What Size Generator Do I Need for a Frisco Home? A Simple Sizing Guide
Your power goes out on a July afternoon in Frisco. You start the generator you bought last year. The lights come on. Then the air conditioner tries to start, and everything shuts down. The generator was not broken. It was too small.
Size is the one decision that determines whether your backup power works when you need it. Guess low, and the unit trips the moment your A/C kicks on. Guess high, and you paid for capacity you will never use. If you are asking what size generator you need for a Frisco home, this guide gives you a real answer.
We will walk you through the number ranges, the math behind them, and how to choose between whole-home backup and essential circuits. You will also learn what shifts the result here in Frisco — newer electrical panels, multiple HVAC zones, EV chargers, and HOA placement rules.
What Size Generator Do I Need for a Frisco Home?
Most Frisco homes are served by a standby generator in the 10 kW to 26 kW range. Where your home lands depends on square footage, HVAC zones, and how much you want running at the same time.
Square footage gives you a rough starting point:
- Under 2,000 sq ft — enough for lights, refrigerator, and one HVAC unit
- 2,000–3,500 sq ft — most Frisco homes; covers full HVAC, kitchen, and water heater
- 3,500 sq ft and up — multiple HVAC zones, EV charger, home office
Square footage alone is not a calculation. A smaller home with electric heat or a large HVAC system can need more capacity than a bigger home with fewer high-demand loads.
The real method is simple. Add the running watts of everything you want on at once, then add the single highest starting wattage on your list.
Understanding Generator Size: What kW Actually Means
Generator size is measured in kilowatts, written as kW. One kilowatt equals 1,000 watts. A 22 kW generator can produce 22,000 watts of power.
That single number hides two different demands your home puts on a generator.
Running watts is what an appliance needs to keep going once it is already on. Your refrigerator hums along at a steady draw. Your lights pull the same amount all evening.
Starting watts is the surge an appliance needs in the first second it turns on. Anything with a motor spikes hard. Your air conditioner is the biggest offender in most Frisco homes.
This is why generators fail on the A/C. The unit handles the running load fine. Then the compressor kicks on, demands several times its normal draw, and the generator cannot deliver it.
Generac recommends leaving headroom — a generator runs best at around 80% of its full capacity. That margin absorbs starting surges and gives you room if your power needs grow later.
So the goal is not the smallest unit that technically works. The goal is a unit that handles your surge, carries your load, and still has room to spare.
How to Calculate Your Home's Real Power Load
The right way to size a generator is to add up what you actually plan to run. Here is the method our electricians use.
Step 1: List what stays on during an outage — Walk your home and write down every appliance you refuse to live without. Refrigerator, lights, A/C, water heater, Wi-Fi router, garage door, sump pump.
Step 2: Find the wattage of each item — Check the owner's manual or the nameplate sticker on the appliance itself. Write down both running watts and starting watts where listed.
Step 3: Add your running watts — Total the running wattage of everything on your list. Say it comes to 8,000 watts.
Step 4: Add the single highest starting wattage — Find the one appliance with the biggest surge. If your central air conditioner needs 5,000 starting watts, add that to your 8,000. Your minimum is 13,000 watts, or 13 kW.
You only add the highest starting wattage, not all of them. Your appliances will not all kick on at the same instant.
Step 5: Leave headroom — That 13 kW is a floor, not a target. Size up from there to run comfortably within capacity.
Undersizing is the failure you feel. The generator trips, and you are sitting in the dark anyway. Oversizing is the failure you pay for — capacity you never touch.
Whole-Home Backup vs. Essential Circuits: Which One Do You Need?
Once you know your load, the next choice is scope. Do you back up the whole house, or just what matters most?
Whole-home backup:
- Every circuit stays live
- Nothing to think about during an outage
- Larger unit, larger install
- Your home runs the way it always does
Essential circuits:
- Only selected circuits stay live
- Smaller unit, smaller install
- You decide in advance what makes the list
- Some things stay dark
Both options run on an automatic transfer switch. That device watches the utility line. When power drops, it disconnects your home from the grid and starts your generator, usually within seconds. When utility power returns, it switches you back.
The Electrical Safety Foundation International notes that transfer switches are not optional — they prevent power from feeding backward into the grid and endangering line crews.
So which do you need? Start with what your household will not give up. In Frisco, that list is short and predictable. Air conditioning in July. Heat during a January freeze. The refrigerator. Wi-Fi, because someone is working from home.
Then ask two more questions. How long could the outage last? And who is home when it happens?
A four-hour outage with adults in the house is an inconvenience. A three-day freeze with kids, elderly parents, or medical equipment is a different problem entirely.
Frisco-Specific Factors That Change Your Generator Size
Every home is different. In Frisco, a few local details shift the math.
Newer construction works in your favor — Much of Frisco was built in the last twenty years. Homes in neighborhoods like Phillips Creek Ranch, Richwoods, and Trinity Falls often already have a 200-amp panel and natural gas run to the house. That usually means no panel upgrade and a cleaner install.
Multiple HVAC zones add real load — Larger homes in Stonebriar or Starwood often run two or three separate systems. Each one carries its own starting surge. Two air conditioners do not double your load — they more than double the demand at startup.
EV chargers are common here — A Level 2 charger is a serious draw. If you have one, or plan to add one, size for it now. Retrofitting capacity later costs more than building it in today.
Texas weather cuts both ways — Summer peak demand and winter storms both stress the grid. Frisco homeowners have lived through outages in both seasons.
HOA rules vary by subdivision — Many Frisco communities require the generator at the side or rear of the home, away from the street. Some require screening with fencing or landscaping. Check your covenants before you choose a location.
Fuel supply matters — Natural gas is available across most of Frisco. Where it is not, propane is the alternative, and tank placement becomes part of the plan.
What Happens During a Professional Generator Load Assessment
A sizing chart gets you close. A load assessment gets you right. Here is what our electricians check when we come to your Frisco home.
At your panel — We look at your service size, usually 100, 150, or 200 amps. We map your breaker layout and identify which circuits feed what. This tells us whether your existing panel can carry a generator, or whether you need a panel upgrade first.
Your HVAC systems — We record the tonnage of each unit and how many zones you run. Starting surge from your air conditioning drives more of the sizing decision than anything else in the house.
Your gas line — A standby generator needs adequate fuel supply. We measure the line size and the distance from your meter. An undersized line starves the unit under load.
Transfer switch placement — We identify where the switch goes and confirm the location meets code.
Permits and inspection — Generator installation in Frisco requires a permit and a final inspection. We handle the paperwork and coordinate with the City of Frisco Building Inspections Department.
We install and service generators from all leading manufacturers, including Generac, Kohler, and Cummins. Our team will help match the right unit to your home and your load.
The assessment is free, and so is the quote. You get a real number, not a guess from a table.
Get Your Generator Sized by a Frisco Electrician
Bringing 50 years of Berkeys expertise to Frisco.
Stop guessing at kilowatts. Our licensed electricians will walk your home, check your panel, measure your load, and give you a firm number. The assessment is free and so is the quote.
Learn more about our Frisco team and the full range of electrical, plumbing, and A/C services we bring to the area.
Call (214) 216-1727 to schedule your free generator sizing consultation.
Business Address: 4645 Avon Ln Suite 260, Frisco, TX 75033
Customer service available 24/7.
We're There When You Need Us!
877-746-6855 
Frequently Asked Questions
For many Frisco homes, yes. A 22 kW unit covers full HVAC, kitchen, water heater, and daily appliances in a typical home. Add a second HVAC zone or an EV charger and you may need more. A load calculation confirms it.
You can, but it works differently. A portable unit requires manual setup and refueling, and it powers only a few circuits. A standby generator starts on its own within seconds and runs on your gas line. If you travel, or if someone at home cannot manage a portable unit, standby is the safer choice.
Often not. Homes built in the last ten to fifteen years usually have a 200-amp panel already, which handles a standby generator without modification. Older homes with 100-amp service frequently do need an upgrade. We confirm this at the assessment.
It trips. The unit carries your running load fine, then your air conditioner tries to start, the surge exceeds capacity, and the generator shuts down. You are left without power during the outage you bought the generator to survive.
As long as fuel holds out. Connected to your natural gas line, a standby unit can run for days. Propane units are limited by tank size.
Berkeys Plumbing, A/C & Electrical in Frisco • 4645 Avon Ln Suite 260, Frisco, TX 75033 • 214-216-1727