- Things to consider before buying
- The Main Power Generator Types
- Categories by Size
- Categories by Power Source
- Categories by Technology
When shopping for a generator, you shouldn’t just concentrate on size and aesthetics. Although those are important considerations, too, it also helps to choose the right type of generator. Why? There are a couple of reasons;
1. Local building codes
Depending on your location, you may not even be allowed to install specific types of generators in the first place. For instance, some areas, especially those prone to earthquakes, tightly regulate natural gas regulator installations.
2. Fuel accessibility
Even if the codes allow the desired type of generator, you must ask whether you can easily access the generator’s fuel within your location. Natural gas is an excellent example here too. If your area doesn’t have natural gas lines, it would be a waste of time purchasing a natural gas generator.
3. Upfront costs
The type of power generator you purchase directly impacts the upfront costs, i.e., purchase price + installation costs. Advanced-technology generators will always cost more to purchase. And, if it requires professional installation, then you need to prepare several hundred dollars more. Indeed, some generator installations can cost up to $2,000.
4. Running costs
Besides upfront costs, you must also think about the cost to run your generator. Take an example of the highly efficient yet very costly to run hydrogen generators. It costs up to $6 to generate a kilowatt of electricity with a hydrogen generator. For context, the average cost of grid electricity in the US is $0.13/kW. Can you comfortably afford the extra budget?
The Main Power Generator Types
Categories by Purpose
The first way we can categorize power generators is by purpose. Yes, all generators are designed to provide electric power in the absence of alternative sources, specifically when grid power is out or unavailable. However, for which application was the generator specifically designed.
1. Standby Generators
Standby generators are large generators designed to power the entire house or office. They can run nonstop for days, generating enough power to run every appliance, device, and application in the intended building.
However, the most identifying characteristic of standby generators is automatic load switching. Unlike standard generators that you must switch on manually to start, the standby generator comes on automatically when there’s a power outage, thanks to a unique switch known as the Automatic Transfer Switch (ATS).
Standby generators are wired to the home’s electric power system such that they can transfer power directly to your home outlets, lights, and devices. When there’s a power outage, microcontrollers on the standby generator detect the outage and automatically engage the generator, instructing the ATS to transfer the home’s entire circuitry from the grid network to the generator. The entire process happens almost instantaneously.
The reverse is true when grid power returns. The ATS switch will transfer power from the generator to the grid circuitry and safely shut down the generator.
Due to the intended applications, standby generators are large units, with some rated as much as 25,000 watts. They’re typically permanently installed.
- Automatic power resumption
- Whole-home support
- Long warranties
- Expensive to purchase and install
- Costly to run
2. Backup Generators
Backup generators and standby generators are almost the same things. In fact, many standby generators are backup generators, and many standby units can be used for standby applications.
However, the two categories differ in a couple of ways. For one, as we’ve seen, an automatic transfer switch (ATS) is standard on standby generators. This isn’t the case for backup generators. While some have the ATS feature, the majority don’t. Secondly, backup generators aren’t always wired to the home’s circuitry. Some are, others aren’t.
Another major difference is size. Standby generators are typically large generators, ranging from 9,000 watts to 25,000+ watts. Although many backup generators are also relatively large, you’ll regularly come across backup units rated as low as 5,000 watts.
So, a great way to look at backup generators is a crossbreed between standby and portable generators. They borrow features from both categories.
The “confusion” doesn’t necessarily have to be a bad thing, though. For instance, backup generators can be invaluable in commercial applications where a portable but potent power solution is needed, such as a construction site. They can also provide a flexible solution to use between major home applications, such as powering the garage, barn, and woodhouse as the need arises.
- They’re a potent power source
- Incredibly versatile
- Are typically mobile
- Bulky, thus challenging to move
- It can be expensive to purchase
3. Camping, Fishing, and RV Generators
Finally, some generators are designed for specific tasks, such as fishing, boating, recreational vehicles, and camping. This doesn’t necessarily mean that you can’t deploy the said generators in other applications. However, the units are often fine-tuned for the target applications thus may not perform as well in other applications.
For instance, if you’re a camping enthusiast, you may choose to purchase a generator specially designed for camping. These units are typically more rugged and durable to withstand the harsh conditions of the wilderness. They may also have longer run times, so you don’t run out of fuel/energy in the middle of the trip.
Fishing enthusiasts may also benefit more from generators explicitly designed with anglers in mind. Among other things, fishing generator manufacturers try to make the units even safer to prevent accidental fuel spills and potential fires on the boat. The generator may also be more compact than standard generators for easier handling. Some are even waterproof to a degree to protect them from water spills.
Finally, RV generators are generally powerful enough to run the entire RV. However, caution is made to make them as quiet as possible, so they don’t make life unlivable inside the RV. They are also typically the most aesthetically sound units among power generally as they need to blend with the rest of the RV décor and even uplift the space.
- Fit for purpose
- Offer greater value for money
- Easy handling and DIY maintenance
- May function poorly in other applications
Categories by Size
Besides purpose, we can also categorize generators based on size, i.e., wattage, weight, and physical dimensions. The two main categories here, excluding industrial generators, are portable and whole-home generators.
1. Portable Generators
As the name suggests, portable generators are generators that you can move from one point to another without significant effort. They are lightweight enough to carry and compact enough to fit multiple applications.
However, the level of portability varies. For instance, whereas some generators are small and compact enough to carry around even in your travel bag, others are impossible to fit in a regular travel bag. A small portable generator for boating, for instance, can be the size of a standard car battery, weighing under 60lbs. Meanwhile, portable backup batteries are as big as a regular municipal garbage can and weigh 150lbs.
Don’t miss: Portable generators buying guide
So, whereas the smaller generator may have an ergonomic handle to carry the generator easily, larger models typically have wheels instead. Since you may not carry the unit over a long distance, wheels provide a more practical way to ensure mobility.
It’s worth noting that portable generators vary widely in size. The smallest units are under 1,000 watts, while the largest models provide more than 12,000 watts.
- Easy to move about
- Extremely versatile
- Highly convenient
- Not all are easily portable
2. Whole-Home Generators
Whole-home generators are large-size generators designed to power the entire home. Standby generators are some of the best examples. They have the power generation capacity to keep every electric-powered item in the home running.
It’s a quality that makes whole-home generators excellent for standby and backup power supply. You can even wire the generator to the home’s circuitry and integrate an ATS to the connection so that the generator automatically transfers the home’s circuitry to the generator when there’s a grid failure.
Whole-home generators are characterized by high power ratings and large physical size. The smallest units are about 9,000 watts, typically backup power systems. Meanwhile, the biggest units provide up to 50,000+ watts per hour. That’s enough to power all electrical appliances and devices in any medium-sized home.
Physical sizes vary from one model to the next. However, the majority are too bulky to move from one location to the next – even on wheels. For instance, a standard standby generator weighs over 400lbs and can be as big as four regular refrigerators placed side by side.
Whole-home generators operate on different fuels, from natural gas to propane and even hydrogen. However, most standby whole-home generators operate on natural gas as it’s more affordable in the long run.
- Serve the entire home
- It can come on automatically with ATS
- Minimal maintenance owing to less movement
- Can be expensive
- Zero mobility means limited flexibility
Categories by Power Source
1. Fossil Fuel Generators
Let’s start with the most common category – fossil fuel generators. Fossil fuels are fuels derived from the remains of decomposing plants and animals. The fuels are found in the earth’s crust and contain two primary ingredients – carbon and hydrogen – partly explaining why they’re also sometimes called hydrocarbon fuels. The five main categories of hydrocarbon fuels used in generators are as follows;
2. Gasoline Generators
Gasoline generators run on gasoline, the most widely used hydrocarbon fuel. Also known as petrol outside the US, gasoline is a transparent petroleum-derived flammable liquid used in most spark-ignition engines.
Gasoline generators are some of the most common, especially among portable units. For instance, if shopping for a camping generator, about 70% of the options you’ll come across are gasoline generators. The main advantage of gas engines and, by extension, gas generators is that they’re lighter than all other fossil fuel alternatives. This is the main reason it’s the most common fuel among portable generators.
That said, though, gasoline generators are available in a wide range of sizes. The smallest units are portable boating generators rated at 1,000 watts or lower, while the biggest models are whole-house standby generators with capacities exceeding 50,000 watts. Gasoline generators also come in various styles and may be designed for specific applications.
Remember that gas generators have a built-in tank that you must continuously refill to keep the engine running. The tank sizes start from around ½ gallon to more than 50 gallons and can often indicate the targeted application. Users are encouraged to take excellent care of the tank and the generators.
- Gasoline is affordable
- It burns cleanly
- It’s the most widely available fossil fuel
- Low energy output per unit volume
- It has a short shelf life
3. Diesel Generators
Gas and diesel are both liquid fuels. In fact, they’re the two most common liquid fossil fuels used in engines and generators.
However, the two aren’t exactly the same. Diesel fuel is a little heavier than gas and has a higher energy value. This means that a gallon of diesel gives off more energy than a gallon of gas. You might have experienced this fact if you’ve used both engines in the past. A gallon of diesel will take you further than a gallon of gas. Diesel is also more stable and less flammable than gas.
Unfortunately, diesel is also a little pricier than gas in many locations. The high price is directly related to the greater energy potential per unit volume.
However, the most important thing you must know about diesel generators is that they only operate on diesel engines. A diesel engine cannot operate on a gas engine and vice versa. Whereas diesel units operate on compression ignition (CI), gas generators operate on spark ignition (SI) engines.
Diesel generators exist in all sizes and styles. They are also found in nearly every applicable scenario, from portable units to whole-home standby systems.
- Higher energy output per gallon
- More stable than gas
- It suits bigger applications better
- It has a long shelf life
- More expensive than gas
- The engine is more complex
4. Natural Gas Generators
Besides liquid fuels, generators can also operate on petroleum gases, with natural gas being the most common.
Natural gas is a product of crude oil. It’s typically supplied to homes and premises via underground pipes. The homeowner can then tap the gas and use it for cooking, heating, and other purposes. You can also use it on your generator.
Running your generator on natural gas isn’t any different from using the fuel for cooking. All you need to do is connect the generator to the gas supply outlet, and you’re ready to go. However, this process is strictly left to licensed professionals. Handling natural gas connections without a valid license can land you in jail.
The permanency of natural gas lines makes it a popular fuel among homeowners who wish to install a standby system. A permanently installed standby generator supplied by a permanent natural gas line makes the perfect combination. However, this doesn’t mean that you won’t find portable natural gas generators. Some brands even make natural gas generators for campers.
Natural gas generators operate on spark ignition (SI) internal combustion engines and are energy-efficient.
- Burns cleanly
- It’s energy-efficient
- Perfect for standby generators
- Availability can be a concern
- NG prices are on an uptrend
5. Propane Generators
The other common petroleum gas used in generators is propane. Propane is a colorless, odorless gas, just like natural gas. However, manufacturers usually add a harmless chemical known as mercaptan to give it the distinctive “rotten egg” smell for safety reasons. Additionally, the gas is supplied in a liquified form under high pressure.
However, unlike natural gas supplied via underground lines, propane is supplied in metal cans of various sizes. So, you can purchase a small 2-gallon can for fishing and a 50-gallon tank for the backup generator. It depends on your needs.
The main advantage of propane over natural gas is the higher power potential. Propane produces more heat per unit volume, which means that the same volume of propane will give you more electrical power output than an equal volume of natural gas.
Propane is also more available than natural gas. Check around the neighborhood, and you’ll rarely miss a few vendors selling propane cylinders. However, the same cannot be said about natural gas, whose availability depends on whether you have company supply lines in your area.
- Greater energy output than natural gas
- More readily available
- A long shelf life
- More expensive than natural gas
- What happens when the cylinder runs dry?
6. Solar Generators
Besides fossil fuel generators, solar-powered models are the next most common. A solar-powered generator harnesses the sun’s solar radiation to recharge a battery which provides power to run the generator.
It’s an entirely different process from fossil fuel generators. Solar generators use solar cells that can trap solar radiation. A solar cell is an electronic device made from silicon, though second-generation solar cells can be made from amorphous silicon or non-silicon material such as cadmium telluride. The standard solar cell is essentially a sandwich of n-type silicon (blue) and p-type silicon (red). It works by making electrons hop across the junction between the different flavors of silicon.
It’s a slightly more complicated process. However, the “jumping” electrons eventually generate an electric field. If you connect the n-type layer to the p-type layer, the free electrons will ultimately flow through the wire as they travel across the two layers, creating an electric current.
The electric current then flows to a rechargeable battery where a series of chemical processes ensure, resulting in charge storage. This charge is readily available from the anode (positively charged electrode) of the battery.
Recently, solar generators have become very popular in the domestic market as a cost-saving alternative to fossil fuel and grid power.
- Solar offers very clean energy
- It’s a renewable energy source
- Very reliable in sunny climates
- Little maintenance
- Batteries take a long time to recharge fully
- The high upfront costs can be off-putting
- Highly dependent on the climate
7. Wind-powered Generators
Speaking of clean, renewable energy sources, wind power is another excellent alternative. Wind-powered generators have a wind turbine that turns propeller-like blades attached to a rotor. The spinning rotor, in turn, rotates the alternator in the generator that ultimately creates electricity.
The wind turbine operates like an airplane wing or helicopter rotor blade. When the wind blows across the attached blades, air pressure under the blade decreases, creating a pressure difference that results in “lift” and “drag” forces. However, the lift forces are typically stronger, thus causing the motor to spin.
Wind turbines can be either horizontal-axis or vertical-axis. Horizontal-axis turbines are what most people think of when they imagine a wind turbine. They typically comprise three blades that operate upwind. Meanwhile, vertical turbines, such as the egg-beater, are omnidirectional, thus don’t need to be adjusted to the direction of the wind.
As with other generator types, wind generators come in many sizes and can fit many purposes. However, the majority are found in commercial and industrial applications.
- Clean, renewable energy
- Little maintenance
- A long operating life
- High upfront costs
- Not every location has enough wind
Hydrogen power generators aren’t as common as the other generators we’ve discussed so far. In fact, very few households have or are thinking about installing a hydrogen generator right now. This is partly because of the novel technology that the wider public doesn’t yet understand. The extremely high cost of putting up a hydrogen generator is also an instant turnoff for many interested customers.
However, many people believe it’s the future of electric energy, alongside solar radiation. The abundance of hydrogen (water covers over 70% of the earth’s surface) and the fact it’s highly renewable makes it the perfect energy source. If the costs of installing and running a hydrogen unit drop, which looks likely, it may even replace gas in our homes.
Hydrogen generators first extract hydrogen atoms from various sources, especially water. This is known as electrolysis. Electrolysis produces two primary substances, i.e., oxygen and positively charged hydrogen ions. The positively charged ions are then directed through a circuit to generate an electron flow, also known as an electric current.
The process is pretty much the same in hydrogen generators that use fossil fuels in place of water. The generator begins by extracting hydrogen atoms from fossil fuel, often via steaming. Then the hydrogen atoms are directed through an electric circuit to create an electric current.
- It’s a clean, renewable fuel source
- Hydrogen generators are highly efficient
- It produces plenty of power
- Purchasing and installing hydrogen generators are expensive
- Running hydrogen generators is also expensive
9. Hand-Crank Generators
As the name suggests, hand crank generators are units that are cranked with the hand to produce electricity. They don’t use any fuel nor rely on weather elements such as the sun or wind. Instead, the user grasps a lever and rotates it many times to generate power.
So, what happens inside the generator to produce power? Well, hand crank generators use electric dynamos. Dynamos have a coil with magnets on each side. Rotating the generator lever causes the coils to rotate, which creates an electromagnetic field within the dynamo.
The magnetic field merely aligns charged electrons in the electric circuit passing through the dynamo, creating an electric circuit.
The biggest advantage of hand crank generators is that they don’t need an external fuel source – your arm is all you need. As such, you don’t have to worry about running out of fuel or the price of gas. Additionally, hand crank generators are typically compact enough to bring anywhere.
On the flip side, hand crank generators are impractical in many applications because of their low power output. Very hand-crank generators produce more than 300 watts per hour, barely enough to power a computer.
- No need for fuel
- Low-cost operation
- Extremely portable
- Limited power output
- Too manual
10. Multi-Fuel Generators
Finally, generators can also use more than one source of power or fuel. Such units are known as multi-fuel generators.
The best example is bi-fuel generators that operate on two different fuels. For instance, some generators use either propane or gasoline. Indeed, some are designed to operate on two fuels simultaneously. The best example here are units that start using propane and operate on natural gas. These units are known as dual-fuel systems.
Besides bi-fuel systems, you’ll also come across generators that operate on three different fuels. For instance, a single generator may use natural gas, propane, or natural gas. This allows the user to choose the most affordable option. It also means you always have options in case you run out of your preferred fuel.
However, multi-fuel units aren’t limited to bi-fuel, dual-fuel, and tri-fuel generators. For instance, some generators can use both fuel and solar. A few modern units can operate on solar during the day and gas at night. Some hand-crank generators also double up as solar-powered units during the day.
The beauty of multi-fuel generators is dependability. Even if you run out of the primary fuel source, you can turn to a different source. The flexibility can be invaluable, especially in areas with fuel availability challenges.
Unfortunately, multi-fuel generators are inherently more complex than single-fuel systems. For this reason, they can be more challenging for DIY installation and maintenance. If you confuse the fuels and pour diesel into a gas engine without proper improvisation, you might have just damaged the engine.
- Invaluable flexibility
- Applicable in a broader range of uses
- Greater complexity
- Make DIY challenging
Categories by Technology
Spark Ignition (SI) vs. Compressor Engine (CI) Generators
Let’s begin with SI vs. CI generators. Spark ignition generators, including gas, natural gas, and propane generators, use a spark plug to ignite the fuel. These generators mix fuel with the air outside the generator and inject the mixture into the combustion chamber, where it’s compressed up to a sixth of the original volume.
Compressing a fuel + air mixture so much raises the temperature of the mixture significantly. At a pre-defined level, the compressed mixture is hot enough to ignite a spark plug at the tip of the combustion chamber.
Meanwhile, compression ignition engines designed for diesel fuel don’t need a spark plug as the air is compressed to a temperature high enough for self-ignition when it comes in contact with diesel.
Diesel engines first draw air into the combustion chamber rather than introduce the fuel and air as a mixture. Then they compress the air up to 20:1, at which point the air is extremely hot. When the air is hot enough, a fuel injector at the tip of the combustion chamber sprays high-temperature diesel into the chamber, causing instant combustion.
In both gases, the combustion generates a significant pressure jump that pushes the engine piston down. The piston connects to the engine shaft via a metal rod. Thus, when the shaft moves down, it causes the attached engine shaft to turn.
Conventional vs. Inverter Generators
The raw electric current from your generator’s alternator is known as conventional or standard electricity.
Unfortunately, the conventional electric current is very unstable as it is highly “distorted.” You’ll commonly hear your technician saying it has a high THD (Total Harmonic Distortion). Harmonic distortion refers to unwanted variations in electric voltage and current frequency. It means that voltage and frequency output typically fluctuate widely.
This is dangerous because many household devices cannot withstand fluctuating voltage and frequencies. For example, radios, TVs, and laptops can malfunction when exposed to high-TDH current. Additionally, high THD tends to make generators noisier.
Inverter generators have a unique component known as the inverter that converts raw alternating current from the alternator into “cleaner” current with minimal distortion. So, whereas a standard generator may have a total harmonic distortion greater than 20%, a modern generator produces less than 3% THD.
Low TDH means cleaner power for your appliances and less noise output. But, more importantly, inverter generators can step down power output when you’re operating below full load, leading to fuel and energy savings and lower operating costs.
There you have it – all the power generator categories in one place. The wide range of options can make shopping a little daunting. However, you cannot understate the value of informed choice. It enables you to pick the perfect solution for your needs.