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The average cost to install a home generator is $5,200, but total costs can range from $500 to $18,000 or more. The final price depends on several factors, including the generator's size, type, brand, fuel source, and the cost of labor and assembly. The generator's size is the most significant cost factor, as units that can power larger homes with higher energy demands cost more.

Cost breakdowns by generator type are typically as follows:

• Portable or Emergency Backup Generators (1kW–7.5kW): $500–$2,000

• Partial-Home Generators (9kW–20kW): $2,000–$6,500

• Whole-House Generators (22kW–48kW): $5,000–$18,000

To ensure you get the right size unit for your needs without overpaying, consider hiring an electrician to calculate the electrical load of your essential appliances. It is also recommended to get at least three quotes from qualified installers to find the best fit for your budget.

Sizing a generator is a careful process that requires calculating the electrical load of your entire house. You have to take into account every device you want to use and their wattage requirements, plus the wattage needed to start them, and look for a generator that can safely run all that at around 80% capacity.

In more practical terms, a small home can run on a 10,000-watt generator (and if you only want to power a few key appliances, much less than that). A mid-sized home may need something between 15,000 and 22,000 watts. Larger homes require 25,000 watts or more. 

Most homeowners won't be able to claim a home generator as a tax write-off. However, a whole-house generator may be tax-deductible in certain situations depending on its purpose. For instance, if it's needed to power essential medical equipment, it may qualify as a medical expense deduction. Also, in some cases, businesses can deduct a generator as a business expense if it supports operations. Always consult a tax professional to determine eligibility based on your specific circumstances and the applicable IRS regulations.

In most municipalities, you will need a permit to install a permanent home generator, including emergency backup, partial-home, and whole-home generators. A permit for a generator usually costs between $50 and $250, depending on where you live. Your electrician or certified generator installer will usually pull the permit for you—and might be required to do so by your building department—but you’ll be on the hook for the cost of the permit. You should ask your installer before agreeing to any work if they will pull the necessary permits for your project.