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Longi Solar LR8-66HGD-595M
Longi Solar Brand review

LR8-66HGD-595M

595 Wp Back Contact Bifacial 80%
ComparePV verdict

Middle of its segment, modest efficiency

Rank 4,543 of 14,005
Compare panels Datasheet PDF
Power (Wp)
595
Typical for its class
Efficiency (%)
22.00
Weak · bottom 2%
Density (Wp/m²)
220.3
Weak · bottom 2%
Temp (%/°C)
-0.280
Weak · bottom 14%
Weight (kg)
32.5
Weak · bottom 2%
Warranty (yrs)
30
Typical · median 30 yrs

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.

Ranking

206 panels in the segment Back Contact 495-695 W
Metric This panel Median Position in segment Overall 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
Colour key Strong - top 25% Typical - middle 50% Weak - bottom 25%

Signals from the data

5 positive · 5 caution
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.

Watch-outs
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.

What owners get
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.

Trade-offs
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.

Notes from the database
  • 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

Specifications

Open datasheet PDF
Nominal power (Pmax) 595 Wp Nameplate at 1000 W/m², 25 °C
Module efficiency 22.00 % Weak Segment median 24.06%
Vmpp · Impp 39.91 V · 14.91 A Operating point at max power
Voc · Isc 47.78 V · 15.80 A Sizes the string length
Max system voltage 1500 V Longer strings than 1000 V modules
Dimensions 2382×1134×30 mm · 2.70 m² of roof
Weight 32.5 kg Weak Weak · bottom 2%
Cells 132 · Back Contact Monocrystalline
Bifaciality 80 % Rear output as a share of front
Coefficient Pmax -0.280 %/°C Weak bottom 14% of its segment
Coefficient Voc · Isc -0.230 · 0.045 %/°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 520 W guaranteed
Degradation 1.00 → 0.40 % First year, then annual

Datasheet charts

Open datasheet PDF

Measured curves published by Longi Solar in this model's datasheet. A chart carrying a wattage was measured on that variant alone - only the ones that describe 595 Wp appear here. The rest cover the whole series.

30-Year Power Warranty 30-Year Power Warranty 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 -0.260
-
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
Longi Solar LR8-66HGD-595M 595 W 22.00% -0.280 32.5 kg You are here
AIKO-A645-MAE72Mw 645 W 25.00% -0.260 27.0 kg +50 W, lighter, +3.0 pp
LR7-60HVH-560M 560 W 24.80% -0.260 25.0 kg -35 W, lighter, +2.8 pp
AIKO-A640-MAE72Mw 640 W 24.80% -0.260 27.0 kg +45 W, lighter, +2.8 pp
LR7-60HVH-555M 555 W 24.60% -0.260 25.0 kg -40 W, lighter, +2.6 pp
AIKO-A635-MAE72Mw 635 W 24.60% -0.260 27.0 kg +40 W, lighter, +2.6 pp
LR7-72HGD-600M 600 W 22.20% -0.280 33.5 kg Heavier
600M 600 W 22.40% -0.280 31.0 kg Lighter, +0.4 pp, -5 yr warranty
LR7-72HTH-605M 605 W 22.40% -0.280 28.5 kg Lighter, +0.4 pp, -5 yr warranty
AIKO-A680-MDE72Mw 680 W 25.20% -0.260 29.0 kg +85 W, lighter, +3.2 pp
AIKO-A675-MDE72Mw 675 W 25.00% -0.260 29.0 kg +80 W, lighter, +3.0 pp
AIKO-A700-MAE78Dw 700 W 25.00% -0.260 34.5 kg +105 W, cooler, +3.0 pp
AIKO-A695-MAE78Dw 695 W 24.90% -0.260 34.5 kg +100 W, cooler, +2.9 pp
AIKO-G670-MCH72Mw 670 W 24.80% -0.260 28.2 kg +75 W, lighter, +2.8 pp
LR7-72HVHF-670M 670 W 24.80% -0.260 28.5 kg +75 W, lighter, +2.8 pp
JKM650-670N-66QL6-BDV (670W class) 670 W 24.80% -0.260 32.5 kg +75 W, cooler, +2.8 pp

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Common questions

6 answered
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.
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