Solar Array

The Solar Array is the first source of energy on a planet and the one nearly every planet leans on. It has no requirements, it costs nothing to run, and it is on the list from the moment you land. Every level adds power for your mines, and it never asks for anything back.

Energy is not a resource. You cannot store it, spend it or ship it. Every planet keeps its own books: if the planet does not produce as much energy as its mines want, every mine on it slows down by the same percentage.

You will find the Solar Array on the Buildings page, right below the three mines.

Where you can build it

There is nothing to unlock. No building requirement, no tech requirement, no cost in credits. It sits at level 0 on the Buildings page of every planet you own, on day one.

Planets only. Moons have no mines and no power plants, and neither does a deployed Hephaestus platform.

Every level uses one field, the same as any other structure, and a planet only builds one thing at a time. A long Solar Array upgrade greys out every other Build button on that planet until it lands.

Build it before the mines

A new colony starts with nothing at all. No mines, no Solar Array, no power.

Notice the top two rows. Every planet hands you 40 ore and 20 crystal an hour for free, with no mine and no energy needed, and a shortage never touches that trickle. Everything above it is affected.

So if you build the Ore Mine first on a fresh colony, it wants 11 energy, the planet makes 0, efficiency is 0%, and the mine produces exactly the free 40 an hour you were already getting. Build a level or two of Solar Array first, or at least alongside. This is the most common new player mistake in SFC2.

Here is what it looks like a bit further along. A level 3 Ore Mine wants 40 energy and makes 278 ore an hour at full power. If all you have is a level 1 Solar Array, that is 22 energy against 40, so the mine runs at 55% and makes 171 an hour instead. Take the Solar Array to level 2 and its 49 energy covers the mine, and you are back to 278.

Energy produced

Energy per hour = 20 × Level × 1.1^Level, rounded up.

Nothing else goes into it. Not Energy Tech, which only touches the Nuclear Power Plant. Not the planet's temperature, which only touches satellites. Not your alliance, your rank or the slot you sit in. A level 16 Solar Array makes 1,471 energy an hour on the hottest inner planet and the same 1,471 on the coldest outer one.

Cost and output by level

Ore = 75 × 1.5^{Level - 1}, rounded up.
Crystal = 30 × 1.5^{Level - 1}, rounded up.
No hydrogen at any level.

Level	Ore	Crystal	Energy/hr
1	75	30	22
2	113	45	49
3	169	68	80
4	254	102	118
5	380	152	162
6	570	228	213
7	855	342	273
8	1,282	513	343
9	1,923	769	425
10	2,884	1,154	519
11	4,325	1,730	628
12	6,488	2,595	754
13	9,731	3,893	898
14	14,597	5,839	1,064
15	21,895	8,758	1,254
16	32,843	13,137	1,471
17	49,264	19,706	1,719
18	73,895	29,558	2,002
19	110,842	44,337	2,325
20	166,263	66,506	2,691
21	249,395	99,758	3,109
22	374,092	149,637	3,582
23	561,138	224,455	4,119
24	841,706	336,683	4,728
25	1,262,559	505,024	5,418
26	1,893,838	757,536	6,198
27	2,840,757	1,136,303	7,080
28	4,261,135	1,704,454	8,076
29	6,391,702	2,556,681	9,201
30	9,587,553	3,835,022	10,470

Those are the costs of each single level, not running totals. Going from nothing to level 20 is 498,648 ore and 199,462 crystal all in. Level 25 is 3.79 million ore and 1.52 million crystal. That 1.5 multiplier is the gentlest cost curve in the game, tied with the Ore Mine and the Hydrogen Synthesizer, and it is a large part of why solar stays worth building for so long. Buildings run at 2.0 and the Nuclear Power Plant at 1.8.

How much do you need

Rough rule: with all three mines at the same level, the Solar Array wants to be about five levels above them. With only the Ore Mine and Crystal Mine running, one or two levels above is enough. The Hydrogen Synthesizer is the expensive one, it eats twice the energy of the other two at the same level.

All three mines at level	Energy they want	Solar Array needed	Energy it makes
5	324	8	343
8	687	12	754
10	1,039	14	1,064
12	1,508	17	1,719
14	2,128	19	2,325
16	2,943	21	3,109
18	4,004	23	4,119
20	5,383	25	5,418
22	7,164	28	8,076
24	9,456	30	10,470
26	12,396	32	13,513

Overshooting does nothing. Efficiency is capped at 100%, so every point of energy above what the mines want is thrown away. If the Energy panel on the Buildings page shows you well clear, the ore is better spent on a mine.

Build time

Hours = (Ore + Crystal) ÷ (5,000 × (Capitol level + 1) × 2^{Foundry level})

Level 17 costs 49,264 ore and 19,706 crystal. On a bare planet with no Capitol and no Foundry that is just under 14 hours. On a planet with Capitol 6 and Foundry 3 the same level lands in 14 minutes 47 seconds. Every Capitol and Foundry level you own pays itself back across every array level you will ever build.

You can cancel a running upgrade and get the full cost back, or finish it early for credits at 1.12 credits per second still to run. It is free once there are under five minutes left.

The Capacity setting

Once it is built, the row carries a Capacity dropdown running from 0% to 100% in steps of 5. On a Solar Array it simply scales the output: a level 16 array at 50% makes 736 energy instead of 1,471. Changing it is free and takes effect straight away.

There is not much reason to turn a Solar Array down. It burns nothing, so surplus power is not costing you anything either. The dropdown earns its keep on the Nuclear Power Plant, where surplus energy means hydrogen thrown away, and on mines you want to starve on purpose.

The More Info panel

The More Info button on the row gives you the next few levels with the energy and the cost side by side, plus a teardown row for the level below.

Tearing it down

Tearing down a level costs a third of what that level cost to build and takes a third of the time, and you pay it. There is no refund. What you get back is the field.

Coming down from 16 to 15 on the planet above costs 10,947 ore and 4,379 crystal, and drops the planet from 1,471 energy to 1,254. It is a repair for a planet you overbuilt, not a way to move resources around.

Solar, reactor or satellites

Three things make energy in SFC2 and they trade off differently.

Solar Array. The cheapest and the safest. Nothing to run, nothing to feed it, works the same on every planet, and nobody can take it off you in a battle. What it costs is fields, and on a crowded planet that is the whole argument against it.
Nuclear Power Plant. Needs a Hydrogen Synthesizer at level 5. Far more power per field, paid for with hydrogen burned every hour forever, and its cost multiplier is 1.8 against solar's 1.5 so it gets expensive fast. At Energy Tech 5 and above it beats a same level Solar Array and keeps pulling away. Below Energy Tech 5 it grows slower than solar, and at Energy Tech 3, the level everyone starts with, a same level Solar Array overtakes it at level 23.
Helios and Genesis satellites. Ships, not buildings, built at the Shipyard. They use no fields at all, and on a hot inner planet they are cheap power: 64 Helios at 42 each is 2,688 energy for 128,000 crystal and 32,000 hydrogen, against 498,648 ore and 199,462 crystal for the same output from a Solar Array 20. The catch is that they sit on the planet as ships, so one lost battle wipes them out. On a cold outer planet they pay almost nothing and solar is the only sensible answer.

Most planets end up on a tall Solar Array with satellites on top, and add a reactor later if the fields run tight or Energy Tech climbs.