Solar arrays: alignment, tracking, day and night

Solar power costs nothing once it is built. In return a panel only delivers when it faces the sun, and nothing at all at night. This page shows how much arrives on each world, how to align an array and how to plan panels and batteries for a constant load.

All numbers are calculated with the same formulas as the Solar calculator. You can recreate every example there for your world and season.

The panel types#

Panel	Rating	Area in the calculator	Ports	Kit
Solar Panel	500 W	4 m²	power and data combined	Kit (Solar Panel)
Solar Panel (Dual)	500 W	4 m²	power and data separate	Kit (Solar Panel)
Solar Panel (Flat)	500 W	4 m²	combined	Kit (Solar Panel Basic)
Solar Panel (Heavy)	500 W	4 m²	combined	Kit (Solar Panel Heavy)
Solar Panel (1x5)	2,750 W	20 m²	combined	4 × Kit (Solar Panel)

All panels share the same logic values: Horizontal and Vertical to aim them, Charge for the current output, Ratio for the alignment efficiency, Maximum for the output at perfect alignment. They need no power themselves.

According to the game data the 2 × 2 m variants differ in two points, not in output:

• Flat and 45°: the Solar Panel (Flat) and the Solar Panel (Angled) have no pivot. Horizontal and Vertical can be written, but nothing moves. The surface always faces the way you built the panel.
• Heavy: the heavy variants such as the Solar Panel (Heavy) take no storm damage. More on that below under storms.

What a panel really delivers#

The rating is not a hard limit. The game calculates like this, and the calculator does the same:

1. Irradiance I = solar constant ÷ distance to the sun². The solar constant is 1,367 W/m², on Vulcan 2,402 W/m².
2. Raw output = I · area · weather share.
3. If the raw output is above 1.4 times the rating, it is damped: P = raw ÷ log₁.₄(raw ÷ rating). So up to 700 W of raw output everything gets through.
4. If a weather event is running at the panel's location, the game uses 1.6 instead of 1.4. Then up to 800 W get through undamped.

Worked example Mars: The yearly mean is 592 W/m². Raw that is 592 · 4 = 2,367 W, i.e. 4.73 times 500 W. log₁.₄(4.73) = ln 4.73 ÷ ln 1.4 = 4.62. The panel delivers 2,367 ÷ 4.62 ≈ 512 W when it faces the sun exactly.

On the Moon that gives about 770 W, on Venus about 1,160 W. On Europa (about 200 W) and Mimas (about 60 W) the raw output stays below 700 W, so there is no damping at all – simply little light arrives.

The damping is not even. Between 700 W and about 1,360 W of raw output the result actually drops: at 1,000 W raw the panel delivers only 485 W, at the lowest point (1,359 W raw) about 457 W. Only above that does it rise again. That is why less light can bring more power – see the storms below.

Alignment costs output quickly#

Efficiency depends on the angle between panel and sun. According to the game code it is 1 − 2 · sin(deviation ÷ 2), limited to 0 to 1:

Deviation	Efficiency
0°	100 %
10°	83 %
20°	65 %
30°	48 %
45°	23 %
60° and more	0 %

So being 30° off already costs more than half, and from 60° the panel delivers nothing. You also get 0 W when the panel faces away from the sun, during an eclipse by the parent planet and when something stands between panel and sun. The game checks that with rays: five for the 2 × 2 m panel (centre and four corners), and each blocked one costs 20 %. The 1x5 panel checks one ray per segment. If terrain blocks the sun, it is completely dark. Damage to the panel lowers the output on top of that, by the same ratio: 30 % damage means 30 % less.

Vertical can only be set between 15° and 165°. When the sun is lower than 15°, even a tracked panel no longer reaches 100 %.

Day and night on each world#

A game day lasts a fixed 1,200 s, on the Moon about 1,297 s. The table shows a 2 × 2 m panel in clear weather, calculated over all twelve seasonal sections of the calculator. "Daily mean" means averaged over the whole day, with the night counted as 0 W.

World	Peak per panel	Daily mean tracked	Daily mean flat	Night
Mars	484–553 W	about 250 W	about 64 W	555–645 s
Moon	754–783 W	about 367 W	about 125 W	642–653 s, plus short eclipses
Venus	1,154–1,172 W	about 565 W	about 49 W	577–628 s
Europa	183–223 W	about 72 W	about 13 W	595–606 s, plus 166–168 s of eclipse
Mimas	53–67 W	about 21 W	0 W	575–625 s
Vulcan	643–1,354 W	about 446 W	about 69 W	344–859 s

What follows from it:

• Tracking pays off everywhere. On Mars a tracked panel brings about four times as much as a flat one.
• Mimas: The sun only climbs 30 to 34°. A flat panel is therefore almost 60° off and delivers nothing.
• Europa: Jupiter hides the sun for about 167 s every day. The longest dark phase lasts up to 776 s.
• Vulcan: The seasons vary wildly. The night lasts between 344 and 859 s – size the battery for the long night.

Planning panels and battery for 1,000 W#

Example: a base on Mars needs 1,000 W around the clock. The calculation uses the worst seasonal section (section 1 in the calculator: night 645 s, daily mean 249 W per tracked panel).

• Panels: 1,000 ÷ 249 = 4.02, so 5 tracked panels. Lying flat, a panel only brings about 31 W in this section – you would need 33 of them.
• Energy for the night: The game shows joules per tick as "W", and a tick lasts 0.5 s. So 1,000 · 645 ÷ 0.5 = 1,290,000 J.
• Battery: A Station Battery holds 3,600,000 J. With a 10 % reserve 3,240,000 J remain, minus the self-discharge of 10 J per tick (24,000 J per day). One battery is enough.
• Cable: Five panels deliver up to 5 · 553 = 2,765 W at noon. Normal cable (5,000 W) holds that. With ten panels it would be 5,530 W – then the line from the array to the battery has to be Heavy Cable (Straight).

Tracking with the daylight sensor#

The Daylight Sensor reports where the sun is: Activate is 1 in sunlight, Horizontal and Vertical give the direction, SolarAngle the angle between sensor and sun. All angles refer to the sensor itself. So build it facing exactly like the panels.

Sensor and panel count angles differently. What has proved itself: take Horizontal over directly and convert Vertical with an offset. If the panels' Ratio stays clearly below 1 at noon, OFFSET or DIRECTION does not match your build – adjust them there.

The program needs a sensor named "Sun" and panels named "SolarField", all on the same network as the IC housing. At night the panels move to a parking position towards the sunrise:

# --- Align a solar field with the daylight sensor ---
define SENSOR 1076425094       # Daylight Sensor (StructureDaylightSensor)
define PANEL -2045627372       # Solar Panel (StructureSolarPanel)
define NSENSOR HASH("Sun")           # name of the sensor
define NFIELD HASH("SolarField")     # name of all panels
define OFFSET 90               # degrees: panel vertical = OFFSET + DIRECTION * sensor
define DIRECTION -1            # 1 or -1, depending on how it is built
define VMIN 15                 # degrees: the panel tilts no flatter
define VMAX 165                # degrees: and no steeper
define PARKH 90                # degrees: parking position horizontal
define PARKV 60                # degrees: parking position vertical
alias light r0
alias h r1
alias v r2

start:
yield
# --- 1. Read the sun ---
lbn light SENSOR NSENSOR Activate 0
bnan light start               # no sensor with this name
lbn h SENSOR NSENSOR Horizontal 0
bnan h start
lbn v SENSOR NSENSOR Vertical 0
bnan v start
# --- 2. Convert sensor angle to panel angle ---
mul v v DIRECTION
add v v OFFSET
max v v VMIN
min v v VMAX
# --- 3. Park at night, then write ---
select h light h PARKH
select v light v PARKV
sbn PANEL NFIELD Horizontal h
sbn PANEL NFIELD Vertical v
j start

If the sensor is missing, bnan jumps back and the panels stay put. That is intended: writing NaN as an angle would be worse than standing still. For other panel types you only swap the hash in PANEL. More about angles and parking is in the academy, see below.

It also works by hand without a chip: the Solar Control in a console sets all panels in reach together. It does not follow the sun on its own, though.

Storms: different light and damage#

A storm changes two things: how much sun arrives and, for most storms, the health of the panels. The table shows a tracked 2 × 2 m panel at mean sun distance, aimed exactly and still undamaged:

World and event	Sun per weather data	clear	in the storm	damage
Mars, dust storm	30 %	512 W	710 W	yes
Venus, storm	30 %	1,164 W	806 W	yes
Europa, snow storm	30 %	202 W	60 W	yes
Vulcan, ash storm	5 %	866 W	334 W	yes
Moon, solar storm	400 %	767 W	2,711 W	no
Vulcan, solar storm	400 %	866 W	3,154 W	no

Why the Mars storm brings more: 592 · 4 · 0.3 = 710 W of raw output. That is below 1.6 · 500 = 800 W and is therefore not damped at all. Under a clear sky it is 2,367 W raw, damped down to 512 W. That is not a calculation error; it is what the game code does.

Storm damage: every tick each panel in the open has a 10 % chance of losing 0.5 % of its health. On average that is 6 % per minute. A storm lasts 2 to 10 minutes per the weather data, so after a long storm about 60 % of the output is missing on average. Alignment plays no part, turning away does not help. Solar storms do no damage. The heavy variants never take storm damage – on worlds with storms they are the better choice. Repair damaged panels with Duct Tape or a glass sheet.

Common mistakes#

• Panel delivers 0 W during the day: more than 60° off, shaded or turned away from the sun. Ratio shows the alignment efficiency.
• Cable burns at noon: the array delivers more than 5,000 W over normal cable.
• Base goes dark at night: battery too small, or the panels do not fill it during the day. A network is only supplied when generation is greater than demand.
• Output drops after every storm: the panels are damaged. Repair them or switch to heavy panels.
• Flat panel does not follow the sun: the flat and the 45° panel cannot be turned.

Further reading#

• Calculate for your world: Solar calculator and Power calculator
• Connecting batteries correctly: Batteries and storage: sizes, charging, discharging, a transformer in between
• Cables and transformers: Sizing cables, fuses and transformers correctly
• IC10 academy: sun angle
• IC10 academy: solar tracking
• IC10 academy: storm mode