--- title: "Waaree WSMD-645 vs Waaree WSMD-665 - Solar Panel Comparison | ComparePV" description: "Compare Waaree WSMD-645 vs Waaree WSMD-665 side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-665" updated: 2026-09-11 --- # Waaree WSMD-645 vs Waaree WSMD-665 665 leads on the differences that matter The largest is module efficiency: 0.64 pp more efficient. 16 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [Waaree WSMD-645](https://comparepv.com/panel/waaree-wsmd-645) | [Waaree WSMD-665](https://comparepv.com/panel/waaree-wsmd-665) | | Manufacturer | Waaree | Waaree | | Power | 645 Wp | 665 Wp | | Efficiency | 20.65 % | 21.29 % | | Technology | PERC | PERC | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | 645 | 665 | Difference | | --- | --- | --- | --- | | Module efficiency | 20.65 % | 21.29 % | +0.64 pp for 665 | | Power density | 206.4 Wp/m² | 212.8 Wp/m² | +6.4 Wp/m² for 665 | | Rated power | 645 Wp | 665 Wp | +20 W for 665 | ## Every compared parameter | Parameter | 645 | 665 | | --- | --- | --- | | Rated power | 645 Wp | 665 Wp | | Module efficiency | 20.65 % | 21.29 % | | Power density | 206.4 Wp/m² | 212.8 Wp/m² | | Open-circuit voltage | 45.94 V | 46.58 V | | Voltage at max power | 37.87 V | 38.10 V | | Short-circuit current | 17.78 A | 18.03 A | | Current at max power | 17.04 A | 17.46 A | | Temperature coefficient | -0.340 %/°C | -0.340 %/°C | | Dimensions | 2400x1302x35 mm | 2400x1302x35 mm | | Module area | 3.125 m² | 3.125 m² | | Weight | 34.5 kg | 34.5 kg | | Weight per kWp | 53.5 kg/kWp | 51.9 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 27 yrs | 27 yrs | | Annual degradation | 0.55 %/yr | 0.55 %/yr | | Cell technology | PERC | PERC | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 132 | 132 | | Bifacial | No | No | ## Thirty-year yield Each panel's own declared degradation curve, at 1,200 kWh/kWp a year Same temp coeff. for both panels (-0.340 %/°C), so a warmer roof scales both curves by the same factor: the totals fall together and neither panel gains on the other. - **Cumulative output, 645:** 20,904 kWh - **Cumulative output, 665:** 21,552 kWh - **Gap:** 648 kWh ## Output when hot | Condition | Cell temperature | 645 | 665 | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 645 W | 665 W | 100.0% of rated power | | Cool, bright day | 40 °C | 612 W | 631 W | 94.9% of rated power | | Typical summer roof | 55 °C | 579 W | 597 W | 89.8% of rated power | | Hot roof | 70 °C | 546 W | 563 W | 84.7% of rated power | ## Against the whole database | Measure | 645 | 665 | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #11,014 | #8,708 | 14,005 | 665 leads by 2,306 places | | Power density | #11,023 | #8,707 | 14,005 | 665 leads by 2,316 places | | Heat behaviour | #8,778 | #8,778 | 14,005 | Tied - the same position in the database | | Weight | #7,451 | #5,294 | 14,005 | 665 leads by 2,157 places | | Warranty | #9,667 | #9,667 | 14,005 | Tied - the same position in the database | | Overall | #4,962 | #3,494 | 14,005 | 665 leads by 1,468 places | ## Questions ### Which panel is better: Waaree WSMD-645 or Waaree WSMD-665? According to our database: **Waaree WSMD-665** has higher module efficiency (**21.29%** vs **20.65%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of Waaree WSMD-645 and Waaree WSMD-665? **Waaree WSMD-645** has a module efficiency of **20.65%**, while **Waaree WSMD-665** is **21.29%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does Waaree WSMD-645 use vs Waaree WSMD-665? **Waaree WSMD-645** uses **PERC** cells; **Waaree WSMD-665** uses **PERC**. Modern **n-type** technologies (**TOPCon**, **HJT**, BC) typically deliver higher efficiency and lower degradation compared to older **PERC** (p-type) cells. ### What is the warranty on Waaree WSMD-645 and Waaree WSMD-665? **Waaree WSMD-645** has a **27 years** power warranty; **Waaree WSMD-665** has a **27 years** power warranty. The power warranty guarantees a minimum percentage of rated output at the end of the warranty period (typically 80**-87%**). Product (materials) warranties are usually shorter. ## Related comparisons - [Waaree WSMD-645 vs Waaree WSMD-660](https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-660) - 3 differences, the largest is module efficiency - [Waaree WSMD-645 vs Waaree WSMD-655](https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-655) - 3 differences, the largest is module efficiency - [Waaree WSMD-645 vs Waaree WSMD-650](https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-650) - The same specification on paper - [Waaree WSMD-645 vs Waaree WSMD-545](https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-545) - 13 differences, the largest is rated power - [Waaree WSMD-645 vs Waaree WSMD-540](https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-540) - 13 differences, the largest is rated power - [Waaree WSMD-645 vs Waaree WSMD-535](https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-535) - 11 differences, the largest is rated power --- Source: https://comparepv.com/compare/waaree-wsmd-645/waaree-wsmd-665 Not in this file, on the page: the thirty-year yield curve year by year at a cell temperature you pick and a written summary generated on request.