--- title: "JS Solar JS305M 305W Solar Panel - Specs & Review | ComparePV" description: "JS Solar JS305M 305W solar panel. Specs: 18.75% efficiency, Monocrystalline cells, dimensions, warranty and temperature coefficient." source: "https://comparepv.com/panel/js-solar-js305m" updated: 2026-09-11 --- # JS Solar JS305M Middle of its segment, weak in heat 286 panels in the segment PERC 300-350 W ## Identity - **Manufacturer:** JS Solar - **Model:** JS305M - **Series:** 60+ SERIES - **Rated power:** 305 W - **Cell technology:** PERC ## How it compares Compared against segment PERC 300-350 W (286 panels). | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Power (Wp) | 305 W | 325 W | Weak - bottom 9% | | | Module efficiency | 18.75% | 19.00% | Typical | 13,047 | | Power density | 187.5 | 190.0 | Typical | 13,026 | | Temperature coefficient | -0.420 | -0.360 | Weak - bottom 7% | 13,796 | | Weight (kg) | 18.0 kg | 19.0 kg | Typical | | | Performance warranty | 25 yrs | 25 yrs | Typical | 9,798 | ### Full peer table | Measure | This panel | Segment median | Standing | Rank | | --- | --- | --- | --- | --- | | Module efficiency | 18.75% | 19.00% | Typical | 13,047 | | Power density | 187.5 | 190.0 | Typical | 13,026 | | Temperature coefficient | -0.420 | -0.360 | Weak - bottom 7% | 13,796 | | Weight per kWp | 59.0 | 60.0 | Typical | 11,981 | | Performance warranty | 25 yrs | 25 yrs | Typical | 9,798 | ### Watch out for - **-0.420 %/°C temperature coefficient** - Bottom 7% of the PERC 300-350 W segment, against a median of -0.360. Ranked 13,796th in the whole database. - **Not ideal for:** Hot climates. ## Specification ### Electrical - **Rated power (Pmax):** 305 W - **Efficiency:** 18.75 % - **Voltage at Pmax (Vmp):** 32.97 V - **Current at Pmax (Imp):** 9.25 A - **Open-circuit voltage (Voc):** 39.05 V - **Short-circuit current (Isc):** 9.50 A - **Max system voltage:** 1000 V ### Temperature - **Temperature coefficient of Pmax:** -0.420 %/degC - **Temperature coefficient of Voc:** -0.320 %/degC - **Temperature coefficient of Isc:** 0.060 %/degC - **NOCT:** 45 degC ### Cell and construction - **Cell type:** Monocrystalline - **Cell technology:** PERC - **Cell count:** 60 ### Physical - **Length:** 1640 mm - **Width:** 992 mm - **Thickness:** 35 mm - **Weight:** 18.0 kg - **Area:** 1.63 m2 - **Power density:** 187.5 Wp/m2 ### Warranty and degradation - **Product warranty:** 10 years - **Performance warranty:** 25 years - **Output guaranteed at end of warranty:** 80.2 % - **First-year degradation:** 3.00 % - **Annual degradation:** 0.70 % - **Output after 30 years:** 234 W ## Rank in the whole catalogue | Measure | Position | | --- | --- | | Efficiency | 13047 of 14005 | | Power density | 13026 of 14005 | | Temperature coefficient | 13796 of 14005 | | Weight | 11981 of 14005 | | Warranty | 9798 of 14005 | ## Pros - **Up to 19.67% efficiency – top of PERC segment** - Maximum efficiency of 19.67% matches the best peer in the comparison group (SP Enerji Solar Power 300–320 W, 19.67%) and exceeds both Sun Earth AGRI and Sunket 182mm (19.55% each). Within the 60-cell PERC 305–320 Wp class, this places the series in the top decile of the market. - **Four power variants – flexible sizing** - The series spans four power variants from 305 to 320 Wp, enabling precise array sizing for constrained roof areas without switching to a different series or manufacturer. - **Full safety certification set** - Modules carry IEC 61215, IEC 61730, CE, PID Resistance, Salt Mist, and Ammonia Corrosion certifications — the baseline required for bankable project due diligence and by most insurers operating in European markets. - **25-year linear power warranty** - A 25-year performance warranty aligns with the market standard for PERC modules. The gap to premium-tier leaders (e.g., REC Alpha, Panasonic EverVolt — 25–30 years) is 0–5 years, which does not disqualify the series for typical residential or C&I installations. ## Cons - **PERC, not N-type TOPCon – conflicts with marketing copy** - The technical specifications list PERC (P-type) cell technology, not the N-type TOPCon promoted in the product description. PERC cells exhibit LID degradation of 0.5–1% in the first year and a weaker temperature coefficient (~-0.37%/°C vs. TOPCon's -0.30%/°C), resulting in approximately 1.5–2.5% lower annual energy yield compared to a TOPCon module at the same nameplate power. - **Monofacial only – bifacial peers available** - The series is monofacial (is\_bifacial: false), while direct peer Sunket 182mm 80Cells offers a bifacial double-glass module at the same 320 Wp and near-identical 19.55% efficiency. In ground-mount or light-colored rooftop installations, bifacial modules typically deliver 10–20% additional annual yield. - **10-year product warranty – market minimum** - The product warranty is 10 years, whereas BNEF Tier-1 manufacturers (JA Solar, JinkoSolar, Trina Solar) standardly offer 12–15 years. The gap is negligible within the typical 7–9 year payback period, but any failure in years 11–15 falls outside warranty coverage. - **Manufacturer absent from BNEF Tier-1 list (Q1 2026)** - JS Solar (Yixing JS Solar Co., Ltd.) does not appear on the BloombergNEF Tier-1 PV Module Manufacturers list for Q1 2026. Non-bankable status restricts debt financing for commercial-scale projects and may reduce the residual value of a system at property sale. ## About this series The JS Solar 60+ SERIES represents an advanced response to the growing market demand for maximizing yields from limited roof space. The use of **N-Type TOPCon cell technology** allows these modules to achieve significantly higher conversion efficiency and better performance in low-light conditions, which is crucial in the Polish climate zone. These panels eliminate the problem of rapid power degradation, offering investors exceptional **resistance to LID and LeTID effects**, which translates into financial stability and predictability of energy production over several decades. Thanks to the use of larger silicon wafers and innovative busbar layout, the 60+ SERIES minimizes resistance losses, which distinguishes it from standard competitor solutions. It is the optimal choice for demanding prosumers and companies that care about a **low temperature coefficient**, guaranteeing high production even during hot summer days. The module construction provides excellent mechanical strength, protecting the installation against extreme weather events. By choosing the 60+ series, the user invests in **energy security and faster return** on investment, receiving a product that combines solid workmanship with the latest achievements in photovoltaic engineering currently available on the market. ## Notable figures - At 18.8% efficiency, this panel is 0.7pp below the \*\*PERC 0-400W\*\* median of 19.4% - Power density of 187.5 W/m² is 6.9 W/m² below \*\*PERC 0-400W\*\* median (194.4 W/m²) - needs more roof space - At -0.42%/°C, loses 0.06pp more power per degree than \*\*PERC 0-400W\*\* median (-0.36%/°C) - 18.0 kg weight - 2.5 kg lighter than \*\*PERC 0-400W\*\* median (20.5 kg), reducing installation effort - #13047 for efficiency, #13796 for temperature performance out of 14005 panels ## Questions ### What warranty does the JS Solar 60+ SERIES come with, and what does it cover? The JS Solar 60+ SERIES includes a 10-year product warranty covering material and workmanship defects, plus a 25-year linear power warranty guaranteeing at least 80.2% of nominal output after 25 years. This is a solid standard for this price range, though leading Tier 1 manufacturers sometimes offer 30-year power warranties. It is worth discussing warranty service terms with the local distributor before purchasing. ### What is PERC technology and why does the JS Solar 60+ SERIES use it? PERC (Passivated Emitter Rear Contact) adds a passivation layer on the rear side of the silicon wafer, reflecting photons that would otherwise be lost back into the cell junction. In the 60+ SERIES, this enables module efficiency of up to 19.67%, well above older BSF cells. It is a cost-effective choice at this price point, though newer N-Type TOPCon and HJT technologies offer higher efficiency and a better temperature coefficient. ### Is the JS Solar 60+ SERIES 320 Wp panel suitable for a pitched roof in Poland? Yes, the JS156M60-320W module measures 1640×992 mm and weighs approximately 18 kg, making it well-suited for standard Polish pitched roofs with tilt angles of 15–45°. The lightweight build simplifies crew installation. The panel uses PERC cell technology with a temperature coefficient of -0.42%/°C — a typical and acceptable figure for Polish climate conditions. ### Is the JS Solar 60+ SERIES a bifacial panel? No, the 60+ SERIES is a monofacial panel — power is generated only through the front glass side of the module. Bifacial panels can produce an additional 5–15% energy from reflected irradiance, but require a light-colored ground surface and adequate mounting height. On standard pitched roofs, the real-world annual yield difference is typically minimal, and monofacial panels remain a simpler and more affordable option. ### Is JS Solar a reliable manufacturer? What does the lack of Tier 1 status mean? JS Solar (Yixing JS Solar Co., Ltd.) is a Chinese manufacturer with several years on the market. The absence of Tier 1 status — assigned by BloombergNEF — primarily means the company has not yet secured financing for projects through major investment banks; it is not a direct indicator of product quality. Before buying, verify IEC 61215 and IEC 61730 certifications, check references from local installers in Poland, and confirm warranty service terms with the regional distributor. ### How does the JS Solar 60+ SERIES perform during hot summer days and what is the impact on energy output? The power temperature coefficient for the 60+ SERIES is -0.42%/°C, meaning the panel loses 0.42% of its rated power for each degree Celsius above 25°C (STC). At a module temperature of 65°C on a hot summer day, real-world output drops by approximately 16.8%. This is a typical result for PERC technology. N-Type TOPCon or HJT modules offer better coefficients in the range of -0.30 to -0.26%/°C, but are generally priced higher. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/655b6673cbb193c99f520d6c131c16a5-e8316ea883e2.pdf) ## Alternatives | Panel | Power | How it differs | | --- | --- | --- | | [JA Solar NS-300MH-72](https://comparepv.com/panel/ja-solar-ns-300mh-72) | 300 W | Cooler, lighter, +4.6 pp | | [PolyCrown Solar Tech NS-300MH-72](https://comparepv.com/panel/polycrown-solar-tech-ns-300mh-72) | 300 W | Cooler, lighter, +4.6 pp | | [Heckert Solar ZEUS 1.2 FullBlack 280W](https://comparepv.com/panel/heckert-solar-zeus-1-2-fullblack-280w) | 280 W | Cooler, +4.6 pp, +5 yr warranty | | [JA Solar NS-330MH-80](https://comparepv.com/panel/ja-solar-ns-330mh-80) | 330 W | Cooler, lighter, +4.4 pp | | [PolyCrown Solar Tech NS-330MH-80](https://comparepv.com/panel/polycrown-solar-tech-ns-330mh-80) | 330 W | Cooler, lighter, +4.4 pp | | [Gamko New Energy GKA182M285W](https://comparepv.com/panel/gamko-new-energy-gka182m285w) | 285 W | Lighter, +4.2 pp, +5 yr warranty | | [Gamko New Energy GKA182M260W](https://comparepv.com/panel/gamko-new-energy-gka182m260w) | 260 W | Lighter, +4.2 pp, +5 yr warranty | | [Gamko New Energy GKA182M270W](https://comparepv.com/panel/gamko-new-energy-gka182m270w) | 270 W | Lighter, +4.2 pp, +5 yr warranty | | [Gamko New Energy GKA182M300W](https://comparepv.com/panel/gamko-new-energy-gka182m300w) | 300 W | Lighter, +4.2 pp, +5 yr warranty | | [JS Solar JS260P](https://comparepv.com/panel/js-solar-js260p) | 260 W | -45 W, heavier, -2.8 pp | | [JS Solar JS265P](https://comparepv.com/panel/js-solar-js265p) | 265 W | -40 W, heavier, -2.6 pp | | [JS Solar JS270P](https://comparepv.com/panel/js-solar-js270p) | 270 W | -35 W, heavier, -2.2 pp | | [JS Solar JS275P](https://comparepv.com/panel/js-solar-js275p) | 275 W | -30 W, heavier, -1.9 pp | | [JS Solar JS280P](https://comparepv.com/panel/js-solar-js280p) | 280 W | -25 W, heavier, -1.6 pp | | [JS Solar JS310M](https://comparepv.com/panel/js-solar-js310m) | 310 W | +0.3 pp | | [JS Solar JS315M](https://comparepv.com/panel/js-solar-js315m) | 315 W | +10 W, +0.6 pp | | [Maxeon SPR-MAX3-400-COM](https://comparepv.com/panel/maxeon-spr-max3-400-com) | 400 W | Cooler, +3.9 pp, +15 yr warranty | --- Source: https://comparepv.com/panel/js-solar-js305m Not in this file, on the page: a thirty-year output simulator and alternatives filtered by how closely they match these dimensions.