# 17.32. Planning a solar farm¶

Module contributed by Paolo Cavallini - Faunalia

This chapter shows how to use several criteria to locate the areas suitable for installing a photovoltaic power station

First of all, create an aspect map from DTM:

• GRASS ▶ r.aspect [Data type: int; cell size:100]

In GRASS, aspect is calculated in degrees, counterclockwise starting from East. To extract only South facing slopes (270 degrees +- 45), we can reclassify it:

• GRASS ▶ r.reclass

with the following rules:

```225 thru 315 = 1 south
* = NULL
```

You can use the text file `reclass_south.txt` provided. Note that with these simple text files we can create also very complex reclassifications.

We want to build a large farm, so we select only large (> 100 ha) contiguous areas:

• GRASS ▶ r.reclass.greater

Finally, we convert to a vector:

• GRASS ▶ r.to.vect [Feature type: area; Smooth corners: yes]

Exercise for the reader: repeat the analysis, replacing GRASS commands with analogous from other programs.