My response is outdated, but I was unable to find an acceptable answer posted elsewhere, and unfortunately, for unknown reasons the SAGA-based solution above was not working for me. So, another option you could consider is to use GDAL. Specifically the tool gdalbuildvrt http://www.gdal.org/gdalbuildvrt.html
As long as your set of input rasters have the same a) format, b) projection, c) cell size, and d) extent, then you can use the option "-r maximum" of gdalbuildvrt.py in the command line. If you have OSGeo4w shell installed, open that, and the syntax would be (assuming your are using .tif files)...
gdalbuildvrt -r maximum -input_file_list [your_list_of_raster_filepaths.txt] output_raster_name.tif
In windows, an easy way to derive a list of raster files for input in the
-input_file_list option above is...
- Open a cmd window
- Navigate to the folder containing your rasters
Type the following command...
dir /b /s *.tif>filelist.txt
I had the same problem for a set of 12 rasters (GeoTiff), where I needed the maximum value from all overlapping rasters stored in a single grid. Unfortunately, I was not able to achieve this using SAGA Mosaic tool, nor with gdal_calc.