--- title: "Tongwei TWMNH-66HD645 645W Solar Panel - Specs & Review | ComparePV" description: "Tongwei TWMNH-66HD645 645W solar panel. Specs: 23.90% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/tongwei-solar-twmnh-66hd645" updated: 2026-09-11 --- # Tongwei TWMNH-66HD645 Efficiency leader, no clear weak spot 359 panels in the segment N-type 600-650 W ## Identity - **Manufacturer:** Tongwei - **Model:** TWMNH-66HD645 - **Series:** TWMNH-66HD - **Rated power:** 645 W - **Cell technology:** N-type - **Bifacial:** yes ## How it compares Compared against segment N-type 600-650 W (359 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 645 W | 625 W | Strong - top 3% | | | Module efficiency | 23.90% | 22.77% | Strong - top 2% | 351 | | Power density | 238.8 | 227.7 | Strong - top 2% | 356 | | Temperature coefficient | -0.280 | -0.290 | Strong - top 14% | 1,309 | | Weight (kg) | 32.2 kg | 32.5 kg | Typical | | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 23.90% | 22.77% | Strong - top 2% | 351 | | Power density | 238.8 | 227.7 | Strong - top 2% | 356 | | Temperature coefficient | -0.280 | -0.290 | Strong - top 14% | 1,309 | | Weight per kWp | 49.9 | 52.7 | Typical | 3,293 | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Strengths - **23.90% module efficiency** - Top 2% of the N-type 600-650 W segment, against a median of 22.77%. Ranked 351st in the whole database. - **238.8 watts per square metre** - Top 2% of the N-type 600-650 W segment, against a median of 227.7. Ranked 356th in the whole database. - **-0.280 %/°C temperature coefficient** - Top 14% of the N-type 600-650 W segment, against a median of -0.290. - **Best for:** Commercial, utility-scale and shaded-installations. ## Specification ### Electrical - **Rated power (Pmax):** 645 W - **Efficiency:** 23.90 % - **Voltage at Pmax (Vmp):** 41.51 V - **Current at Pmax (Imp):** 15.54 A - **Open-circuit voltage (Voc):** 49.85 V - **Short-circuit current (Isc):** 16.39 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.280 %/degC - **Temperature coefficient of Voc:** -0.240 %/degC - **Temperature coefficient of Isc:** 0.046 %/degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** N-type - **Cell count:** 132 - **Bifacial:** yes ### Physical - **Length:** 2382 mm - **Width:** 1134 mm - **Thickness:** 30 mm - **Weight:** 32.2 kg - **Area:** 2.70 m2 - **Power density:** 238.8 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:** 564 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 351 of 14005 | | Power density | 356 of 14005 | | Temperature coefficient | 1309 of 14005 | | Weight | 3293 of 14005 | | Warranty | 21 of 14005 | ## About this series Tongwei TWMNH-66HD series are N-type half-cut modules designed for high energy yield in real-world operating conditions - including low irradiance and applications subject to periodic shading. The key advantage lies in combining technologies boosting both-sided gain with solutions enhancing long-term reliability: **high bifaciality** translates to additional rear-side generation, while **ultra-low degradation** helps maintain predictable energy production for years. This series also features **908 Technology (0BB)**, an interconnection architecture minimizing optical losses and improving resistance to micro-cracking, crucial during transport and operation. Furthermore, **Stencil Printing** and **TPE** support metallization precision and cell performance quality, contributing to stable parameters. The TWMNH-66HD is ideal for C&I and utility-scale PV farms, where low LCOE, reliability, and maximum yield per square meter matter. ## Notable figures - Efficiency of 23.9% is 1.1pp above the \*\*N-type 600-650W\*\* median (22.8%) - Power density of 238.8 W/m² packs 11.1 W/m² more into the same footprint vs \*\*N-type 600-650W\*\* median (227.7 W/m²) - Temperature coefficient of -0.28%/°C matches the \*\*N-type 600-650W\*\* median - Bifacial design (80% factor) captures reflected light - adds 4-12% yield on ground-mount or white roof - Ranked #351 out of 14005 panels for efficiency in the database ## Questions ### What is the maximum power output of the Tongwei TWMNH-66HD panel and how many cells does it have? The most powerful variant in the TWMNH-66HD series reaches 655 Wp with efficiency up to 24.2%. The module is built from 132 N-type half-cut cells in a dual-glass configuration, delivering high power density per unit area — important where roof or ground space is limited in C&I projects and PV farms. ### What warranty comes with the Tongwei TWMNH-66HD solar panels? The manufacturer provides a 12-year product warranty and a 30-year power output warranty, guaranteeing 99% of nominal power after the first year and no less than 87.4% after 30 years. Tongwei is a Tier 1 manufacturer headquartered in China, which adds confidence for long-term warranty support. ### What is 908 Technology (0BB) used in the TWMNH-66HD, and what benefits does it offer? 908 Technology (0BB) is a busbar-free cell interconnection architecture based on multi-wire bonding. It reduces optical losses caused by busbar shading and improves mechanical resistance to microcracks that can occur during transport, installation, and operation. In practice, this means more stable energy output and lower risk of degradation from cell damage. ### How much extra energy does bifaciality add on the TWMNH-66HD, and where does it perform best? Thanks to high bifaciality, the module generates additional energy from its rear side by capturing light reflected off the ground — the gain depends on the mounting surface's albedo and typically ranges from a few to over a dozen percent of front-side power. This works best on PV farms with light-colored ground or gravel and in ground-mounted C&I installations where the panel is raised above the surface. ### Are Tongwei TWMNH-66HD panels suitable for a sloped residential roof? The TWMNH-66HD is a large module measuring about 2382x1134 mm and weighing around 32 kg, designed primarily for C&I installations and PV farms where maximum yield per square meter and low LCOE matter most. For typical sloped residential roofs, smaller and lighter modules are a better fit, as they're easier to transport and mount on rafters. ### How does the TWMNH-66HD perform in high summer temperatures? The module has a power temperature coefficient of -0.28%/°C, better than many P-type panels, meaning less power loss as cell operating temperature rises above 25°C. In practice, TWMNH-66HD panels lose less efficiency on hot days than older technologies, resulting in higher real-world energy production during summer. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/TNC2-0-TWMNH-66HD635-655W-B30-28-5-116-effa3c88f1e5.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-A650-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a650-mae72mw) | 650 W | Cooler, lighter, +1.3 pp | | [AIKO AIKO-A680-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a680-mde72mw) | 680 W | +35 W, lighter, +1.3 pp | | [AIKO AIKO-A675-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a675-mde72mw) | 675 W | +30 W, lighter, +1.1 pp | | [AIKO AIKO-A645-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a645-mae72mw) | 645 W | Cooler, lighter, +1.1 pp | | [AIKO AIKO-A695-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a695-mae78dw) | 695 W | +50 W, heavier, +1.0 pp | | [AIKO AIKO-G670-MCH72Mw](https://comparepv.com/panel/aiko-aiko-g670-mch72mw) | 670 W | +25 W, lighter, +0.9 pp | | [Longi Solar LR7-72HVHF-670M](https://comparepv.com/panel/longi-lr7-72hvhf-670m) | 670 W | +25 W, lighter, +0.9 pp | | [Tongwei TWMNH-48HC](https://comparepv.com/panel/tongwei-twmnh-48hc) | 450 W | -195 W, lighter, -7.2 pp | | [Tongwei TWMNH-54HD](https://comparepv.com/panel/tongwei-twmnh-54hd) | 515 W | -130 W, lighter, -4.8 pp | | [Tongwei TWMNH-66HD600](https://comparepv.com/panel/tongwei-twmnh-66hd600) | 600 W | -45 W, -1.7 pp | | [Tongwei TWMNH-66HD605](https://comparepv.com/panel/tongwei-twmnh-66hd605) | 605 W | -40 W, -1.5 pp | | [Tongwei TWMNH-66HD610](https://comparepv.com/panel/tongwei-solar-twmnh-66hd610) | 610 W | -35 W, -1.3 pp | | [Tongwei TWMNH-66HD615](https://comparepv.com/panel/tongwei-solar-twmnh-66hd615) | 615 W | -30 W, -1.1 pp | | [Tongwei TWMNH-66HD620](https://comparepv.com/panel/tongwei-solar-twmnh-66hd620) | 620 W | -25 W, -0.9 pp | | [AIKO AIKO-A700-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a700-mae78dw) | 700 W | +55 W, heavier, +1.1 pp | | [Jinko Solar JKM650-670N-66QL6-BDV (670W class)](https://comparepv.com/panel/jinko-solar-jkm650-670n-66ql6-bdv-670w-class) | 670 W | +25 W, cooler, +0.9 pp | --- Source: https://comparepv.com/panel/tongwei-solar-twmnh-66hd645 Not in this file, on the page: the I-V and temperature curves lifted from the manufacturer's datasheet, a thirty-year output simulator, a bifacial gain calculator and alternatives filtered by how closely they match these dimensions.