Beacon

Beacon is a late-game support building that projects the effects of modules installed inside it to nearby buildings. It lets a single set of modules influence multiple machines, which makes it a major part of high-throughput factory design, especially in compact production areas and in setups where a single machine must be pushed far beyond its normal operating speed.

Only buildings with module slots can benefit from beacon effects, and beacons themselves do not benefit from modules inserted into themselves or into other beacons, so their own energy use cannot be reduced. At present, only speed and efficiency modules can be placed in beacons; productivity and quality modules cannot. Because the effect from a beacon is weaker than placing the same module directly into a machine, the game applies a transmission strength based on beacon quality and on how many beacons affect the target. For a normal beacon, the distribution efficiency is 1.5, and the combined effect on a machine rises with the square root of the number of beacons, so each additional beacon gives less benefit than the previous one.

In practice, beacons are most effective when many compatible machines are packed closely together, because one beacon can support several of them at once. They are also useful when a single machine needs extreme speed, such as a mining drill on a rich but small ore patch where adding more drills is not practical. In that case, multiple speed-module beacons around the drill, combined with modules in the drill itself, can raise its output several times over.

Beacons are a poor choice when the affected machines run infrequently, because the beacons still draw power even while the machines are idle. That wasted power can be avoided with careful planning, including the use of a power switch. They are also useless for non-module-compatible buildings, since those buildings cannot receive beacon effects at all.

• Beacons consume 480 kW each, so large beacon grids are expensive to run.
• Overlapping beacons on the same machine suffer diminishing returns, so the marginal gain from additional beacons drops quickly.
• It is usually more efficient to place buildings around beacons than to place beacons around a single building, especially for full production lines.
• For isolated buildings, the maximum beacon count depends on footprint size: 12 for 2×2 to 4×4 buildings, 16 for 5×5 to 7×7 buildings, and 20 for 8×8 to 10×10 buildings.
• In row-based layouts, the best alignment depends on machine width, and small positional shifts can change how many beacons affect each machine.

For large factories, beacon arrays are usually the preferred design. A row of production buildings surrounded by one or more rows of beacons is far more economical than trying to maximize the beacon count around each individual machine. This reduces the number of beacons needed, simplifies logistics, and makes layouts easier to tile. In long arrays, neighboring production rows can even share beacons, further improving efficiency. However, because the gap between a beacon and a machine cannot exceed two tiles without pushing the machine out of range, belt routing can become awkward; in some cases, a logistic network is the easier way to supply the machines.