Generators (portable & stand-by) are practical tools for the modern age. Engineered to provide you with back-up power — whenever and wherever you need it. Essential for emergencies, disasters, power outages, on the jobsite and even permanently connected to you home, in case the electrical grid goes down.
Complete Generator Guide / Directory
This article provides you with an overview on everything you need to know about generators, including links throughout to more detailed articles, depending on what you’re looking for.
What is a generator?
Any device that converts mechanical energy into electrical energy, using Faraday’s law of electromagnetic induction. Normally we use the term “generator” to define a piece of equipment which employs the rotational force from a prime mover (engine, steam turbine, etc.) to drive an alternator, generating AC power as a result.
Generators range in size from portable models that you can push around with your hands, to giant 50kW behemoths which power entire facilities like hospitals, schools, and apartment buildings.
Uses and applications
You can use generators to power small electrical appliances like a toaster, or to run an entire house. Often, portable generators are purchased by homeowners to power important stuff during an outage- sump pumps, lights, fridges, TVs, etc. But that’s not the only place where generators are used. Here are a few more use cases-
Recreational: Small 2000- watt inverter generators are very popular for camping and fishing. A lot of motor homes and RVs use gasoline generators to power their 15k BTU air conditioners.
Work: Construction crews and landscapers use portable generators to run their saws, lights, and air compressors on a jobsite. These generators are designed to be rugged, and pack plenty of power to run multiple tools at the same time.
Emergency: Standby generators are installed in hospitals to power mission-critical medical equipment such as life support systems, dialysis machines, defibrillators, etc. Large commercial generators are used in combination with battery backup to provide uninterruptible power at data centers and server farms.
Types of Generators
There’s actually a ton of variety in the way generators are designed and sized. Different people have different requirements, and there is almost always a generator that fits your specific needs. Based on physical size and mobility, we can categorize generators as either portable or stationary. And we can further break down each category on the basis of fuel type, the method by which they generate electricity, feature set, etc. Sometimes, people will designate classes to generators based on the type of work they’re good at- recreation (RV generators), emergency backup (standby generators), work (jobsite generators), etc. Let’s take a look at the main types of generators-
A portable generator normally refers to an engine + alternator combination which generates anywhere from 1000 to 12000 watts, while also being small enough that a single person can move it around. Depending on the design and weight of the portable generator, it may or may not have mobility wheels or folding handles. Apart from the engine and alternator, a portable generator also contains some type of fuel system and a starting mechanism (pull cord/ electric). Portable generators are used for home backup, in RVs, and on jobsites.
Conventional gasoline generator: The most commonly found style of generator, designed to run on gasoline only. All of the main components are easily accessible, since the tubular metal frame is exposed with no plastic enclosure like you’d find on an inverter generator. These types of generators are less efficient, louder, and produce approximated sine wave power which isn’t suitable for delicate electronics. But you’ll find them being used for emergency home backup, construction, outdoor events, etc. They use an AVR to regulate voltage.
Dual-fuel generator: Sometimes, gasoline is hard to obtain in the aftermath of a hurricane or other natural disaster. Gas stations will be inoperable since their pumps require electricity. But you’ll still be able to purchase propane tanks. Besides, propane is incredibly easy to store since it requires no fuel stabilizer. And on top of that, it also burns cleaner than gasoline which results in lower greenhouse gas emissions.
Natural gas generator: A lot of people have natural gas lines connected to their homes, which can be used as a supply of virtually unlimited generator fuel. Just like propane, natural gas burns cleaner than gasoline and natural gas generators can be relied upon during floods or hurricanes.
Propane generator: Propane generators run slightly quieter and cleaner compared to gasoline models. But they will require some initial setup in the form of plumbing and propane tank placement before you can actually use them. Propane tanks can range in size from the small 20lb ones that you use for barbecues, to giant 1000lb underground tanks which will power your generator for more than a week without requiring any refilling. Most consumer-grade propane generators are dual- fuel, meaning they can run on both gasoline and propane. Finally, propane generators require less maintenance compared to their gasoline-powered counterparts.
Tri-fuel generator: A generator that can operate on either one of these 3 fuels- gasoline, propane, natural gas. While some portable generators are tri-fuel, this type of fuel configuration is mostly found in standby generators. You can also purchase an aftermarket conversion kit to turn your open-frame gasoline generator into a tri-fuel compatible model.
Diesel generator: Mostly used in enterprise and commercial sectors. Diesel fuel has a higher energy content per unit volume compared to gas, and is more economical to use in large-scale applications. Diesel generators are perfect for any equipment that draws a lot of power and is intended to be run for long periods of time. They can operate for days, or even weeks, until main power is restored. Hospitals, data centers, water treatment plants, and military installations are powered by diesel generators. Cargo ships with diesel to electric drive-trains use diesel generators to supply the power for their giant electric motors.
Technically, inverter generators fall into the “portable” category since none of them are used as standby units/ commercial generators. But the way in which they generate AC power is so different from conventional portable generators, that we decided to give them their own category. Just like a conventional generator, inverters use an engine + alternator combo to create alternating current.
But instead of outputting this raw AC to an outlet, they first rectify it into low voltage DC power. Then, this low voltage DC is fed to an inverter module within the generator, which smooths out the irregularities within the electric signal to generate a pure sine wave AC output. This AC current is comparable in quality to what you get from the wall outlet, and is perfectly safe for delicate electronics like computers, phones, smart TVs, etc.
Gasoline-powered : Similar to conventional open-frame gasoline generators, except the power is much cleaner. These range in capacity from 800 to 3500 watts (running wattage). The shell is typically made from plastic/ composite materials, while sound deadening foam on the inside keeps noise levels low. Most inverter generators are compliant with both EPA and CARB standards, so they can be operated in all 50 U.S. states.
Bi-fuel: Inverter generator models that can be powered with either gasoline or propane. The Champion 100263 3400-watt generator is a nice example, it allows you to conveniently switch between fuel type using a selector dial.
Hybrid: A term that’s used when referring to an open-frame inverter generator. These portable generators cost less than true inverters, but more than conventional gasoline- powered models. They blend the ruggedness and affordability of conventional models with the quiet, clean nature of inverters. Basically, it is an open-frame generator with inverter circuitry added on top, so the AC power is much cleaner. They usually have 5V USB or 12V DC outlets on board, and support parallel operation. The Westinghouse iGen4200 is an example of a hybrid gas-powered portable generator.
Sometimes, you just need to power an entire array of circuits instead of just a few appliances. And, you need that backup power to turn on automatically when the mains go down. That’s where standby generators come in- these stationary units are very similar in principle to conventional portable generators, but they are much larger (both physically and in terms of wattage capacity). Also, they will automatically turn on with just seconds after an outage. Specially designed weather-resistant enclosures protect them from rain and snow, while internal sound deadening materials keep noise levels lower than portable generators. And, they are hooked up to your home with a transfer switch.
Special types of generators
To be perfectly clear, there is no such thing as an “indoor generator”. Because any generator with an internal combustion engine that consumes petroleum-based fuels will emit dangerous exhaust gases such as carbon monoxide. These gases are fatal to humans in large enough dosage, which is why homeowners often install CO monitors inside the house. You should never use your portable generator INSIDE the house, basement, or garage. But you can purchase rechargeable power banks which hook up to a solar panel array installed on the rooftop. Essentially, you’re “generating” electricity from solar power. It is 100% eco-friendly, noiseless, and relatively easy to install. Indoor generators won’t power your whole home, but they can be used for tailgate parties and camping.
Solar generators: Perfect for people who are trying to switch over their homes to renewable energy. There are solar generator kits which contain solar panels, rechargeable lead- acid/ lithium ion batteries, and a wheeled cart for portability. Most of them also include an inverter, usually the battery and inverter are combined into one package with digital displays for showing crucial data like voltage, amps, runtime, etc. These can be used indoors, and are safe for powering delicate electronics. The Goal Zero Yeti 400 Lithium is a good example, it can supply 300w of continuous power and 1200w of surge power.
Hydraulic generators: A type of PTO (power take off) generator used in commercial applications. It replaces the big bulky diesel engine, with a much more compact and virtually noiseless hydraulic pump that requires far less maintenance in comparison. A PTO system is bolted onto the transmission of a vehicle, which may be a truck or tractor. This PTO drives the hydraulic pump, which sends hydraulic fluid through pipes to the alternator which may be located anywhere on the vehicle’s chassis- engine housings, compartments, slide out trays, etc.
Generators — sorted by application
Emergency generator: Typically a standby generator that is powered by diesel or propane, but it can also be a portable generator that uses gasoline. Depending on your requirements, it can be a 5kW, 10kW, or even a 20kW model. The most basic emergency backup generators are intended to power essential equipment like lights, refrigerators, sump pumps, etc. when a storm/ flood knocks out the grid. Larger and more expensive models will turn on automatically when the transfer switch detects that mains power is out.
RV generator: Used to power the air conditioner and other essential equipment inside an RV or mobile home. Should have at least 3000 starting watts and 2000 running watts for a 13.5k BTU RV air conditioner. For a 15k BTU air conditioner, you’ll need a portable generator with 3500 starting watts and 2000 to 2500 running watts. Can also power the electric stove, lights, refrigerator, TV, etc. in an RV. Generators that are designed for RVs will feature a twist locking 30amp outlet, the TT-30R.
Camping generator: Designed to be silent, since most camping grounds have noise limits stated in decibels. Camping generators are usually inverter models, since the total wattage requirements for camping are relatively modest. You’ll be powering equipment like a mini-fridge, lights, phone, laptop, battery charger, etc. Portability and fuel efficiency are more important, and you might want to look for features like USB outlets, electric start, etc.
Jobsite generator: Designed to be rugged, with lots of power for starting and running heavy-duty electrical tools such as table saws and jackhammers. An entry-level jobsite generator will have at least 3500 to 4000 watts of continuous power output, with around 4200 to 5000 watts of starting power. These are generally conventional open-frame type designs, because pure sine wave power isn’t a necessity when you want to rip through steel pipes with a circular saw. Instead, the focus is placed on delivering tons of power through multiple 120 and 240V outlets. Outlets are shielded from rain and dust with snap-fit rubber covers, and feature GFCI protection to keep you safe. Larger jobsite generators also come with electric start, and a crane hook on top of the frame.
If you’re operating a generator, you have to deal with noise. Most portable generators, especially the open-frame gasoline powered models, will make upwards of 75dB. That can be quite annoying, even from a distance of 20 or 30 feet. It isn’t a pleasant experience for others, which is why camping grounds and national parks usually place a 60dB (measured from 50 feet) noise limit during the day. And you can’t even operate a generator during nighttime in some localities. People take various measures to quite down their generators- building sound walls around it, upgrading the muffler, reducing vibration by installing additional padding between the engine and frame, etc. The easiest way to do it is by purchasing a quiet inverter generator like the Honda EU2200i or Generac GP2200i.
Deciding between portable and standby generators
Depending on where you live and your wattage requirements, there are two types of generators to choose from when you want to power your home during an outage :
Portable generators are smaller, mobile units which can be pushed around by hand. They generate anywhere from 1000 to 10000 watts (continuous), and the engine is normally powered by gasoline although dual-fuel and tri-fuel options like the Pramac WGCT7500 are available. Standby generators are installed by licensed contractors who will make sure your installation complies with all local building and electrical codes. These generator units are larger, and have their own weather-resistant aluminum alloy/ composite enclosures.
They connect to your home with a transfer switch, which allows them to safely power multiple appliances without backfeeding into the electrical lines on the street. They also cost more, but are capable of powering your entire house.
So which one is right for you? Here’s a list of the pros and cons for both types of generators. Decide based on your specific needs.
Pros — Portable generators
- Cheaper, a typical 5000 watt open-frame model will cost you under 1000 bucks. And it requires no professional installation (except for the transfer switch).
- Can be moved around, so you can use the same generator to power your home appliances, RV air conditioner, jobsite tools, or a battery charger at your camping site.
- Maintenance is easier and cheaper, compared to a standby generator.
Cons — Portable generator
- You will have to go through a lot more hassle to power your appliances with one of these- refueling, hooking up extension cords to individual appliances, walking outside to start the generator every time the power goes out, etc.
- Unless you have got an extremely large model like the DuroMax XP12000EH, a portable generator will only power certain appliances. Not the whole house.
- You’ll need to install a transfer switch for your portable generator if you intend to power hardwired appliances with it, and it will keep the linesmen/ emergency responders safe.
- Can’t be turned on unless you’re in the house, which is a huge problem if you’ve got a basement that floods when the sump pump isn’t running.
Pros — Standby generator
- These will power your entire house, since the higher end models generate upwards of 20kW (enough for a 5000 sq. Ft home).
- Standby models use self-feeding fuel sources such as propane and natural gas, so you won’t have to bother with constant refueling.
- They turn on automatically within seconds of an outage, which is crucial if you’ve got any medical equipment in the house that needs to stay running.
- Since they turn on automatically with input from the transfer switch, you don’t have to be at home to prevent your basement from flooding. And, they will automatically turn off when mains power is restored.
- All standby units are connected to your home with a transfer switch, so there’s zero chances of a linesman getting electrocuted through backfeeding.
- You can power hardwired appliances (permanent electrical circuits which don’t use plugs) such as dishwashers, water heaters, cooktops, lights, etc.
- You get clean sine wave power which is 100% safe for delicate electronics appliances.
- Despite their size, they are actually much quieter than portable generators thanks to the sound- deadening enclosure and larger mufflers.
Cons — Standby generator cons
- Much more expensive than a portable generator. For instance, this Generac 7032 (11Kw) standby unit costs over 2000 dollars (50amp transfer switch and installation included).
- Maintenance doesn’t have to be done as frequently, but when needed, it is recommended that you hire a professional.
- Since standby generators are stationary, they can only be used for powering stuff that is connected to the transfer switch. For anything that isn’t included in your home circuit, you’ll need a portable genset.
Homeowner generators, or residential-grade models are designed to be used by the average Joe for powering common appliances at home like the TV, washing machine, refrigerator, etc. They aren’t built to be rugged, or operated for 10 hours without refueling. The engine and air filters aren’t designed for prolonged heavy-load usage, like you would need on a jobsite. And the size is fairly compact, so even your 60- year old dad or mom can push these around. Hollow axles, unprotected outlets, plastic shells, and basic air filters are common features on most residential generators. The power generally ranges from 1000 to 8000 watts.
Unlike homeowners who sporadically use their generators for powering home appliances during emergencies, jobsite generators are used on a regular basis for running tools in harsh environments. There’s a lot of dust, falling debris, and rough terrain for these generators to deal with. Which is why, they are built to be extremely rugged and only contain the essential features. If you’re looking for USB outlets or fancy digital displays, this isn’t the type for you. And don’t expect to find any inverter generators here, since clean sine-wave AC power isn’t a necessity for powering drills or chainsaws.
Features: Lifting eyes, hour meters, GFCI protected outlets, etc. are features you expect to find on serious jobsite generators. They are also capable of outputting a lot more power, for example- the Generac GP17500E packs enough juice to run an entire crew. It has low oil shutdown, idle speed control, and multiple 30amp outlets (including a 240V).
Quality: Solid steel axles, heavy duty air filters, commercial grade engines, thick tubular steel cradles, anti-corrosion powder coating, etc. are included on jobsite generators to make them far more durable than the average residential model.
Sizes, uses, and cost range
Say you’re planning to purchase a generator for emergency backup power during a hurricane or flood, how much money should you expect to spend? And how many watts will you get for your money? We’ll discuss generator sizing and how to decide which model is best for you in the next section, but for now let’s take a look at some of the most common generator sizes and how much they will cost you. Plus, we included a short list of items you can power within each range.
1000 to 1999 watts
Here, you’ll find a bunch of inverter generators from companies like Honda, Generac, and WEN. These units are designed for recreational applications like camping and fishing. Take the Generac iQ2000 for example — it is lightweight, portable, and provides clean sine wave power for all your sensitive electronics.
With 1000 to 2000 watts, you can appliances like the following- refrigerator, microwave oven, coffee maker, toaster, radio, TV, and computer. An inverter generator in the 1000 to 2000 watt range will cost you around 500 bucks. Looking for something cheaper? Check out open-frame gasoline generators like the Firman P01201 which provides 1500 starting watts and 1200 running watts. It costs less than half of most inverter generators in this power range.
2000 to 3999 watts
Now, we’re stepping into the realm of high-end inverters and entry- level open frame models. You can power crucial home appliances like sump pumps and refrigerators during an outage with these. Most open- frame generators in this power range will cost you around 250 to 400 dollars. Inverters like the Honda EU3000iS fall a bit higher on the price spectrum, and you can buy 2 to 3 portable open-frame gasoline generators for the price of one EU3000iS, if you really don’t care about true sine wave power or super quiet operation. With 2 to 4 kilo watts of power, you’ll be able to run 10k BTU air conditioners, 1/2hp sump pumps, dishwashers, and tabletop electric grills.
4000 to 5999 watts
Generators in this range are intended for emergency home backup, and RVs. Inverters don’t normally generate over 4kW of power, unless we’re talking about open-frame hybrids like the Westinghouse iGen4200. But you can hook up two inverters in parallel to generate twice the power. Most of the generators in the 4 to 6 kilo watt range are going to be open-frame models designed for the jobsite and home backup. They’ll include 30amp RV outlets, and are likely to be transfer switch compatible. Expect to pay anywhere from 350 to 1000 dollars for a generator in this power range. You’ll be able to run items such as 15k BTU RV air conditioners, water heaters, pressure washers, electric ranges, etc.
6000 to 7999 watts
Now we’re getting into high-end residential generator territory, and you’ll even find some jobsite units in this range. Expect to pay anywhere from 800 to 1000+ dollars for a well-built genset from reputable companies like Champion or Westinghouse. The Westinghouse WGen 7500 is a great example — it features electric start and is transfer switch ready, so you can power your home with it. Portable generators in the 6 to 8 kW range have large fuel tanks, and some of them even support bi-fuel operation so you can hook up propane tanks. With this much power, you can run 4 to 5 home circuits via a transfer switch, and power pretty much any tool at the jobsite. Hot water heaters, garage door openers, electric clothes dryers- these generators will handle everything.
8000 to 9999 watts
If you want to power a portion of your home or run a whole crew at the jobsite, you are looking for something in the 8 to 10 kW range. While a standby generator would be a better choice for home backup, you can get away with a portable model if you prefer to have more versatility instead. Most of the generators in this range are designed for home back or industrial applications. They can be used to run high demand residential items such as electric clothes dryers, or heavy duty tools on the jobsite like concrete vibrators. Expect to pay upwards of 1000 dollars for a good industrial grade 8kW generator such as the CRAFTSMAN CMXGGAS030791. Farmers on the ranch can use one of these to run a 60amp battery charger or milking machine.
10000 to 15999 watts
These are for people who want the power of an entry-level home standby model, but don’t want to pay for professional installation and need the mobility of a portable genset. You can run multiple high power draw appliances in your home at the same time with a generator in the 10 to 16 kilo watt range. With 16kW of power, you can run a 2-ton split AC, electric clothes dryer, 20 cubic foot refrigerator, coffee machine, and dishwasher- all the same time! Expect to pay upwards of 1200 dollars for a generator in the 10 to 16kW range.
16000 watts and higher
Most of the generators in this range are home standby/ commercial units, i.e. non- portable models. They will run on propane or natural gas, and connect to your home through automatic transfer switches. With over 16 kilo watts of power, you can run almost every appliance in a 3000 square foot house. There is only one portable generator you can buy, if you need this much power on the go- a Generac GP17500E.
What Size Generator Do You Need?
How to size your generator/ understanding power requirements
Make a list of all the items you need to power simultaneously during an outage. Don’t throw everything in there, unless you intend to purchase a home standby generator. If you’re going after a portable model, only include the essential items in your list- sump pump, TV, fridge, lights, air conditioning, heating, etc.
Continuous vs Surge watts
There are two types of power ratings you need to consider- starting, and running. Starting wattage is the power drawn by an appliance for a short burst of time during startup, it is usually 50 to 200 percent more than the running wattage. Any appliance with a motor or compressor has starting wattage that’s higher than its running wattage- refrigerators, air compressors, ACs, etc. For appliances that don’t have motors or “reactive loads”, the starting wattage will be the same as running wattage. Take the appliance with the highest starting wattage in your list, and make sure your generator has enough “surge power” to get it going.
In an ideal world, your 1000-watt microwave oven would draw exactly 1000 watts of power. But it doesn’t, because conductors have electrical resistance. The power rating on your microwaves or hair dryer refers to the amount of heat energy it puts out, not how much it draws from the wall. Same goes for your computer- just because it’s using 300 watts according to software, doesn’t mean the actual power draw from your wall is 300 watts. It could be closer to 330, depending on the efficiency of your computer’s power supply. If you want to measure how much power an appliance draws at the plug, get an . Or check out the manufacturer’s spec sheet for efficiency ratings.
Recommended generator brands
Jobsite: You can’t go wrong with Honda generators for the jobsite. On the lower end, you’ve got OSHA- approved models like the Honda EB2800i with GFCI protection and commercial- grade OHV engines. Move it up a notch, and there’s the Honda EB6500 with 7000 watts of surge power and a USDA approved muffler/ spark arrestor.
Look for jobsite generators with features like welded steel frames, solid steel axles, auto-oil shutdown, etc. CAT, Champion, and DuroMax make some of the best jobsite/ industrial generators.
Consumer: Generac, Westinghouse, and Ryobi make great inverter generators for camping, tailgating, and emergency home backup. With consumer generators you are looking for portability, low noise, and convenience. Features such as remote start, digital displays, USB ports, parallel operation, and RV outlets are highly desirable in residential generators.
A generator is just like your car- it requires timely maintenance to keep running optimally. If you think you’re going to save money by not replacing that air filter or spark plug, think again. Because it will end up costing you in the long run, and a small 20 dollar purchase today can end up saving hundreds of dollars down the line. If your generator runs on propane or natural gas, it won’t require as much maintenance because these fuels don’t gum up the lines and burn much cleaner. Are you storing a bunch of gasoline in preparation for that hurricane? Make sure you’ve added fuel stabilizer, and only use containers approved for fuel storage.
Sometimes, you might run into issues with your generator. It may not start, the engine might sound weird, or you might not be getting any voltage from the outlets. Depending on the type of fuel your generator uses (diesel, gas, propane), the causes for these issues can vary greatly. They may or may not be related to improper maintenance, and you might require professional help to get them fixed. But there are a few checks you can make before starting your generator. Is the battery dead? Is there enough engine oil? Did the breakers trip last time you were using the generator? It can be easy to forget basic starting and maintenance procedures, so do practice runs with your generator at least once or twice every year.