Grain Silos are used for offline income. Each base silo adds a stored hour of income.
The number of silos one can build is dependent on their Permit. A standard permit allows for 2 silos, while a pro permit allows for 10 silos. Silos also have two qualities: with the standard permit, offline income is earned at half the normal rate, while with the pro permit, offline income is earned at the full rate.
The base cost of each silo is listed in the following table. The first silo is free. The formula for calculating silo costs changed in update 1.9.
The cost of the nth silo is calculated via the formula .
Silo Capacity allows you to increase the away-time by six minutes per level. There are twenty levels, maxing out at an additional two hours per silo.
As of 1.9, silo quality no longer can be upgraded by epic researching. The Pro Permit will automatically grant the user full quality silos, whereas with standard permit, you will only get half quality.