disadvantages: expensive, you need to have it professionally installed.
If you just need power for camping, or for occasional jobs, a portable generator is enough. If you need backup power for your house or business, a standby generator is worth the investment.
Step 3: Choose the Right Fuel Type
Generators run on different fuels:
- Gasoline: The most common fuel for small portable generators. Advantages: easy to find, cheap. Disadvantages: gasoline goes bad after a few months, it's flammable, you can't store a lot of it safely.
- Diesel: The most common fuel for big standby generators. Advantages: diesel is more efficient, it lasts longer, it's safer to store. Disadvantages: more expensive, diesel generators are noisier.
- Natural gas: Some standby generators run on natural gas, connected to the gas line. Advantages: you never run out of fuel, no need to refuel. Disadvantages: if the gas line is damaged, the generator won't work.
- Propane: Some generators run on propane, from a propane tank. Advantages: propane stores forever, it's clean burning. Disadvantages: you have to refill the propane tank, and it's less energy-dense than diesel or gasoline.
Step 4: New or Used?
New generators come with a warranty, and you know exactly what you're getting. But they're expensive. Used generators are 40-60% cheaper, but you have to inspect them carefully. Bring a mechanic or an electrician with you to inspect any used generator before you buy.
FAQ
Q: How big of a generator do I need for a whole house?
A: It depends on how big your house is, and what you want to power. A small house (1,500 square feet) needs a 7,000-10,000 watt generator, to power the essentials. A bigger house (2,500+ square feet) needs a 15,000-20,000 watt generator, to power everything. Always size up a little — it's better to have too much power than not enough.