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Tongwei TWMND-78HD635
Tongwei Brand review

TWMND-78HD635

635 Wp TOPCon Bifacial 80%
ComparePV verdict

Strong in heat, no clear weak spot

Rank 2,385 of 14,005
Compare panels Datasheet PDF
Power (Wp)
635
Strong · top 16%
Efficiency (%)
22.70
Typical · median 22.80%
Density (Wp/m²)
227.2
Typical · median 227.7
Temp (%/°C)
-0.280
Strong · top 7%
Weight (kg)
33.8
Typical · median 32.7 kg
Warranty (yrs)
30
Typical · median 30 yrs

The Tongwei TWMND series is an advanced solution based on N-type TOPCon cell technology, which sets new standards for efficiency in difficult lighting conditions. Thanks to the use of this innovative cell type, the modules are characterized by almost zero initial degradation effect and a significantly lower annual power drop, guaranteeing energy stability for investors for decades. A key feature of the series is its excellent temperature coefficient, allowing for high yields even during summer heat when traditional panels lose efficiency. The design utilizing a multi-busbar (MBB) system shortens the electron flow path and reduces the risk of micro-cracks, which directly increases the mechanical reliability of the product. The TWMND series is designed for demanding residential users and commercial projects where maximizing profit from the available roof or ground area matters. What sets these panels above the competition is full control over silicon purity, resulting from the manufacturer's position as a leader in raw material production, which translates into exceptional durability and consistency of parameters for every module. It is an uncompromising choice for those looking for modern technology that realistically shortens the return on investment in photovoltaics.

Ranking

1,086 panels in the segment TOPCon 600-650 W
Metric This panel Median Position in segment Overall rank
Module efficiency 22.70% 22.80% Typical 3,307
Power density 227.2 227.7 Typical 3,252
Temperature coefficient -0.280 -0.290 Strong · top 7% 1,309
Weight per kWp 53.2 53.1 Typical 7,071
Performance warranty 30 yrs 30 yrs Typical 21
Colour key Strong - top 25% Typical - middle 50% Weak - bottom 25%

Signals from the data

1 positive · 0 caution
Best for

Residential, commercial and hot-climate.

Strengths
-0.280 %/°C temperature coefficient

Top 7% of the TOPCon 600-650 W segment, against a median of -0.290. Ranked 1,309th in the whole database.

Notes from the database
  • At 22.7% efficiency, this panel is on par with typical TOPCon 600-650W modules
  • Power density of 227.2 W/m² matches the TOPCon 600-650W median
  • At -0.28%/°C, hot weather performance is typical for TOPCon 600-650W panels
  • At 33.8 kg (1.1 kg above TOPCon 600-650W median of 32.7 kg), requires checking roof load capacity
  • Bifaciality factor of 80% can add 4-12% extra yield with reflective mounting surface

Specifications

Open datasheet PDF
Nominal power (Pmax) 635 Wp Nameplate at 1000 W/m², 25 °C
Module efficiency 22.70 % Typical Segment median 22.80%
Vmpp · Impp 48.05 V · 13.22 A Operating point at max power
Voc · Isc 57.20 V · 13.82 A Sizes the string length
Max system voltage 1500 V Longer strings than 1000 V modules
Dimensions 2465×1134×30 mm · 2.80 m² of roof
Weight 33.8 kg Typical Typical · median 32.7 kg
Cells 156 · TOPCon Monocrystalline
Bifaciality 80 % Rear output as a share of front
Coefficient Pmax -0.280 %/°C Strong top 7% of its segment
Coefficient Voc · Isc -0.240 · 0.046 %/°C
NOCT 45 °C At 800 W/m², 20 °C ambient
Product warranty 12 years Hardware defects only
Performance warranty 30 years Typical median 30 yrs · median 30 yrs
End-of-warranty output 87.4 % Equals 555 W guaranteed
Degradation 1.00 → 0.40 % First year, then annual

Datasheet charts

Open datasheet PDF

Measured curves published by Tongwei in this model's datasheet. A chart carrying a wattage was measured on that variant alone - only the ones that describe 635 Wp appear here. The rest cover the whole series.

Linear Power Output Warranty Linear Power Output Warranty Whole series Cell temperature 25°C Cell temperature 25°C Whole series P-V curve (Power vs. Voltage) P-V curve (Power vs. Voltage) Whole series

Simulations

Live - change any input
Lifetime output & value
30 years at 1200 kWh/kWp/year and €0.50 per kWh
Power in year 30
-
Lifetime energy
-
Energy value
-
With bifacial gain
-

Degradation from this panel's own datasheet figures. No inverter, soiling or shading losses.

Heat losses
-0.280 %/°C against a segment median of -0.290
-
Bifacial gain
Rear gain over light concrete: -
-

Model: bifaciality × albedo × 0.6 view factor. A first-order estimate, not a yield simulation.

Filter these
Size
Panel Power Eff. Temp. Weight Difference
Tongwei TWMND-78HD635 635 W 22.70% -0.280 33.8 kg You are here
AIKO-A650-MAE72Mw 650 W 25.20% -0.260 27.0 kg Cooler, lighter, +2.5 pp
AIKO-A680-MDE72Mw 680 W 25.20% -0.260 29.0 kg +45 W, lighter, +2.5 pp
AIKO-A675-MDE72Mw 675 W 25.00% -0.260 29.0 kg +40 W, lighter, +2.3 pp
AIKO-A645-MAE72Mw 645 W 25.00% -0.260 27.0 kg Cooler, lighter, +2.3 pp
AIKO-G670-MCH72Mw 670 W 24.80% -0.260 28.2 kg +35 W, lighter, +2.1 pp
LR7-72HVHF-670M 670 W 24.80% -0.260 28.5 kg +35 W, lighter, +2.1 pp
AIKO-A640-MAE72Mw 640 W 24.80% -0.260 27.0 kg Cooler, lighter, +2.1 pp
TWMND-78HD625 625 W 22.40% -0.280 33.8 kg -10 W, -0.3 pp
TWMND-78HD630 630 W 22.50% -0.280 33.8 kg Very close match
TWMND-78HD640 640 W 22.90% -0.280 33.8 kg Very close match
TWMND-78HD645 645 W 23.10% -0.280 33.8 kg +10 W, +0.4 pp
AIKO-A700-MAE78Dw 700 W 25.00% -0.260 34.5 kg +65 W, cooler, +2.3 pp
AIKO-A695-MAE78Dw 695 W 24.90% -0.260 34.5 kg +60 W, cooler, +2.2 pp
JKM650-670N-66QL6-BDV (670W class) 670 W 24.80% -0.260 32.5 kg +35 W, cooler, +2.1 pp

Found 616 panels of the same or similar size to this one, within ±10 mm. See them here Found 616 panels of the same or similar size to this one, within ±25 mm. See them here Found 616 panels of the same or similar size to this one, within ±50 mm. See them here Found 1813 panels of the same or similar size to this one, within ±100 mm. See them here

Common questions

6 answered
How does the N-type TOPCon technology in Tongwei TWMND panels differ from older P-type PERC cells?
The N-type TOPCon cells used in the TWMND series deliver higher base efficiency and near-zero initial light-induced degradation (LID), which noticeably reduces power output in P-type PERC panels within the first days of operation. TOPCon also has a lower annual degradation rate, which, combined with the 30-year power warranty, translates into higher total energy yield over the system's lifetime compared to older technologies.
What warranty comes with Tongwei TWMND panels and what does it cover?
The TWMND series comes with a 12-year product warranty covering material and manufacturing defects, plus a 30-year linear power warranty guaranteeing a minimum percentage of rated output over time. These are among the longer warranty periods available on the market, making the series an attractive investment for both residential and commercial projects.
What is multi-busbar (MBB) technology in Tongwei TWMND panels and why does it matter?
Multi-busbar (MBB) technology uses a larger number of thin conductive paths on the cell surface instead of a few wide soldered ribbons. This shortens the electron flow path, reduces resistive losses, and significantly lowers the risk of micro-cracks during transport, installation, and operation. In practice, this results in higher mechanical reliability of the TWMND modules and more stable long-term energy output.
Do Tongwei TWMND panels lose performance in hot weather?
The TWMND series has a favorable temperature coefficient of power, typical of N-type TOPCon technology, meaning performance drop at high module operating temperatures is smaller than with panels based on older P-type cells. In practice, this results in higher energy yields on hot summer days, when traditional PERC panels start losing significant efficiency once module temperature exceeds 25°C.
Are Tongwei TWMND panels bifacial?
No, panels in this TWMND configuration are monofacial modules — they generate power only from the front side. This is well suited to installations where mounting on bifacial racking with reflected ground light isn't practical, such as sloped roofs. Customers looking for extra yield from reflected light should check other bifacial series in Tongwei's lineup.
How many Tongwei TWMND 645 Wp panels are needed for a roughly 5 kWp system?
With a maximum module output of 645 Wp, 8 panels are enough for a system of around 5 kWp (8 x 645 W ≈ 5.16 kWp). The high per-module power lets you reach a larger system size with fewer modules, reducing installation costs, the number of optimizers or microinverters needed, and the roof area required.
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