What to Look for When Buying a Home Generator
Walk into any hardware store or browse online, and you'll find dozens of generators with overlapping specs and confusing marketing language. Before you spend several hundred — or several thousand — dollars, it pays to know exactly what features matter and which are just selling points. Here are the 7 most important factors to evaluate before buying a home generator.
1. Power Output (Watts)
This is the single most critical spec. Generators list two wattage figures:
- Running (rated) watts: The continuous power the generator can deliver.
- Starting (surge) watts: A brief burst of extra power for starting motors in fridges, AC units, and pumps.
Add up the running wattage of all appliances you need to power simultaneously, then make sure the generator's running watts exceed that total. Size up rather than down — running a generator at or near its maximum load shortens its lifespan.
2. Fuel Type
Each fuel option has trade-offs:
- Gasoline: Widely available, but has a short shelf life (3–6 months with stabilizer) and requires storage planning.
- Propane: Stores indefinitely, burns cleaner, but you need tanks on hand and output may be slightly lower.
- Dual-fuel: Runs on both gasoline and propane — excellent flexibility during extended outages when one fuel may be scarce.
- Natural gas: Ideal for standby generators; connected directly to your home supply so you never run out.
- Diesel: Efficient and durable, common in commercial/industrial units; fuel can gel in cold temperatures.
3. Runtime Per Tank
Look for how long the generator runs at 50% load on a full tank. Longer runtime means fewer refueling interruptions during an outage. A good portable generator should run at least 8–10 hours on a tank. Standby generators on natural gas have essentially unlimited runtime.
4. Noise Level
Generators are measured in decibels (dB) at a set distance (usually 23 feet). For reference:
- Under 60 dB — Quiet (similar to a normal conversation)
- 60–70 dB — Moderate (like a vacuum cleaner)
- 70+ dB — Loud (some municipalities restrict this level)
Inverter generators are significantly quieter than conventional models and adjust engine speed to match load, saving fuel in the process. They're worth the extra cost if noise is a concern.
5. Total Harmonic Distortion (THD)
If you plan to run sensitive electronics — laptops, TVs, medical equipment — pay attention to THD. Conventional generators produce "dirtier" power with higher THD (often 10–25%), which can damage sensitive devices. Inverter generators typically produce THD below 3%, making them safe for electronics.
6. Transfer Switch Compatibility
To safely connect a generator to your home's circuits, you need a transfer switch — a device that disconnects your home from the grid before connecting the generator. Never back-feed into the grid; it's dangerous and illegal. Check whether the generator you're considering is compatible with a manual or automatic transfer switch, or whether it has a built-in transfer switch option.
7. Portability & Convenience Features
For portable units, practical features matter a lot:
- Wheel kit and folding handles for easy movement
- Electric start (vs. recoil/pull start) for convenience, especially in cold weather
- Low-oil shutoff to protect the engine automatically
- CO shutoff sensor — now required on newer models, shuts the generator down if carbon monoxide builds up nearby
- Multiple outlet types including 30A and 50A outlets for RV/larger loads
Final Checklist Before You Buy
- Calculate total wattage needed (don't forget surge loads)
- Choose the right fuel type for your situation
- Match runtime to your expected outage length
- Check noise level against local ordinances
- Prioritize low THD if running sensitive electronics
- Plan for a proper transfer switch installation
- Look for safety features like CO shutoff
Taking a methodical approach means you won't overpay for power you don't need — or worse, end up underpowered when it counts most.