--- title: "JA Solar JAM66D45-625/LB vs JA Solar JAM72D42-625/LB - Solar Panel Comparison | ComparePV" description: "Compare JA Solar JAM66D45-625/LB vs JA Solar JAM72D42-625/LB side by side: what actually differs, output when it is hot, thirty-year production, and the full specification." source: "https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam72d42-625-lb" updated: 2026-09-11 --- # JA Solar JAM66D45-625/LB vs JA Solar JAM72D42-625/LB JAM66D45-625/LB leads on the differences that matter The largest is module efficiency: 0.70 pp more efficient. 8 of 19 comparable parameters are identical. ## The two panels | Attribute | A | B | | --- | --- | --- | | Panel | [JA Solar JAM66D45-625/LB](https://comparepv.com/panel/ja-solar-jam66d45-625-lb) | [JA Solar JAM72D42-625/LB](https://comparepv.com/panel/ja-solar-jam72d42-625-lb) | | Manufacturer | JA Solar | JA Solar | | Power | 625 Wp | 625 Wp | | Efficiency | 23.10 % | 22.40 % | | Technology | TOPCon | TOPCon | ## Where they differ Ranked by how much the difference matters, not by datasheet order. | Parameter | JAM66D45-625/LB | JAM72D42-625/LB | Difference | | --- | --- | --- | --- | | Module efficiency | 23.10 % | 22.40 % | +0.70 pp for JAM66D45-625/LB | | Power density | 231.4 Wp/m² | 223.6 Wp/m² | +7.8 Wp/m² for JAM66D45-625/LB | | Module area | 2.701 m² | 2.795 m² | 0.094 m² apart | | Open-circuit voltage | 48.70 V | 52.27 V | 3.57 V apart | | Weight | 33.1 kg | 34.6 kg | -1.5 kg for JAM66D45-625/LB | | Cell count | 132 | 144 | 12 cells apart | | Short-circuit current | 16.15 A | 15.16 A | 0.99 A apart | | Weight per kWp | 53.0 kg/kWp | 55.4 kg/kWp | -2.4 kg/kWp for JAM66D45-625/LB | | Voltage at max power | 40.45 V | 43.71 V | 3.26 V apart | | Current at max power | 15.45 A | 14.30 A | 1.15 A apart | | Dimensions | 2382x1134x30 mm | 2465x1134x30 mm | 2382x1134x30 mm vs 2465x1134x30 mm | ## Every compared parameter | Parameter | JAM66D45-625/LB | JAM72D42-625/LB | | --- | --- | --- | | Rated power | 625 Wp | 625 Wp | | Module efficiency | 23.10 % | 22.40 % | | Power density | 231.4 Wp/m² | 223.6 Wp/m² | | Open-circuit voltage | 48.70 V | 52.27 V | | Voltage at max power | 40.45 V | 43.71 V | | Short-circuit current | 16.15 A | 15.16 A | | Current at max power | 15.45 A | 14.30 A | | Temperature coefficient | -0.290 %/°C | -0.290 %/°C | | Dimensions | 2382x1134x30 mm | 2465x1134x30 mm | | Module area | 2.701 m² | 2.795 m² | | Weight | 33.1 kg | 34.6 kg | | Weight per kWp | 53.0 kg/kWp | 55.4 kg/kWp | | Product warranty | 12 yrs | 12 yrs | | Performance warranty | 30 yrs | 30 yrs | | Annual degradation | 0.40 %/yr | 0.40 %/yr | | Cell technology | TOPCon | TOPCon | | Cell type | Monocrystalline | Monocrystalline | | Cell count | 132 | 144 | | Bifacial | Yes | Yes | ## Thirty-year yield Each panel's own declared degradation curve, at 1,200 kWh/kWp a year Same temp coeff. for both panels (-0.290 %/°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, JAM66D45-625/LB:** 20,970 kWh - **Cumulative output, JAM72D42-625/LB:** 20,970 kWh - **Gap:** No difference ## Output when hot | Condition | Cell temperature | JAM66D45-625/LB | JAM72D42-625/LB | Retained | | --- | --- | --- | --- | --- | | Standard test conditions | 25 °C | 625 W | 625 W | 100.0% of rated power | | Cool, bright day | 40 °C | 598 W | 598 W | 95.7% of rated power | | Typical summer roof | 55 °C | 571 W | 571 W | 91.3% of rated power | | Hot roof | 70 °C | 543 W | 543 W | 87.0% of rated power | ## Against the whole database | Measure | JAM66D45-625/LB | JAM72D42-625/LB | Out of | Note | | --- | --- | --- | --- | --- | | Efficiency | #1,570 | #4,774 | 14,005 | JAM66D45-625/LB leads by 3,204 places | | Power density | #1,513 | #4,955 | 14,005 | JAM66D45-625/LB leads by 3,442 places | | Heat behaviour | #2,165 | #2,165 | 14,005 | Tied - the same position in the database | | Weight | #6,680 | #9,802 | 14,005 | JAM66D45-625/LB leads by 3,122 places | | Warranty | #21 | #21 | 14,005 | Tied - the same position in the database | | Overall | #2,270 | #3,028 | 14,005 | JAM66D45-625/LB leads by 758 places | ## Questions ### Which panel is better: JA Solar JAM66D45-625/LB or JA Solar JAM72D42-625/LB? According to our database: **JA Solar JAM66D45-625/LB** has higher module efficiency (**23.10%** vs **22.40%**). See the full spec comparison and 30-year energy simulation above for a complete picture. ### What is the efficiency of JA Solar JAM66D45-625/LB and JA Solar JAM72D42-625/LB? **JA Solar JAM66D45-625/LB** has a module efficiency of **23.10%**, while **JA Solar JAM72D42-625/LB** is **22.40%**. Higher efficiency means more electricity from the same roof area - useful when space is limited. ### What cell technology does JA Solar JAM66D45-625/LB use vs JA Solar JAM72D42-625/LB? **JA Solar JAM66D45-625/LB** uses **TOPCon** cells; **JA Solar JAM72D42-625/LB** uses **TOPCon**. 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 JA Solar JAM66D45-625/LB and JA Solar JAM72D42-625/LB? **JA Solar JAM66D45-625/LB** has a **30 years** power warranty; **JA Solar JAM72D42-625/LB** has a **30 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. ### Are JA Solar JAM66D45-625/LB and JA Solar JAM72D42-625/LB bifacial panels? Both **JA Solar JAM66D45-625/LB** and **JA Solar JAM72D42-625/LB** are bifacial - they capture reflected light from the ground, which can add 5**-15%** more annual energy on ground-mount or elevated rooftop installations with a light surface beneath. ## Related comparisons - [JA Solar JAM66D45-625/LB vs JA Solar JAM66D45-630/LB](https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam66d45-630-lb) - One difference: module efficiency - [JA Solar JAM66D45-625/LB vs JA Solar JAM66D45-620/LB](https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam66d45-620-lb) - The same specification on paper - [JA Solar JAM66D45-625/LB vs JA Solar JAM66D45-615/LB](https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam66d45-615-lb) - 3 differences, the largest is module efficiency - [JA Solar JAM66D45-625/LB vs JA Solar JAM66D45-610/LB](https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam66d45-610-lb) - 3 differences, the largest is module efficiency - [JA Solar JAM66D45-625/LB vs JA Solar JAM66D45-605/LB](https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam66d45-605-lb) - 3 differences, the largest is module efficiency - [JA Solar JAM66D45-625/LB vs JA Solar JAM72D30-580/LB/1500V](https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam72d30-580-lb-1500v) - 14 differences, the largest is module efficiency --- Source: https://comparepv.com/compare/ja-solar-jam66d45-625-lb/ja-solar-jam72d42-625-lb 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.