Electricity is something we all take for granted. Even though we use electric power all the time, very few people actually understand it. This is mostly because we cannot see it or touch it, electricity is an invisible force that’s always there when we need it. Unfortunately, it isn’t actually always there and power failures do occur. People living in areas where the weather, natural disasters, and high demand cause occasional blackouts or brownouts will know exactly what an inconvenience this can be. In some cases, we may find ourselves in a situation where there simply is no grid connection. Farmers and those who enjoy camping trips in the wilderness often want a portable power source to provide electricity where there is none.
If you find yourself in any of these situations, you’ll probably be considering getting a generator, either to back up your home or supply power for your camping needs or perhaps your business. This article is going to provide you with all the information you’ll need when deciding which generator is right for you. Whether you need a generator for home, for recreational use or you’re a contractor who needs a generator on site, there are several factors you’ll want to consider.
With prices ranging from a few hundred dollars to a few thousand, knowing more about generators will certainly help you spend your money more wisely. Knowing your power consumption needs is a good starting point, from there we’ll look at the different types of generators and how their various features may be beneficial to you.
Calculating Your Power Needs
Calculating how much power you need to backup your home will take some serious consideration as this will greatly affect how much you’re going to pay for a backup generator. Being willing to compromise can save you a lot, both when you purchase the generator and on your running costs. Large generators use a lot of fuel, so you need to take this into account.
No matter what you intend using a generator for, calculating your energy consumption must be done carefully. It’s best to make a list of the appliances and equipment that are essential and separately calculate those that would be convenient but not a necessity. It’s not always easy to know how long each appliance will be used for or how many items you’ll be using at the same time but having an idea of your average running load will help.
Peak and Running Watts
Power consumption is measured in Watts and you’ll notice that most generator specs include two types of watt ratings, namely peak wattage and running wattage. Running watts can also be referred to as continuous power or operating power. Understanding this is important.
There are a number of electrical appliances that require a start-up current. Induction (brushless) electric motors use a capacitor to increase the power needed to get the motor started. Fridges, washing machines, and air conditioners all use this technology. When these appliances start, they need extra power (up to three times their normal running power). This will only be for a fraction of a second but without the extra power, they won’t be able to start. This brief increase in load is known as peak power demand – a short burst of extra power to start the appliance. There are other electrical appliances that use a ballast to start, these include lighting fixtures that use gas in place of a filament (like fluorescent tube lights), microwaves and the light source used in computer screens and TVs. The peak power used for ballasts is lower than that of capacitors, usually, double the normal running watts. To allow for this, generators are able to increase their power output for a short period while these devices start. So when calculating your needs, you’ll need to look at normal operating load and peak load.
Finding the power consumption of all your appliances is not too easy and peak load is not usually indicated in the electrical specifications. The table below gives an indication of the typical watt ratings for general household appliances and tools. This should help you to get a general estimate of your power consumption.
| Description | Starting Watts | Running Watts |
|---|---|---|
| Refrigerator | 3000 | 1200 |
| Microwave | 1500-2400 | 750-1200 |
| Room Air Conditioner | 3000 | 2000 |
| Washing Machine | 3000 | 2000 |
| Clothes Dryer | 3800 | 2500 |
| Oven | 0 | 2200 |
| Central AC | 6000 | 2800 |
| Plasma TV | 450 | 380 |
| Computer (standard) | 0 | 180 |
| Computer (gaming) | 0 | 350 |
| 16” LCD Monitor | 300 | 150 |
| Heat Pump | 3000 | 1200 |
| Electric Toaster | 0 | 800 |
| Portable Fan | 0 | 100 |
| 1 HP Well Pump | 2000 | 1200 |
| USB Chargers | 0 | 4 - 7 |
| Laptop | 0 | 40 - 120 |
| Hair Dryer | 0 | 1200 |
| 1/4” Drill | 375 | 250 |
| 1/2” Drill | 750 | 500 |
| 1” Drill | 1500 | 1000 |
| 9” Disc Sander | 1800 | 1200 |
| 3” Belt Sander | 1500 | 1000 |
| 12” Chainsaw | 1650 | 1100 |
| 7-1/4” Circular Saw | 1350 | 900 |
| 8-1/4” Circular Saw | 2100 | 1400 |
| 14” Band Saw | 1650 | 1100 |
| Incandescent Bulbs | 0 | 40 - 100 |
| Halogen Flood Lights | 0 | 250 - 500 |
| Halogen Downlights | 0 | 30 |
| Fluorescent Tubes | 60 - 160 | 30 - 80 |
| LED | 10 - 20 | 5 - 10 |
| CFL | 30 - 50 | 15 - 25 |
Once you’ve calculated your consumption, you’ll probably find that your total running and peak power demand is quite high. So before you match your energy needs to the generator you intend buying, you need to apply some logic to the equation. First, you need to assess what likelihood there is of all these appliances running or starting at the same time. There’s no exact way of determining this, so you just have to use your personal judgment. Then look at how much you’re prepared to compromise – are you willing to switch off some appliances whilst using others?
The fact is, you can get any size generator and there isn’t really any limit to what you can run off generator power. You will be looking at what you’re prepared to spend, so this will affect how you view your priorities. If portability is a factor, you’ll need to consider how much power you can get from a portable generator, these can go up to 10KW, but they become heavier and bulkier as they increase in power output.
Now that you have an idea of what size generator you need, let’s look at your options.
Standby Generators
These are large units and provide enough power to run an entire home or even large buildings like high-rise apartment blocks and hospitals. If you’re looking for a home backup generator, you’ll probably be wanting something that can produce between 15KW and 40KW, depending on your requirements.
Standby generators start automatically when the grid power fails. They use an automatic transfer switch the starts the generator and then switches the main supply to your home over to the generator circuit. When the mains power is restored, it will switch back to the grid power circuit and then switch the generator off. This is all done for you and you have the least amount of inconvenience with a system like this. There is a delay between the automatic power transfer, so your power will be disconnected for a few seconds. This can be a problem with computers and other items like satellite receivers that will shut down and need to reboot. A small UPS unit will be able to keep these items powered up during the switch over period.
Standby Generators need to be installed by certified electrician and it is a specialized industry. The cost to install and run these generators are high and therefore, not in the price range of many. There are cheaper options for home backup power but you will need to make a sacrifice when it comes to your power consumption and you’ll forego the luxury of automatic transfer.
Portable Generators
Small generators that are easy to transport are popular with recreational users and contractors who work on sites where there is no grid power supply. Many home users also make use of portable generators to backup their homes during power outages. This can be done by simply running an extension cord from the generator to the appliances you’re using. Though, it is possible to have a portable generator connected to the main power supply of your home using a manual transfer switch. An electrician who is familiar with this procedure can install a separate breaker box that will run a few selected circuits, usually lights and a few plugs. You will be limited to the generator’s output as to what appliances you can run off it. You’ll also need to start the generator and switch the power over manually when the power fails. This is not ideal but it’s much cheaper than installing a large standby generator with automatic transfer.
Most RV’s have AC wiring built-in and can be plugged directly into a generator that has the correct power outlet socket for a high-current circuit. This is a very convenient situation for campers. If you don’t have this luxury, you’ll need to run an extension cord from the generator when camping.
Portable generators can be very small, with some weighing as little as 30 LBS. A small generator will have a very low power output, starting from 1KW. Larger generators can weigh in excess of 100 LBS and are not as easy to move about but can provide enough power to run most of essential household needs. Most people using a portable generator for their homes and RVs, use one that is rated for 5KW-6KW constant running power, peak power for these generators range from 7KW-12KW.
There are some other options that people look at when choosing a portable generator. One of these options is an inverter generator. I’m not going to go into too many technical details about this technology because it can get quite complicated. Essentially, an inverter converts the AC power produced by the generator’s alternator into DC power and then uses transistors to convert it back to AC power. This provides a stable AC sine wave with low harmonic distortion. Electronic equipment will be become damaged if exposed to unstable voltage and frequency repeatedly. Even high-quality generators, fitted with a voltage regulator will not provide a perfect (pure) sinewave, particularly when running at more than 70% of their load capacity. So, many people who use electronic equipment (which is virtually everyone, these days) prefer to use an inverter generator to protect these devices.
Paralleling Generators
Another, less common, feature on generators is parallel functioning. Some inverter generators have the ability to run more than one generator together which increases the power output to the combined output of both generators. The inverter will synchronize the sine waves of both generators to work as one. Many users prefer this level of versatility because it allows one to upgrade rather than replace and some users will have multiple uses for their generator, for example, home and recreational use. Having two generators that can run in parallel means that you can use one unit when going camping where portability is important. When using this generator to backup your home, you can add another unit to increase the amount of power available to you.
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