--- title: "JA Solar JAM66D42-605/MB Solar Panel: Specs & Datasheet | ComparePV" description: "JA Solar JAM66D42-605/MB solar panel. Specs: 23.40% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/ja-solar-jam66d42-605-mb" image: "https://comparepv.com/og/panel/ja-solar-jam66d42-605-mb.png" updated: 2026-09-11 --- # JA Solar JAM66D42-605/MB Space saver, no clear weak spot 1,085 panels in the segment TOPCon 600-650 W ## Identity - **Manufacturer:** JA Solar - **Model:** JAM66D42-605/MB - **Series:** JAM66D42 MB - **Rated power:** 605 W - **Cell technology:** TOPCon - **Bifacial:** yes ## How it compares Compared against segment TOPCon 600-650 W (1085 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 605 W | 620 W | Weak - bottom 15% | | | Module efficiency | 23.40% | 22.80% | Strong - top 12% | 919 | | Power density | 234.2 | 227.7 | Strong - top 11% | 900 | | Temperature coefficient | -0.290 | -0.290 | Typical | 2,220 | | Weight (kg) | 31.8 kg | 32.8 kg | Typical | | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 23.40% | 22.80% | Strong - top 12% | 919 | | Power density | 234.2 | 227.7 | Strong - top 11% | 900 | | Temperature coefficient | -0.290 | -0.290 | Typical | 2,220 | | Weight per kWp | 52.6 | 53.1 | Typical | 6,237 | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Strengths - **234.2 watts per square metre** - Top 11% of the TOPCon 600-650 W segment, against a median of 227.7. - **23.40% module efficiency** - Top 12% of the TOPCon 600-650 W segment, against a median of 22.80%. - **Best for:** Commercial, utility-scale and shaded-installations. ## Specification ### Electrical - **Rated power (Pmax):** 605 W - **Efficiency:** 23.40 % - **Voltage at Pmax (Vmp):** 41.44 V - **Current at Pmax (Imp):** 14.60 A - **Open-circuit voltage (Voc):** 49.19 V - **Short-circuit current (Isc):** 15.46 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.290 %/degC - **Temperature coefficient of Voc:** -0.250 %/degC - **Temperature coefficient of Isc:** 0.045 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** TOPCon - **Cell count:** 132 - **Bifacial:** yes - **Bifacial gain:** 10.00 ### Physical - **Length:** 2278 mm - **Width:** 1134 mm - **Thickness:** 30 mm - **Weight:** 31.8 kg - **Area:** 2.58 m2 - **Power density:** 234.2 Wp/m2 ### Warranty and degradation - **Product warranty:** 12 years - **Performance warranty:** 30 years - **Output guaranteed at end of warranty:** 87.4 % - **First-year degradation:** 1.00 % - **Annual degradation:** 0.40 % - **Output after 30 years:** 529 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 919 of 14129 | | Power density | 900 of 14129 | | Temperature coefficient | 2220 of 14129 | | Weight | 6237 of 14129 | | Warranty | 21 of 14129 | ## Pros - **Low temperature coefficient - N-type TOPCon** - The temperature coefficient of Pmax is -0.29 %/°C, significantly better than the typical -0.34 to -0.35 %/°C of P-type PERC modules. This translates to measurably higher energy yield during summer peak-irradiance hours, a critical advantage for large utility-scale PV farms. - **22.5-23.4% efficiency - above peer median** - The series reaches up to 23.4% module efficiency, well above comparably priced peers: JS Solar JS210MHC120 (21.4%) and LEDVANCE M585-605P60UB (21.37%). This equates to approximately 9-10% more energy per unit of roof or land area compared to those alternatives at the same power class. - **Bifacial double glass - durability and rear-side gain** - The double-glass construction eliminates the rear EVA backsheet as a degradation vector, reducing LID/PID risk. The bifacial design enables an additional 5-15% energy gain via ground albedo reflection, particularly valuable on PV farms with light-colored gravel surfaces or seasonal snow cover. - **30-year linear performance warranty - min. 87.4% power** - JA Solar guarantees ≥87.4% of rated power output after 30 years, with an annual degradation rate of 0.4% and a first-year cap of ≤1%. This is among the more stringent performance thresholds in the large-format TOPCon segment, directly de-risking project LCOE projections over a 25-30 year horizon. - **BNEF Tier-1 bankability + IEC certifications** - JA Solar maintains a continuous BNEF Tier-1 listing, a prerequisite for non-recourse project financing on assets exceeding 10 MW. The module holds IEC 61215, IEC 61730, and UL 61730 certifications, with a mechanical load rating of 5,400 Pa (snow) / 2,400 Pa (wind), qualifying it for utility-scale deployment in temperate and continental climate zones. ## Cons - **12-year product warranty - below segment leaders** - Within the premium TOPCon class, Jinko Tiger Neo 3.0 offers a 15-year product warranty, meaning the JAM66D42 MB falls 3 years short in factory-defect coverage. For EPC projects with O&M contracts exceeding 12 years, this gap may necessitate additional module insurance or warranty top-up arrangements. ## About this series JA Solar JAM66D42 MB series modules are designed for installations where high energy yield from the same surface area and stable performance over years are crucial - especially for commercial rooftops and utility-scale PV farms. These modules feature **N-type TOPCon cells**, which maintain their parameters better in the long term and are less susceptible to typical operational losses, effectively mitigating the risk of disappointment with production after several seasons. The **double glass construction** enhances resistance to environmental conditions and improves laminate durability, which is vital for projects with a long payback period. Thanks to **bifacial technology**, the module can utilize reflected light from the ground, boosting energy yield where every percentage point counts. The semi-lattice design supports **better tolerance to partial shading** and minimizes connection losses, while the refined cell architecture aids performance under lower irradiance. This is an excellent choice for investors, EPC contractors, and companies optimizing LCOE who seek advantages over standard P-type PERC modules. ## Notable figures - At 23.4% efficiency, this panel is 0.6pp above typical \*\*TOPCon 600-650W\*\* modules (median: 22.8%) - 234.2 W/m² power density - 6.5 W/m² more than \*\*TOPCon 600-650W\*\* median (227.7 W/m²), more power per roof area - Temperature coefficient of -0.29%/°C matches the \*\*TOPCon 600-650W\*\* median - Bifaciality factor of 80% can add 4-12% extra yield with reflective mounting surface - #919 for efficiency, #2220 for temperature performance out of 14129 panels ## Questions ### What warranty does JA Solar offer for the JAM66D42 MB series? JA Solar provides a 12-year product warranty and a 30-year linear power warranty for the JAM66D42 MB series. Under the power warranty, degradation is capped at 1% in the first year and no more than 0.4% per year thereafter, guaranteeing at least 87.4% of nameplate power after 30 years. This is among the best degradation specs currently available for N-type TOPCon modules. ### How do N-type TOPCon cells in the JAM66D42 MB differ from standard PERC cells? N-type TOPCon cells eliminate light-induced degradation (LID) common in P-type silicon and are less sensitive to boron-oxygen defects, resulting in more stable long-term output. The JAM66D42 MB achieves module efficiency up to 23.4%, compared to the 21-22% typical of PERC modules. Over a 30-year system life, this translates to meaningfully higher energy yield from the same roof area, directly improving LCOE. ### Does the bifacial design of the JAM66D42 MB actually increase energy output on a commercial rooftop? Yes - the bifacial rear side captures light reflected from the surface below. On light-colored roofing membranes (white TPO, gravel ballast) the bifacial gain typically ranges from 5 to 15% above a monofacial module of equal nameplate power. The gain is lower on dark bituminous roofs and higher on ground-mount systems over light-colored soil or white geotextile. An accurate MPPT-based simulation will quantify the site-specific yield. ### What mechanical load ratings does the JAM66D42 MB carry - is it suitable for heavy-snow regions? The JAM66D42 MB is rated for snow loads up to 5400 Pa and wind loads up to 2400 Pa. The double-glass construction adds rigidity that prevents frame deformation under asymmetric load. For reference, standard backsheet modules are typically rated at 2400-4000 Pa. This makes the series a reliable choice for industrial rooftops and ground-mount farms in regions with significant snowfall. ### What are the dimensions and weight of the JAM66D42 MB - is it safe to install on an older industrial roof? The module measures 2278 × 1134 × 30 mm and weighs 31.8 kg, reflecting the double-glass construction. This is roughly 3-4 kg heavier than comparable backsheet modules. Before installing on an older industrial roof, a structural engineering assessment is recommended. For new buildings or roofs that have passed a load audit, these dimensions present no special challenges. ### Does the JAM66D42 MB perform well in low temperatures and overcast winter conditions? The JAM66D42 MB has a power temperature coefficient of -0.30%/°C, which is better than typical P-type PERC modules at -0.35%/°C. This means on cold, sunny winter days the module produces comparatively more power. The half-cut cell layout also improves tolerance to partial shading and diffuse irradiance, extending the effective daily production window during overcast northern European winters. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/4eb0807968d7afe-5accda1bea21.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-A650-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a650-mae72mw) | 650 W | +45 W, lighter, +1.8 pp | | [AIKO AIKO-A645-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a645-mae72mw) | 645 W | +40 W, lighter, +1.6 pp | | [Longi Solar LR7-60HVH-560M](https://comparepv.com/panel/longi-lr7-60hvh-560m) | 560 W | -45 W, lighter, +1.4 pp | | [AIKO AIKO-A640-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a640-mae72mw) | 640 W | +35 W, lighter, +1.4 pp | | [Longi Solar LR7-60HVH-555M](https://comparepv.com/panel/longi-lr7-60hvh-555m) | 555 W | -50 W, lighter, +1.2 pp | | [AIKO AIKO-A635-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a635-mae72mw) | 635 W | +30 W, lighter, +1.2 pp | | [JA Solar JAM72D30-525/MB/1500V](https://comparepv.com/panel/ja-solar-jam72d30-525-mb-1500v) | 525 W | -80 W, hotter, -3.1 pp | | [JA Solar JAM72S30-530/MR](https://comparepv.com/panel/ja-solar-jam72s30-530-mr) | 530 W | -75 W, hotter, -2.9 pp | | [JA Solar JAM72S30-535/MR](https://comparepv.com/panel/ja-solar-jam72s30-535-mr) | 535 W | -70 W, hotter, -2.7 pp | | [JA Solar JAM72S30-540/MR](https://comparepv.com/panel/ja-solar-jam72s30-540-mr) | 540 W | -65 W, hotter, -2.5 pp | | [AIKO AIKO-A630-MAH72Dw](https://comparepv.com/panel/aiko-aiko-a630-mah72dw) | 630 W | +25 W, cooler, +1.0 pp | --- Source: https://comparepv.com/panel/ja-solar-jam66d42-605-mb Not in this file, on the page: a thirty-year output simulator, a bifacial gain calculator and alternatives filtered by how closely they match these dimensions.