Find the Right Size Standby Generator for Your Needs

Standby Generator | Lee Mechanical

You might be enjoying the summer heat these days but, in the frozen tundra, it’s never too early to start preparing for winter. 

In Kenosha, you can expect to see 35 inches of rain and 39 inches of snow every year. Some of the crazy storms, especially along Lake Michigan and in Downtown Kenosha, also cause power outages. However, you can protect your home with a standby generator, which provides backup electricity that switches on automatically if you lose power. Wouldn’t you like to have uninterrupted power in a blackout?

When you buy a generator, you’re investing in the safety and comfort of your family. Occasional power failures are a fact of life for most homeowners. According to Consumer Report, a generator also increases the value of your home by 3 to 5%.  

If you choose wisely, a standby generator can power all your essential needs. Installation may cost from $7,000 to $15,000, according to Porch, and a generator may run between $3,500 to $5,000 and beyond, depending on your needs.

When purchasing a standby generator, it’s important to calculate the right size for your home or business.

How to Size a Standby Generator for Your Needs

This is a significant and, hopefully, one-time purchase, so it’s a good idea to take your time to make the right decision. The type of fuel (propane, diesel or natural gas) often depends on the brand and model you purchase. Although there are many manufacturers, the Lee Service team recommends and sells Generac for its affordability and reliability. 

One of Lee’s skilled team members will help you determine what size generator can meet the needs of your home. 

Standby Generator Sizing Considerations

You can make a well-informed purchase by following a few guidelines. The size of your generator depends on what you expect it to do. A homeowner looking for backup power usually chooses a portable generator or a stationary standby generator. Standby generators are typically more reliable. Sizes range but a 20kW generator will run most house receptacles, lights, and up to a 5-ton central air conditioner. Phase-power electricity can power small appliances that don’t pull constant high-voltage power.

The first step is calculating your electricity usage, which is simpler than it sounds. You basically list all the electrical equipment you’ll need if the electricity goes out.

You can simplify this process also by having a Lee expert electrician review your home and  your needs, to help you determine the best generator for your home.

Make a List of Your Electrical Appliances and Gadgets 

Make a list of every gadget that will pull power from the standby generator. It’s better to overestimate even if you plan to ration power for the kids’ games and phones. Then, determine the energy needed to turn on the generator and how much power it takes to run each piece of budgeted equipment.

Appliances usually have this information documented on the back, or you may be able to look it up online or in the owner’s manual. The more accurate your information, the more accurate your calculation will be. Simply add up the kW or KVA totals to get the final number.

Converting Amperes 

Some equipment provides the power required in amperes. Here’s the formula to convert amps to watts:

  • Resistant Volts (most common): Wattage = amperes times volts
  • Reactive loads: Wattage = amperes times volts times load factor

The load factor is the rate of electrical energy use. It’s expressed in kilowatt-hours during peak demand. You can review your electric bill to get this data (or call the utility company if you need help figuring this out).

Here is the formula to figure out the load factor:

  • Total kWh used in the previous month / (your peak demand x 30 days x 24 hours)

While it’s better to figure out the correct wattage from your manual or online, you can also estimate how much you use.

The following table provides an estimate for common tools and electronics for starting/running load:

  • Air compressor 4000/2000
  • Electric chainsaw 2400/1200
  • Water heater 4500/4500
  • Router 1500/600
  • Laptop 250/250
  • Printer 500/500
  • Dishwasher 1450/1400
  • LCD TV (55”) 230/230
  • Air conditioner (10k BTU) 2200/1500
  • Refrigerator/freezer 500 750
  • Portable oil filled heater 1500/1800
  • Microwave 100/0
  • Coffee maker 1200/0
  • Radio 225/0
  • Clothes washer 1150/2200
  • Small refrigerator 500/2000

Consider investing in an outdoor grill to prepare food or subsisting on nonperishable items during the blackout to save electricity.

Choosing a Generator Size

After you estimate the wattage, you are ready to choose the right generator size for your home. Remember to leave plenty of room to pad for all the items you forgot. Add an additional 20% to your estimate. That way if you get new equipment and need more power, you have covered your bases. Also, many factors affect the performance of your generator, including extreme temperatures and low or high altitudes.

Should You Buy a Single Generator or Run Multiple Generators

Most homeowners have to decide whether to buy a single or multiple generators. If you have significant power needs, you may worry about whether to get a single, large generator or split the load between two or more units. For instance, instead of a single 1200kW generator, you can run three 400kW generators in parallel.

Here’s why paralleling is sometimes the best choice:

  • Reliability. Having more than one generator increases the reliability of your backup system. After all, you get a generator to ensure you have electricity all the time. What if the generator fails? If you run more than one generator, you can count on having some power if one generator goes down or runs out of fuel. If you have a small business, multiple standby generators is recommended.
  • More cost-effective. Fuel for your standby generator can quickly run into hundreds or even thousands of dollars if the power stays out for a number of days. So efficient backup systems are essential to keep your budget in check. The economics vary depending on the brand, conditions and prices of the generators you choose. However, it’s often more affordable to run multiple small generators to power your appliances, electronic devices and gadgets.
  • Practicality: Running multiple generators can be more practical. Depending on the size of your home, you might be able to fit two or three smaller generators more easily than one large one. Our technicians can help you determine the configuration that would work for your home and give you tips on where to store the generators securely during and after use.
  • Easier load on generators. Essentially, your standby generator is another piece of equipment. The more strain placed on it, the sooner it wears out. Load sharing between two or more units can increase the useful life of each one. It also helps you avoid overloading one small unit. Running your standby unit at 80% capacity increases the longevity compared to overburdening the unit and having it wear out quickly.  

Fuel Consumption Considerations

Fuel consumption also affects your generator sizing considerations. A 3500-level truck uses more fuel than a 1500-level truck. Similarly, bigger generators use fuel faster than smaller standby units. When you are making your final decision, consider fuel costs, as that is a major factor in how much it takes to run your generators in an emergency.

Large generators take more fuel and you’re likely to have to refuel them more often than two smaller generators. If you have storage tanks, this could require an additional tank, another additional cost.   

When it comes to a generator for your home, choose the right configuration for your needs. Ensure that you have more capacity than you think you need.

Why Is Choosing the Right Size Important?

You may be tempted to skimp and downsize the generator for budgetary purposes. After all, it could save you a few thousand dollars. However, choosing an undersized generator could end up costing you a lot more money. You can damage your appliances if you run them off a generator that can’t handle the load. You can also ruin the generator itself.

Error on the side of caution and go with a larger generator. Here are some of the benefits of going this route:

  • Generator will last longer
  • Consistent performance
  • Limited capacity overloads
  • Limited system failures
  • Reduced chance of frying your electronics
  • Improved safety
  • Decreased risk of electrical fires
  • Decrease in maintenance or replacement cost

Safety Considerations

Never exceed the capacity of your generator. You can turn off appliances to decrease the load and occasionally shut the generator shut to avoid overheating. 

Start with your largest appliances first and plug other items in one by one to avoid overloading the unit. Grounding the standby generator you choose prevents electrical shock when you adjust the unit. Use the appropriate cored to power appliances. For example, choose large gauge, three-prong extension cords for appliances. 

Your safety is important to you and our team. Our electricians can go over all safety options with you when helping you determine the best generator to purchase and review them again during installation.

What’s Next?

Select Lee for the installation of your standby generator. We are a “Generac Select” supplier and the only certified dealer Generac dealer in Kenosha, WI.