By default, NuGet restores packages into the packages folder in the solution root. This folder is shared between all solution projects. In some cases it is useful to change the location of the restored packages (for instance, to share them between several solutions).
Its can be achieved by creating the file nuget.config in the same folder where solution is located:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<config>
<add key="repositoryPath" value="../packages" />
</config>
</configuration>
repositoryPath setting points to the new packages location and automatically read by the NuGet during the restoring.
The config affects only one solution and it is enough just to put file near the .sln, no need to reference it inside solution itself.