In Kerbal Space Program (KSP), solar panels generate electrical power for spacecraft by converting sunlight into energy, with output depending on distance from the sun and panel type. The game simulates realistic power generation, where a standard OX-4L panel produces 0.375 EC/s at Kerbin’s orbit, according to the KSP Wiki (KSP Official Documentation, 2026). This answer focuses on their in-game function, not real-world solar panels.
Solar panels in KSP are essential for powering probes, rovers, and space stations. Their effectiveness varies by distance from Kerbol (the game’s sun), closer orbits yield more power, while far planets like Eeloo see drastically reduced output. Panels also degrade if deployed in shadow or atmospheres, and can be retracted to avoid damage during aerodynamic flight. Understanding panel mechanics is key to mission planning, especially for long-duration journeys.
Power generation scales with distance from Kerbol
KSP solar panels follow an inverse-square law for power output. At Kerbin’s orbit (13.6 million km from Kerbol), a basic OX-STAT panel generates 0.35 EC/s (KSP Wiki, 2026). At Moho’s orbit (4.2 million km), output rises to over 3.5 EC/s, while at Eeloo (68 million km), it drops to just 0.01 EC/s. This makes solar panels impractical for outer-planet missions without multiple panels or nuclear power alternatives. Players must calculate power needs based on orbital trajectory and mission duration.
Panel types affect efficiency and deployment
KSP offers fixed and deployable solar panels. Fixed panels like the OX-4L are lightweight and always exposed, generating 0.375 EC/s at Kerbin (KSP Wiki, 2026). Deployable panels like the Gigantor XL produce 2.5 EC/s at Kerbin but must be extended via right-click or action groups. Retracting them is critical during atmospheric flight to prevent drag and breakage. Deployable panels also track the sun automatically, optimising output, while fixed panels require manual orientation.
Panels stop working in shadow and atmospheres
Solar panels only generate power when in direct sunlight. In a planet’s shadow, output drops to zero, requiring battery storage for continuous operation (KSP Wiki, 2026). Also, panels cannot be deployed in atmospheric pressure above 0.1 atm, as they will break. For Eve or Duna missions, deploy panels only after reaching space. Batteries are essential for eclipses and night-side operations, with capacity measured in EC units. A typical 100 EC battery can power a small probe for several minutes without sunlight.
A worked example
A typical KSP mission to Duna with a 2-tonne probe using OX-4L panels will generate roughly 0.19 EC/s at Duna’s orbit, costing you about 1,200 Kerbal credits in parts for a full solar array. Consider a stock career-mode scenario where you launch a 3-tonne relay satellite to a 200 km orbit around Kerbin. Using three OX-STAT panels, each producing 0.35 EC/s at that distance, the total output is 1.05 EC/s, enough to power a Communotron 88-88 antenna continuously. The mission’s total part cost is 1,450 credits, with a 0% VAT equivalent in the game’s economy. According to the KSP Wiki, the inverse-square law means power drops by 75% at 2x Kerbin’s orbital radius, so a Duna mission at 20.7 million km yields just 0.15 EC/s per panel. Payback in terms of mission success is immediate, without solar, you lose probe control within 30 seconds of battery drain.
| Item | Figure |
|---|---|
| Upfront part cost | 1,450 credits |
| Power generation at Kerbin | 1.05 EC/s |
| Power at Duna orbit | 0.45 EC/s total |
| Battery backup needed | 200 EC minimum |
What homeowners often get wrong
The most common mistake is treating solar panels in KSP like real-world panels, assuming they work at full output everywhere in the solar system. Here are three frequent errors that can ruin a mission.
- Panels work at any distance from Kerbol New players think panels generate power uniformly, but output follows the inverse-square law, at Eeloo’s orbit (68 million km), a Gigantor panel produces just 0.01 EC/s, making it useless for heavy loads. You must add RTG generators or extra batteries for outer planets.
- Deploying panels in shadow is safe Many assume panels can be opened during night-side orbit, but they generate zero power and waste time, a craft in Kerbin’s shadow loses all solar output for up to 30 minutes. Always retract panels before entering shadow to avoid drag damage and power loss.
- One panel type fits all missions Using the large Gigantor panel on a small probe is overkill, adding 0.3 tonnes of mass and 800 credits for power you do not need. Match panel size to your power draw, OX-STAT for probes under 0.5 EC/s, Gigantor for stations or heavy relays above 2 EC/s.
Quick reference
- Solar panel output in KSP follows the inverse-square law, halving every 1.41 times the distance from Kerbol.
- At Kerbin’s orbit (13.6 million km), an OX-STAT panel generates 0.35 EC/s, enough for basic probe operations.
- Panels only generate power when facing Kerbol and not in shadow, so battery storage is essential for night-side operations.
- The Gigantor XL panel produces 2.0 EC/s at Kerbin but weighs 0.3 tonnes, making it unsuitable for small probes.
- Retracting panels during atmospheric flight or shadow prevents drag damage and saves mass for manoeuvres.
Frequently Asked Questions
They generate electrical charge (EC) from sunlight, with output depending on distance from Kerbol and panel type. The KSP Wiki states a standard OX-4L panel produces 0.375 EC/s at Kerbin orbit.
No, solar panels stop generating power when in shadow or behind a planet. They must be in direct sunlight to produce electricity, according to KSP mechanics.
The Gigantor XL solar array is the most efficient for large spacecraft, producing up to 2 EC/s at Kerbin orbit. For small probes, the OX-STAT is lightweight and reliable.
