Generator Sizing Guide for Florida Homes

# Generator Sizing Guide for Florida Homes Living in Florida means accepting that power outages are not a matter of "if" but "when." Between hurricane season, tropical storms, summer thunderstorms, and the occasional transformer failure from heat stress, Florida homeowners experience more outages than residents of most other states. A standby generator transforms an outage from a household emergency into a minor inconvenience. But generators are a significant investment, and getting the sizing wrong creates real problems. An undersized generator struggles to power your home, trips on overload, and can even damage itself and your appliances. An oversized generator wastes fuel, costs more upfront, and runs inefficiently at low loads. This guide walks you through sizing a generator correctly for your Florida home, choosing between fuel types and brands, and understanding the full cost of installation. ## Table of Contents - [Calculating Your Power Needs](#calculating-your-power-needs) - [Whole-Home vs Partial Backup](#whole-home-vs-partial-backup) - [Fuel Types: Natural Gas vs Propane vs Diesel](#fuel-types-natural-gas-vs-propane-vs-diesel) - [Generator Brand Comparison: Generac vs Kohler](#generator-brand-comparison-generac-vs-kohler) - [Hurricane Preparedness and Generators](#hurricane-preparedness-and-generators) - [Transfer Switch Types](#transfer-switch-types) - [Cost Breakdown](#cost-breakdown) - [Installation Process](#installation-process) - [Maintenance Requirements](#maintenance-requirements) - [Frequently Asked Questions](#frequently-asked-questions) ## Calculating Your Power Needs The single most important step in choosing a generator is accurately calculating how much power your home needs. This is not guesswork; it is arithmetic. ### The Worksheet Approach Start by listing every appliance and system you want to power during an outage. For each item, record two numbers: the **running watts** (the power it uses during normal operation) and the **starting watts** (the momentary surge of power needed when the motor or compressor starts up). Here is a worksheet based on typical Florida home loads: **Essential Systems:** | Appliance | Running Watts | Starting Watts | |-----------|--------------|----------------| | Central AC (3-ton) | 3,500 | 7,000 | | Central AC (5-ton) | 5,000 | 10,000 | | Refrigerator | 150 | 400 | | Freezer | 100 | 350 | | Well pump (1/2 HP) | 750 | 1,500 | | Sump pump (1/3 HP) | 500 | 1,000 | | Lights (10 LED fixtures) | 100 | 100 | | Garage door opener | 550 | 1,100 | **Comfort and Convenience:** | Appliance | Running Watts | Starting Watts | |-----------|--------------|----------------| | Electric water heater | 4,500 | 4,500 | | Microwave | 1,000 | 1,000 | | TV and internet equipment | 250 | 250 | | Washing machine | 500 | 1,200 | | Electric dryer | 5,400 | 5,400 | | Electric range/oven | 3,000 | 3,000 | | Pool pump (1.5 HP) | 1,800 | 3,600 | ### How to Calculate Total Load 1. Add up the running watts of everything you want to power simultaneously. 2. Identify the appliance with the highest starting watts. 3. Add that starting wattage surplus (starting watts minus running watts) to your total running watts. 4. This gives you the minimum generator capacity needed. **Example for a typical Florida home:** You want to power the central AC (3-ton), refrigerator, freezer, lights, TV/internet, water heater, and microwave. Running watts: 3,500 + 150 + 100 + 100 + 250 + 4,500 + 1,000 = 9,600 watts Largest starting surge: Central AC (7,000 - 3,500 = 3,500 watts surplus) Minimum generator size: 9,600 + 3,500 = 13,100 watts, or approximately **14 kW** ### The Florida AC Factor Air conditioning is the single largest electrical load in Florida homes, and it is also the appliance you are least willing to live without during a summer outage. A power outage during a July heat wave without AC is not just uncomfortable; it can be dangerous, especially for elderly residents and young children. For this reason, Florida generator sizing almost always starts with the AC system. If you have a 3-ton unit (36,000 BTU), plan for at least 7,000 watts of starting capacity just for the AC. If you have a 5-ton unit, plan for 10,000 watts. If you have two AC units, as many Florida homes over 2,500 square feet do, you may need to decide whether to back up both or just one. Modern inverter-based AC systems and variable-speed compressors draw less starting current than older units, so if you have a newer HVAC system, your starting watts may be lower than the table above indicates. Your electrician can measure actual starting current during the site assessment. ## Whole-Home vs Partial Backup This is the most consequential decision in generator selection. It determines the size, cost, and complexity of your installation. ### Whole-Home Backup A whole-home generator powers every circuit in your house. When the power goes out, everything keeps running: AC, kitchen, laundry, pool pump, garage, all of it. The generator connects to your main panel through an automatic transfer switch, and the transition from grid power to generator power happens within 10 to 30 seconds. **Pros:** - No lifestyle changes during an outage - No need to prioritize circuits - Simplest operation (fully automatic) - Protects all electrical systems, including those you might not think about (security systems, irrigation controllers, powered attic ventilators) **Cons:** - Higher equipment cost (typically 20-40 kW generators for Florida homes) - Higher fuel consumption - Larger physical footprint - Higher installation cost For homeowners in [Sarasota](/areas/sarasota), [Bradenton](/areas/bradenton), and [Clearwater](/areas/clearwater) who want complete peace of mind during hurricane season, whole-home backup is often the preferred choice. ### Partial Backup A partial backup generator powers only selected circuits, those your electrician identifies as essential. The AC, refrigerator, lights, and a few outlets might be on the backup system, while the dryer, oven, pool pump, and non-essential outlets are not. This approach requires a sub-panel or load-shedding system that separates essential circuits from non-essential ones. Your electrician moves the circuits you want backed up to the generator sub-panel, and the transfer switch only feeds that sub-panel. **Pros:** - Smaller, less expensive generator (10-16 kW for most homes) - Lower fuel consumption - Smaller physical footprint - Lower installation cost **Cons:** - Must decide in advance which circuits to back up - Cannot run large appliances on non-essential circuits during an outage - Less convenient during extended outages ### Load Management Systems Some modern generators and transfer switches include load management capabilities that blur the line between whole-home and partial backup. These systems monitor the generator's output and selectively shed non-essential loads when demand exceeds capacity. For example, if the AC compressor kicks on, the system might temporarily pause the water heater to keep the generator within its capacity. Load management allows a smaller generator to back up more circuits by intelligently managing when high-draw appliances run. This can be a cost-effective middle ground between full whole-home backup and a limited partial system. ## Fuel Types: Natural Gas vs Propane vs Diesel The fuel your generator runs on affects everything from operating cost to maintenance to how long you can run during an extended outage. ### Natural Gas **Advantages:** - Unlimited fuel supply (as long as gas lines are intact) - No fuel storage on your property - Lower maintenance than diesel - Clean burning (less carbon buildup) - Lower per-hour fuel cost **Disadvantages:** - Gas lines can be disrupted during hurricanes and major storms - Lower energy density means natural gas generators produce slightly less power per unit of fuel - Not available in all Florida neighborhoods (many developments are all-electric) - Slightly higher equipment cost than propane equivalents **Florida consideration:** Natural gas availability varies significantly across Florida. Urban areas of Tampa, St. Petersburg, and parts of Sarasota have extensive natural gas infrastructure. Newer subdivisions in Lakewood Ranch, North Port, and outlying areas often lack natural gas service entirely. If natural gas is available at your property, it is often the most convenient fuel choice for a standby generator. ### Propane (LP Gas) **Advantages:** - Available everywhere, regardless of natural gas infrastructure - Stores indefinitely without degrading (unlike gasoline or diesel) - Clean burning - Propane tanks can be sized to provide days of continuous run time - Slightly higher energy density than natural gas **Disadvantages:** - Requires a propane storage tank on your property (250-1,000 gallons for a standby generator) - Tank must be refilled periodically, and refueling during a widespread outage may be delayed - Higher per-gallon cost than natural gas (though still reasonable) - Tank installation adds cost and requires a suitable location on your property **Florida consideration:** Propane is the most common fuel choice for Florida standby generators outside of natural gas service areas. A 500-gallon propane tank, which is a common installation size, provides approximately 5 to 7 days of continuous generator run time at 50% load for a 20 kW unit. If you live in an area prone to extended outages from hurricanes, consider a larger tank. ### Diesel **Advantages:** - Highest energy density of any generator fuel - Very reliable and durable engines - Widely available fuel - Excellent for continuous-duty applications **Disadvantages:** - Louder operation than gas or propane generators - Diesel fuel degrades over time (6-12 months without stabilizer) - Higher maintenance costs (fuel filter changes, fuel polishing) - Higher emissions and odor - Requires on-site fuel storage - More expensive equipment - More stringent EPA regulations **Florida consideration:** Diesel generators are less common in residential applications in Florida and more common for commercial backup. For most homeowners, natural gas or propane is a better fit. Diesel makes sense for large homes or properties in remote areas where extended run time and maximum reliability justify the higher cost and maintenance. ## Generator Brand Comparison: Generac vs Kohler Two brands dominate the residential standby generator market, and most Florida homeowners will choose between them. ### Generac Generac invented the home standby generator market and commands the largest market share. Their residential lineup ranges from 10 kW to 26 kW for air-cooled units and up to 150 kW for liquid-cooled models. **Strengths:** - Widest dealer and service network in Florida - Competitive pricing, especially for air-cooled units - Mobile Link remote monitoring (included with Wi-Fi models) - True Power Technology for clean power output - Extensive parts availability **Considerations:** - Air-cooled models (under 26 kW) are louder than Kohler equivalents - Some service technicians report that Generac air-cooled engines have a shorter lifespan than Kohler engines, though both are rated for similar hours - The Guardian series (residential) uses a proprietary engine, while the Protector series (commercial) uses more widely available engine platforms ### Kohler Kohler has been making engines and generators for over a century. Their residential generators range from 14 kW to 150 kW. **Strengths:** - Quieter operation, particularly at partial load - Commercial-grade engines across the entire lineup - Corrosion-resistant enclosures (important in Florida's salt air, especially in coastal areas of Sarasota, Clearwater, and St. Petersburg) - Clean, consistent power output - Strong reputation for longevity **Considerations:** - Higher upfront cost (typically 10-20% more than comparable Generac models) - Smaller dealer network in some Florida areas - Fewer model options in the 10-14 kW range ### Which Should You Choose? For most Florida homeowners, both brands will serve well. Generac offers better value for air-cooled generators under 22 kW and has a broader service network. Kohler offers a quieter, more refined product that may justify the premium for homes where noise is a concern (close neighbors, outdoor living areas near the generator pad) or where coastal corrosion is a factor. Regardless of brand, what matters most is proper sizing, professional installation, and regular maintenance. A well-maintained Generac will outlast a neglected Kohler, and vice versa. ## Hurricane Preparedness and Generators Generators and hurricane season go hand in hand in Florida. Here is how to make sure your generator is ready when the next storm arrives. ### Pre-Season Preparation Every year before June 1 (the start of Atlantic hurricane season), your generator should be inspected and serviced. This includes: - Oil and filter change - Air filter inspection or replacement - Spark plug inspection or replacement - Battery test and replacement if needed - Fuel system check (for propane, verify tank level; for natural gas, test supply pressure) - Transfer switch test (simulate an outage to confirm automatic operation) - Load test (run the generator under load for 15-30 minutes) ### During a Hurricane Once a hurricane watch or warning is issued for your area: - Verify your propane tank is full (if applicable) - Test the generator manually - Clear debris from around the generator pad - Ensure nothing is stored within 5 feet of the generator that could become a projectile - Review your generator's operating procedures with all household members During the storm, the generator will start automatically when utility power is lost. You do not need to go outside to start it, which is important since going outside during a hurricane is extremely dangerous. ### After the Storm After the storm passes, check for visible damage to the generator and its fuel connections before relying on it for extended operation. Listen for unusual sounds and watch for any error codes on the control panel. If the generator ran during the storm, check the oil level and be prepared to refuel if needed. For more detailed storm preparation guidance, see our [hurricane electrical preparedness guide](/guides/hurricane-electrical-preparedness). ## Transfer Switch Types The transfer switch is what connects your generator to your home's electrical system. It detects when utility power is lost, signals the generator to start, and switches your home from grid power to generator power. ### Automatic Transfer Switch (ATS) An automatic transfer switch handles everything without intervention. When utility power fails, the ATS detects the loss within seconds, sends a start signal to the generator, waits for the generator to reach stable operating speed (usually 10-30 seconds), and then transfers the load from the utility to the generator. When utility power returns, the ATS reverses the process, transferring back to utility power and shutting down the generator after a cooldown period. This is the standard for permanently installed standby generators and the type we install for our [generator installation](/services/generator-installation) customers. ### Manual Transfer Switch A manual transfer switch requires you to physically flip a switch or turn a handle to transfer from utility to generator power. These are typically used with portable generators rather than permanent standby units. Manual transfer switches are less expensive but require you to be home and able to operate the switch during an outage. ### Load Center Transfer Switch Some transfer switches are integrated into a dedicated load center (sub-panel) that feeds only the circuits you want to back up. This is common in partial backup installations. Essential circuits are moved to the generator sub-panel, and the transfer switch only controls power to that sub-panel. ### Service Entrance Rated Transfer Switch For whole-home backup, a service entrance rated transfer switch installs between the meter and the main panel. This allows the generator to power the entire panel without any circuit modifications. This type of installation is more complex and more expensive but provides the most seamless whole-home backup experience. ## Cost Breakdown Generator installation costs in Florida vary widely based on the generator size, fuel type, installation complexity, and site conditions. ### Equipment Costs | Generator Size | Fuel Type | Approximate Equipment Cost | |---------------|-----------|---------------------------| | 10-14 kW | Natural gas/propane | $3,500-$5,500 | | 16-20 kW | Natural gas/propane | $4,500-$7,000 | | 22-26 kW (air-cooled) | Natural gas/propane | $5,500-$8,500 | | 30-48 kW (liquid-cooled) | Natural gas/propane/diesel | $10,000-$20,000 | ### Installation Costs Installation typically adds **$3,000 to $7,000** to the equipment cost, covering: - Concrete pad (generator must sit on a level pad meeting manufacturer specifications) - Transfer switch and installation - Electrical connections from transfer switch to panel - Gas line connection (natural gas or propane) - Propane tank installation (if applicable, add $1,500-$3,000 for tank and pad) - Permit fees and inspections - Utility coordination - Startup and commissioning ### Total Installed Cost Ranges - **Partial backup (10-16 kW):** $5,000-$10,000 - **Whole-home backup (20-26 kW, air-cooled):** $8,000-$15,000 - **Large whole-home backup (30+ kW, liquid-cooled):** $15,000-$30,000+ These ranges reflect the Florida market as of early 2025. Supply chain conditions, local labor rates, and seasonal demand (costs often increase approaching hurricane season) all affect pricing. ### Ongoing Costs Beyond the initial installation, budget for: - **Annual maintenance:** $200-$400 for a professional service visit - **Fuel:** Varies with usage. A 22 kW generator running at 50% load uses approximately 2 gallons of propane per hour or 200 cubic feet of natural gas per hour - **Battery replacement:** Generator starting batteries last 3-5 years and cost $100-$200 to replace - **Extended warranty:** Optional, typically $500-$1,000 for 5-year extension beyond the standard warranty ## Installation Process Here is what to expect when you schedule a [generator installation](/services/generator-installation) with a licensed electrician in Florida. ### Step 1: Site Assessment and Sizing An electrician visits your home to assess the installation site, evaluate your [electrical panel](/services/electrical-panel-upgrades), perform a load calculation, and recommend a generator size and type. They will also identify the optimal location for the generator pad, considering setback requirements (typically 5 feet from any opening like windows or doors, and 18 inches from the building wall), noise considerations, and fuel line routing. ### Step 2: Proposal and Ordering Based on the assessment, you receive a detailed proposal with equipment specifications, installation scope, and total cost. Once approved, the generator is ordered. Lead times vary from one to six weeks depending on the model and current demand. ### Step 3: Permitting Your electrician handles all permit applications with the local building department and, if applicable, the gas utility. Florida requires electrical and sometimes mechanical permits for generator installations. ### Step 4: Site Preparation A concrete pad is poured for the generator. The pad must be level and meet the manufacturer's size and thickness specifications (typically 4 inches of concrete with a gravel base). Pad preparation takes one day, and the concrete needs to cure for at least 24-48 hours before the generator is placed. ### Step 5: Equipment Installation The generator is placed on the pad, the transfer switch is installed at the electrical panel, and all electrical and fuel connections are made. This typically takes one full day for a standard installation. ### Step 6: Inspection and Commissioning The local building inspector reviews the installation. Once approved, your electrician commissions the generator: programming the controller, setting exercise schedules, configuring the transfer switch, and running a full load test. ### Step 7: Owner Training Your electrician walks you through the generator's operation, shows you how to check oil and fuel levels, explains the control panel indicators, and reviews the maintenance schedule. ## Maintenance Requirements A standby generator is a mechanical system with an engine, and like any engine, it requires regular maintenance to operate reliably. ### Weekly Exercise Most standby generators are programmed to run for 15-20 minutes once per week, automatically. This exercise cycle keeps the engine lubricated, charges the starting battery, and confirms that all systems are operational. You will hear the generator start and run at the same time each week. This is normal and expected. ### Annual Professional Service Once per year, a qualified technician should perform: - Oil and filter change - Air filter replacement - Spark plug inspection and replacement (if needed) - Coolant check (liquid-cooled units) - Battery load test - Transfer switch test - Full load test - Control panel diagnostics - Visual inspection of fuel connections and exhaust system ### Biennial and As-Needed Maintenance Every two years or as indicated by the manufacturer: - Coolant flush and replacement (liquid-cooled units) - Valve clearance check - Fuel system cleaning or replacement (diesel units) - Full electrical connection inspection and tightening Protecting your generator with [whole-home surge protection](/services/whole-home-surge-protection) also ensures that power surges during transfer events do not damage your generator's electronic controls or your home's electrical systems. ## Frequently Asked Questions ### What size generator do I need for a 2,500 square foot Florida home? For a 2,500 square foot home with a 3-ton AC unit, electric water heater, and standard kitchen appliances, a 20-22 kW generator provides comfortable whole-home backup. If you have a 5-ton AC, a pool pump, or other large loads, consider stepping up to 24-26 kW. The only way to know for certain is a proper load calculation performed by a licensed electrician. ### How long can a standby generator run continuously? Most standby generators can run indefinitely as long as they have fuel and receive periodic oil checks (every 24-48 hours during continuous operation). Generac and Kohler both design their residential units for extended operation, which is essential in Florida where hurricane-related outages can last days or even weeks. ### How loud is a standby generator? Air-cooled residential generators typically operate at 65-70 decibels measured at 23 feet, roughly the volume of a normal conversation. Liquid-cooled units are quieter, often 62-66 decibels. For comparison, a window air conditioner runs at about 60 decibels. Most Florida HOAs have noise requirements, and modern generators from Generac and Kohler generally comply with these limits. ### Do I need a permit for a generator in Florida? Yes. Generator installations in Florida require both an electrical permit (for the transfer switch and wiring) and often a building permit (for the concrete pad and equipment placement). If a gas line is being run, a mechanical or plumbing permit may also be required. Your electrician handles all of this as part of the installation. ### Can I install a generator myself? No. Florida requires that generator electrical connections be performed by a licensed electrical contractor. The gas line connection must be performed by a licensed plumber or gas fitter. Beyond the legal requirements, improper installation can result in carbon monoxide exposure, electrical backfeed (which is deadly to utility workers), fire, and voided warranties. ### What happens to my generator during a hurricane? Standby generators are designed to operate in severe weather, including heavy rain and high winds. The enclosures are weather-rated, and the units are bolted to a concrete pad. During a hurricane, the generator starts automatically when power fails and continues running throughout the outage. The main concern is fuel supply, so ensure your propane tank is full before the storm arrives. ### Will a generator work with my solar panels? Yes, but integration requires careful planning. Your electrician must ensure that the generator, solar inverter, and transfer switch all work together safely. In most cases, the solar system will shut down during a grid outage (as required by code) unless you have battery backup. If you have a [Tesla Powerwall](/services/tesla-powerwall-battery-backup) or similar battery system, it can work alongside a generator for extended backup capability. --- Need help choosing and installing the right generator for your Florida home? Ranch and Coast Electric serves homeowners in [Sarasota](/areas/sarasota), [Bradenton](/areas/bradenton), [Clearwater](/areas/clearwater), and surrounding areas. Call **(708) 378-6058** or visit [ranchandcoastelectric.com](https://ranchandcoastelectric.com) for a consultation.