How to size a portable power system for your home: a step-by-step guide for 2026

The single most common question we get at Reserve Power Co. is some version of: "How do I know which size station I actually need?" It's a fair question, and the answer is more straightforward than most people expect once you have a framework to work from.

This guide walks you through exactly how to size a portable power system for home backup use — from listing what you want to power to calculating battery capacity to choosing a recharge strategy. By the end, you'll know precisely what to look for and why.

Step 1: Decide what you want to power

Start with a simple list. Write down every device you'd want to keep running during a power outage. Don't filter yet — just inventory everything. The list typically breaks into three tiers:

• Non-negotiables: Medical devices (CPAP, oxygen concentrators), refrigerator, lighting, phone charging. These are the devices an outage cannot interrupt.
• High comfort: Fans, television, internet router, laptop. These make an outage livable rather than just survivable.
• Nice to have: Small appliances, electric blankets, window AC unit. Possible with a larger system; lower priority for basic backup.

Your tier-one devices define your minimum viable system. Everything else expands from there.

Step 2: Find the wattage of each device

Every device has a wattage — the rate at which it consumes power while running. Check the back of the device, the manual, or the manufacturer's website. Here are reliable benchmarks for common household devices:

Step 3: Calculate your simultaneous load (inverter wattage requirement)

Add up the running wattage of everything you'd want to operate at the same time. This number tells you the minimum inverter output your station needs to sustain.

Example — a typical household running tier-one essentials simultaneously:

• Refrigerator: 150W
• CPAP machine: 45W
• LED lights (x6): 60W
• Phone charging (x2): 40W
• Internet router: 15W
• Laptop: 65W

Total simultaneous draw: 375W. You need a station with at least 400W of continuous inverter output — but realistically, you want 2,000W+ to give yourself headroom when the fridge compressor kicks on (startup surge) and space to add devices without approaching the inverter ceiling.

Step 4: Calculate your daily watt-hour requirement (battery capacity)

Battery capacity, measured in watt-hours (Wh), determines how long your system can run before it needs to recharge. Calculate it by multiplying each device's wattage by the hours per day you'd run it, then summing the results.

Continuing the example above — assuming 24-hour coverage:

• Refrigerator (150W × 24h, compressor cycles ~30% of the time): ~1,080Wh
• CPAP (45W × 8h): 360Wh
• LED lights (60W × 6h): 360Wh
• Phone charging (40W × 2h): 80Wh
• Router (15W × 24h): 360Wh
• Laptop (65W × 4h): 260Wh

Total: approximately 2,500Wh per day. A 3,000Wh station covers one full day of essentials with a comfortable buffer. A 2,000Wh station covers roughly 18–20 hours.

Step 5: Match to a real product

With your two numbers — simultaneous load (inverter watts) and daily capacity (Wh) — you can match directly to a station:

• Under 2,000W simultaneous / under 2,000Wh daily: The AFERIY P280 (2,800W, 2,048Wh) or PECRON E2400LFP (2,400W, 2,048Wh) cover most households comfortably.
• 2,000–3,000W simultaneous / 2,000–3,000Wh daily: The PECRON F3000LFP (3,600W, 3,072Wh) or AFERIY P310 (3,600W, 3,840Wh) are the right targets.
• Need expandability for multi-day outages: The AFERIY P280 expands to 10,240Wh; the AFERIY P310 expands to 11,520Wh. Add batteries as your needs grow.
• Need rugged outdoor durability alongside home backup: The Arkpax Ark PRO (2,400W, 2,300Wh, expandable to 25.3kWh) adds IP67 weatherproofing to a full-featured system.

Step 6: Plan your recharge strategy

A power station is only as useful as your ability to refill it. There are three primary recharge sources, and you'll likely want a combination:

• AC wall power: The fastest and most reliable option when the grid is up. Most of our stations charge in 1.5–2 hours at full AC input. Pre-charge before a predicted storm and you're ready before the outage hits.
• Solar panels: The independence play. Pair a 2,000–3,000Wh station with 400–800W of panels and you can cover most daily essential loads indefinitely on good sun days. Solar recharge speed depends on panel wattage and sun hours — figure 4–6 peak sun hours per day in most of the US.
• Car charging: Useful for overlanders and emergency situations, but slow (typically 100–240W depending on the station). Best as a supplement, not a primary recharge source.

For home backup, we recommend choosing a station that can accept at least 400W of solar input, even if you don't buy panels immediately. It keeps your options open as outage durations grow longer and more unpredictable.

The bottom line

Most households running essential loads for 12–24 hours need a station in the 2,000–3,500Wh range with 2,000W+ inverter capacity. Families with medical equipment, larger homes, or multi-day outage risk should think about expandable systems in the 3,000Wh+ range with solar pairing.

Not sure where you land? We offer free pre-purchase consultation — just reach out via the contact page or live chat at reservepowerco.com. We'll walk through your specific devices, usage patterns, and budget and come back with a concrete recommendation. No obligation, no pressure.

And right now, use code SPRING10 for 10% off your purchase. Free shipping on every order.