--- title: "Longi Solar LR8-66HGD-595M 595W Solar Panel - Specs & Review | ComparePV" description: "Longi Solar LR8-66HGD-595M 595W solar panel. Specs: 22.00% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/longi-lr8-66hgd-595m" updated: 2026-09-11 --- # Longi Solar LR8-66HGD-595M Middle of its segment, modest efficiency 206 panels in the segment Back Contact 495-695 W ## Identity - **Manufacturer:** Longi Solar - **Model:** LR8-66HGD-595M - **Series:** Hi-MO 7 / LR8-66HGD 595~625M - **Rated power:** 595 W - **Cell technology:** Back Contact - **Bifacial:** yes ## How it compares Compared against segment Back Contact 495-695 W (206 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 595 W | 640 W | Typical | | | Module efficiency | 22.00% | 24.06% | Weak - bottom 2% | 6,517 | | Power density | 220.3 | 240.6 | Weak - bottom 2% | 6,299 | | Temperature coefficient | -0.280 | -0.260 | Weak - bottom 14% | 1,309 | | Weight (kg) | 32.5 kg | 31.6 kg | Weak - bottom 2% | | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 22.00% | 24.06% | Weak - bottom 2% | 6,517 | | Power density | 220.3 | 240.6 | Weak - bottom 2% | 6,299 | | Temperature coefficient | -0.280 | -0.260 | Weak - bottom 14% | 1,309 | | Weight per kWp | 54.6 | 49.2 | Weak - bottom 2% | 8,977 | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Watch out for - **22.00% module efficiency** - Bottom 2% of the Back Contact 495-695 W segment, against a median of 24.06%. Ranked 6,517th in the whole database. - **220.3 watts per square metre** - Bottom 2% of the Back Contact 495-695 W segment, against a median of 240.6. Ranked 6,299th in the whole database. - **54.6 kg per kWp** - Bottom 2% of the Back Contact 495-695 W segment, against a median of 49.2. Ranked 8,977th in the whole database. - **Best for:** Commercial, utility-scale, cold-climate and hot-climate. - **Not ideal for:** Tight roof space, roofs where every square metre has to count and weight-limited structures. ## Specification ### Electrical - **Rated power (Pmax):** 595 W - **Efficiency:** 22.00 % - **Voltage at Pmax (Vmp):** 39.91 V - **Current at Pmax (Imp):** 14.91 A - **Open-circuit voltage (Voc):** 47.78 V - **Short-circuit current (Isc):** 15.80 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:** 0.045 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** Back Contact - **Cell count:** 132 - **Bifacial:** yes ### Physical - **Length:** 2382 mm - **Width:** 1134 mm - **Thickness:** 30 mm - **Weight:** 32.5 kg - **Area:** 2.70 m2 - **Power density:** 220.3 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:** 520 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 6517 of 14005 | | Power density | 6299 of 14005 | | Temperature coefficient | 1309 of 14005 | | Weight | 8977 of 14005 | | Warranty | 21 of 14005 | ## Pros - **Back Contact cells with HPDC technology** - Efficiency up to 23.1% places the series in the top tier of large-format module segment - for comparison, peer DAH Solar DHN-66Z16/DG reaches 23.14% at the same 625W power class, while Leapton LP182\*182-M-78-NH only reaches 22.36%. HPDC technology with half-cut monocrystalline cells meaningfully increases yield per roof or ground area. - **Bifacial design with dual-glass construction** - Two-sided energy generation captures light reflected from the ground, boosting output without increasing installation footprint - especially valuable for PV farms and C&I projects. The dual-glass build improves resistance to wind, snow, humidity, and temperature swings, supporting long-term stable operation in harsh site conditions. - **30-year power warranty with low degradation** - The manufacturer declares under 1% degradation in year one, followed by a linear ~0.4% annual decline, resulting in roughly 87.4% retained power at year 30. This outperforms standard 25-year warranties with ~84.8% retention, easing long-term LCOE planning for large-scale projects. - **High module power lowers BoS costs** - Power output of 595-625Wp across 7 available variants means fewer modules, mounts, cables, and connection points per megawatt, meaningfully reducing Balance of System costs and installation time in large ground-mount and C&I projects. - **Bankable Tier-1 manufacturer** - LONGi Solar has operated since 2000 and holds Tier-1 bankable status, easing access to project financing and reducing risk for institutional investors backing this series introduced in 2023. ## Cons - **Limited field data for HPDC technology** - Back Contact cells with HPDC technology have only been in mass production since 2023, so the declared 30-year degradation profile relies mainly on accelerated lab testing and modeling rather than multi-year field data, unlike more mature PERC or TOPCon technologies. - **12-year product warranty below market trend** - The materials and workmanship warranty is 12 years, while a growing number of Tier-1 n-type lines introduced after 2023 (including Trina and JinkoSolar series) offer 15 years as standard - a factor worth weighing when comparing bids for large-scale installations. ## About this series Longi Solar Hi-MO 7 LR8-66HGD 595~665M modules are designed for maximum yield from the same installation surface - especially where every meter of construction and every logistics stage counts. The use of monocrystalline cells in a half-cell configuration, along with bifacial solutions, enables better utilization of reflected light from the ground, genuinely boosting energy production in PV farms and large commercial installations. In practice, this series combines dual-glass construction with high environmental resilience - making it an excellent choice for projects exposed to wind, snow, humidity, and intense temperature fluctuations. The HPDC technology supports stable operation in tougher working conditions, while the declared, gradually decreasing performance degradation facilitates long-term LCOE planning. The Hi-MO 7 LR8-66HGD is primarily intended for solar farms, C&I projects, and ground installations, where lower BOS costs, predictable yields, and module longevity are key. ## Notable figures - Efficiency of 22.0% matches the \*\*Back Contact 550-600W\*\* median - Power density of 220.3 W/m² is 4.2 W/m² below \*\*Back Contact 550-600W\*\* median (224.5 W/m²) - needs more roof space - At -0.28%/°C, hot weather performance is typical for \*\*Back Contact 550-600W\*\* panels - At 32.5 kg (5.3 kg above \*\*Back Contact 550-600W\*\* median of 27.2 kg), requires checking roof load capacity - Bifacial design (80% factor) captures reflected light - adds 4-12% yield on ground-mount or white roof ## Questions ### What warranty does LONGi Solar offer on the Hi-MO 7 LR8-66HGD series? LONGi Solar backs the Hi-MO 7 LR8-66HGD with a 12-year product warranty covering materials and workmanship, plus a 30-year linear power output warranty. First-year power retention is guaranteed at no less than 99%, and after 30 years the module must still deliver at least 87.4% of its rated output. This warranty structure ranks among the strongest in the industry and supports long-term project financing for utility-scale PV farms and C&I installations. ### What is HPDC technology in the Hi-MO 7 panels and does it actually improve energy yield? HPDC is a Back Contact cell technology that relocates all electrodes and interconnects to the rear of the cell, leaving the entire front surface unobstructed for light absorption. This eliminates optical shading losses from front-side busbars and contributes to a peak module efficiency of 23.1%. Compared to standard PERC cells, the removal of front metallization increases energy yield per square meter, making the Hi-MO 7 particularly effective in large-scale PV farms. ### Is the Hi-MO 7 LR8-66HGD bifacial module worth it for ground-mounted solar farms? Yes. With a bifaciality factor of approximately 80%, the module captures reflected irradiance from the ground surface and generates meaningful additional energy. On ground-mounted farms with gravel, sand, or grass cover, bifacial gain typically ranges from 5 to 15% over a monofacial module. Higher ground albedo increases the benefit. This is why the Hi-MO 7 LR8-66HGD is specifically recommended for utility-scale and C&I projects where maximizing energy yield per installed watt is critical. ### How does the LONGi Hi-MO 7 perform in winter and variable climate conditions? The Hi-MO 7 LR8-66HGD has a power temperature coefficient of -0.28%/°C, meaning it loses less power on hot days than typical PERC modules. The dual-glass construction and an operating temperature range of -40°C to +85°C provide strong resistance to frost, rapid thermal cycling, snow loads, and moisture ingress. This makes the series a reliable choice for projects in continental climates with large seasonal temperature swings. ### What are the dimensions and weight of the Hi-MO 7 LR8-66HGD 625M — does it fit standard residential racking? The module measures 2382 × 1134 × 30 mm and weighs approximately 32.5 kg. It is a large-format panel designed primarily for ground-mounted solar farms and large-scale C&I rooftop installations using commercial racking systems. For standard sloped residential roofs, structural load capacity must be assessed before installation, as the module's size and weight significantly exceed typical residential panel specifications. ### What is the annual power degradation of LONGi Hi-MO 7 panels and how does it affect project LCOE? LONGi guarantees less than 1% power degradation in year one and no more than 0.35% per year from years 2 through 30, resulting in a minimum 87.4% power retention after three decades. This low degradation rate directly reduces the levelized cost of energy (LCOE) over the system's lifetime, making the Hi-MO 7 LR8-66HGD an attractive choice for revenue-driven financing models such as PPAs or long-term energy offtake contracts. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/hi-mo-7-lr-8-66-hgd-595-625-m-v3-2-en-fcf4fbe47f-dd2c5c25c0d6.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-A645-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a645-mae72mw) | 645 W | +50 W, lighter, +3.0 pp | | [Longi Solar LR7-60HVH-560M](https://comparepv.com/panel/longi-lr7-60hvh-560m) | 560 W | -35 W, lighter, +2.8 pp | | [AIKO AIKO-A640-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a640-mae72mw) | 640 W | +45 W, lighter, +2.8 pp | | [Longi Solar LR7-60HVH-555M](https://comparepv.com/panel/longi-lr7-60hvh-555m) | 555 W | -40 W, lighter, +2.6 pp | | [AIKO AIKO-A635-MAE72Mw](https://comparepv.com/panel/aiko-aiko-a635-mae72mw) | 635 W | +40 W, lighter, +2.6 pp | | [Longi Solar LR7-72HGD-600M](https://comparepv.com/panel/longi-lr7-72hgd-600m) | 600 W | Heavier | | [Longi Solar 600M](https://comparepv.com/panel/longi-600m) | 600 W | Lighter, +0.4 pp, -5 yr warranty | | [Longi Solar LR7-72HTH-605M](https://comparepv.com/panel/longi-lr7-72hth-605m) | 605 W | Lighter, +0.4 pp, -5 yr warranty | | [AIKO AIKO-A680-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a680-mde72mw) | 680 W | +85 W, lighter, +3.2 pp | | [AIKO AIKO-A675-MDE72Mw](https://comparepv.com/panel/aiko-aiko-a675-mde72mw) | 675 W | +80 W, lighter, +3.0 pp | | [AIKO AIKO-A700-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a700-mae78dw) | 700 W | +105 W, cooler, +3.0 pp | | [AIKO AIKO-A695-MAE78Dw](https://comparepv.com/panel/aiko-aiko-a695-mae78dw) | 695 W | +100 W, cooler, +2.9 pp | | [AIKO AIKO-G670-MCH72Mw](https://comparepv.com/panel/aiko-aiko-g670-mch72mw) | 670 W | +75 W, lighter, +2.8 pp | | [Longi Solar LR7-72HVHF-670M](https://comparepv.com/panel/longi-lr7-72hvhf-670m) | 670 W | +75 W, lighter, +2.8 pp | | [Jinko Solar JKM650-670N-66QL6-BDV (670W class)](https://comparepv.com/panel/jinko-solar-jkm650-670n-66ql6-bdv-670w-class) | 670 W | +75 W, cooler, +2.8 pp | --- Source: https://comparepv.com/panel/longi-lr8-66hgd-595m 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.