Do Fuel Cells shut down when you have solar power?

[davidpsummers]

If you have a mix of solar panels and fuel cells, will the fuel cells shut down when solar power is available? Or will they keep using fuel?

Edited November 2, 2015 by davidpsummers

[Alshain]

They will keep using fuel. But fuel cells can be manually turned on and off via right click or action group setup.

[Laie]

Fuel Cells also include some amount of battery charge. Last time I used them, they would start/stop working when their own charge went above/below a 95% theshold. So for the most part, I could just forget about them: As long as there was enough solar power, the fuel cells would remain inactive.

That said: setting up a short experiment to find out for yourself would take you a whole two minutes, if that.

[NeatCrown]

Fuel cells have a "load" that allows variable charge rates depending on your usage and stops using LF+O when full or near full.

[magnemoe]

They will shut down then batteries is full however they will run on full power even then the solar cells are enough to fill the batteries.

One tricks for miners is to leave them alone during the night. Kerbals want some privacy too.

Then it will continue to produce ore but not use power at all.

This does not work like normal operations first it will fill the ore tanks then it will generate fuel while normally you will convert all ore to fuel until fuel tanks are filled.

Still the ore to fuel conversion will be faster than mining and during daylight you should have enough power to run it.

[davidpsummers]

So as I understand it....

If the batteries are below 95%, then having solar power doesn't help (except it charges the batteries faster). But if solar power can keep the batteries above 95%, then the fuel cell won't consume fuel.

[Laie]

So as I understand it....

Not quite. The following might be nitpicking that doesn't concern you, but hey.

The only battery that matters is the one that's included in the fuel cell. It switches on/off depending on that battery's charge. All other batteries on your vessel (if any) do not matter for the purpose of whether the fuel cell will become active or not. You can effectively turn off a fuel cell if you lock it's battery while fully charged. If you have several fuel cells, each will only consider it's own battery.

That distinction matters because, usually, not all batteries discharge evenly.

[BoilingOil]

Assuming that the tech and the funds are available, I try to make sure that my main battery bank is of sufficient capacity to make it to the point where it can rely on solar. And ofcourse, that sufficient solar panels are present to recharge rather quickly. That way, I don't need fuel cells at all.

But ofcourse, I understand that at times this simplest of all solutions is not at your disposal. Good luck with those...

[davidpsummers]

not all batteries discharge evenly.

Really. I did not know that. I'll have to keep an eye out for which ones discharge first.

[Laie]

Assuming that the tech and the funds are available, I try to make sure that my main battery bank is of sufficient capacity to make it to the point where it can rely on solar. And ofcourse, that sufficient solar panels are present to recharge rather quickly. That way, I don't need fuel cells at all.

Up to 0.90, you could run a huge vessel on a single RTG and a large battery. Most of the time, power requirements were (nearly) zero; you only need enough charge to turn the vessel around and had lots of time (like hours to months) for recharging between maneuvers. Either that, or the maneuvers would require you to run the engines long enough to recharge the batteries -- nearly every engine has an alternator, after all.

These days, that approach can still work... unless you want to run a lab or ISRU unit.