The simulation results presented in this chapter demonstrate how bifacial PV systems can bring a performance gain all around the globe, resolving a certain misbelief that they may only form a niche market restricted to specific locations or installations. Global predictions, based on irradiance, indicate bifacial gains in the order of 50% of the natural albedo for equator-facing systems with optimized tilt angle. In locations with low clearness index, the bifacial gain can even be higher. At system level the bifacial gain will be reduced by 20% to 50% relative to a free-standing panel, due to increased self-shading and to limitation of the diffuse irradiance on the rear by adjacent sheds. Even though the rear side irradiance of a bifacial module is inherently inhomogeneous, due to self-shading and external mounting structures, our simulations have shown that the RSD of the total irradiance does not exceed 5%, even at very high albedo, and will usually be much smaller. The simulation methods applied in this chapter and their ongoing integration into commercially available software tools, like PVsyst, will give system designers and installers more visibility on the configuration layout of a bifacial PV plant at their specific location, the associated bifacial gain and the effect on their return on investment.

Chapter Contents:

• 8.1 Introduction
• 8.2 Some design rules (of thumb) for bifacial PV installations–as presented in the indicated sections of this chapter
• 8.3 Location-specific factors
• 8.3.1 Albedo
• 8.3.2 Latitude
• 8.3.3 Clearness index
• 8.4 Single-module factors
• 8.4.1 Single modules–ground clearance
• 8.4.2 Single module—tilt angle
• 8.4.3 Spacing between cells
• 8.5 System-level configuration and effects
• 8.5.1 Fixed-tilt systems—ground clearance
• 8.5.2 Fixed-tilt systems—tilt angle
• 8.5.3 Fixed-tilt systems—latitude effects
• 8.5.4 Combined empirical formulae
• 8.5.5 Global combined analysis—bifacial irradiance gain for fixed-tilt systems
• 8.6 Single-axis tracking systems
• 8.7 Vertically mounted panels
• 8.7.1 East-west–latitude effects
• 8.7.2 Azimuth angle
• 8.8 Other factors affecting the gain
• 8.8.1 Thermal effects
• 8.8.2 Electrical effects
• 8.9 Summary and outlook
• Glossary of terms
• References

Inspec keywords: solar cells; environmental factors; photovoltaic power systems; power system simulation

Other keywords: self-shading; equator-facing systems; free-standing panel; PVsyst simulation; low clearness index; rear side irradiance; irradiance prediction; diffuse irradiance; global predictions; bifacial PV systems; geographic location dependence; bifacial gain; environmental conditions dependence

Subjects: Solar power stations and photovoltaic power systems; Photoelectric conversion; solar cells and arrays; Solar cells and arrays; Environmental factors