So I thought about this a little more. Let’s say in addition to the refinery I did an extraction settlement for the wealth boost and an industrial for the industry boost. Will the system still be refinery? Or some sort of refinery/extraction/industry mashup? I’m not clear what triggers the economy type…the first built? Or what ever tour you have more facilities for?
System economy is the two largest components of the weighted sum of all station economies in the system. It doesn't do anything directly (except that the largest component sets the colour for the system on the map filter). So my system at the moment has three stations in it:
- a T1 Industrial outpost
- a T1 Colony planetary base (the biggest, about four times bigger than the outpost)
- a T1 Military settlement on a different planet (the smallest, about a tenth of the size of the outpost)
and its economy type is Colony/Industrial
My current build is a T2 Agricultural settlement on the same planet as the Colony base
I expect this to change the Colony base to Agricultural somewhat, as well as adding its own (small) Agricultural boost, so depending on how much it changes the Colony one I'll get one of these as the system economy:
- stays as Colony/Industrial (the shift of the Colony base isn't very large, so the Industrial is still the second biggest)
- moves to Colony/Agricultural (the Colony base is about a third Agricultural now, so the Colony component is the biggest bit, but the Agricultural bit is bigger than the outpost's Industrial contribution
- moves to Agricultural/Colony (the Colony base is half or more Agricultural, so that's now the biggest thing in the system, but the Colony half is still bigger)
- moves to Agricultural/Industrial (almost all the Colony economy is gone, what's left is smaller than the Industrial outpost)
Station economy - yes, you can influence a single station towards multiple economies, by building different types of System Economy Influence buildings near to it. Be careful when doing this, though - there are both advantages and disadvantages to hybrid economies.
Advantage: a hybrid economy will generally import more products, and a wider range of them, so you can trade into it for big profits later. If you're building the station to use it to make money, this can be very helpful.
Disadvantage: a hybrid economy will consume some of its own production, so e.g. a Refinery-Industrial station will export a small variety of products than separate Refinery and Industrial stations would. If you're building the station to use it to produce commodities for future colony builds, keep it single-economy.
You can certainly build up multiple different economy types on different planets where they won't interfere with each other, though - my Military settlement on the other side of the system isn't affecting the Colony base at all, other than providing a bit of +Security to the entire system and therefore letting me get it out of Lockdown.