Part One: Why Fusion Would be the Main Power Source.
The main power source should be fusion, the best power source for an industrial civilization.
Fusion power works equally well wherever it is located on the surface of a planet, or wherever it is located in interstellar space, unlike any other power source except for other forms of atomic energy.
Fission uses rather rare elements and isotopes instead of the much more common elements and isotopes which can be fusioned for energy. The earliest fusion generaters will use isotopes of hyrogen, the most common element in the universe.
A fission chain reaction can possibly get out of control, resulting in a messy reactor meltdown,and it has happeneda few times. Despite many science fiction stories depicting fusion power plants running out of control and exploding, it would take a very evil genius indeed to design a fusion power plant that could explode. Fusion needs constant application of power to occur, and the power imput can be precisely controlled and shut off with the turn of a switch, instantly ending the fusion process. The machines which produce the fusion are not designed to produce an explosion and cannot be forced to produce explosive amounts of fusion.
Fusion is the closest thing to an all around perfect power source. If a society has developed practical fusion power generation using fusion power should be their first power generation choice for almost every imaginable situation.
Part two: Redundent Power Sources.
It seems obvious that the colony would want redundant power sources. If their power fails, they will be literally light years of distance and even more years of travel time from any possible outside assistance.
If the main body of the interstellar vehicle remains in orbit a small part of its fusion power plant could be run, and the energy it generates - a tiny fraciton of the total propulsion energy - beamed down to receivers at the colony site.
If the main vehicle lands, or if smaller landing craft are used that make any sort of powered landings, those landings are likely to be powered by fusion. The energy energy generated by fusion could power rockets, or jets, or magnetohydrodynamic drive, or anti gravity drive, or whatever. But unless fusion generators would be far too large for the craft that land, fusion would be the obvious choice to generate the power for a powered landing.
So once a landing craft is no longer needed to land the colony, they can hook up its power source by a cable to the main power distribution unit of the colony. If the landing vehicle(s) use rockets, the powerful rocket exhausts may scorch the land for kilometers and miles around, so the colony site might be kilometers or miles from the landing site and a long cable may be needed.
And an entire fusion genrator, or the parts for one, can be brought down and set up at the colony.
And the first thing that the 3-D printer of the colonly will make will presumably be all the parts to assemble a second 3-D printer, and the second thing it will make will be all the parts for a second fusion power generator, and the third thing it will make should be the parts for a third 3-D prince, and the fouth thing it will make should be the parts for a third fusion power generator, and so on. The colonists will want to have all the necessary parts for several spare fusion power generatiors and 3-D printers before they start making less vital stuff.
And of course fusion power will be supplimented by other sources. All of the buildings' outer walls should be covered with thin film solar panals for auxillary power generation. And many thin film solar panels will be set up apart from the buildings, and thin film mirrors to reflect additional light onto them.
Of course the solar power panels will be rather flimsey and could be blowndown in high winds. So the colonists would also build some sort of wind turbines capable of powering the colony if some disaster disables both the fusion power plant and the solar panals.
But the wind turbines could be damaged or destroyed by really violent winds or alien-planet-quakes. So the colonists should also dig deep, deep wells for alien-planet-thermal power generation, for example.
And the colonists should continued to live in their landing vehicle(s) until many redundant power sources are established and then they can start assembling prefabricated houses and other buildings and other ewquipment.
And of course the colonists would want to build power storage in case all the redundent power sources fail at the same time. So they will build water towers and use power to pump water up into the water towers so it can be used for hydroelectric power if necessary. And they might build giant flywheels and spin them extremely fast so that they generate power by braking the flywheels.
And they might use some of their generated energy to make chemical fuels and store those chemeical fuels in case of need.
For example, a method has been developed to use sunlight to produce hydrogen peroxide from seawater, which can then be used to produce more energy in fuel cells than was needed to make the hydrogen peroxide.
Part Three: A Frame Challenge.
Food and plants from Earth for consumption and future farming on the planet
And I wonder if you imagine that they would plant plants in the unearthly earth or soil of that alien planet to grow.
Plants and seeds imported from Earth need Earthlike conditions to grow in the unearthly earth of an alien planet.
As we all know, photosynthetic plants use sunlight to break up carbon dioxide in the air to make complex food chemicals, and release oxygen into the air, a process which created Earth's oxygen rich atmosphere. But plants also need oxygen in the air for their metabolisms havig adapted to use oxygenover hundeds of millions of years, so Earthly plants couldn't survive in a pure carbon dioxide atmosphere. Plants also need some nitrogen in the atmosphere.
What sort of atmosphere would the colonists need on their new planet if they don't have to wear spacesuits every time they go outside?
Habitable Planets for Man, 1964, by Stephen H. Dole, discusses human atmospheric requirements on pages 13 to 19.
To summarize, then, the atmosphere of a habitable planet must contain oxygen with an inspired partial pressure between 60 and 400 millimeters of mercury and carbon dioxide with a partial pressure roughly between 0.05 and 7 millimeters of Mercury. In addition, the partial pressures of the inert gases must be below certain specified limits andothertoxic gases must not be present in more than trace amounts. Some nitrogen must be present so that nitrogen in combined form can find its way into plants.
And the next section, on water, mentions that some water vapor in the atmosphere is necessary for human health.
So any food plants humans would plant on an alien planet would need an atmosphere similar to one which humans would require to breath. Of course different Earth plants and animals have different upper and/or lower limits to the amounts of various gases they can tolerate, but the ranges of all Earthly food plants overlap with that of humans quite extensively.
And where did the oxygen in Earth's atmosphere come from? From photosynthetic plants. So either the colonists will have to live in orbit, or sealed buildings, and wear spacesuits on the surface of the planet, for meany generations, possibly for milllennia while they terraform the planet, giving it a breathable atmosphere - or else they will find a planet which already has a breathable atmosphere produced by native photosynthasizing plants.
So are the colonists going to just plant Earth plants in the unearthly soil of the alien planet to complete with the alien plants?
Some people would have problems with that.
Maybe alien plants adapted to condiditons on the alien planet will constantly out compete for resources with Earth plants, &bthe colonist will be unable to grow crops in the alien soil,band will starve.
Maybe the two sets of lifeforms will be mutually edible, and Earth germs will infect alien plants and alien germs will infect Earth plants.
Mybe the two sets of lifeforms will be mutually poisonous, and the settlers will have to exterminate all native life within a region before introducing Earth lifeforms.
And those three possibilities are not good ones.
So maybe the settlers will put all their farms inside buildings and grow hydroponic or aeroponic crops in those buildings.
Or maybe the settlers will make a number of 3-D pinters to make sythasized food out of various elements and compounds in storage.
And some people might think that if they do that, why settle on the planet at all? Why not just build artifical space habitats to live in? And that is a question that you might want to think about for this story, or for future stories you mgiht write.