What is the sheds (rows) spacing optimum ?

[André Mermoud]

There is no optimal solution. This is a multicriteria choice resulting in a compromise between several requirements. You have to decide which aspect is to be optimized (maximum installed power on the available area, investment, efficiency, amount of energy yield, price of the energy, simplcity and price of the supports, etc).

PVsyst provides a pedagogic tool for the understanding of the performances as function of plane tilt and row pitch (for a given limit shading angle): in the "Orientation" part, choose "Unlimited sheds" / "Show optimization". The graph shows the annual yield (by respect to horizontal) for unshaded plane (in green) and shaded system (irradiance or electrical effect).

This tool clearly shows that the optimal tilt angle for unshaded plane is significantly reduced when considering the shaded performances.

And this becomes dramatically worse when considering sheds not well oriented toward the south.

Further, the power which can be installed on a given area decreases when the tilt increases. With 30° collector tilt, you can in general not put more collectors area than 45-50% of the available area. With low tilt angles (around 3°), this increases to 80% or more.

The mechanical structures are much more simple with low tilts (reduced wind sensitivity).

But the low tilts may induce cleaning problems with rain. You are advised to use frameless modules.

NB: for the final optimization of your system, you are advised to perform the full hourly simulation and vary the parameters.

You can easily do that by using the "Batch mode" (version 6 only).