Shading from adjacent modules is often referred to as ‘inter-shading’
Shading on PV modules can significantly reduce the energy harvest and need to be minimized. The PV cells are connected in long strings and if the current in one cell is reduced because of shading, it affects the whole string, resulting in a much greater energy reduction than just from the shaded cell.
Setting array of modules apart reduces inter-shading but increases the total area of the solar plant and therefore ancillary costs such as land preparation or cabling. There is a trade-off between the additional revenue gained by reduced shading and the additional cost resulting from increased project footprint.

shadingGraph

 

System with trackers

Trackers must be spaced apart in both directions to minimize inter-shading at every hour of the day including morning and evening when the low sun produces long shading. A larger space between trackers (both N/S & E/W) reduces shading and increases energy yield but also increases site preparation and cabling costs.

The usual rectangular grid formation is less efficient in terms of space versus shading than the theater formation shown in the figure below. The theater setting reduces shading and allows a smaller footprint for the solar farm.

Theather-Regular
Trackers Theater vs Regular Setting

EcoSmart developed a computer program to minimize shading losses and site area. Our program creates numeric data on a case-by-case basis.  We developed also a graphical interactive tool to check the results and have made this available to the public.
Run this interactive simulation to visualize shading in a field of trackers.

Instructions

The simulation needs the CDF Player Plug-in installed.

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Other performance factors

  1. GHI to POA ratio
  2. Far shading
  3. Inter-shading
  4. IAM
  5. Soiling
  6. Snow
  7. Low irradiance
  8. Temperature
  9. Module quality
  10. Mismatch
  11. Inverter efficiency
  12. Power clipping
  13. Wiring
  14. Transformer
  15. Dispatch
  16. PID
  17. Light soaking
  18. Aging