--- title: "Longi Solar LGi7-72HTD-615M Solar Panel: Specs & Datasheet | ComparePV" description: "Longi Solar LGi7-72HTD-615M solar panel. Specs: 22.90% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/longi-solar-lgi7-72htd-615m" image: "https://comparepv.com/og/panel/longi-solar-lgi7-72htd-615m.png" updated: 2026-09-11 --- # Longi Solar LGi7-72HTD-615M Strong in heat, short guarantee 6,088 panels in the 515-715 W band, all technologies ## Identity - **Manufacturer:** Longi Solar - **Model:** LGi7-72HTD-615M - **Series:** LONGi ROOF 4 - **Rated power:** 615 W - **Cell technology:** Monocrystalline ## How it compares Compared against 515-715 W band, all technologies (6088 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 615 W | 600 W | Typical | | | Module efficiency | 22.90% | 22.30% | Strong - top 22% | 2,412 | | Power density | 229.5 | 222.6 | Strong - top 21% | 2,367 | | Temperature coefficient | -0.280 | -0.300 | Strong - top 14% | 1,347 | | Weight (kg) | 31.0 kg | 32.0 kg | Typical | | | Performance warranty | 25 yrs | 30 yrs | Weak - bottom 10% | 9,912 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 22.90% | 22.30% | Strong - top 22% | 2,412 | | Power density | 229.5 | 222.6 | Strong - top 21% | 2,367 | | Temperature coefficient | -0.280 | -0.300 | Strong - top 14% | 1,347 | | Weight per kWp | 50.4 | 53.0 | Typical | 3,802 | | Performance warranty | 25 yrs | 30 yrs | Weak - bottom 10% | 9,912 | ### Strengths - **-0.280 %/°C temperature coefficient** - Top 14% of the 515-715 W band, against a median of -0.300. - **229.5 watts per square metre** - Top 21% of the 515-715 W band, against a median of 222.6. - **22.90% module efficiency** - Top 22% of the 515-715 W band, against a median of 22.30%. ### Watch out for - **25 year performance warranty** - Bottom 10% of the 515-715 W band, against a median of 30 yrs. - **Best for:** Residential, commercial and hot-climate. - **Not ideal for:** Owners who want a long output guarantee. ## Specification ### Electrical - **Rated power (Pmax):** 615 W - **Efficiency:** 22.90 % - **Voltage at Pmax (Vmp):** 44.63 V - **Current at Pmax (Imp):** 13.78 A - **Open-circuit voltage (Voc):** 52.96 V - **Short-circuit current (Isc):** 14.75 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.280 %/degC - **Temperature coefficient of Voc:** -0.230 %/degC - **Temperature coefficient of Isc:** 0.050 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell count:** 72 ### Physical - **Length:** 2376 mm - **Width:** 1128 mm - **Thickness:** 5 mm - **Weight:** 31.0 kg - **Area:** 2.68 m2 - **Power density:** 229.5 Wp/m2 ### Warranty and degradation - **Product warranty:** 25 years - **Performance warranty:** 25 years - **Output guaranteed at end of warranty:** 89.4 % - **First-year degradation:** 1.00 % - **Annual degradation:** 0.40 % - **Output after 30 years:** 538 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 2412 of 14129 | | Power density | 2367 of 14129 | | Temperature coefficient | 1347 of 14129 | | Weight | 3802 of 14129 | | Warranty | 9912 of 14129 | ## Pros - **Zero front busbars, up to 23.1% efficiency** - HPBC technology removes metallic busbars from the cell front, allowing the ROOF 4 series to reach 22.4-23.1% efficiency - matching or exceeding N-type TOPCon peer comparables (HT-SAAE 23%, MY Solar 22.95%, Weran Solar 23%), despite those competitors being bifacial. - **Certified hot-spot resistance** - LONGi's HPBC 2.0 cell architecture is TÜV Rheinland certified for anti-shading performance, with hot-spot temperatures up to 77°C lower than TOPCon modules. Current is routed around only the shaded cell rather than an entire bypass-diode string, reducing losses from partial shading by chimneys or antennas. - **Improved power temperature coefficient** - The HPBC design delivers a power temperature coefficient of approximately -0.26%/°C, about 0.03 percentage points better than typical TOPCon modules. In practice this means a smaller output drop on hot summer days compared to older PERC technology. - **Symmetrical 25-year Tier-1 warranty** - Both product and power warranties are set equally at 25 years, meeting premium-segment standards, and manufacturer LONGi (founded 2000, Tier-1 bankable status) is the world's largest module producer, limiting risk of unfulfilled warranty claims down the line. ## Cons - **No bifacial variant available** - The ROOF 4 series is monofacial only, while a direct peer comparable of identical power class (MY Solar G&A N-Type TOPCon Bifacial, 620 Wp, 22.95%) offers additional rear-side yield. For ground-mount or high-albedo installations this represents a real energy-yield gap versus that competitor. - **Shorter warranty than LONGi's own flagship lines** - While ROOF 4 carries a 25-year power warranty, LONGi's newer flagship back-contact lines (Hi-MO X9/X10), built on related HPBC technology, extend coverage to 30 years. Buyers seeking the longest protection period within LONGi's portfolio should consider those series instead of ROOF 4. ## About this series The LONGi ROOF 4 series introduces a new level of quality to home energy systems, basing its operation on advanced **HPBC cell technology**. The key innovation is the complete removal of busbars from the front of the module, which allows for significantly more efficient light absorption and eliminates losses resulting from cell shading by metal elements. This approach ensures that these panels offer **higher energy conversion efficiency** even with limited mounting space, solving the problem of small or complex roof areas. The aesthetic, deep black design makes the installation an integral part of the building rather than just a technical device. Modules in this series are characterized by **exceptional thermal stability**, which guarantees high power production on hot days when traditional panels lose efficiency. Additionally, the reinforced cell structure provides **increased resistance to micro-cracks** and weather conditions, directly translating into the security of a long-term investment. The ROOF 4 series is a choice for homeowners and businesses who do not want to compromise between performance and appearance. Thanks to **optimized performance in low light**, these systems generate more energy in the morning and evening, outperforming the competition in terms of annual kilowatt-hour yield per kilowatt of installed capacity. ## Notable figures - Efficiency of 22.9% is 1.1pp above the \*\*database\*\* median (21.8%) - 229.5 W/m² power density - 11.4 W/m² more than \*\*database\*\* median (218.1 W/m²), more power per roof area - Temperature coefficient of -0.28%/°C matches the \*\*database\*\* median - At 31.0 kg (4.5 kg above \*\*database\*\* median of 26.5 kg), requires checking roof load capacity - #2359 for efficiency, #1309 for temperature performance out of 14005 panels ## Questions ### What warranty comes with LONGi ROOF 4 panels? The LONGi ROOF 4 series comes with a 25-year product warranty covering materials and workmanship, plus a 25-year linear power output warranty. LONGi Solar is a Tier 1 manufacturer with a proven financial track record, which provides realistic assurance that warranty claims will be honored for the full 25 years. For a typical residential installation, this secures the investment throughout the entire payback period. ### What is HPBC technology and why do LONGi ROOF 4 panels use it? HPBC (Hybrid Passivated Back Contact) relocates all metal electrical contacts to the rear of the cell, completely eliminating busbars from the front surface. The result is a larger active light-absorbing area and module efficiency reaching 23.1% under STC. Compared to mainstream PERC and TOPCon technologies, ROOF 4 panels deliver more energy from the same roof area, which is critical whenever available mounting space is limited. ### Are LONGi ROOF 4 panels a good fit for small or complex roof sections? Yes, the ROOF 4 series was specifically engineered for this use case. With up to 620 Wp per module and efficiency up to 23.1%, it generates more power from a constrained surface than lower-efficiency alternatives. On roofs broken up by chimneys, dormers, or skylights, every square foot matters, and the ROOF 4 maximizes energy yield from whatever usable area is available. ### How do LONGi ROOF 4 panels perform in high summer temperatures? The ROOF 4 series features exceptional thermal stability with a temperature coefficient of power around -0.28%/°C. This means for every degree Celsius above 25°C, output drops only 0.28% versus the typical 0.35-0.40% seen in older technologies. On hot summer days when module temperatures can exceed 60°C, a ROOF 4 installation produces noticeably more power than systems based on conventional PERC cells. ### Do LONGi ROOF 4 panels generate power on overcast days and in low-light conditions? Yes. The busbar-free HPBC cell design is more responsive to diffuse irradiance, which translates to better output on overcast days, early mornings, and late evenings. Optimized low-light performance is one of the key differentiators of this series versus PERC technology. In climates with limited full-sun hours, this characteristic meaningfully increases the annual kilowatt-hour yield per installed kilowatt of capacity. ### Is the all-black look of LONGi ROOF 4 purely aesthetic, or does it affect performance? The all-black appearance of the ROOF 4 series is a direct result of the HPBC technology, not just a styling choice. Removing metal busbars from the front of the cell eliminates the reflective silver lines visible on conventional panels, creating a uniform deep-black surface. The installation integrates seamlessly into the roofline rather than looking like mounted equipment, all without any efficiency trade-off, since the same innovation that delivers the clean look is also responsible for module efficiency reaching 23.1%. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/lon-gi-roof-4-datasheet-en-202406-fae456a6fe-eb421009d573.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-A650-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a650-mae72mw) | 650 W | Lighter, +2.3 pp, +5 yr warranty | | [AIKO AIKO-A645-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a645-mae72mw) | 645 W | Lighter, +2.1 pp, +5 yr warranty | | [AIKO AIKO-A640-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a640-mae72mw) | 640 W | Lighter, +1.9 pp, +5 yr warranty | | [Longi Solar LR8-66HVD-665M](https://comparepv.com/panel/longi-lr8-66hvd-665m) | 665 W | +50 W, +1.7 pp, +5 yr warranty | | [Jinko Solar JKM650-670N-66QL6-BDV (665W class)](https://comparepv.com/panel/jinko-solar-jkm650-670n-66ql6-bdv-665w-class) | 665 W | +50 W, +1.7 pp, +5 yr warranty | | [Huayao HY665-B144DSS](https://comparepv.com/panel/huayao-hy665-b144dss) | 665 W | +50 W, +1.7 pp, +5 yr warranty | | [Sunpro Power SPDG665-BC132R12](https://comparepv.com/panel/sunpro-spdg665-bc132r12) | 665 W | +50 W, +1.7 pp, +5 yr warranty | | [Longi Solar LR8-66HGD-595M](https://comparepv.com/panel/longi-lr8-66hgd-595m) | 595 W | -20 W, -0.9 pp, +5 yr warranty | | [Longi Solar LR7-72HGD-600M](https://comparepv.com/panel/longi-lr7-72hgd-600m) | 600 W | Heavier, -0.7 pp, +5 yr warranty | | [Longi Solar 600M](https://comparepv.com/panel/longi-600m) | 600 W | -15 W, -0.5 pp | | [Longi Solar LR7-72HTH-605M](https://comparepv.com/panel/longi-lr7-72hth-605m) | 605 W | -10 W, lighter, -0.5 pp | | [AIKO AIKO-A680-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a680-mde72mw) | 680 W | +65 W, +2.3 pp, +5 yr warranty | | [AIKO AIKO-A675-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a675-mde72mw) | 675 W | +60 W, +2.1 pp, +5 yr warranty | | [AIKO AIKO-A700-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a700-mae78dw) | 700 W | +85 W, +2.1 pp, +5 yr warranty | | [WINAICO WST-675BKX72-A2](https://comparepv.com/panel/winaico-wst-675bkx72-a2) | 675 W | +60 W, +2.1 pp, +5 yr warranty | | [AIKO AIKO-A695-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a695-mae78dw) | 695 W | +80 W, +2.0 pp, +5 yr warranty | --- Source: https://comparepv.com/panel/longi-solar-lgi7-72htd-615m Not in this file, on the page: a thirty-year output simulator and alternatives filtered by how closely they match these dimensions.