Are Fuel Cell Arrays efficient enough for mining ships?

Solution 1:

Yes - conditionally.

You NEED a good engineer on board.

I don't have the calculation on hand, but it was found that a three-star engineer is able to break even (with a microscopic surplus) between mining efficiency and fuel consumption of fuel cells to power said mining. You need a 4-star engineer for mining to be of actually practical use, and a 5-star one for something resembling efficiency.

With anything less than a 3-star engineer, you will not be breaking even, burning more fuel than you produce.

RTGs are impractical for the reasons you have mentioned, but if you're very hard-pressed to go mining and unable to get a 4-star engineer, replacing some of your power supply with RTGs will bring you somewhere above the "break even" line and allow a constant, if minimal trickle of surplus fuel.

Also, use Fuel Cell Arrays. They look like a set of 6 Fuel Cells, they weigh about as much as 6 fuel cells, but they produce power of 12 Fuel Cells.

Solution 2:

Yes - conditionally. You do not need an engineer on board - even though having one greatly helps.

The first and most important thing is to use the correct parts (the large ones):

• Drill-O-Matic --- 5x as efficient while consuming "only" 4.5x power
• Convert-O-Tron 250 --- 10x as efficient as the 125 variant
• Fuel cell array --- 2x power per kg as the regular fuel cell)

The Convert-O-Tron 250 makes by far the biggest difference but every bit helps.

The second thing (even more important than an engineer) is the landing spot. Mining with fuel cells on 1% ore concentration is not going to be successful. Choose your landing spot carefully to get at least around 5% concentration. The more the better.

The third most important thing is the engineer.

Given the conditions above are fulfilled you can get away with one fuel cell array per Drill-O-Matic on a mining rig that has at least four Drill-O-Matics. In this case the fuel cells can also power the Convert-O-Tron 250 and heat dissipation parts without fully maxing out its capacities.

My small mining rig has such setup and runs the 4 fuel cell arrays at 95% capacity while still producing a (small) surplus of both ore and fuel simultaneously (8% ore concentration, no engineer).

Also on inner planets fuel cells on mining rigs have the advantage of enabling mining during the night and/or greatly simplifying the setup.

Sidenote: I know that this question has a bit of dust on it but since the only answer is somewhat incorrect I chose to post an update. The answer is technically for KSP 1.6.x but it is likely valid for all other versions > 1.0 as well as mining hasn't changed since if i remember correctly.