When it comes to purchasing a generator, one of the most important questions is: “What size generator do I need?” This question is crucial because selecting the wrong size generator can result in wasted money, power shortages, or even equipment damage. To choose the correct generator size, it is important to understand the power requirements of the devices or systems you intend to run. In this guide, we will break down the factors to consider when determining the size of a generator you need and how to make an informed decision based on your specific needs.
What Is a Generator?
Before we dive into how to determine the right size generator, let’s briefly explain what a generator is and its role. A generator is a device that converts mechanical energy into electrical energy. This electrical energy can power various appliances, tools, or entire homes, depending on the generator’s size. Whether you’re preparing for an emergency, running a business, or planning a camping trip, knowing the right size of generator will ensure you have enough power to meet your needs without overloading the system.
Understanding Generator Ratings
Generators are rated in terms of wattage, which is the amount of electrical power they can provide. Understanding this rating is critical when determining the right size generator. Here are the two main types of ratings you’ll come across:
Starting Wattage (Surge Wattage): This is the amount of power a generator can provide momentarily when starting up electrical devices with motors, such as refrigerators, air conditioners, or pumps. Starting wattage is typically higher than running wattage and is needed only for a brief period.
Running Wattage (Continuous Wattage): This is the steady amount of power a generator can provide once a device or appliance is running. It is lower than the surge wattage but is sufficient to keep things operating continuously.
The key to selecting the correct generator size is ensuring that the generator can handle both the surge and running wattage of all the equipment you plan to power.
Step 1: Identify Your Power Requirements
Determine What You Want to Power
The first step in choosing the right generator is to make a list of all the appliances, devices, or systems you want to power. For instance, if you are preparing for a power outage in your home, you might want to power lights, a refrigerator, a television, and a few other essential appliances. If you’re using the generator for outdoor activities, you may only need to power a few lights and a small refrigerator.
Calculate the Wattage of Each Appliance
Once you know what you want to power, you’ll need to find out the wattage requirements of each device or appliance. You can find the wattage information in one of three places:
- The Nameplate or Manufacturer’s Label: Most appliances and devices have a label that lists the required wattage.
- The Owner’s Manual: If the label is missing or unreadable, the owner’s manual should list the wattage requirement.
- Online Resources: For many common devices, you can look up their wattage requirements online.
For example, a typical refrigerator may require 800 watts to run continuously, but when it starts, it may require 2,000 watts for a short period (this is the surge wattage).
Add Up the Wattage
Once you have the wattage for each device or appliance, add them up. This will give you the total running wattage required. Be sure to include the starting wattage for devices that have a motor (such as refrigerators, air conditioners, and well pumps), because these will need more power when they first start up.
Step 2: Choose the Right Generator Size
Understand the Total Power Needs
Now that you know the total wattage required for all your devices, it’s time to choose the appropriate generator. Generally, you want a generator that can handle 20-30% more than your total running wattage. This extra power capacity ensures that your generator won’t run at full load all the time, which increases its lifespan.
Let’s take an example. Suppose you want to power the following:
- A refrigerator: 800 watts (running), 2,000 watts (starting)
- A microwave: 1,000 watts
- A television: 200 watts
- A few lights: 400 watts
Total running wattage: 800 + 1,000 + 200 + 400 = 2,400 watts
Total starting wattage: 2,000 (refrigerator) + 1,200 (microwave) = 3,200 watts
Based on this, you would need a generator with at least 2,400 watts of running capacity and 3,200 watts of starting capacity.
However, it’s important to account for the 20-30% safety margin. For this example, the generator size you would likely need is:
- Running wattage: 2,400 watts × 1.2 = 2,880 watts
- Starting wattage: 3,200 watts × 1.2 = 3,840 watts
A generator with 3,800-4,000 watts of running capacity would be sufficient to handle both your starting and running wattage requirements.
Consider Future Power Needs
When selecting a generator, it’s important to think not only about your current power needs but also any future expansion. If you plan to add more appliances or devices to your setup in the future, consider selecting a generator that offers a little more capacity than you need right now. This will ensure that your generator can grow with you over time.
Step 3: Choose the Type of Generator
There are different types of generators, and choosing the right type depends on your specific needs. Here are the most common types of generators:
Portable Generators
Portable generators are typically used for smaller applications, such as powering a few appliances in an emergency situation, providing backup power during outdoor events, or supplying power to recreational vehicles (RVs). These generators are usually powered by gasoline or propane.
Portable generators come in a range of sizes. You can find models with ratings from 1,000 watts to over 10,000 watts. The key here is to match the portable generator’s capacity with your wattage requirements, ensuring it meets both running and starting wattage needs.
Standby Generators
Standby generators are larger units designed to provide backup power to an entire home or business during an outage. They are permanently installed outside and connected to your home’s electrical system, automatically turning on when the power goes out.
These generators tend to have much higher power capacities than portable generators. Standby generators usually range from 5,000 to 20,000 watts, with some even going up to 50,000 watts for larger applications. If you are looking to power an entire home, especially if you want to run high-demand appliances like air conditioners or heating systems, a standby generator is a good choice.
Inverter Generators
Inverter generators provide cleaner and more stable power, making them ideal for sensitive electronic equipment like laptops, TVs, and phones. They are also quieter and more fuel-efficient than conventional portable generators. Inverter generators are available in smaller capacities, ranging from 1,000 watts to 4,000 watts, making them a good option for powering a few devices or appliances.
Solar Generators
Solar generators are powered by solar panels and are an environmentally friendly alternative to fuel-powered generators. They are typically smaller in capacity (ranging from 300 to 1,500 watts) and are ideal for use in off-grid situations, such as camping or powering a few essential appliances during an outage. However, solar generators require direct sunlight to charge their batteries, which may limit their use during cloudy or rainy weather.
Step 4: Account for Fuel Type
The type of fuel a generator uses can affect its overall performance and your decision on which generator size to choose. Here’s a breakdown of the most common fuel types:
Gasoline
Gasoline-powered generators are the most common and are typically available in smaller sizes, ranging from 1,000 to 10,000 watts. They are ideal for short-term power needs, but gasoline has a shorter shelf life and may not be ideal for long-term storage.
Diesel
Diesel-powered generators are more efficient and last longer than gasoline models. They are commonly used for larger generators (greater than 5,000 watts) and are typically more durable. Diesel generators are a good option for businesses or homeowners who need a reliable power source for extended periods.
Propane
Propane generators are more eco-friendly than gasoline generators and can be used for both portable and standby generators. Propane fuel has a longer shelf life than gasoline, and propane-powered generators tend to have lower emissions. They are a good option for those looking to reduce their carbon footprint.
Natural Gas
Natural gas generators are usually standby generators, as they require a direct connection to your home’s natural gas supply. They are very convenient, as you don’t need to worry about refueling them, but they may not be suitable for all locations.
Step 5: Calculate Runtime and Efficiency
Another important factor to consider when selecting a generator is its runtime and fuel efficiency. Most generators will have an estimated runtime, which indicates how long the generator can run on a full tank of fuel. Choose a generator with a longer runtime if you plan to use it for extended periods without refueling. Additionally, some generators are more fuel-efficient, offering more hours of power for less fuel.
Conclusion
Determining the correct size generator requires careful calculation of your power needs, consideration of surge and running wattage, and an understanding of your specific usage requirements. By following the steps outlined in this guide, you can confidently select the generator that will meet your needs, whether you’re looking to power a few household appliances during an emergency or run an entire home or business with a standby unit.
Remember, choosing a generator with a higher capacity than your exact needs ensures that you have enough power to handle any unforeseen demands, improves the longevity of the generator, and provides a buffer for future additions to your power load. By considering all these factors, you’ll have the right generator that fits your needs, providing reliable and efficient power when you need it most.
