Why do my accumulators drain so fast?

[Maltebyte]

Im ♥♥♥♥ at maths and i need an explanation please. So i have 50 Accumulators as backup from 52 solarpannels. so i should have 15.000 MW bit of a calculator there 300kw x 50.
My main net is using 30MW at the moment and i try out my backup power which drains in seconds! Do i need something like 2000 Accumulators to last me at least 2 minutes!?

[knighttemplar1960]

It takes 23.8 solar panels to operate 1 MW of factory and charge 20 accumulators to sustain that 1 MW through the night.

(That means you need 714 solar panels and 600 accumulators to run your entire 30 MW factory on solar only.)

[Maltebyte]

Originally posted by knighttemplar1960:

It takes 23.8 solar panels to operate 1 MW of factory and charge 20 accumulators to sustain that 1 MW through the night.

So makes sense if im using 30MW aprox that they drain within seconds! i guess like i said maths is not my strong suit! and how can i have 0.8 of a solar panel? either i have 1 solar panel or i dont? there is now build an 8/10 of a solar panel lol sorry for being dumb here!

[knighttemplar1960]

Originally posted by Maltebyte:

Originally posted by knighttemplar1960:

It takes 23.8 solar panels to operate 1 MW of factory and charge 20 accumulators to sustain that 1 MW through the night.

So makes sense if im using 30MW aprox that they drain within seconds! i guess like i said maths is not my strong suit!

Yeah solar takes ALOT of space.

[AlexMBrennan]

It's a battery. Batteries have finite charge.

That's not a maths issue but you just ignoring the energy capacity the game gives you. Factorio accumulators have a capacity of 5MJ and a maximum output of 300kW so they can fully discharge in 16 seconds.

[Shurenai]

The TL;DR of it is that you need a ratio of 21:25 accumulators:solar panels, ish. And at least 24~ solar panels per MW your base consumes to run fully on solar.

If you're riding the line too close, the accumulators discharge at full speed and the whole bank will empty in 17 seconds- Which is what you're experiencing.

One accumulator can hold 5MJ of power and can discharge that in 17 seconds at full load, You need 20 accumulators (100MJ of storage) to supply 1MW of power over the course of the night, which is 42~ seconds long, ish.

So for your base, you have 30MW consumption, so you need about 600 accumulators and 720~ solar panels to support your base on solar full time. You mentioned this is a backup system, so, same number of accumulators, but far less solar panels'd do you alright.


And to answer the unasked question, Yes, Running your base on Solar power takes a LOT of space. Even just as a backup is space heavy.

[Shurenai]

Originally posted by Maltebyte:

Originally posted by knighttemplar1960:

It takes 23.8 solar panels to operate 1 MW of factory and charge 20 accumulators to sustain that 1 MW through the night.

So makes sense if im using 30MW aprox that they drain within seconds! i guess like i said maths is not my strong suit! and how can i have 0.8 of a solar panel? either i have 1 solar panel or i dont? there is now build an 8/10 of a solar panel lol sorry for being dumb here!

It's a ratio- You don't make 0.8 of a solar panel, You try to match the ratio as close as you can- And if you have a partial number, you always round up.

And as you get to bigger numbers, it stops being an odd number out. 23.8 becomes 238 if you multiply it by 10(As in, place 10 times as many solar panels.)

[Hurkyl]

Originally posted by Maltebyte:

Originally posted by knighttemplar1960:

It takes 23.8 solar panels to operate 1 MW of factory and charge 20 accumulators to sustain that 1 MW through the night.

So makes sense if im using 30MW aprox that they drain within seconds! i guess like i said maths is not my strong suit! and how can i have 0.8 of a solar panel? either i have 1 solar panel or i dont? there is now build an 8/10 of a solar panel lol sorry for being dumb here!

The issue is that there are two numbers that matter.

To use the fluid analogy to electricity... Joules are how much water you have, and Watts are how big your pipes are.

Since you were looking at MW, you were looking at the question of how big the 'pipes' need to be in order to supply electricity to your factory.

But you also need to look at MJ, which is how much energy is stored.

1 MW means you're sending 1 MJ of energy every second. So your 30 MW factory consumes 3600 MJ of energy over 120 minutes, as mentioned previously.

And since the accumulator holds 5 MJ, you need 720 of them to do so at night (since solar isn't helping supply energy), as mentioned above.

[Hurkyl]

Incidentally, if you want to design your factory to shut off less critical portions when energy is low, it is possible to do so!

You can use a power switch to separate portions of the electric grid, and design less critical portions to connect only to the power switch, and not to the rest of the power grid.

Then you can place an accumulator next to the power switch and make a circuit network connecting them, and tell the power switch to turn off when the accumulator charge is low.

(and when power is low, this tends to rapidly flip power on and off... with more work you can make an SR latch so that power turns back on at a different level than when it turns off)

[Fel]

23.8 solar panel and 20 accumulators for a constant 1MW is the math ratio.
The easier ratio is 25 solar panels and 21 accumulators for 1MW.
You get a bit more than 1MW from that but having a bit of surplus is always better in this game anyway.

ALso, an accumulator takes about 17 seconds to fully charge or discharge at its maximum input/output.
This means that in the majority of cases you would not need the maximum input/output, the capacity is what matters more.
OP started to go wrong when treating an accumulator as a machine capable of outputing a constant 300 kW through the night.

Basically solar power takes a whole lot of space (and often time to set it up), if you need a lot of power from a more compact thing you might want to go towards nuclear power instead (which does have its drawbacks as well of course).

[Defektiv]

I just slow crawled to end of non space research using solar/accumulator banks and it was painful. It seemed like every tiny little factory upgrade meant I was building huge fields of panels and another accumulator bank. I eventually put back down some steam engines with a single accumulator tied with automation cable to their water pump set to only turn on if the accumulator got below 30% and that helped buffer the gaps a little. But ultimately getting to Mk2 armor and being able to run around the map using 3 exo legs with 5 personal lasers pew pewing everything I pass got me to the point where I said screw it, cleared the nests for double the distance and put back down a steam engine network. Its still tied to automation but if solar comes up short I can just ignore it now.

Btw you CAN get accumulators to hold the load the entire night but its a LOT of panels per bank.

[rdbury]

It may help to keep track of the units. Accumulators store energy and the unit of energy used in the game is Joules (J), or more frequently kilojoules (kJ=1000 J) or megajoules (MJ=1000000 J). Meanwhile your power usage is in Watts (W) or kilowatts (kW=1000W) or megawatts (MW=1000000 W). The relation between them is using 1 Watt = 1 Joule per sec. To get the power usage divide the Joules used by the period of time (in sec). So if you use 5 MJ (the capacity of the accumulator) in 20 seconds that would be 5/20 MW = .25MW =250kW. There is also a limit to how fact the accumulator can charge or discharge given in energy per second, i.e. power. This is 300kW for both charging and discharging. If your power consumption is 15 MW then you'd need 15 MW/300 kW = 15000000/300000 = 50 accumulators to keep up. But accumulators only have a finite amount of power, and you can figure out how long it would last at full output by dividing the energy available by the energy used per second, so 5MJ/300kW = 5000kJ/300kW = 16.67 sec. In my experience, the charge/discharge rate rarely comes into play because if you need backup power at all it's going to be for more than 16 sec. So it's more useful to ask how how many accumulators do you need to provide power (15MW) for 2 minutes (120 sec.) That would be 15 MW x 120 sec = 1800 MJ. Each accumulator stores 5 MJ, so you'd need 360 accumulators to provide power for two minute. The upshot is that each accumulator has both a power limit and an energy limit, and you need to enough of them to exceed both these limits to do what you want to do with them. None of this relates to solar panels btw, That's a whole new level of calculations.

Actually I'm kind of surprised how popular this game is given the amount of math involved. I happen to like math so it's no problem for me, but math seems to be most people's least favorite subject.

[Defektiv]

I think its because you don't necessarily need the math. The game is complicated but forgiving enough for you to keep backing up and driving forward until your square peg fits through the round hole.

[Fel]

Yeah, as long as you are good enough at figuring out the source of the problems then math is mostly not required.

Accumulators finished charging before the start of the night but the power cuts off during the night?
More accumulators.

The accumulators don't finish charging before the night?
More solar panels.

It's the same for pretty much the whole game too.
Knowing how many iron plates per minutes you need to run your factory is not that useful, just knowing when you don't have enough is all you really need.

Of course having a good enough understanding of numbers and ratios helps, especially in the planning phase, but it is never a requirement to have a functional factory.

[Premu]

Originally posted by Defektiv:

I just slow crawled to end of non space research using solar/accumulator banks and it was painful. It seemed like every tiny little factory upgrade meant I was building huge fields of panels and another accumulator bank. I eventually put back down some steam engines with a single accumulator tied with automation cable to their water pump set to only turn on if the accumulator got below 30% and that helped buffer the gaps a little. But ultimately getting to Mk2 armor and being able to run around the map using 3 exo legs with 5 personal lasers pew pewing everything I pass got me to the point where I said screw it, cleared the nests for double the distance and put back down a steam engine network. Its still tied to automation but if solar comes up short I can just ignore it now.

Btw you CAN get accumulators to hold the load the entire night but its a LOT of panels per bank.

In general I would advice:

For just starting a single rocket you'd need around 5 to 10k solar panels and a similar amount of batteries. Using steam engines is far easier and mostly sufficient. You could use nuclear power if you want to, but you have to set up the infrastructure first.

Solar panels can still be useful in some cases, though - as emergency system to repower or for localized, autonomous power supply.

If you're going for a megabase, it might depend how large it really should get. Solar power is often recommended as it is the most UPS efficient. But I built 1k and 2k SPM factories with just very large nuclear power plants and still achieved 60 UPS. For 2.7 SPM the UPS started to fall below, so at this level you might go for solar power. Of course, you need a massive amount of it. For my new 2.7k SPM base I've already built close to 400k solar panels and will probably need up to 450k to 500k. In order to achieve that you need not only set up a large scale production for those, but also an efficient way to deploy them in large numbers.