Efficiency leader, no clear weak spot
The Horay Solar HS 199R-120 TC-D Delta series of photovoltaic panels is an advanced solution based on innovative N-type TOPCon cells, which redefine efficiency standards in challenging lighting conditions. Thanks to the use of bifacial double glass technology, these modules effectively utilize light reflected from the ground, significantly increasing total energy yield compared to single-sided counterparts. The Delta design solves the problem of limited installation space, offering high power density while maintaining compact dimensions. The use of rectangular R-type cells allows for better filling of the module surface, which minimizes energy losses and improves the aesthetics of the installation. These panels are characterized by exceptional resistance to PID and LID degradation, guaranteeing stable operation and a fast return on investment for decades. This product is dedicated to demanding prosumers and commercial investors seeking uncompromising durability and a low temperature coefficient. It is precisely the excellent performance at high temperatures that distinguishes this series from the competition, making it an ideal choice for roofs with high solar exposure. By choosing the Delta series, the user receives a product combining modern design with technology that realistically lowers the cost of producing a kilowatt-hour of energy.
Ranking
Signals from the data
Small roofs that need every watt and hot roofs and southern climates.
Top 21% of the N-type 500-550 W segment, against a median of 22.55%.
Top 23% of the N-type 500-550 W segment, against a median of -0.290.
The 22.2-23.1% efficiency range clearly outperforms two of three peer comparables: DMEGC GHxxxM10T-B66HST and Heliene 144HC M10 SL Bifacial, both at 20.9%. A gap of ~1.3-2.2 percentage points translates into meaningfully higher energy yield per unit of roof area, reducing LCOE.
N-type cells exhibit LID degradation below 1% in year one, versus up to 2-3% for PERC. A lower temperature coefficient (typically ~-0.30%/°C for TOPCon vs. -0.35%/°C for PERC) delivers higher real-world yield on hot, high-irradiance rooftops - a decisive advantage for south-facing pitches with minimal shading.
The bifacial double-glass construction captures albedo from the rear surface. Over high-reflectivity substrates (gravel, white EPDM, snow), a bifaciality factor in the 70-85% range typical for this module class adds 5-15% to annual energy yield compared to monofacial equivalents. The dual-glass encapsulation also eliminates backsheet degradation risk.
Horay Solar has appeared on the BNEF Tier 1 solar module manufacturer list since Q1 2025, confirming financial credibility and module acceptance as collateral by project-finance lenders for commercial and utility-scale projects. The 2,500 MW/year production capacity reduces supply-chain disruption risk.
The 30-year linear power warranty exceeds the 25-year standard offered by many peers including DMEGC and Heliene. The extended warranty horizon lowers residual risk in long-tenor project finance structures (PPAs, lease agreements).
Gokin GK-5-60HG achieves 24.4% efficiency at the same 540 Wp power class, representing a ~1.3-2.2 percentage-point advantage over the Delta series (22.2-23.1%). The gap likely reflects Gokin's use of back-contact (BC) cell technology; however, in space-constrained installations (small industrial rooftops), this translates to measurably fewer watts per m².
The materials and workmanship warranty is 15 years, whereas leading Tier-1 manufacturers - Trina Solar, JA Solar, LONGi - standardly offer 25 years. For institutional investors and projects with 20-25-year financing horizons, the shorter product warranty increases O&M cost risk beyond year 15.
- At 23.1% efficiency, this panel is 0.6pp above typical N-type 500-550W modules (median: 22.6%)
- Power density of 227.4 W/m² matches the N-type 500-550W median
- Temperature coefficient of -0.28%/°C matches the N-type 500-550W median
- At 29.0 kg (2.8 kg above N-type 500-550W median of 26.2 kg), requires checking roof load capacity
- Bifacial design (80% factor) captures reflected light - adds 4-12% yield on ground-mount or white roof
Specifications
Datasheet charts
Measured curves published by Horay Solar in this model's datasheet. A chart carrying a wattage was measured on that variant alone - only the ones that describe 540 Wp appear here. The rest cover the whole series.
Simulations
Degradation from this panel's own datasheet figures. No inverter, soiling or shading losses.
Model: bifaciality × albedo × 0.6 view factor. A first-order estimate, not a yield simulation.
Alternatives
Found 405 panels of the same or similar size to this one, within ±10 mm. See them here Found 416 panels of the same or similar size to this one, within ±25 mm. See them here Found 433 panels of the same or similar size to this one, within ±50 mm. See them here Found 961 panels of the same or similar size to this one, within ±100 mm. See them here
About the HS 199R-120 TC-D Delta series
These answers cover the whole series. Where a figure differs, the specification above is this module's own.