How the power station calculator works
Pick the appliances you want to run, set how many days you need power, and the calculator sizes your battery in real-world watt-hours. It checks three numbers against every portable power station and solar generator we have in stock:
- Running load (W): the watts of everything running at the same time. A station's continuous output has to cover this.
- Startup surge (W): motors and compressors, like refrigerators, well pumps and air conditioners, pull 2 to 3 times their running watts for a second when they start. A station's surge rating has to cover your running load plus the largest single startup.
- Energy per day (Wh): each appliance's average watts multiplied by the hours it runs. Multiply by the number of days you need and you get the battery capacity you need.
Rated Wh vs. usable Wh
A battery's rated capacity is not what you can actually use. Inverter losses, the battery management system and cold weather all take a share. We size every recommendation with the same rule used on our product pages: usable Wh = rated Wh x 0.85. A 3,072Wh portable power station gives you about 2,611Wh of real-world power.
Typical appliance power use
These are the starting values in the calculator. Check the label on your own device and adjust the watts and hours to match.
| Appliance | Average watts | Typical daily use |
|---|---|---|
| Refrigerator (full-size) | 60W average (150W running) | 24 hours |
| Chest freezer | 40W average (100W running) | 24 hours |
| 12V compressor fridge | 50W average | 24 hours |
| Wi-Fi router and modem | 20W | 24 hours |
| LED light bulb | 10W | 5 hours |
| Laptop and monitor | 100W | 8 hours |
| Starlink (standard) | 75W | 8 hours |
| TV (55 inch LED) | 100W | 4 hours |
| Microwave | 1,500W | 15 minutes |
| Window AC (5,000 BTU) | 500W | 6 hours |
| RV rooftop AC (13,500 BTU) | 1,300W | 4 hours |
| Space heater | 1,500W | 2 hours |
Example: keeping a refrigerator running during a power outage
A full-size refrigerator averages about 60W as its compressor cycles on and off. Over 24 hours that is about 1,440Wh of usable energy, or about 1,700Wh of rated capacity once you divide by 0.85. For a 3-day outage, plan on roughly 5,100Wh rated for the fridge alone. Add a Wi-Fi router, a few LED lights and phone charging and most homes land between 6,000Wh and 9,000Wh rated, which usually means a 3,000Wh to 4,000Wh portable power station plus one or two expansion batteries, or a solar generator kit that recharges during the day.
Adding solar
When you choose solar recharging, the calculator estimates daily solar output as: panel watts (capped at the station's maximum solar input) x 4.5 peak sun hours x 75% real-world efficiency. A 600W panel array adds about 2,000Wh on a sunny day. Your location, season, panel angle and shade will change this.
Frequently asked questions
What size power station do I need to run a refrigerator?
For one day, a portable power station of about 2,000Wh rated covers a typical full-size refrigerator with room for a few small devices. For several days without recharging, plan on about 1,700Wh rated per day, or pair a smaller station with solar panels.
Can a portable power station run an RV air conditioner?
A 13,500 BTU rooftop unit runs at about 1,300W but can surge to 2,500W to 3,500W when the compressor starts. You need a station with enough surge capacity and, for most RVs, a 30A TT-30 outlet. A soft-start kit on the AC lowers the startup surge. Expect a few hours of run time per charge, not a full day.
Why does the calculator only show some products?
It only recommends portable power stations and solar generator kits that are in stock and ready to ship, and that can handle both your running load and startup surge. Pre-order items are left out, so everything it recommends is ready to ship.
Are these numbers exact?
No. They are planning estimates based on typical appliance use and the manufacturer's published specs. Real run time varies with temperature, battery age, and how often appliances cycle. If you are sizing a larger system, call or text us and a real person will help.
Why buy from Reserve Power Co.
We are an authorized dealer for every brand we carry, including Pecron, Aferiy, Lion Energy, Comvolt Energy and Renogy. Every order ships free within the Lower 48, every product is backed by the manufacturer's warranty, and our price match guarantee means you don't have to shop around.