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645 vs 665 16 of 19 identical Swap Change panels

Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-DEG21C.20-665

Trina Solar TSM-DEG21C.20-645
TSM-DEG21C.20-645
645 Wp 20.80 % PERC Bifacial
Open panel page Datasheet PDF
VS
Trina Solar TSM-DEG21C.20-665
TSM-DEG21C.20-665
665 Wp 21.40 % PERC Bifacial
Open panel page Datasheet PDF
The verdict

665 leads on the differences that matter

The largest is module efficiency: 0.60 pp more efficient. 16 of 19 comparable parameters are identical.

See all 3 differences
How alike are they
16 of 19 comparable
parameters are identical
identical differs
01

What actually differs

3 of 19 parameters
Parameter 645 665 Difference
Module efficiency 20.80 % 21.40 % 0.60 pp more efficient
Power density 207.6 Wp/m² 214.1 Wp/m² 6.4 Wp/m² higher
Rated power 645 Wp 665 Wp 20 W more power
02

What it means on a roof

Thirty years of production
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.
645
21,240 kWh
665
21,899 kWh
Lifetime gap
659 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 645 665
Standard test conditions 25 °C 100.0% of rated power 645 W 665 W
Cool, bright day 40 °C 94.9% of rated power 612 W 631 W
Typical summer roof 55 °C 89.8% of rated power 579 W 597 W
Hot roof 70 °C 84.7% of rated power 546 W 563 W
03

Full specification

Parameter 645 665 Difference
Power and efficiency
Rated power 645 Wp 665 Wp +20 W for 665
Module efficiency 20.80 % 21.40 % +0.60 pp for 665
Power density 207.6 Wp/m² 214.1 Wp/m² +6.4 Wp/m² for 665
Open-circuit voltage 45.30 V 46.10 V Effectively the same
Voltage at max power 37.50 V 38.30 V Effectively the same
Short-circuit current 18.31 A 18.50 A Effectively the same
Current at max power 17.23 A 17.39 A Effectively the same
Temperature
Temperature coefficient -0.340 %/°C -0.340 %/°C Same
Mechanical
Dimensions 2384x1303x33 mm 2384x1303x33 mm Same
Module area 3.106 m² 3.106 m² Same
Weight 38.3 kg 38.3 kg Same
Weight per kWp 59.4 kg/kWp 57.6 kg/kWp Effectively the same
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.45 %/yr 0.45 %/yr Same
Technology
Cell technology PERC PERC Same
Cell type Monocrystalline Monocrystalline Same
Cell count 132 132 Same
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#10,457 vs #8,323
665 leads by 2,134 places
Power density
#10,562 vs #8,250
665 leads by 2,312 places
Heat behaviour
#8,778 vs #8,778
Tied - the same position in the database
Weight
#12,126 vs #11,303
665 leads by 823 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#4,248 vs #2,833
665 leads by 1,415 places
05

More useful comparisons

Open the full database
Same series, other bin
Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-DEG21C.20-660
3 differences, the largest is module efficiency
Same series, other bin
Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-DEG21C.20-655
3 differences, the largest is module efficiency
Same series, other bin
Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-DEG21C.20-650
The same specification on paper
Same manufacturer
Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-NEG21C.20Q-760
11 differences, the largest is module efficiency
Same manufacturer
Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-NEG21C.20Q-755
11 differences, the largest is module efficiency
Same manufacturer
Trina Solar TSM-DEG21C.20-645 vs Trina Solar TSM-NEG21C.20Q-750
10 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Trina Solar TSM-DEG21C.20-645 or Trina Solar TSM-DEG21C.20-665?
According to our database: Trina Solar TSM-DEG21C.20-665 has higher module efficiency (21.40% vs 20.80%). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Trina Solar TSM-DEG21C.20-645 and Trina Solar TSM-DEG21C.20-665?
Trina Solar TSM-DEG21C.20-645 has a module efficiency of 20.80%, while Trina Solar TSM-DEG21C.20-665 is 21.40%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Trina Solar TSM-DEG21C.20-645 use vs Trina Solar TSM-DEG21C.20-665?
Trina Solar TSM-DEG21C.20-645 uses PERC cells; Trina Solar TSM-DEG21C.20-665 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 Trina Solar TSM-DEG21C.20-645 and Trina Solar TSM-DEG21C.20-665?
Trina Solar TSM-DEG21C.20-645 has a 30 years power warranty; Trina Solar TSM-DEG21C.20-665 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 Trina Solar TSM-DEG21C.20-645 and Trina Solar TSM-DEG21C.20-665 bifacial panels?
Both Trina Solar TSM-DEG21C.20-645 and Trina Solar TSM-DEG21C.20-665 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.

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Every figure here is from the manufacturers' own datasheets - a dash means the value is not published, never an estimate. The thirty-year projection and the temperature scenarios are calculations from those figures, and each states its assumption above.