--- title: "Runtech China RT 4BW 4W Solar Panel - Specs & Review | ComparePV" description: "Runtech China RT 4BW 4W solar panel. Specs: 24.30% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/runtech-china-rt-4bw" updated: 2026-09-11 --- # Runtech China RT 4BW Efficiency leader, heavy for its output 50 panels in the 0-104 W band, all technologies ## Identity - **Manufacturer:** Runtech China - **Model:** RT 4BW - **Series:** RT 4BW - **Rated power:** 4 W - **Cell technology:** Monocrystalline - **Bifacial:** yes ## How it compares Compared against 0-104 W band, all technologies (50 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 4 W | 95 W | Weak - bottom 1% | | | Module efficiency | 24.30% | 15.37% | Strong - top 1% | 131 | | Power density | - | 149.3 | | | | Temperature coefficient | -0.290 | -0.360 | Strong - top 17% | 2,165 | | Weight (kg) | 3.0 kg | 5.8 kg | Weak - bottom 3% | | | Performance warranty | - | 25 yrs | | | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 24.30% | 15.37% | Strong - top 1% | 131 | | Power density | - | 149.3 | | | | Temperature coefficient | -0.290 | -0.360 | Strong - top 17% | 2,165 | | Weight per kWp | 750.0 | 71.4 | Weak - bottom 3% | 13,986 | | Performance warranty | - | 25 yrs | | | ### Strengths - **24.30% module efficiency** - Top 1% of the 0-104 W band, against a median of 15.37%. Ranked 131st in the whole database. - **-0.290 %/°C temperature coefficient** - Top 17% of the 0-104 W band, against a median of -0.360. ### Watch out for - **750.0 kg per kWp** - Bottom 3% of the 0-104 W band, against a median of 71.4. Ranked 13,986th in the whole database. - **Best for:** Small roofs that need every watt and hot roofs and southern climates. - **Not ideal for:** Weight-limited structures. ## Specification ### Electrical - **Rated power (Pmax):** 4 W - **Efficiency:** 24.30 % - **Voltage at Pmax (Vmp):** 1.33 V - **Current at Pmax (Imp):** 3.00 A - **Open-circuit voltage (Voc):** 1.56 V - **Short-circuit current (Isc):** 3.16 A - **Max system voltage:** 500 V ### Temperature - **Temperature coefficient of Pmax:** -0.290 %/degC - **Temperature coefficient of Voc:** -0.250 %/degC - **Temperature coefficient of Isc:** 0.045 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell count:** 2 - **Bifacial:** yes ### Physical - **Thickness:** 20 mm - **Weight:** 3.0 kg ### Warranty and degradation ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 131 of 14005 | | Power density | 13991 of 14005 | | Temperature coefficient | 2165 of 14005 | | Weight | 13986 of 14005 | | Warranty | 13880 of 14005 | ## About this series The Runtech RT 4BW series of photovoltaic panels is an advanced solution based on monocrystalline cells that redefines performance standards in the medium-power segment. A key feature is **Multi-busbar technology**, which, thanks to a denser arrangement of conductive paths, effectively reduces energy losses and increases the module's resistance to micro-cracks. The use of Half-Cut cell architecture makes these panels perform much better in partial shading conditions, which solves a common problem for installations on roofs with dormers or chimneys. The RT 4BW series is characterized by a **low temperature coefficient**, which allows for maintaining high efficiency even during summer heatwaves when standard modules lose effectiveness. This product is dedicated to both individual prosumers and small businesses for whom the priority is an **excellent price-to-quality ratio** and a quick return on investment. A robust frame and high-transmittance tempered glass guarantee **high resistance to mechanical loads**, such as accumulated snow or strong winds. By choosing the RT 4BW series, the user receives a product resistant to LID degradation processes, which ensures **long-term stability of energy production** at a constant level, setting these panels apart from the budget solutions of competitors. ## Notable figures - Efficiency of 24.3% is 2.5pp above the \*\*database\*\* median (21.8%) - At -0.29%/°C, hot weather performance is typical for \*\*database\*\* panels - At 3.0 kg, this panel is 23.5 kg lighter than \*\*database\*\* median (26.5 kg) - easier handling during installation - Ranked #131 out of 14005 panels for efficiency in the database ## Questions ### Are the Runtech RT 4BW panels bifacial, and what does that mean for my installation? Yes, the RT 4BW series features bifacial technology, meaning the cells generate power from both the front and rear surfaces. The rear side captures light reflected from the ground, potentially boosting annual energy yield by several percentage points compared to standard monofacial modules. The gain is most noticeable over light-colored surfaces such as concrete, white gravel, or snow. ### How does the half-cut cell architecture in the RT 4BW series handle partial roof shading? The half-cut design splits each cell in two, so shading on one portion of the module does not shut down production from the rest. In practice, a chimney, dormer, or antenna will not kill the entire panel's output. The RT 4BW series is therefore well suited to roofs with irregular shapes or obstacles that would severely impact traditional full-cell modules. ### Does the Runtech RT 4BW series lose efficiency during hot summer weather? Thanks to a low temperature coefficient, the RT 4BW series maintains high efficiency even in extreme heat. Standard modules lose roughly 0.4–0.5% of rated power per degree Celsius above 25°C; the RT 4BW's advanced monocrystalline cells minimize those losses. This is a meaningful advantage given that rooftop surface temperatures in summer can easily exceed 60–70°C. ### What is multi-busbar technology, and why choose RT 4BW panels over modules with fewer busbars? Multi-busbar means a higher density of conductive ribbons across the cell surface. Because current travels a shorter distance to the nearest busbar, resistive losses are reduced and overall yield is higher. The additional busbars also lower mechanical stress on the cells, reducing the risk of microcracks during both transport and long-term operation in the field. ### How do Runtech RT 4BW panels hold up mechanically against snow loads and strong winds? The RT 4BW series features a robust aluminum frame and high-transmittance tempered glass engineered for significant mechanical loads. The modules withstand heavy snow accumulation and strong wind gusts typical of Central European climates. This is especially important for rooftops in mountain regions or in areas where high solar irradiance coincides with intense snowfall. ### Are RT 4BW panels resistant to LID degradation, and how long will they produce energy at a stable level? Yes, the RT 4BW series is engineered to resist LID (Light Induced Degradation), the power loss that standard monocrystalline cells can experience after their first exposure to sunlight. As a result, the panels maintain stable rated output throughout their service life. This sets them apart from budget modules that may lose several percent of efficiency within the first year of operation, negatively impacting the return on investment. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/rt4bw-2ef6d24fcff5.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [SpolarPV Type Q](https://comparepv.com/panel/spolarpv-type-q) | 45 W | +41 W, hotter, -9.1 pp | | [Gamko New Energy GKA157F50W](https://comparepv.com/panel/gamko-new-energy-gka157f50w) | 50 W | +46 W, -10.6 pp | | [Runtech China RT30WM](https://comparepv.com/panel/runtech-china-rt30wm) | 30 W | +26 W, cooler, -11.2 pp | --- Source: https://comparepv.com/panel/runtech-china-rt-4bw Not in this file, on the page: a thirty-year output simulator.