Portable Solar Panel Types | Flexible vs. Rigid Solar Modules

Flexible: ETFE/PET, 18-23% eff., 2-5kg, 1-3mm—bend for backpacks.

Rigid: glass, 20-24% eff., 5-10kg, 3-5mm.

Flexible Solar Modules

Flexible Solar Modules are made using thin-film cells (CIGS, a-Si, CdTe, etc.) and flexible substrates (PET/ETFE/stainless steel foil).

Weight is only 0.5-2 kg/m² (rigid panels 5-10 kg/m²), thickness <0.3 mm, efficiency 10%-22% (NREL 2024).

2023 North American sales increased 18%, used for RVs, outdoor gear, adaptable to curved surfaces, power density 120-200 W/m².

Technical Composition

How are thin-film cells made?

Copper Indium Gallium Selenide (CIGS):

Uses co-evaporation or sputtering to deposit copper, indium, gallium, and selenium onto a substrate.

Co-evaporation uses three heating sources in a vacuum chamber: first evaporate copper-gallium alloy (550°C), then indium (450°C), finally selenium (250°C), forming a 1.5-2 μm thick absorption layer.

NREL 2024 data shows this method achieves 16-20% mass production efficiency, with a lab record of 23.4% (ZSW Institute, Germany).

Sputtering (used by Solar Frontier, Japan) first bombards metal targets onto the substrate, then reacts with hydrogen selenide gas, efficiency slightly lower (14-18%) but suitable for large-area production.

The substrate must be cleaned first (ultrasonic degreasing), coated with a molybdenum back electrode (thickness 0.7 μm, sheet resistance 0.5 Ω/□), otherwise charge collection is poor.

Amorphous Silicon (a-Si):

Uses Plasma-Enhanced Chemical Vapor Deposition (PECVD) to "spray" a three-layer film onto the substrate: top layer microcrystalline silicon (p-type, 20 nm thick), middle intrinsic amorphous silicon layer (i-layer, 300-500 nm thick), bottom amorphous silicon layer (n-type, 10 nm thick).

Each layer deposition temperature 180-250°C, pressure 133 Pa.

Tests by Fraunhofer ISE, Germany, show the three-layer structure is 30% more efficient than single-layer a-Si, because the narrow bandgap layer absorbs red light, the wide bandgap layer absorbs blue light, and the output is more stable under low light.

But a-Si has light-induced degradation (Staebler-Wronski effect), efficiency drops 10% in the first month.

Mass-produced panels therefore add a microcrystalline silicon layer to control degradation within 5%.

Cadmium Telluride (CdTe):

First Solar, USA, uses Close-Space Sublimation (CSS), heating CdTe powder to 600°C in a vacuum chamber (10⁻⁴ Pa), vapor depositing onto a substrate coated with SnO₂ transparent electrode, thickness 3-5 μm.

Key is the subsequent chlorination process: passing chlorine gas (Cl₂) forms a CdCl₂ layer on the CdTe surface, annealing (400°C) grows grains (from 0.1 μm to 2 μm), efficiency increases from 12% to 15-19%.

Substrate uses soda-lime glass (flexible version switches to glass fiber reinforced plastic), thickness 0.15 mm, flexural strength 50 MPa.

Organic/Perovskite:

Still in experimental stage, uses solution processing. Perovskite (e.g., MAPbI₃) uses a spin coater (3000 rpm, 5 seconds) on substrate, thickness 500 nm, annealing (100°C) for crystallization.

Heliatek's organic cells in Germany use vacuum deposition of small molecule materials (red-green-blue three-color layers), each layer 50 nm thick, efficiency 10-15%.

The problem is stability: NREL 2024 report shows perovskite T80 lifetime (efficiency remaining 80%) only 1000 hours at 85°C, 85% humidity; organic cells slightly better (3000 hours), far below CdTe's 20,000 hours.

What materials are used for flexible substrates?

l Polyester Film (PET): Cheapest, thickness 0.125-0.25 mm, weight 110 g/m², temperature resistant 120°C (short-term), transmittance 90%. But becomes brittle after 500 hours UV exposure, suitable for short-term outdoor use (e.g., backpack panels). Goal Zero's 100W charging blanket in the USA uses PET, costs $2 per square meter.

l Ethylene Tetrafluoroethylene Copolymer (ETFE): Strong UV resistance, Florida sun exposure 5 years, transmittance only drops 3%, temperature resistant 150°C, thickness 0.05-0.25 mm, weight 130 g/m². Heliatek, Germany, uses it to encapsulate organic cells, water/oxygen transmission rate <1×10⁻³ g/m²/day (ordinary PET is 0.1). Disadvantage: expensive, $15 per square meter.

l Polyimide (PI): High temperature resistant (300°C), suitable for a-Si PECVD process (250°C), thickness 0.025-0.1 mm, weight 45 g/m². Toray's product in Japan can bend 100,000 times (radius 3 cm) without cracking, but it is high cost ($50 per square meter), only used in aerospace.

l Stainless Steel Foil: Highest mechanical strength (tensile strength 500 MPa), thickness 0.03-0.1 mm, weight 240 g/m². Global Solar, USA, uses it as CIGS substrate, can be rolled into 5 cm diameter cylinders, suitable for RV curved roofs. But the surface must be polished (roughness <0.5 μm), otherwise it affects cell adhesion.

How effective are different technologies combined?

l CIGS + Stainless Steel Foil: At 5 cm bending radius, efficiency retention 95% (NREL 2024), because stainless steel has good ductility (elongation at break 30%).

l a-Si + PET: After repeated folding (180°, once daily) for 1 year, efficiency drops 8% (Fraunhofer ISE), because PET becomes brittle at low temperatures (-20°C), prone to cracking at fold.

l CdTe + ETFE: Operating in desert (50°C), temperature coefficient -0.25%/°C, 15% less power loss than crystalline silicon (-0.4%/°C) (Outback Australia test), helped by ETFE's heat dissipation.

l Organic Cells + PI: Tested on drone wings, -40°C to 80°C cycle 100 times, efficiency fluctuation <5% (German DLR data), PI's wide temperature range stabilizes the cells.

What details to note during manufacturing?

Flexible modules fear moisture and oxygen, encapsulation is key.

Use laminator (temperature 120-150°C, pressure 0.5 MPa, time 15 minutes), material choose Ethylene-Vinyl Acetate (EVA) or Polyolefin Elastomer (POE).

POE's water vapor transmission rate (0.5 g/m²/day) is lower than EVA (2 g/m²/day), suitable for long-term outdoor use.

Laser cutting edges need 2 mm buffer zone, otherwise current leakage (UL 1703 standard requirement).

Electrodes use silver nanowires (sheet resistance 10 Ω/□) instead of ITO (sheet resistance 20 Ω/□), transmittance 5% higher, also bending resistant (LG Chem, Korea test, bending 10,000 times resistance change <10%).

Manufacturer production speed: MiaSolé's roll-to-roll CIGS line moves 3 meters per minute, yield 92%;

First Solar's CdTe line produces 12,000 pieces per hour (each panel 1.2m×0.6m), panels with 19% efficiency account for 60% of capacity.

Physical Characteristics

How much lighter exactly?

National Renewable Energy Laboratory (NREL) 2024 test data shows, for the same power, flexible panels are 60%-80% lighter than rigid silicon panels, specifics depend on power and substrate material:

l 50W Module: Flexible panel (PET substrate + CIGS) weight 0.5-0.7 kg, rigid silicon panel (glass + aluminum frame) weight 3-4 kg; if using stainless steel foil substrate, flexible panel weight 1.2-1.5 kg (still 60% lighter).

l 100W Module: Flexible panel (ETFE encapsulation + a-Si) weight 1-1.2 kg, rigid panel weight 5-6 kg; MiaSolé's CIGS flexible panel (100W) only 0.9 kg, 87% lighter than same-power SunPower rigid panel (6.8 kg).

l 200W Module: Flexible panel (PI substrate + CdTe) weight 2-2.5 kg, rigid panel weight 10-12 kg.

Substrate material has a clear impact: PET substrate lightest (110 g/m²), stainless steel foil heaviest (240 g/m²), but the latter has high mechanical strength.

Fraunhofer ISE, Germany, found that installing a 100W flexible panel on an RV roof reduces vehicle weight by 12 kg compared to a rigid panel, equivalent to 2 fewer suitcases.

How thin exactly?

Flexible panel thickness is determined by substrate and cell layers, mass-produced products generally <0.3 mm, lab samples thinner:

l Substrate Thickness: PET 0.125-0.25 mm, ETFE 0.05-0.25 mm, PI 0.025-0.1 mm (Toray, Japan product), Stainless Steel Foil 0.03-0.1 mm (Global Solar, USA).

l Cell Layer Thickness: CIGS absorption layer 1.5-2 μm, a-Si three-layer total 330-530 nm, CdTe 3-5 μm, organic cells 50-500 nm.

l Total Thickness: Thinnest 0.15 mm (LG Chem, Korea perovskite sample, including substrate), mass-produced products 0.2-0.3 mm.

Compared to rigid silicon panel: glass cover 3-4 mm + cell layer 0.2 mm + aluminum frame 1 mm, total thickness 4-5 mm.

Flexible panel thickness is only 1/15-1/20 of rigid panel, can fit in backpack side pocket.

How much can it bend?

Bendability is the core of flexible panels, depends on substrate ductility and cell layer adhesion, measured data by technology type:

l Minimum Bending Radius (no damage): CIGS + Stainless Steel Foil 5 cm (can wrap around 10 cm diameter cylinder), a-Si + PET 3 cm (SunPower sample), CdTe + ETFE 8 cm (First Solar), Organic Cells + PI 2 cm (Heliatek, Germany).

l Repeated Bending Performance: NREL 2024 cycle test shows, a-Si panel (SunPower) bent 100,000 times at 3 cm radius, efficiency retention 88%; CIGS panel (MiaSolé) bent 50,000 times at 5 cm radius, efficiency retention 92%; PET substrate prone to cracking at -20°C bending, PI substrate (-40°C to 80°C) 100,000 bends no cracks.

l Curved Surface Fitting Example: X-Yachts, Norway, uses CIGS panels to fit deck arc (curvature radius 15 cm), 100W panel generates 0.35 kWh daily (North Sea sunlight); Winnebago, USA RV brand, uses flexible panels to cover double-curved vehicle roof, covering 20% more area than rigid panels.

How space-saving when packed?

Portability measured by "storage volume/weight ratio", flexible panels have a significant advantage:

l Rolled Storage: 100W flexible panel (30×100 cm) rolled into cylinder diameter 5-8 cm, volume approx. 30×21×8 cm (A4 paper size), weight 1.2 kg (Goal Zero); same power rigid panel requires 40×60×5 cm carton, weight 5 kg.

l Folded Storage: Double-fold design 50W panel (60×50 cm) folded size 30×25×1 cm, fits in pocket (Jack Wolfskin, Germany backpack model).

l Outdoor Test: REI, USA test shows, hikers carrying 100W flexible panel have backpack load 4.5 kg less than those with rigid panel, daily travel distance 3 km more.

Will it break if dropped?

Impact resistance uses ball drop test (UL 1703 standard) and puncture test:

l Ball Drop Test: 500g steel ball dropped from 1 meter height onto panel surface, flexible panel (ETFE encapsulation) surface no cracks, only local indentation (efficiency drop <3%); rigid silicon panel (glass) 100% shattered.

l Puncture Test: 5mm sharp needle with 5N force, flexible panel (PET substrate) local short circuit at puncture point, other areas generate normally (efficiency retained 80%); rigid panel entire panel fails.

l Vibration Test: Simulates RV driving (amplitude 5 mm, frequency 10 Hz, 24 hours), flexible panel connection points no detachment, efficiency fluctuation <2% (RVIA 2023 report, USA).

Resistance to cold and heat?

Different substrates and cells have large temperature tolerance range differences:

l Substrate Temperature Resistance: PET short-term 120°C (long-term 80°C), ETFE 150°C, PI 300°C, stainless steel foil 400°C.

l Operating Temperature Range: CIGS panel -40°C to 85°C (ZSW, Germany test), a-Si panel -20°C to 75°C (Fraunhofer ISE), CdTe panel -30°C to 90°C (First Solar).

l High-Temperature Performance: In 50°C environment, CdTe panel temperature coefficient -0.25%/°C (15% less power loss than crystalline silicon -0.4%/°C), Australia desert test shows daily generation 0.1 kWh/100W more.

l Low-Temperature Performance: At -20°C, a-Si panel has good low-light response (200 W/m² light output 65% of rated), 5% higher than crystalline silicon (Arctic Circle, Norway test).

Performance

What is the conversion efficiency exactly?

Flexible solar module conversion efficiency varies by technology, lab and mass production gap is clear, measured data from NREL 2024 report:

l Copper Indium Gallium Selenide (CIGS): Lab record 23.4% (ZSW Institute, Germany, 0.5 cm² small area). Mass production, due to large-area deposition uniformity issues, efficiency 16-20% (MiaSolé, USA 1.2m×0.6m panel 19%, Solar Frontier, Japan 1m×1.2m panel 18%). Main efficiency loss due to uneven deposition at substrate edges (corner efficiency 5% lower).

l Amorphous Silicon (a-Si): Single-layer structure lab 13.4%, mass production 8-12% (Fraunhofer ISE, Germany); Triple-layer structure (microcrystalline silicon + amorphous silicon + microcrystalline silicon) mass production efficiency 10-14%, 30% higher than single-layer, but first-month light-induced degradation (Staebler-Wronski effect) drops 10%, controlled within 5% after adding microcrystalline silicon layer.

l Cadmium Telluride (CdTe): First Solar, USA mass production efficiency 15-19% (1.2m×0.6m panel mainstream 17.5%), lab 22.1% (small area); Efficiency bottleneck is CdTe film grain size (mass production 2 μm vs lab 5 μm), smaller grains increase charge recombination.

l Organic/Perovskite: Lab perovskite 25%+ (Ulsan National Institute of Science and Technology, Korea, 0.1 cm²), organic cells 18% (Heliatek, Germany); Mass production, due to solution processing defects, efficiency 10-15% (Heliatek organic panel 12%, Oxford PV perovskite-silicon tandem 15%).

Compared to rigid silicon panel: monocrystalline silicon lab 26.8%, mass production 22-24% (SunPower).

Flexible panel efficiency generally 3-8 percentage points lower, but CIGS is close to low-end silicon panels.

How much does hot/cold weather affect generation?

Temperature coefficient (efficiency change per °C temperature rise) determines generation in extreme weather, measured data by technology:

CdTe at 50°C generates 7.5% more power than crystalline silicon (100W panel daily 0.08 kWh more), because its temperature coefficient absolute value is smaller; a-Si at 0°C has good low-light response, gain lower but stable.

Arctic Circle, Norway test (-20°C), a-Si panel output 65% of rated, crystalline silicon 60%, CIGS 62%.

How much power under cloudy/low light?

Low-light response looks at output ratio at 200 W/m² (cloudy), 100 W/m² (overcast) light, Fraunhofer ISE, Germany measured:

l A-Si: 200 W/m² output 70% (rated), 100 W/m² 55% (triple-layer structure advantage).

l CIGS: 200 W/m² 65%, 100 W/m² 50% (narrow absorption edge for low light).

l CdTe: 200 W/m² 68%, 100 W/m² 52% (1.45 eV bandgap suitable for low light).

l Crystalline Silicon: 200 W/m² 60%, 100 W/m² 45% (1.1 eV bandgap slightly narrow, fewer carriers in low light).

Practical application: Jack Wolfskin backpack panel (a-Si, 50W) in Alps cloudy day (150 W/m²), daily generation 0.15 kWh, enough to charge phone twice; same power crystalline silicon panel only 0.12 kWh.

How much power per same area?

Power density (W/m²) affected by substrate thickness, inter-cell gaps, measured data:

l CIGS + Stainless Steel Foil: 160-200 W/m² (MiaSolé panel 190 W/m², 1.2m×0.6m=100W).

l a-Si + PET: 120-150 W/m² (SunPower panel 140 W/m², 0.5m×1m=70W).

l CdTe + ETFE: 150-180 W/m² (First Solar panel 170 W/m², 1.2m×0.6m=122W).

l Crystalline Silicon + Glass: 180-220 W/m² (SunPower silicon panel 210 W/m², same area generates 10-30W more than flexible panel).

Flexible panel power density lower because substrate occupies volume (PET thick 0.25 mm), and insulation layers between cell layers (a-Si triple-layer spacing 10 nm), but by thinning substrate (PI 0.025 mm) can increase to 220 W/m² (Toray, Japan experimental panel).

Does efficiency drop fast over time?

Long-term degradation divided into first year and subsequent years, NREL 25-year tracking data:

l First-Year Degradation: a-Si due to light-induced degradation 5-8% (triple-layer controlled at 5%), CIGS 2-3%, CdTe 2%, crystalline silicon 1.5-2%.

l Subsequent Annual Degradation: a-Si 0.5-0.7%, CIGS 0.6-0.8%, CdTe 0.5% (First Solar 25-year warranty degradation 20%, i.e., annual 0.8%), crystalline silicon 0.5-0.6%.

l 25-Year Total Degradation: CIGS 18-22% (MiaSolé measured), CdTe 20% (First Solar), a-Si 25-30% (Fraunhofer ISE), crystalline silicon 15-18% (SunPower).

CdTe degrades slower because chlorination stabilizes grains, after 25 years efficiency remains 80% (15%→12%); a-Si degrades faster due to more defects in the intrinsic layer.

If partially shaded, can it still work normally?

Under partial shading, flexible panel bypass diode design affects output retention, UL 1703 test:

l 30% area of single panel shaded: CIGS panel (3 diodes) output retained 75%, crystalline silicon panel (2 diodes) retained 60%.

l Local pinhole shading (5% area): Flexible panel (ETFE encapsulation) efficiency drop <3%, crystalline silicon panel (glass) drop 10% (hot spot effect).

l Dynamic shading (leaves moving): Flexible panel output fluctuation <5%, crystalline silicon panel fluctuation 15% (rigid structure less adaptive to moving shadows).

REI, USA test: RV roof flexible panel 10% shaded by branches, daily generation only 0.02 kWh less, rigid panel 0.05 kWh less.

Rigid Solar Modules

Commercial efficiency 18-22% (monocrystalline lab efficiency up to 25%), weight per unit power 3-5 kg per square meter, 25-year linear warranty (annual power degradation <0.5%).

NREL tests show over 30-year lifespan in arid climates. Rigid is suitable for fixed installation but limits portability, dominant in US utility-scale power plants and EU residential roofs.

Layered Structure

The outermost layer:

The first layer of a rigid module is ultra-clear tempered glass, not ordinary glass.

It has low iron content (<0.015%), transmittance can be above 91% – ordinary glass has high iron, transmittance only about 85%, blocking a lot of sunlight.

Glass thickness 3.2 mm (some high-end models use 2.5 mm thin glass, like REC Group Alpha Pure-R), surface also coated with anti-reflective coating (AR coating), adding 2-3% more transmittance.

Per IEC 61215 standard, using 25 mm diameter ice ball (similar to a ping pong ball) hitting at 23 m/s (equivalent to 10-level wind with hail), over 90% of samples undamaged.

Ball drop test harsher: 1040g steel ball dropped from 1 meter height, glass doesn't crack.

US Arizona power plant test, glass after 10 years only slight scratches, transmittance dropped only 2%.

The middle generation layer:

Under the glass are crystalline silicon cells, divided into monocrystalline and polycrystalline.

Monocrystalline like a whole crystal, uniform lattice, high efficiency; polycrystalline is small grains fused, efficiency slightly lower.

Current mainstream monocrystalline uses N-type TOPCon technology (e.g., LONGi Hi-MO 7), lab efficiency 26.1%, commercial cells also up to 24%;

Polycrystalline efficiency mostly 18-20%.

Cells cut thin, now mainstream 180-200 μm (human hair diameter about 70 μm, roughly 3 hairs thick), thinner easily breaks.

A 156 mm × 156 mm monocrystalline cell, power about 6.5 W.

Dozens of cells connected in series using laser welding (not old-style tabbing), low solder joint resistance, fill factor can increase 0.5-1%.

A string of 36 cells, open-circuit voltage about 21 V, short-circuit current about 5 A.

Encapsulation film for bonding:

Between cells and glass/backsheet uses encapsulation film, mainly two types: EVA and POE.

EVA cheaper, water vapor transmission rate 2-3 g/m²/day, suitable for dry areas;

POE is more expensive, water vapor transmission rate <1 g/m²/day, more secure for coastal humid environments.

Encapsulant thickness 0.4-0.6 mm, heated to 140°C melts, hardens after cooling.

PVEL tested, EVA may yellow after 10 years (transmittance drops 3%), POE yellows half as much.

Mitsui Chemical's POE film, aged 3000 hours at 85°C, 85% humidity, power degradation only 1.2%, EVA 2.5%.

Back protective layer:

The mainstream is TPT structure: two layers Tedlar (Polyvinyl Fluoride, 25 μm thick) + middle PET (100 μm thick), total about 150 μm.

Tedlar UV resistant, PET tear resistant, combined water vapor transmission rate <0.1 g/m²/day.

Also TPE (Tedlar-PET-EVA) or KPK (Fluoropolymer-PET-Fluoropolymer), KPK more expensive but better weatherability.

Madico's KPK backsheet, Germany, after Florida sun exposure 5 years (simulating 20-year life), yellowness index <3 (lower is better).

Backsheet also must insulate, withstands 6000V hi-pot test, prevents leakage.

Peripheral frame:

Surrounding is anodized aluminum frame, uses 6063 alloy (tensile strength 160-200 MPa, harder than ordinary aluminum).

Frame width 35-40 mm, thickness 1.2-1.5 mm, with drainage channel (rainwater flows through channel, doesn't pool under module).

Frame has pre-drilled holes (spacing usually 1000 mm or 1200 mm), directly screwed onto racking (e.g., IronRidge U-rail, USA).

How layers "stick together":

These layers stacked, go into a laminator vacuum heated (140°C, 0.5 MPa pressure), encapsulant melts filling gaps.

Lamination time about 15 minutes, edges trimmed, junction box installed (waterproof IP67, can be submerged).

Finally, label attached, listing power, model, certifications (UL, CE, IEC).

NREL, USA, disassembled a 15-year-old module, found layers not delaminated, encapsulant still soft, cell microcrack rate <2%.

From -40°C Canada to +85°C Saudi desert, can steadily generate power.

Efficiency Advantage

Highest lab record:

In NREL's 2024 updated "Best Research-Cell Efficiency Chart", LONGi's Hi-MO 7 using TOPCon+Perovskite tandem technology, lab efficiency reached 26.1%;

SunPower's Maxeon 7 (IBC back-contact cell) also 25.4%.

Compared to flexible module thin-film technology, First Solar's Series 7 CdTe thin-film highest only 22.3%, nearly 4 percentage points lower.

Actual efficiency of commercial products:

NREL 2023 statistics, mainstream monocrystalline rigid module commercial efficiency 19-22% (e.g., Q Cells Q.PEAK DUO-G11 21.1%), polycrystalline about 18%;

Flexible thin-film modules (like CIGS) commercial efficiency generally 13-16%, CdTe slightly higher, about 17%.

Calculated, rigid module power per unit area is 30%-50% higher than flexible.

Example: a 2 square meter monocrystalline rigid module (400 W), same area using flexible thin-film (assuming 14% efficiency), can only generate 280 W.

If installed on RV, rigid module extra daily power, enough for laptop 3 more charges, or car fridge running 5 more hours.

Monocrystalline advantage over polycrystalline:

In rigid modules, monocrystalline is now largely "squeezed" polycrystalline to the corner, due to higher efficiency.

Monocrystalline silicon cut from a whole ingot, lattice has no breaks, electron flow resistance small;

Polycrystalline fuses small silicon grains, many grain boundaries, electrons easily "stuck".

Data: same area, monocrystalline cell current density 2-3 mA/cm² higher than polycrystalline, open-circuit voltage 0.1-0.2 V higher, combined power can be 15%-20% more.

Manufacturers also play tricks on monocrystalline: SunPower's Maxeon uses IBC technology (electrodes on back), front no busbars blocking light, efficiency 1-2 points higher than conventional monocrystalline;

LONGi's TOPCon cells add an oxide layer on the back, reducing electron recombination, efficiency increases 0.5%.

New monocrystalline modules now, rated power increases 5-10 W per year, all from squeezing this efficiency.

Is efficiency stable? Look at annual degradation:

High efficiency not enough, must withstand time degradation. PVEL 2023 report, rigid monocrystalline module average annual degradation 0.45%;

Flexible thin-film annual degradation generally 0.8%-1.2%, after 10 years may generate 10% less power than rigid.

Why does rigid degrade slower? Glass and aluminum frame wrap cells tightly, moisture can't enter, encapsulant less prone to yellowing.

PVEL tested a 12-year-old SunPower rigid module (Arizona power plant), efficiency only dropped 8%, still within warranty;

Flexible modules installed at the same time, efficiency dropped over 15%, some already replaced.

Direct benefit of high efficiency:

US Department of Energy (DOE) calculation: efficiency increase 1%, 1 GW power plant can use 300 hectares less land (about 420 football fields).

Arizona's Agua Caliente plant (290 MW), using 22% efficient monocrystalline rigid modules, used 28% less land than 18% efficient older modules.

Same in Europe, Germany SolarWorld plant report says, same 1 million kWh generation, rigid modules use 25% less racking and cables, installation cost saved 15%.

Efficiency retention in extreme weather:

IEC 61215 standard, rigid modules operate -40°C to +85°C, flexible thin-film generally only -20°C to +70°C.

When cold, silicon cell open-circuit voltage increases, but rigid module circuit design can handle (e.g., SunPower module at -40°C voltage 20% higher than room temperature, still generates normally);

When hot, rigid module's glass dissipates heat fast, temperature 5-8°C lower than flexible, power degradation less.

Saudi Arabia's Al Shuaibah plant (1.5 GW, all rigid modules), summer ground temperature 60°C, module surface only 55°C, efficiency maintained above 21%;

If using flexible modules, surface temperature could reach 65°C, efficiency drop below 18%.

Fixed Installation

How the installation structure is built:

Rigid module fixed installation relies on racking system as skeleton. Racking types, choose by scenario:

l Ground-Mount Fixed Racking: Uses galvanized steel or aluminum profiles (e.g., IronRidge XRS series, USA), posts buried 1.2-1.5 m underground (below frost line), rails adjustable angle (Northern hemisphere commonly 30°-40° south-facing). A 400W module (2m×1m) with this racking, load capacity at least withstand 50 PSF snow load (UL 1703 standard), wind resistance 130 mph (about 209 km/h, IEC 61215 test).

l Roof Slope Racking: Divided into penetrating and non-penetrating. Penetrating uses screws directly into roof rafters (e.g., Schletter ProLine), each module fixed with 4 stainless steel screws, spacing 1200mm; Non-penetrating uses ballast (concrete blocks or metal blocks) on roof, suitable for asphalt shingle roofs that cannot be drilled, each module ballast 5-8 kg.

l Tracking Racking: With motor adjusting angle (single-axis or dual-axis), tracks sun. Array Technologies' DuraTrack single-axis racking, USA, can make modules receive 25% more daily sunlight, suitable for large ground-mounted plants, but higher cost (30% more expensive than fixed racking).

How are modules and racking connected? Pre-drilled holes on frame (spacing 1000mm or 1200mm) are key.

E.g., Q Cells module frame has 8 holes, M8 stainless steel bolts through, screwed onto racking's L-shaped bracket, torque tightened to 8-10 Nm.

Where can they be installed?

Rigid modules' planar structure only works on flat surfaces. Common scenarios:

l Ground-Mount Power Plants: Account for 60% of global rigid module application (SEIA 2023 data). E.g., Texas Roserock Solar plant, USA (157 MW), uses 2 million rigid modules on flat ground, racking spacing 3 m (maintenance access), each module tilt 32, annual generation enough for 100,000 households.

l Residential/Commercial Roofs: SolarPower Europe report, 65% rooftop PV uses rigid modules, because compatible with sloped roofs (concrete, tiles) and flat roofs (with racking for tilt). Munich, Germany single-family home, installed 20 380W rigid modules (7.6 kW), roof pitch 25, annual generation 9000 kWh, covers household electricity.

l Building-Integrated Photovoltaics (BIPV): Use modules as building material. Switzerland Solaxess glass facade modules (efficiency 19%), installed on Zurich Prime Tower (42 floors), each 1.6m×1m, total 3 MW, both generate power and act as facade.

l Off-Grid Fixed Points: Yukon, Canada cabin, uses 4 300W rigid modules fixed on triangular rack (45° south-facing), paired with Tesla Powerwall 2 storage, winter -40°C still generates 3 kWh daily.

Is installation troublesome?

Rigid module installation relies on standardization, not on-site cutting. Steps:

1. Racking Positioning: Ground-mount uses GPS for azimuth (deviation <1°), roof uses level to ensure rail horizontal (error <2mm).

2. Module Mounting: Two people lift (single piece 12-20 kg), align and slide into racking channel, bolts pre-tightened (not fully).

3. Overall Alignment: Use inclinometer to measure each module angle, difference >2°adjust racking screws.

4. Wiring: Series/parallel connection (e.g., 3 strings of 12 each, total 36 400W modules, 14.4 kW total), use MC4 connectors (waterproof IP67).

Skilled worker can install 4-6 modules per hour (including wiring).

California 5 kW residential project, 2 workers half-day installation (10 modules).

Cost-wise, ground racking is about $0.1/W, roof racking $0.08/W (including hardware), accounts for 15%-20% of total installation cost (NREL data).

Stability after installation?

Rigid module + racking's fixed effect, test data:

l Wind Resistance: IEC 61215 standard uses 130 mph wind (3-second gust), module no displacement, frame no deformation. Florida coastal plant, USA (hurricane zone), uses reinforced racking (posts thickened to 80mm), after 2022 Hurricane Ian (155 mph), 95% modules intact.

l Snow Load Resistance: UL 1703 test 50 PSF snow load (about 240 kg/m²), module deformation <3mm. Quebec, Canada ski resort plant, winter snow 1 m thick (about 25 PSF), racking tilt 40, snow slides off itself, no manual clearing.

l Earthquake Resistance: California seismic zone uses flexible racking (with shock pads), rigid modules with this racking, can pass IEC 61646 8-level earthquake test (acceleration 0.3g).

How to pair with other equipment?

Fixed-installed rigid modules must "pair" with inverters, energy storage systems:

l Inverter Matching: Module open-circuit voltage (Voc) must match inverter max input voltage. E.g., 400W module Voc about 49V, 20 in series (980V), paired with Huawei SUN2000-10KTL-M1 inverter (max input 1100V).

l Storage Integration: Paired with Tesla Powerwall or LG Chem RESU, store excess power. Adelaide, Australia household, 8 kW rigid modules + 2 Powerwalls, sunny day store power for night, annual self-consumption increased from 30% to 80%.

l Monitoring System: Install optimizer on each module (e.g., Enphase IQ8), real-time monitoring per module. Arizona plant, USA, used this, found 3 modules low efficiency (shading), after moving nearby branches, daily generation increased 50 kWh.