--- title: "First Solar FS-6435 435W Solar Panel - Specs & Review | ComparePV" description: "First Solar FS-6435 435W solar panel. Specs: 17.60% efficiency, Thin film cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/first-solar-fs-6435" updated: 2026-09-11 --- # First Solar FS-6435 Middle of its segment, modest efficiency 43 panels in the segment CdTe 335-535 W ## Identity - **Manufacturer:** First Solar - **Model:** FS-6435 - **Series:** First Solar Series 6 - **Rated power:** 435 W - **Cell technology:** CdTe ## How it compares Compared against segment CdTe 335-535 W (43 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 435 W | 465 W | Weak - bottom 7% | | | Module efficiency | 17.60% | 18.40% | Weak - bottom 7% | 13,317 | | Power density | 175.8 | 184.1 | Weak - bottom 7% | 13,311 | | Temperature coefficient | -0.320 | -0.320 | Typical | 8,312 | | Weight (kg) | 34.5 kg | 34.5 kg | Weak - bottom 7% | | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 17.60% | 18.40% | Weak - bottom 7% | 13,317 | | Power density | 175.8 | 184.1 | Weak - bottom 7% | 13,311 | | Temperature coefficient | -0.320 | -0.320 | Typical | 8,312 | | Weight per kWp | 79.3 | 74.7 | Weak - bottom 7% | 13,715 | | Performance warranty | 30 yrs | 30 yrs | Typical | 21 | ### Watch out for - **17.60% module efficiency** - Bottom 7% of the CdTe 335-535 W segment, against a median of 18.40%. Ranked 13,317th in the whole database. - **175.8 watts per square metre** - Bottom 7% of the CdTe 335-535 W segment, against a median of 184.1. Ranked 13,311th in the whole database. - **79.3 kg per kWp** - Bottom 7% of the CdTe 335-535 W segment, against a median of 74.7. Ranked 13,715th in the whole database. - **Best for:** Commercial, utility-scale 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):** 435 W - **Efficiency:** 17.60 % - **Voltage at Pmax (Vmp):** 183.60 V - **Current at Pmax (Imp):** 2.37 A - **Open-circuit voltage (Voc):** 219.60 V - **Short-circuit current (Isc):** 2.55 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.320 %/degC - **Temperature coefficient of Voc:** -0.280 %/degC - **Temperature coefficient of Isc:** 0.040 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Thin film - **Cell technology:** CdTe ### Physical - **Length:** 2009 mm - **Width:** 1232 mm - **Thickness:** 49 mm - **Weight:** 34.5 kg - **Area:** 2.48 m2 - **Power density:** 175.8 Wp/m2 ### Warranty and degradation - **Product warranty:** 12 years - **Performance warranty:** 30 years - **Output guaranteed at end of warranty:** 91.0 % - **First-year degradation:** 0.30 % - **Annual degradation:** 0.30 % - **Output after 30 years:** 396 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 13317 of 14005 | | Power density | 13311 of 14005 | | Temperature coefficient | 8312 of 14005 | | Weight | 13715 of 14005 | | Warranty | 21 of 14005 | ## Pros - **Low Temperature Coefficient of CdTe Technology** - CdTe technology exhibits a power temperature coefficient of approximately -0.28%/°C, compared to -0.40% to -0.45%/°C for standard monocrystalline modules. In practice, at a cell temperature of 70°C (typical during summer), the Series 6 loses approximately 14% of rated power, while a PERC module loses roughly 20-22%. This translates into meaningfully higher annual energy yield in warm climates. - **Zero LID and LeTID Degradation** - The thin-film CdTe structure is inherently immune to both Light-Induced Degradation (LID) and Light and elevated Temperature Induced Degradation (LeTID), phenomena that can cause a permanent power loss of 1–3% in silicon-based PERC modules during the first months of operation. This ensures full rated power output from day one of system commissioning. - **Industry-Leading Low Carbon Footprint** - The life-cycle carbon footprint of Series 6 modules is approximately 15.83 gCO2eq/kWh — roughly 2.5× lower than monocrystalline silicon panels (approx. 38 gCO2eq/kWh per LCA data) and a 3× lower water footprint. Series 6 Plus and Series 7 were the first modules in the world to achieve EPEAT Climate+ certification (threshold: ≤400 kg CO2e/kWp). - **30-Year Linear Power Warranty** - The manufacturer offers a 30-year linear power warranty — one of the longest standard warranty terms in the commercial PV segment — underpinned by a declared annual degradation rate of 0.30%/year (vs. 0.45–0.55%/year for typical silicon modules). This yields an estimated 2–3% higher cumulative energy output over a 30-year project lifetime. - **Comprehensive End-of-Life CdTe Recycling Program** - First Solar is the only module manufacturer in the world operating its own pre-funded collection and recycling program for end-of-life modules, active since 2005. In 2023, the global average material recovery rate reached 95%, covering glass, aluminum, steel, and semiconductor material. This eliminates the risk of toxic cadmium disposal and fully complies with the EU's most stringent environmental standards. ## Cons - **Significantly Lower Module Efficiency** - The efficiency range of 17.4–18.6% is materially below that of direct peer comparables: the Risen RSM96-11 achieves 23%, the SunKean SKT440–460 reaches 23.02%, and even the Zonergy ZPM MH3-72 delivers 21.16%. Achieving 1 MWp with Series 6 modules therefore requires approximately 20–25% more land area than the most efficient silicon alternatives — a significant constraint for projects with limited land availability. - **No Bifacial Configuration Available** - The Series 6 is a monofacial module (is\_bifacial: false), whereas direct competitors such as the Risen RSM96-11-440-460BNDG offer bifacial technology, enabling additional energy harvest from albedo reflectance — typically 5–15% extra yield in ground-mounted systems with high-reflectivity ground surfaces. The absence of a bifacial option in the standard series limits yield optimization on newly designed utility-scale ground-mount projects. - **Short Product Warranty (12 Years)** - The 12-year product warranty falls below the rising market benchmark, with many Tier-1 manufacturers now offering 15–25 years of product warranty coverage. For long-term financed projects — including project finance structures and PPA agreements of 20+ years — this may necessitate additional risk analysis from lending institutions. ## About this series First Solar Series 6 panels redefine performance standards in the commercial sector thanks to the use of advanced **CdTe thin-film technology**, which significantly distinguishes them from commonly used silicon modules. Their unique design makes these modules significantly less sensitive to high temperatures, which in practice translates into a **higher annual energy yield**, especially in demanding and variable climatic conditions. This series effectively solves the problem of power drops during summer heat and heavy cloud cover, offering a much better spectral response to diffuse light than traditional solutions. These models are characterized by **total resistance to LID and LeTID degradation**, which guarantees stable and predictable system operation for decades. Designed primarily for large-scale photovoltaic farms, Series 6 panels offer an optimized mounting system, significantly reducing structural costs and installation time. What distinguishes them most from the competition is the **lowest carbon footprint** throughout the entire product life cycle, making this series the most ecological choice for conscious investors. Thanks to their innovative structure, the modules also provide **excellent tolerance to linear shading**, allowing for maximum row density on ground-mounted farms without the risk of drastic power losses. It is a solution that combines uncompromising durability with the highest standards of sustainability. ## Notable figures - At 17.6% efficiency, this panel is on par with typical \*\*CdTe 400-450W\*\* modules - Power density of 175.8 W/m² matches the \*\*CdTe 400-450W\*\* median - At -0.32%/°C, hot weather performance is typical for \*\*CdTe 400-450W\*\* panels - Ranked #13317 out of 14005 panels for efficiency in the database ## Questions ### What warranty is offered on First Solar Series 6 panels? First Solar Series 6 panels come with a 12-year product warranty covering material and workmanship defects, along with a 30-year linear power output warranty. The annual degradation rate is just 0.3%, meaning modules retain at least 90% of their nominal power after 30 years. This represents one of the longest and most favorable power warranties available in the photovoltaic panel market. ### Do First Solar Series 6 panels perform well during summer heat? Yes, and significantly better than typical silicon-based modules. The CdTe thin-film technology delivers a temperature coefficient of power of just -0.32%/°C, compared to approximately -0.35 to -0.40%/°C for standard monocrystalline panels. In practice, at a module temperature of 70°C, the difference in energy yield can reach several percentage points annually — translating into measurably higher revenue for large-scale PV farms. ### Are First Solar Series 6 modules susceptible to LID and LeTID degradation? No. First Solar Series 6 panels are completely immune to LID (Light Induced Degradation) and LeTID (Light and elevated Temperature Induced Degradation), both of which are well-known issues affecting silicon-based modules. The absence of these phenomena ensures that module power does not drop sharply during the first weeks of operation and remains stable throughout the entire 30-year linear power warranty period. ### Are First Solar Series 6 panels suitable for installation on a residential rooftop? The First Solar Series 6 series is engineered for utility-scale PV farms and commercial installations, not for residential rooftops. The modules have large physical dimensions and require a dedicated racking system. For typical prosumer installations on pitched roofs, smaller silicon panels from manufacturers offering residential solutions are a far more practical choice. ### What is the maximum power output of a First Solar Series 6 panel, and what is its efficiency? The highest-rated model in the series reaches a peak power of 460 Wp. Module efficiency across the series ranges from 17.4% to 18.6%, which is an excellent result for CdTe thin-film technology. The modules are rated for DC systems up to 1500 V DC, enabling longer string configurations and reducing BoS electrical infrastructure costs on utility-scale farms. ### How does the CdTe technology used in First Solar Series 6 differ from standard silicon panels? CdTe (cadmium telluride) is a thin-film technology in which the active semiconductor layer is only a few micrometers thick, setting it apart from the thick crystalline silicon cells used in conventional modules. As a result, First Solar Series 6 panels offer better spectral response to diffuse light, superior thermal stability, and the lowest carbon footprint over the full product lifecycle of any commercially available PV technology. The trade-offs include the absence of a bifacial variant and limited availability in the prosumer segment. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/Series-6-Datasheetashx-64ac2f4c0c63.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [First Solar FS-6480-P-I / FS-6480A-P-I (SL) or FS-6480-P / FS-6480A-P (HL)](https://comparepv.com/panel/first-solar-fs-6480-p-i-fs-6480a-p-i-sl-or-fs-6480-p-fs-6480a-p-hl) | 480 W | +45 W, +1.4 pp | | [First Solar FS-6475-P-I / FS-6475A-P-I (SL) or FS-6475-P / FS-6475A-P (HL)](https://comparepv.com/panel/first-solar-fs-6475-p-i-fs-6475a-p-i-sl-or-fs-6475-p-fs-6475a-p-hl) | 475 W | +40 W, +1.3 pp | | [First Solar FS-6430](https://comparepv.com/panel/first-solar-fs-6430) | 430 W | -0.2 pp | | [First Solar FS-6440](https://comparepv.com/panel/first-solar-fs-6440) | 440 W | Very close match | | [First Solar FS-6445](https://comparepv.com/panel/first-solar-fs-6445) | 445 W | +10 W, +0.4 pp | | [First Solar FS-6450](https://comparepv.com/panel/first-solar-fs-6450) | 450 W | +15 W, +0.6 pp | | [Longi Solar LR7-60HVH-560M](https://comparepv.com/panel/longi-lr7-60hvh-560m) | 560 W | +125 W, lighter, +7.2 pp | | [Longi Solar LR7-60HVH-555M](https://comparepv.com/panel/longi-lr7-60hvh-555m) | 555 W | +120 W, lighter, +7.0 pp | | [Longi Solar LR7-60HVHL-550M](https://comparepv.com/panel/longi-lr7-60hvhl-550m) | 550 W | +115 W, 18 kg lighter, +6.8 pp | | [JA Solar JAT60S40-540/LR](https://comparepv.com/panel/ja-solar-jat60s40-540-lr) | 540 W | +105 W, lighter, +6.8 pp | | [Gokin GK-5-60HG-540M](https://comparepv.com/panel/gokin-gk-5-60hg-540m) | 540 W | +105 W, lighter, +6.8 pp | | [Jinko Solar JKM545-54QL6-DV-F1-EU](https://comparepv.com/panel/jinko-solar-jkm545-54ql6-dv-f1-eu) | 545 W | +110 W, lighter, +6.7 pp | | [Longi Solar LR7-60HVH-545M](https://comparepv.com/panel/longi-lr7-60hvh-545m) | 545 W | +110 W, lighter, +6.6 pp | --- Source: https://comparepv.com/panel/first-solar-fs-6435 Not in this file, on the page: a thirty-year output simulator and alternatives filtered by how closely they match these dimensions.