Choosing the right generator size is the fastest way to avoid two common problems: buying too small and tripping overload, or buying too large and wasting fuel and budget. Whether your customers need backup power for a home, quiet electricity for an RV, or reliable output for tools on a jobsite, the sizing logic is the same—match the generator to real running demand and motor starting surge.
As a generator manufacturer, Erayak designs each power tier around typical use cases, so distributors and end users can select confidently with minimal guesswork. The guide below breaks sizing into simple levels, from quick rules to a practical example.
Level 1 — The Simple Idea (for fast decisions)
Choosing a generator is about two numbers:
1. Running watts — what you need continuously.
2. Starting watts — the extra burst needed when motors start.
Erayak tip: All Erayak generators provide clear running/starting watt labels, making sizing straightforward for distributors and end users.
Level 2 — Understand Your Loads (what customers want to power)
2.1 Two load groups
A) Motor loads (need surge): Fridge, freezer, AC, pumps, air compressors, power tools.
A practical rule: starting watts are often ~3× running watts.
B) Non-motor loads (steady use): Lights, TV, Wi‑Fi/router, chargers, microwave, coffee maker.
Starting watts ≈ running watts.
Erayak positioning:
• For mixed loads (tools + motors), Erayak open‑frame portable generators are a cost‑effective choice.
• For electronics‑heavy use (routers, laptops, medical devices), Erayak inverter generators deliver cleaner, stable output.
Level 3 — The Easy Sizing Method (most buyers use)
Step 1: List what will run at the same time.
Step 2: Add up running watts.
Step 3: Add extra starting watts for motor devices.
Extra starting watts ≈ running watts × 2.
Step 4: Add a comfort buffer (recommend 80–90% rated usage).
Quick formula:
Generator size ≈ (Total running watts + Largest extra starting watts) × 1.2
Erayak tip: When buyers are uncertain, suggest moving up one Erayak size tier.
Level 4 — Example (ready for customer materials)
Scenario: Essentials backup
Device | Running W | Motor?
Refrigerator | 700 | Yes
Microwave | 1200 | No
TV + router | 250 | No
Lights | 300 | No
Running total = 2450 W
Extra starting watts (fridge) ≈ 1400 W
Add buffer: (2450 + 1400) × 1.2 ≈ 4620 W
Recommendation: An Erayak generator in the 4.5–5.0 kW running class with sufficient surge.
Erayak product nudge: This sits in our mid‑range home‑backup line.
Level 5 — Choose a Size Tier (Erayak product buckets)
5.1 Entry Tier: 1–3 kW class
Best for: camping, RV, tailgating, small outages.
Erayak fit: compact inverter generators—quiet, stable, fuel‑efficient.
5.2 Mid Tier: 3–7 kW class
Best for: home essentials backup, small retail sites, mobile work.
Erayak fit: core best‑seller range in inverter and open‑frame:
• Inverter models for clean power + low noise
• Open‑frame models for stronger motor starting and better price‑per‑watt
5.3 High Tier: 7 kW+ class
Best for: whole‑home partial backup, farms, job sites, light commercial.
Erayak fit: high‑output portable and standby‑ready generators for long runtime and robust surge loads.
Level 6 — Pick the Right Type (how Erayak simplifies choice)
Choose if: price sensitivity, tools/motors/pumps, noise less critical.
Erayak advantage: reliable surge and easy serviceability.
Choose if: electronics/sensitive devices, low noise, variable loads.
Erayak advantage: clean sine‑wave output and superior partial‑load efficiency.
Standby / ATS‑capable Setup
Choose if: automatic backup, critical uptime.
Erayak note: ATS‑compatible solutions in selected ranges—confirm voltage/phase.
Level 7 — Safety & Usage Notes
• Never use generators indoors or in enclosed spaces.
• Keep exhaust away from windows/vents.
• Use correctly rated cables and avoid overload.
• If usage is regularly >90% load, step up one Erayak tier.
Level 8 — Distributor / Buyer Checklist (Erayak sales tool)
Ask buyers for:
1. Load list (simultaneous use)
2. Running watts or nameplate amps
3. Motor devices
4. Voltage / frequency / phase
5. Expected runtime per day
6. Noise limit
7. Environment (altitude / hot climate)