Editing Sun lamp

{{Page Under Construction|reason=Recent unreported change to lit area. update still in progress}} 
{{See also|Standing lamp}}
{{Infobox main|furniture
| name = Sun lamp
| image = LampSun.png
| description = An industrial lamp which lights an area brightly enough to grow crops, but consumes a huge amount of power. Automatically turns itself off at night.
| type = Building
| type2 = Furniture
| placeable = true
| path cost = 14
| passability = pass through only
| blockswind = true
| cover = 0.2
| minifiable = true
| size = 1 ˣ 1
| mass base = 4.5
| flammability = 1
| hp = 50
| sell price multiplier = 0.7
| power = -2900
| glowradius = 14
| glowcolor = (370, 370, 370)
| heatpersecond = 3
| terrain affordance = light
| research = Electricity
| thingCategories = BuildingsFurniture
| work to make = 330
| resource 1 = Steel
| resource 1 amount = 40
| destroyyield = nothing
}}
'''Sun lamps''' provide artificial light in the absence of sunlight, such as an indoor [[growing zone]].

== Acquisition ==
{{Acquisition}}

== Summary ==
[[File:Sun lamp grow radius.png|thumb|left|Radius of light sufficient to grow. Displayed radius shown in [[sterile tile]], tiles where plants can be grown outside of the radius shown in [[gold tile]]]]
A sun lamp consumes {{#expr:-{{P|Power Consumption #}}}} W of [[power]] from 06:00 to 19:12, the period where plants can grow. While online, it provides 100% [[light]] within a 6.5-tile radius. This provides 120 tiles with sufficient light to grow. Note that this is '''not''' reflected by the radius displayed when constructing a sun lamp, and following the displayed radius would result in 100 growable tiles, ignoring 20 tiles that could otherwise be used.

This allows [[crop]]s like [[rice plant]]s to grow in a [[roof]]ed room. As the natural sun doesn't always provide 100% light at day, a sun lamp causes plants to grow somewhat faster. They also provide at least 30% light in a 13-tile radius, which is enough to prevent penalties for being in darkness. 

Due to RimWorld's [[temperature]] mechanics, an enclosed room with a mostly complete [[roof]] is required to actually heat or cool an area.  Lamps themselves give a marginal amount of heat, 3 heat per second.

[[Rain]] or [[snow]] on a powered sun lamp will cause [[short circuit]]s and [[fire]]s. A roof will prevent this.

== Analysis ==
{{Image wanted|section=1|reason=replacement for [[:File:Optimal_sunlamps.png]] with new radius}}
A sun lamp's main purpose is to create growing zones indoors, often called greenhouses. This allows plants to grow in the winter, when used with a [[heater]]. In extremely hot [[biome]]s, you might need coolers to grow during in the summer. Even in an "year-round" growing season, unpredictable events such as [[Events#Toxic_fallout|toxic fallout]] and [[Events#Volcanic_winter|volcanic winter]]s can disrupt plant growth. Double-width walls provide more insulation against temperature changes, and potentially save on heater/cooler costs.

[[Events#Solar flare|Solar flares]] will cut the power, so prepare a [[shelf]] with emergency wood to build [[campfire]]s to keep the room temperature above {{Temperature|-10}} (below which most plants will rapidly die).

As they cannot be grown under roofs, trees such as pine, birch, saguaro or cocoa trees may not be grown in completely closed greenhouses.  They may only be grown in greenhouses with roofs open in a grid pattern, and those leak a lot of temperature-controlled air. As these roofs will let in sufficient natural sunlight in most biomes, there is no need to place a sun lamp inside tree greenhouses.
<div style="clear:left></div>

=== Power ===
If you have [[Biofuel refinery|biofuel refineries]] available, you can use food produced by hydroponics to fuel chemfuel generators to help power the greenhouse array. This is so efficient that it violates thermodynamics, and leaves you with spare food for your colonists as well.

As sun lamps turn off at night, they consume an average of {{#expr: -(0.8-0.25)*{{P|Power Consumption #}}}} W⋅Days. [[Batteries]] can be used to average out power usage. However, batteries only take in energy at a 50% rate, effectively meaning double the power is required at night, for a required power generation of {{#expr: -floor(2*(0.8-0.25)/(1+0.8-0.25)*{{P|Power Consumption #}})+10}} W⋅Days assuming 100% consistent power generation and a single battery with a passive loss of -5W⋅Days per day. As this only requires {{#expr: -((0.8-0.25)*{{P|Power Consumption #}})*(1-0.8+0.25)*0.5/(1-0.5*(1-0.8+0.25)) round 1}} W⋅Days of storage and a battery holds 600 W⋅Days, fewer batteries and infinitesimally less generation is needed when multiple sun lamps are supported. 

Otherwise, 2{{Check Tag|Verify/Detail|Added equator note, but where exactly is this true and how close a call is it?}} [[solar generator]]s are roughly enough to power a single sun lamp in equatorial regions, not counting any hydroponics basins.

=== Hydroponics ===
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You can grow crops indoors with or without [[hydroponics basin]]s. It is more cost effective to grow on soil, assuming you have soil available.

* The 24 hydroponics basins would cost {{Required Resources|Hydroponics basin|24}} for a total of 2.8 sun lamp's worth of growth. This does not count the extra 1680 W of power required for those basins.
* You could instead make and power 2 more sun lamps. 4 [[solar generator]]s are enough to power those lamps, and would only cost {{Required Resources|Solar generator|4}}. Even when considering [[batteries]], [[heater]]s, and the {{Icon Small|steel}} 80 for sun lamps themselves, making ''more'' sun lamps is more efficient than building hydroponics for 1.

If your only goal is to grow crops during the winter, then placing multiple sun lamps without hydroponics is more resource efficient than using hydroponics. However, the lamps would end up taking up more space. Therefore, hydroponics are best used when growing space is limited, like inside a mountain or in an [[biomes#Ice sheet|ice sheet]]. 

In the late game, hydroponics have a few advantages. Due to their reduced space, it takes less travel time, which makes work more efficient and defense easier. They take up less power per tile, too. When you have access to [[deep drill]]s and [[fabrication bench|fabrication]], you can easily afford the steel and component cost.

==== Hydroponic packing ====
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Hydroponic packing is not a solved issue. There are two general approaches.
# Minimizing unlit hydroponic basin slots to ensure no planter work goes to waste, but at the expense of having lit spots not growing any crops. 
# Minimizing wasted light, but at the expense of having planters occasionally plant crops in basin slots that are unlit and will eventually die without providing any yield. Note that it usually takes several{{Check Tag|How many?}} days for the crop to die, so the losses are relatively small compared to the entirety of the 
In the gallery below, two example set ups are presented. They are, at the time of writing, the most best solutions known to the two approaches presented above, however, they have not been demonstrated to be the most optimal possible. 
<gallery>
File:New sun lamp optimal with no wasted hydro spots.png|Maximum hydroponics basins without having basin slots unlit.<br>(25 basins, 100 growing tiles, 0 unlit basin slots, 20 lit tiles unused)
File:new sun lamp optimal with wasted hydro spots.png|Minimum number of hydroponics basin slots left unlit without leaving lit area unused.<br>(32 basins, 120 growing tiles, 8 unlit basin slots, 0 lit tiles unused)
</gallery>

== Version history ==
* [[Version/0.17.1546|0.17.1546]] - Now turn themselves off when plants are resting.
* [[Version/1.2.2753|1.2.2753]] - Fix: [[Gloomlight]] would prevent a sun lamp from producing "brightly lit" cells within the radius of the Gloomlight. Due to: the glowColor of the Gloomlight not having an explicit alpha of zero. It now correctly ignores the alpha from the xml.
* [[Version/1.3.3117|1.3.3117]] - Fix: Sunlamp does not trigger blinding light for [[Ideoligion#Darkness|Darkness]]{{IdeologyIcon}} pawns.
* [[Version/1.5.4062|1.5.4062]] - Unreported change to sun lamp lit radius, increasing it, without increasing the displayed radius when constructing the lamp. 

<gallery>
SunlampHydroponics.png|Pre-1.5 densest hydroponics set up.
</gallery>
{{Nav|furniture|wide}}

[[Category:Furniture]] [[Category:Lamp]]
[[Category:Food Production]]