Pure sine vs modified sine — inverter honesty
Which devices care (motors, medical gear, sensitive electronics), marketing vs reality, and when a cheaper modified-sine inverter is actually fine. Most current ~1 kWh apartment kits QuietWatt tracks advertise pure sine — still verify the SKU.
What the labels mean (without the brochure)
- Pure sine (PSW). AC output that closely matches utility waveform. Better for inductive motors, many medical bricks, audio gear, and devices with “dirty power” fussy PSUs. Default ask for CPAP / medical backup — CPAP overnight · medical device backup (power math only — not medical advice).
- Modified / square-ish sine (MSW). Stepped approximation. Cheaper inverters historically. Fine for many resistive heaters, simple phone bricks, and some tools — can buzz motors, overheat some clocks/PSUs, or refuse to start compressors cleanly.
- Marketing vs reality. “Pure sine” on a box does not fix undersized Wh or continuous watts. An induction cooktop that wants 1,500 W+ still loses on a 600 W inverter — waveform is irrelevant if the watt ceiling is wrong. See induction / hot plate · Wh class guide.
- UPS transfer ≠ waveform. Fast switchover and clean sine are separate axes. Transfer/Wh/expand/noise: UPS vs portable station · pass-through caveats: pass-through charging.
Specs and product examples below from manufacturer pages (checked Oct 2026). Device-fit notes are honesty framing / estimates — not lab certification or medical advice. Always follow your device and station manuals.
Which devices actually care
Motors / compressors
Medical / CPAP class
Sensitive electronics
Resistive / simple loads
When modified sine is fine — and when to ignore the slogan
MSW can win when…
Buy pure sine when…
Ignore “pure sine” when…
Cross-link: CPAP overnight · medical device backup · induction / hot plate · fridge runtime · UPS vs portable station · pass-through / UPS mode. Estimates only. Not medical advice.
Current mid stations QuietWatt tracks (PSW-labelled class)
Filter by role. Confirm “pure sine” on the live OEM page — QuietWatt does not re-test waveforms.
| Model | Wh · waveform note | Why it lands here | Approx. USD |
|---|---|---|---|
| EcoFlow RIVER 3 Plus Compact | 286 Wh · pure sine class (EcoFlow AC inverter) | Electronics / CPAP-light kits — not a fridge night. Waveform ≠ Wh. | ~$180–300 |
| Jackery Explorer 1000 v2 Quiet apt | 1,070 Wh · pure sine (mfr) | Stairs-friendly ~1 kWh PSW for sleep / desk / many fridge duty cycles (estimate). | ~$499–589 |
| BLUETTI Elite 100 V2 Value | 1,024 Wh · pure sine-wave inverter (BLUETTI) | Common QuietWatt CPAP / apartment cite — confirm continuous W for motors. | ~$380–500 |
| Anker SOLIX C1000 Expand | 1,056 Wh · pure sine class + UPS <20 ms (mfr) | PSW + expand path — waveform plus Wh for multi-hour WFH / storm. | ~$400–600 |
| EcoFlow DELTA 3 Plus Storm / expand | 1,024 Wh · pure sine class · expand toward ~5 kWh | Higher continuous W headroom for cooktop / fridge jobs that still need PSW. | ~$600–900+ |
| BLUETTI AC200L Longer | 2,048 Wh · pure sine wave (BLUETTI) | Multi-night essentials — still indoor-safe vs petrol gen; heavy floor unit. | ~$800–1,100 |
| Anker SOLIX C300 Grab-and-go | 288 Wh · pure sine class (compact) | Phones / modem / laptop brick — not induction or medical-high-draw. | ~$200–280 |
QuietWatt is independent. We do not sell stations or certify waveforms. “Pure sine” on a listing does not change Wh math, lease rules, or medical guidance. Runtime figures are estimates. Medical / CPAP notes are not medical advice.
Where to buy (affiliate placeholders)
Tracked affiliate links will replace these placeholders once QuietWatt is enrolled in each program. Until then, use the official product URLs in the table above.
Placeholder anchors: #aff-ecoflow, #aff-bluetti,
#aff-anker, #aff-jackery, #aff-amazon.