--- title: "Viessmann M405WK 405W Solar Panel - Specs & Review | ComparePV" description: "Viessmann M405WK 405W solar panel. Specs: 20.66% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/viessmann-m405wk" updated: 2026-09-11 --- # Viessmann M405WK Strong in heat, no clear weak spot 954 panels in the segment PERC 400-450 W ## Identity - **Manufacturer:** Viessmann - **Model:** M405WK - **Series:** Vitovolt 300 - **Rated power:** 405 W - **Cell technology:** PERC ## How it compares Compared against segment PERC 400-450 W (954 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 405 W | 410 W | Typical | | | Module efficiency | 20.66% | 20.60% | Typical | 11,009 | | Power density | 206.7 | 206.2 | Typical | 10,965 | | Temperature coefficient | -0.340 | -0.350 | Strong - top 24% | 8,778 | | Weight (kg) | 22.0 kg | 22.0 kg | Typical | | | Performance warranty | 25 yrs | 25 yrs | Typical | 9,798 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 20.66% | 20.60% | Typical | 11,009 | | Power density | 206.7 | 206.2 | Typical | 10,965 | | Temperature coefficient | -0.340 | -0.350 | Strong - top 24% | 8,778 | | Weight per kWp | 54.3 | 53.0 | Typical | 8,586 | | Performance warranty | 25 yrs | 25 yrs | Typical | 9,798 | ### Strengths - **-0.340 %/°C temperature coefficient** - Top 24% of the PERC 400-450 W segment, against a median of -0.350. - **Best for:** Residential, shaded-installations and cold-climate. ## Specification ### Electrical - **Rated power (Pmax):** 405 W - **Efficiency:** 20.66 % - **Voltage at Pmax (Vmp):** 38.70 V - **Current at Pmax (Imp):** 10.47 A - **Open-circuit voltage (Voc):** 46.50 V - **Short-circuit current (Isc):** 11.02 A - **Max system voltage:** 1500 V ### Temperature - **Temperature coefficient of Pmax:** -0.340 %/degC - **Temperature coefficient of Voc:** -0.270 %/degC - **Temperature coefficient of Isc:** 0.040 %/degC - **NOCT:** 42 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** PERC ### Physical - **Length:** 1719 mm - **Width:** 1140 mm - **Thickness:** 30 mm - **Weight:** 22.0 kg - **Area:** 1.96 m2 - **Power density:** 206.7 Wp/m2 ### Warranty and degradation - **Product warranty:** 15 years - **Performance warranty:** 25 years - **Output guaranteed at end of warranty:** 84.8 % - **First-year degradation:** 3.00 % - **Output after 30 years:** 333 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 11009 of 14005 | | Power density | 10965 of 14005 | | Temperature coefficient | 8778 of 14005 | | Weight | 8586 of 14005 | | Warranty | 9798 of 14005 | ## About this series Vitovolt 300 is an advanced line of photovoltaic modules that combines high efficiency with exceptional durability, meeting the needs of investors seeking full energy security. This series utilizes innovative **shingled cell technology**, which eliminates gaps between cells, increasing the active surface area and performance in difficult lighting conditions. Thanks to this solution, the panels handle shading much better than standard products, maintaining high electricity production even when the module surface is partially covered. These products solve the problem of power degradation over time, offering a **25-year performance warranty** and excellent resistance to aggressive external factors, such as ammonia or salt spray. It is an ideal choice for modern farms, single-family homes, and buildings in demanding coastal areas. Compared to the competition, Vitovolt 300 stands out with **high mechanical strength** of 6000 Pa, which guarantees structural stability even during extreme snowfall. The series provides an **elegant design with a black frame**, which harmoniously blends with any roof architecture. It is a complete system for those who value European engineering standards, offering **positive power tolerance**, which translates into real yields above nominal values and a faster return on investment in the variable Polish climate. ## Notable figures - Efficiency of 20.7% matches the \*\*PERC 400-450W\*\* median - At 206.7 W/m² power density, roof space requirements are typical for \*\*PERC 400-450W\*\* panels - At -0.34%/°C, hot weather performance is typical for \*\*PERC 400-450W\*\* panels - #11009 for efficiency, #8778 for temperature performance out of 14005 panels ## Questions ### What is shingled cell technology used in Vitovolt 300 and is it worth choosing? Shingled technology connects strips of PERC cells with no gaps between them, increasing the module's active surface area and reducing losses at cell junctions. In practice, the panel handles partial shading - from a chimney or antenna, for example - better than modules with conventional cell layouts, maintaining higher power output. It also gives the surface a more uniform look, without visible busbar grids. ### What warranty comes with Viessmann Vitovolt 300 modules? Vitovolt 300 comes with a 15-year product warranty covering material and workmanship defects, plus a 25-year linear power warranty guaranteeing a minimum performance level over the module's service life. This warranty structure gives investors confidence that the installation will keep producing at a high level throughout the typical loan repayment or depreciation period used in most Polish PV subsidy programs. ### Are Vitovolt 300 panels suitable for a farm building roof or a coastal location? Yes, Vitovolt 300 modules are tested for resistance to ammonia and salt mist, making them a solid choice for farm buildings (barns, poultry houses) and structures near the sea, where standard panels can corrode faster. The black frame and clean design also blend well with both agricultural roofs and single-family homes in more demanding environmental conditions. ### What is the maximum power output of Vitovolt 300 panels, and how many are needed for a 5 kWp system? Vitovolt 300 modules reach a maximum power output of up to 405 Wp. For a residential 5 kWp system, that means roughly 12-13 panels, depending on the exact inverter configuration and available roof space. Thanks to the positive power tolerance, individual modules often slightly exceed their rated output in practice, resulting in somewhat higher yields than theoretical calculations alone would suggest. ### Can Vitovolt 300 panels handle heavy snow loads and strong wind? Yes, the series offers high mechanical load resistance of up to 6000 Pa, well above typical requirements for the Polish climate. This construction allows the panels to safely handle heavy snow accumulation on the roof as well as strong wind gusts, without risk of glass cracking or frame deformation - a key advantage for buildings in regions with variable weather. ### Are Viessmann Vitovolt 300 panels bifacial? No, Vitovolt 300 modules are mono-facial, using shingled PERC cells enclosed in a conventional, non-transparent backsheet structure. This means they generate power only from light hitting the front side of the panel, unlike bifacial modules that also capture light reflected off the ground. For typical sloped roofs, this is a fully sufficient and more cost-effective solution. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/Vitovolt_300_WK_new_panel_for_2023-3f9b6342dedf.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [AIKO AIKO-455-MAH54Db](https://comparepv.com/panel/aiko-aiko-455-mah54db) | 455 W | +50 W, cooler, +2.6 pp | | [Longi Solar LR5-54HTH-455M](https://comparepv.com/panel/longi-lr5-54hth-455m) | 455 W | +50 W, cooler, +2.6 pp | | [Yingli YL455CF54 e/2](https://comparepv.com/panel/yingli-yl455cf54-e-2) | 455 W | +50 W, cooler, +2.6 pp | | [Einnova Solarline ESM-455T](https://comparepv.com/panel/einnova-solarline-esm-455t) | 455 W | +50 W, +2.6 pp, +5 yr warranty | | [SunEvo Solar SE5-54HBC-455W](https://comparepv.com/panel/sunevo-solar-se5-54hbc-455w) | 455 W | +50 W, cooler, +2.6 pp | | [Just Solar JST-EDMH-(445-465)W-TD (455W class)](https://comparepv.com/panel/just-solar-jst-edmh-445-465-w-td-455w-class) | 455 W | +50 W, +2.6 pp, +5 yr warranty | | [Luxor Solar LX-455M/182R-96+ GG](https://comparepv.com/panel/luxor-lx-455m-182r-96-gg) | 455 W | +50 W, cooler, +2.6 pp | | [Viessmann M395WK](https://comparepv.com/panel/viessmann-m395wk) | 395 W | -10 W, -0.5 pp | | [Viessmann M400WE](https://comparepv.com/panel/viessmann-m400we) | 400 W | -0.3 pp | | [Longi Solar LR7-54HJD-510M](https://comparepv.com/panel/longi-lr7-54hjd-510m) | 510 W | +105 W, cooler, +4.3 pp | | [AIKO AIKO-A495-MCE54Mw](https://comparepv.com/panel/aiko-aiko-a495-mce54mw) | 495 W | +90 W, cooler, +4.1 pp | | [Longi Solar LR7-54HJD-505M](https://comparepv.com/panel/longi-lr7-54hjd-505m) | 505 W | +100 W, cooler, +4.0 pp | | [AIKO AIKO-A490-MCE54Mw](https://comparepv.com/panel/aiko-aiko-a490-mce54mw) | 490 W | +85 W, cooler, +3.8 pp | | [Longi Solar LR7-54HJD-500M](https://comparepv.com/panel/longi-lr7-54hjd-500m) | 500 W | +95 W, cooler, +3.8 pp | | [Talesun CIPRO-TN9C54M-500W](https://comparepv.com/panel/talesun-cipro-tn9c54m-500w) | 500 W | +95 W, cooler, +3.8 pp | --- Source: https://comparepv.com/panel/viessmann-m405wk Not in this file, on the page: a thirty-year output simulator and alternatives filtered by how closely they match these dimensions.