Solar Array Panels
Multi-Junction GaAs/Ge Photovoltaic Array Assembly
The multi-junction GaAs/Ge photovoltaic array assembly is a 14-square-meter deployable panel system that converts solar illumination into 3 to 5 kWe of electrical power to augment a primary nuclear source. Lunar operation imposes severe environmental demands on the high-efficiency cells. The 14-day lunar night halts generation for half the synodic period, while the lack of atmospheric scattering requires tracking to capture direct solar flux. Additionally, cell interconnects must endure thermal cycling between -170°C and +120°C without fatigue cracking, while accumulating regolith dust degrades optical transmission through the protective coverglass.
High-efficiency triple-junction gallium arsenide photovoltaic array panels generating 3-5 kWe from solar illumination. Provides supplemental power during lunar day to augment the nuclear primary source and charge energy storage systems.
Purpose
Convert solar photon energy to electrical power using multi-junction III-V semiconductor cells, providing supplemental daytime power generation to reduce nuclear reactor loading and provide redundant power capability.
Context
Primary element of the solar power subsystem. Array output is fed through MPPT controllers (L3-PWR-SOL-COND) and then to power conversion (L2-PWR-CONV). Panels are mounted on dual-axis trackers (L3-PWR-SOL-TRACK) and protected by electrostatic dust shields (L3-PWR-SOL-DUST).
Principles
- ▸Triple-junction InGaP/GaAs/Ge cells achieve >30% AM0 efficiency by absorbing three spectral bands
- ▸Series-parallel string architecture balances voltage output with fault tolerance against individual cell failures
- ▸Cell interconnects must accommodate thermal cycling strain from -170C to +120C without fatigue cracking
- ▸Coverglass (CMX or CMG) protects cells from UV degradation and micrometeorite damage
- ▸Bypass diodes prevent hot-spot damage from shadowed or failed cells in series strings
Typical implementations
- ▸SpectroLab XTJ Prime — 30.7% efficiency triple-junction space solar cells used on ISS and GEO satellites
- ▸SolAero ZTJ — inverted metamorphic multi-junction cells, 33.3% efficiency
- ▸Orbital ATK UltraFlex — lightweight deployable circular array used on InSight Mars lander
- ▸Airbus Eurostar Neo — large deployable GaAs array panels for GEO communications satellites
Lunar considerations
- ▸Lunar regolith dust accumulation degrades optical transmission — requires active mitigation (EDS)
- ▸14-day lunar night means zero solar output for half the synodic period
- ▸No atmospheric scattering — direct illumination only, making tracking essential for efficiency
- ▸Solar constant at Moon (1361 W/m2) similar to Earth orbit but with no atmospheric losses
Specifications
Functional
| primary function | Convert solar irradiance to DC electrical power at 3-5 kWe during lunar day |
| inputs | Solar irradiance: 1361 W/m2 (AM0 equivalent at lunar surface), Pointing commands from tracking system (L3-PWR-SOL-TRACK) |
| outputs | DC electrical power: 3-5 kWe at ~100-120 VDC string voltage, Array temperature telemetry, String current/voltage monitoring data |
| power output kwe bol | 5.0 |
| power output kwe eol 15yr | 3.5 |
| cell efficiency percent | 30 |
| array area m2 | 14 |
| degradation rate per year percent | 1.5 |
Physical
| mass kg | 35 |
| dimensions | Approximately 14 m2 total active area across multiple deployable panels |
| materials | InGaP/GaAs/Ge triple-junction solar cells, CMX coverglass (ceria-doped microsheet), Carbon fiber composite panel substrate, Kapton/copper flex circuit cell interconnects, Germanium cell substrate wafers |
| operating temperature c | -170 to +120 |
| radiation environment | Galactic cosmic rays, solar proton events (no magnetosphere protection) |
| dust environment | Lunar regolith particles (electrostatic levitation and mechanical) |
Operational
| power consumption w | 0 |
| operating min | -170 |
| operating max | 120 |
| optimal efficiency | 28 |
| lifetime years | 15 |
| mtbf hours | 200000 |
Interfaces
Provides
- Raw DC power from PV strings at variable voltage depending on illumination and temperature
- Array performance telemetry: string voltages, currents, temperatures, and health status
Requires
- Dual-axis pointing platform maintaining array normal within 2 degrees of solar vector
- Electrostatic dust removal maintaining >90% optical transmission on coverglass
- Structural support frame and deployment mechanism for array panels
Cite this entry
Lunar Ark Codex. "Solar Array Panels" (L3-PWR-SOL-ARRAY). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PWR-SOL-ARRAY
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.