Solar Power Tower

The Solar Power Tower is a concentrated-solar building that works like a solar-powered boiler. On its own it does nothing: it must be surrounded by Solar Power Mirrors, which reflect sunlight onto the tower and heat it up. While the tower is hot enough, it converts a fluid piped into it into a hotter fluid piped out, which then drives power generation elsewhere.

In-game description
"The Solar Power Tower acts as a boiler converting water into steam or molten salt to hot molten salt. Place multiple mirrors to increase the heat level of this tower."

How it works

  1. Link Solar Power Mirrors to the tower. Mirrors should be arranged into concentric rings around the tower and the mirrors will automatically link.

  2. During the day each linked mirror with a clear line of sight generates heat.

  3. Pipe the input fluid into the tower’s input pipe. The tower automatically selects the matching recipe (Water or Molten Salt).

  4. As long as tower heat is at or above the recipe’s minimum, the tower converts the fluid and pushes the result out of its output pipe.

Production runs at a flat rate whenever the tower is hot enough. Extra heat beyond the recipe minimum does not increase throughput, but it keeps the tower producing for a longer as the suns set.

Heat, mirrors, and the two recipes

Each Solar Power Mirror contributes up to 15 heat at solar noon, scaled down by how high the sun is (0 at night). The tower’s heat is the sum of its mirrors' heat, clamped to a maximum of 600.

The tower has two recipes, each requiring a minimum tower heat to run:

Recipe Input Output Rate Min. tower heat

Water → Steam

Water

High Pressure Steam

120 m³/min

200 (≈ 14 mirrors at noon)

Molten Salt → Hot Molten Salt

Molten Salt

Hot Molten Salt

120 m³/min

300 (≈ 20 mirrors at noon)

The "mirrors at noon" figures are the number of mirrors needed to reach that heat level at midday. Because mirror heat scales with the height of the sun, a field sized only for the minimum will produce for just a short window around noon. Building more mirrors keeps the tower above the threshold for a much larger part of the day.

The two power chains

The tower does not generate power itself — it produces a fluid that is used elsewhere:

Steam chain (Water → Steam mode):

In this mode the tower is a drop-in replacement for a Modular Power Boiler: it makes the exact same High Pressure Steam a boiler does, but from sunlight instead of burning fuel for heat.

Molten salt chain (Molten Salt → Hot Molten Salt mode):

  • Solar Power Tower (Molten Salt → Hot Molten Salt, 120 m³/min) → Solution Heater (Hot Molten Salt → Molten Salt + heat) → boiler/turbine/generator chain → MW.

This is a closed loop: the Solution Heater extracts the heat the tower stored in the salt and returns cool Molten Salt to be piped back to the tower. It lets a solar field feed the Modular Power steam system without burning any fuel. One tower (120 m³/min Hot Molten Salt) can supply two Solution Heaters running the Molten Salt recipe (60 m³/min each).

Building Information

Solar Power Tower

Build Cost

20x Steel Beam (Steel Plate)
25x Modular Frame
10x Versatile Framework
15x Copper Sheet

Fluid Inputs

1 (input pipe) Water or Molten Salt

Fluid Outputs

1 (output pipe) High Pressure Steam or Hot Molten Salt

Throughput

120 m³/min (one production cycle every 0.5 s)

Power Output

None directly, the tower outputs a fluid; power is generated by the downstream turbine/generator.

Milestones

Solar Power Tower

Available with

HUB Tier 3: "Refined Power Mk2" milestone

Research Cost

200x Steel Pipe
1 000x Wire
50x Steel Beam (Steel Plate)

The same milestone also unlocks the Solar Power Mirror, Solar Panel Mk1, Water Turbine Mk1, and the Photovoltaic Cell recipe.

Tips

  • A tower does nothing without mirrors, and mirrors only work in daylight. Plan Solar Power Towers for daytime power and pair them with another generator type or storage for night.

  • Aim for 40 mirrors or more per tower. Thit maxes out the heat at solar noon and gives the lengthens daily production window. Fewer mirrors still work but only produce around midday.

  • Keep the area around the tower clear so mirrors keep line of sight.

  • Molten Salt mode is a closed loop; you only need to charge the loop with Molten Salt once, then recirculate it between the tower and Solution Heaters.

See also

References and Links