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This post is intended as a hint to anyone building up combined power systems, not sure where was the right place for such thread so I'm posting it here.

I've encountered steam turbines keep generating power during the day despite solar panels providing more than enough power.

It started when I tried to set up combined solar+steam power plant where energy was stored in steam tanks instead of batteries. Basic steam setup was: 1 boiler supporting 10 steam engines + storage tanks. According to https://wiki.factorio.com/Power_production, this should be correct ratio assuming steam engines work only during the night and steam is stored during the day.

Yet, instead of shutting down during the day, boilers kept working, engines kpt working... They VERY slowly seem to be filling up, but it seems that as long as there's an empty boiler somewhere on the pipeline, you can 'force' boilers/engines to work even during the day, cheaty or not, this can be an useful information while building power systems.

I were expecting they would eventually fill up and get up to proper ratios, yet they didn't. I probably could 'force' the system to do so with radar spam as power consumers, but there seems to exist a greater issue that it didn't get on own level on its own.

Would test more but cba without creative mods updated lol.

Avezo wrote:1 boiler supporting 10 steam engines + storage tanks. According to https://wiki.factorio.com/Power_production, this should be correct ratio assuming steam engines work only during the night and steam is stored during the day.

Unless I misunderstood something, the ratio should be 1 boiler, 2 steam engines.

Now (I think since 0.15) Steam Engines have a priority over Accumulators so if both are just turned on Steam Engines will work at full power and only lacking power will be supplied from accumulators.

I think this is totally intended cause accumulators can back up steam power too or provide some kind of a buffer for peak loads like lasers or whatever.

So to make a mixed system you have to establish circuit network control over steam/water pumps based on your accumulator charge.

If you are using only Solar Panels they will have a priority over Steam Engines if they are enough. However if you are using both Solar Panels and Accumulators the later have insane consumption during morning recharge cycle which will most probably activate all available power generators until they are fully charged.

Also as Koub said - one boiler can feed only 2 steam engines right now (not 10) so you got to adopt your design to that. Taking into consideration day/night lengths if you intend steam power to work only at night I think 1 boiler will feed near 4-5 steam engines if you got enough storage for steam.

Boilers will also work during day as long as the steam doesn't back up. So they will refill all the steam engines and storage tanks before they stop.

But steam engines should stop instantly as soon as your power needs are met by solar cells in the morning. As mentioned that includes accumulators. So check that your accumulators are fully charged and then check if your steam engines still run. If they are still running then you don't have enough solar cells.

Note: If you have enough solar cells then refilling accumulators with steam power is wasteful. Better to use solar power. But for that you need to separate the power grids. You can use power switches and circuit logic or (ironically) use accumulators as limited power bridge. An accumulator that is within reach of 2 power poles that aren't connected (use copper wire to cut the connection) will conduct power up to a maximum rate that can't be used to charge other accumulators. It will also only conduct power if the other side has a surplus.

You can read the accumulator charge with the circuit network. Hook up one accumulator to an SR-Latch and set its limits to 10 and 30 for example. And hook up its output to your water pumps. Then the pumps will turn on when the charge has dropped to 10% and charge them up to 30%

You can do an SR-Latch with 2 combinators, but I find this one easier to understand:
https://wiki.factorio.com/Tutorial:Circ ... am_example
But as said, instead of using the switch, simply connect it directly to the pumps

Yes, having the steam engines act as a backup like that can be considered wasteful. But you can look if they have to kick in regularly and build more solar when they do. And eventually you will have so much solar, that a tiny steam backup power plant is a drop in the ocean anyways

The point of this build was to not use accumulators and store energy in tanks as a steam instead though. Boilers are supposed to work all the time, but since steam engines were supposed to kick in only during the night, there could be more of them than just 2 per 1 boiler.

It all got screwed because they kept working during the day too, despite there being much more solar power available than needed.

I suppose you can use the same principle and read the content of a steam tank. If it drops below a certain value it's time to make more.

Well I checked the boilers I setup for burning excess wood in my base. Their steam engines are only working during the night/whilst accumulators are still recharging (on 16.7). Are you 100% sure the steam engines are working during the day? eg did you check the power production graph? Do you have any mods that could be affecting this?
Also there is a creative mod 0.16 fix (or some similar name) that seems to be working well enough for testing things.

I went and rechecked power graphs and it turned out I actually didn't have enough solar power and that's why they kept working during the day... Smaller experimental setup with enough solar power worked as intended - steam engines did shut down during the day.

So basically, my initial observations are just wrong and I should've rechecked it before making a thread lol.

By the way the proper ideal ratio for boilers to steam engine is 1:6.667 or 3:20. The reason for this is that if there is just enough solar power to provide full daytime needs the steam engines will only need to run 30% of the day (this is abstracting the twilight period, they actually run at full power for less than 30% of the day and at partial power for more, but it averages out to 30%), so it is 1 : (2 / 0.3). You will also need 2 steam tanks per 3 boilers.