This is hand written by owner Austin Belcik. This is strictly my own opinion based on my schooling & my own experiences
Choosing the right products - Generators - Solar products - home Batteries - Car Charging - lighting
WHY ARE THEY SO IMPORTANT?
- Generators are used in a very wide range of applications. From big diesel generators the size of a tractor trailers that supply healthcare facilities, to small lawnmower size propane generators that power your house with during an outage. These can be good for a simple peace of mind during harsh weather or running 24/7 important life critical equipment. Either way its important that the generator you are choosing is right for your application.
ARE ALL GENERATORS THE SAME?
There are lots of different types of generators specifically designed for the application at hand. The most simple way to differentiate these generators is by looking at SIZE (KW rating) or whether they are ( Portable, Standby, Primepower, Air-cooled, Liquid-cooled, Diesel, Propane, Gasoline, Natural gas, Residential, Commercial, or Marine ).
SIZING YOUR GENERATOR (KW)
KW stands for Kilo-Watt. And it means just like it sounds, kilo as in thousand and watt meaning the amount of power it can produce. 20kw meaning "twenty thousand watts". This is your typical "whole house" residential generator. Ohms law says if you divide watts by volts you get amps. ( 20,000 / 240 = 83.33 amps ). a 20kw generator will produce around 80 amps roughly before it starts to have issues. This also takes a lot of other things into consideration such as heat and horsepower. If the generator is working hard for a long period of time on a hot summer day it won't be able to produce as many amps as it could on a cold winter day. So us New England electricians try to size your generator based on your needs the best we can at 80% load. Meaning we want this particular generator at 80% capacity to produce an average of 80-(80/10*2) = 62amps at (80%). This way there is wiggle room incase you want to turn on a couple extra light bulbs or appliances without any issues. There are also several products on the market that help with sizing issues, us electricians call them "load sheds" for a broad term because each manufacturer calls them something different. What they are is exactly what it sounds like, "a device that sheds the load". Meaning power is out, your hot tub kicks on, youre cooking that thanksgiving turkey dinner, and the main breaker trips. now you have zero power because the generator couldn't handle all that. A load shed module goes in middle of this scenario, right before the generator is about to trip it will disconnect the least important circuit. (The priority of loosing your hot tub before your stove is chosen with your electrician during the installation). This module also allows you to install a much smaller generator if you don't mind that only half the house working when the power is out.
HEAT / COOLING / PRIME POWER
First lets talk about heat. All generators big and small generate a very large amount of heat. This can cause damage to internal parts of a generator very quickly if it is not kept at a cool operating temperature. The most common generator that people think of is the residential back up generator & these are typically air-cooled. This means that the engine running the generator uses the outdoor ambient air to cycle through the enclosure to keep all the moving parts from overheating. These are more cost effective for residential applications.
Most common sizes that generator companies make range from a portable 6.5kw to a stationary 35kw. You can also get into the bigger generators and these are typically made by heavy equipment companies such as CAT and JOHNDEERE. These generators can be rated for extremely high amounts of power but we are not going to get into that on this page.
The most common & smallest liquid cooled generator on the market is a 20kw. Don't get confused though, they also make an air-cooled 20kw as well. The difference is - One is a 4cylinder car engine that is water cooled with a very quiet exhaust, compared to your typical some-what noisy, small engine and air-cooled residential back - up generator. These are 8-10 grand different in price. (liquid cooled being more expensive). This is because these generators are typically producing much more power than what you would need at your home. More power, equals more heat, which calls for a stronger cooling system. More power also equals more money. I am writing this article in 2022 and currently a "20kw air-cooled" Kohler generator is right around 6000 dollars. This same generated power from a "20kw liquid-cooled" is closer to 15,000 dollars.
One other difference that you might come across is the term "prime power". This is a rating that refers to a generator that is designed to run 2000/hours per year. The normal term is "standby" which is designed to run 200/hours per year. So nine times out of ten Jonny homeowner takes a gamble on Mother Nature and saves himself 10grand by going with an air-cooled propane generator.
TYPES OF FUEL The most common Fuels generators run on are, Gasoline, Natural Gas / Propane, and Diesel. Not to often do you see a stand by generator running on gasoline. A lot of people use gasoline portable generators to run their home during an outage but by no means is this a "stand-by" generator. These are made to run on gasoline because its portable and that's an easy fuel to find right at the pump. In my own opinion gasoline is a horrible fuel for generators to run on due to gel up issues / bad fuel etc. Gasoline doesn't like to sit. If your stand by generator ran once a week for 10 minutes and 53 weeks out of the year you will still be on the same tank of gasoline most likely. a year later that gas will start to go bad, and sure they make stable and everything else to help prevent gel but when choosing a generator in my own opinion I would choose a vapor over a liquid. Such as the Natural gas / propane powered. Most standby generators run on both natural gas and propane, which gets chosen at the time of the installation. most home owners go with this style fuel. For one, propane doesn't ever go bad. For two its a vapor, and a with vapors nothing has to be cleaned internally to guarantee a reliable start up when Mother Nature is at her worst. Also conveniently most households have propane or natural gas that you can tie the generator into so your fuel company keeps it filled. Most gasoline / propane / natural gas generators are 9 times out of 10 air cooled engines which range up to 20kw in most cases. When you get into generators larger than 20kw you will start to see most companies switching to Diesel engines due to the horsepower needed to make that amount of power. Like we talked about earlier more power equals more heat, these generators that produce higher KW ratings are mostly liquid cooled.
- Marine / Military use
These generators are more rare and you don't see a whole lot of them. they are self excited & liquid cooled. Fueled by diesel and installed with no muffler. These generators are what we call DC compound generators. These are very simple generators & they have less moving parts internally. Unfortunately the power output is not consistent but the thing is, is that they are very reliable. These are used in applications where you want to have less problems out on the ocean or when you're somewhere with limited tools in case of a breakdown. These generators are designed to run induction powered appliances only. This is because they are not voltage sensitive like most household appliances. This particular generator will ruin TVs & anything computer driven if you were to run your house on one of these generators. ((((This is why its critical when it comes to buying the right generator))))). These are also designed with a closed loop coolant system. This is to avoid the internals corroding because they use sea water to cool the engine. Along with the exhaust as well its designed to exhaust into the ocean keeping it quiet. These are not designed to be "back-up" generators.