Hi! I'm really fascinated by this mod, the whole execution of it seems really good and I plan to add it to my main save soon!

I was just wondering, is there a clear ratio for solar panels, per basic heat exchanger, per steam engines, per steam-storage for the nights? The mod page says that 27 panels can reliably power 1 heat exchanger and 1 steam engine, with 5.6k units of steam storage for overnight. But also, if heat exchangers can produce 60 steam per second, wouldn't that mean they can power 2 steam engines? Would an extra steam engine still mean twice as many solar panels?
So that would lead me to think that the effective ratio would be something like:
54 panels: 1 heat exchanger: 2 steam engines: 11.2k steam storage

Is that accurate, or is there a better way to figure this all out?

Thank you for the praise!

There are no clear-cut numbers, but I have determined experimentally that 27 panels (rated at 67.5kW * 27 = 1,822.5kW) can sustain something like 948kW of electricity production around the clock on Nauvis, given sufficient steam storage for the night. (Large panels are a bit more efficient than the small ones, for technical reasons.) So an 1,800kW heat exchanger will run at full capacity for the equivalent of ~52.7% of the day to produce steam, and that steam can reliably drive a single 900kW steam engine non-stop. Of course, you can expand with any number of steam engines/turbines to pull out that remaining ~48kW of energy and simultaneously increase the discharge rate of the system as desired (with the risk of nightly power outage, if there is no backup). This is one of the things I wanted to showcase with the screenshot on the info page.

My ratio of 27 panels, 1 heat exchanger, 1 steam engine, with ~5.6k units of steam storage is correct. You cannot fully utilize the heat exchanger! Or to be exact, you should not attempt that, because the panels would then heat up way beyond the required threshold of 165°C. Doubling the number of panels like you suggest would eventually make the panel that is closest to the exchanger reach a max. temperature of ~250°C during the day, and dissipate as much as ~56% more heat as a result (and it gets progressively worse for those further away). In any case, the overall day cycle efficiency would fall from ~52.0% to just ~36.2%.

For the same reason, it is impossible to drive the 500°C heat exchanger with the thermal panels, because all their heat energy would dissipate at the rate it is produced well before that threshold could even be reached (at ~367°C, to be exact).

Steam storage is not only important for dealing with the intermittency of solar power; the immediate conversion greatly helps with minimizing heat loss and keeping the overall efficiency as high as possible. Admittedly, steam acting as lossless energy storage is not realistic, but that's Factorio for you, and relying on this still seems better than letting the thermal panels fulfill the role of both energy production and storage entirely on its own.

I can't give any formulars for calculation, aside from the one in the FAQ, but I hope that this helps to clear things up!

That helps a lot, thank you!
Since larger and hotter fields dissipate heat quicker, would it be more efficient to leave a 1-tile gap between each region of 27 panels?

It is a minor difference, but yes, it is best to limit the amount of panels connected to each other. Heat transfer relies on there being a small temperature difference, so heat tends to accumulate more in panels that are further away from the point of consumption (the heat exchanger), and that increases overall heat dissipation a bit. (For this reason, the large thermal panels turn out to be a bit more efficient than the small ones when covering the same area, even if they are coded to have the same transfer limit and no transfer loss.)

I figure that having separate blocks also simplifies calculations and thus improves performance, but that only matters on an extremely large scale. I haven't specifically tested for this. Anyway, 27 small panels + 1 exchanger, or 27 large panels + 9 exchangers are neat arrangements that both work well.

Oh, and try to avoid using heat pipes, since they add unnecessary heat capacity to the network and thus lowers efficiency. I have balanced things to allow the power target to be reached even with 1 or 2 heat pipes between a solar field and a heat exchanger (for aesthetic or practical purposes), but they are not meant to be used extensively.

Ah alright! Thank you so much!! I'm sure I'll be double-checking these messages while playing to make sure things are working lol

You are welcome!