DWG SP-0 / SP-1 · Rev A · 24 Sep 2026

SPROCKET

Crown CPV+Split

A vertical photovoltaic face that yaws with the sun, and a high-flux crown that breaks the beam into bands. The article you can build today is neither of those shafts. It is a 1.5 m dish, a CPC, a prism, and cells on a cold plate.

Dish, first article: 1,500 mm
Focus at DNI 900, η 0.75: ≈ 1.2 kW
First-article concentration: 80–200×
Cell hold, trip at 85: < 80 °C

Architecture section of a slender rotating solar tower with a high-flux crown, a vertical photovoltaic face, a yaw bearing, and a flared parking podium. — Architecture section. Labeled 500 stories, about 2,000 m. The scale bar on that sheet belongs to the podium study — do not use it to check the shaft. Not the Phase 0 article.

Phase 0 · Lab or rooftop

Optical switchyard

1,500 mm dish, CPC secondary, fused-silica prism, band-matched cells on a cold plate, IR dump. The sheet calls the design focus about 1.2 kW thermal at DNI 900 and η 0.75, from 1.77 m² of aperture. The bench below multiplies those three numbers directly. Do not open the full aperture until coolant is proven.

1
Coolant
Wait
2
Envelope
Wait
3
Aperture
Wait

Direct normal irradiance900 W/m²

Design point is 900.

Geometric concentration140×

First article 80–200×. Hard envelope 50–500×.

IR share after the prism28%

Assumed split into the dump. Not a measured spectrum.

Coolant not proven. Flow before sun.

Instrument view. Geometry is schematic, not a ray trace.

Optical power: —
To the cells: —
Delivered flux: —
Bed rise: —

Power is DNI × 1.77 m² × 0.75. Delivered flux is geometric concentration times the same 0.75, so optical loss cuts intensity as well as watts. Bed rise assumes a 20 L mineral-pebble charge, about 30 kg at 0.8 kJ/kg·K, taking only the IR share. The bench does not measure cell temperature. Hold under 80 °C. Trip at 85 °C. Bed design is 400 °C; 600 °C only after the materials qualify.

Diagram of parallel sunlight reflected by a parabolic dish into a CPC funnel, then dispersed by a triangular prism onto red, orange, yellow, green, blue, and violet solar cells. — Path
Dish, then CPC, then prism. A prism alone, with no concentration, is the weak case in the inset.

Three-step diagram of sunlight reflected from a parabolic dish and concentrated about a thousand times into a receiver that can take multi-junction cells, a Stirling engine, or a thermal absorber. — Dish CPV
Reference receiver heads: multi-junction cells, a Stirling engine, or a thermal absorber. Phase 0 uses the cells, and dumps the IR.

0 Sun
1 Dish
2 CPC
3 Prism
4 MJ
5 Load

Sun → dish → CPC → prism → multi-junction → load. The orange drop after the prism is residual IR into the dump, then the 20 L bed, then the optional column.

Architecture · not Phase 0

The crown splits the beam

The tower drawings put a high-flux ring on the shaft: primary mirrors, a CPC funnel ring, one prism, rainbow cell bands, and a cooling loop. That stack is the same path as the switchyard, built as a crown instead of a single tracked dish. It is not sized, and it is not in the first article.

Exploded view of a parabolic primary ring, CPC secondary funnels, a spectral prism, rainbow multi-junction cells, and a cooling loop. — Optical explode
High-flux solar input into the CPC throats. The prism disperses onto the cell bands.

A segmented ring focuses direct sun downward into the throats of the CPC secondaries.

Cutaway of the crown CPV and split tower: parabolic ring, CPC funnels, rainbow cell bands, cooling pipes, a vertical PV skin, a yaw flywheel, and pebble thermal tanks. — Crown section
Section through the concept stack, crown to pebble beds. Scale bar on the sheet is 20 m — a machine, not the 2 km shaft.

Prism tracker

A compact collector can steer with a rotating prism over a fixed semi-parabolic trough. Smaller ground pitch than a full trough or a flat plate.

Trough

The long classic. The sheet shows it taking more length on the ground for the same idea of a line focus.

Flat plate

No concentration. This is the cousin of the vertical PV skin: it works on diffuse light, and it does not feed a prism.

One face · one bearing

The shaft yaws. The skin follows.

Morning east, noon south, evening west. The vertical array lives on one face, so the tower turns on a yaw bearing instead of tiling every azimuth. The crown rides the same structure. This study is not the Phase 0 article — Phase 0 has no shaft and no bearing.

NESW

Shaft facing south

12:00

Hour, equinox sketch

Elevation: 68°
Face factor: 0.93

Top view. Brass edge is the photovoltaic face; it points at the sun’s azimuth. Elevation is a sine from sunrise to sunset, peaking near 68°. On a vertical face that already tracks azimuth, the beam factor is the sine of elevation. Diffuse still reaches the skin when that factor is low. Not a yield model.

Three views of a tall solar tower in a desert: morning with the shaft yawed east, noon facing south, evening yawed west, each with a flared podium. — Morning · noon · evening
Same structure, three yaw angles. The sheet calls it a 2,000 m tower. Scale is consistent across the three panels and is not a measured height.

Machined circular bearing with a steel spoked hub, brass races, and a carbon-fiber hoop. — Yaw ring study
Steel hub, brass races, carbon hoop, stub shaft. A study of the bearing, not a duty cycle.

Split metal housing with three copper coils arranged around a central lens. — Coil triad
Three-coil assembly in a split housing. Not assigned a Phase 0 duty.

Band-matched cells

Two ways to split the same sun

The crown paints bands sideways with a prism, one color to one cell. The coupon sheet peels a narrow infrared slice onto silicon and sends the rest through a monolithic triple junction. Same intent: stop asking one bandgap to waste the rest of the spectrum.

Solar spectrum diagram with a band-reflect filter sending 900 to 1050 nanometers to a silicon cell and the remaining bands through GaInP, GaInAs, and germanium. — Filter and triple junction
Colours on the sheet are indicative. Energies are the labels that matter.

Junction	Gap	Role
Si	1.10 eV	Side cell, via the band-reflect filter
Filter	1.18–1.38 eV	900–1050 nm peeled off the stack
GaInP	1.88 eV	Top junction of the monolithic triple
GaInAs	1.41 eV	Middle junction
Ge	0.67 eV	Bottom junction

Phase 1 · still closed

Heat goes into pebbles first

Residual infrared after the prism is the first thermal stream. It lands in a 20 L packed bed, design 400 °C. A catalytic column that turns heat and intermediates into fuel is drawn, and it stays shut. No process gas until the bed is isothermal and the relief is set.

Stacked plate coupon beside a glass column of gold beads on a laboratory bench. — Bench scale
Cold plate and a bead column. This is the size of the work.

Glass-walled hexagonal canister filled with mixed metal and glass pebbles. — Media
Low-cost pebble media. Mixed sizes, packed, not a structured catalyst yet.

Gold nanoparticle clusters with glowing molecules on a gray surface. — Surface
The reaction the later column is for. Not licensed by a pretty picture.

Row of stainless packed-bed reactors in an industrial hall. — If it qualifies
R-301 and its neighbors are the picture after materials qualify. Not the 20 L vessel.

Cutaway radial turbine with a separate stacked rotor. — Smoothing machine
A heat engine on the thermal stream would smooth output the way the flywheel smooths yaw. Study only.

Ground, as drawn

One podium against a field

The land sheet puts a conventional spread at 1,500–2,000 acres beside a single circular podium of about 741 acres. The podium is the flared base under the yawing shaft, with stalls drawn as an EV garage. It is out of scope for Phase 0, same as the shaft and the utility tie-in.

Plan comparing a rectangular field of many small collectors labeled 1500 to 2000 acres with a circular Sprocket 500 podium of about 741 acres. — Acreage sheet
Graphic comparison. The 741 acre figure is the label on the sheet, not a survey.

Field of collectors

1,500–2,000 acres

Sprocket podium

~741 acres

Flow from the sun into a PV wall and a crown concentrator, through inverters marked 250 to 350 megawatts, out to a city grid and EV chargers. — Where the watts would go
PV wall and crown meet at the inverters. 250–350 MW is the class written on that sheet. The switchyard on this page calculates about a kilowatt.

Build sequence

Concentrated sun can ignite, blind, and melt.

Cap the dish when idle.
Never look into the CPC throat.
Uncooled cells die in seconds above 50 suns.
No process gas until the bed is isothermal and the relief is set.

Phase 0 · Open
Optical switchyard
Lab or rooftop. Dish, CPC, prism, coupons, cold plate, IR dump. This is the open work.
Phase 1 · Next
Heat and chemistry
20 L bed at 400 °C design. 600 °C only after materials qualify. Gas stays off until the bed is isothermal and the relief is set.
Phase 2 · Later
Facade coupon and yaw ring
One vertical PV coupon, and a bearing that can actually turn a mass. Not a two-kilometer shaft.
Phase 3 · Shut
Closed
Switchyard signed off. Only then does a shaft, a podium, or a utility tie-in become a drawing someone can build.

Out of scope until Phase 3: the 2 km shaft, the podium, and a utility tie-in. Drawing note is in millimeters. It is not a drawing for a two-kilometer tower.

Drawing index