royhenderson
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Annual running cost of RPi4?

Tue Apr 14, 2020 8:40 am

Just trying to estimate annual electricity cost of running an RPi4 24x7.

I'm coming up with just about £26 which seems high compared to other figures I've seen from various sources.

I'm deliberately not sharing my maths (yet) because I don't want to influence calculations by others but I am using an assumption of 20W draw from the mains to allow for efficiency losses and a unit cost of 15p.

Would appreciate a couple of estimates from fellow members to either support or correct my own estimate.

TIA

jamesh
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 8:47 am

It depends on what it is doing and what is plugged in to it. If running full tilt, with a high demand USB device plugged in you could be using the entire 3A of the supply. If not you might only be using 1.5A or less. 3A at 5.1V is 15.3W, so your 20 seems high even including losses and that would be worse case.
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royhenderson
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 9:03 am

Thanks James.

Specific use case is a 4GB RPi4 running Rosetta@home to contribute to the Covid-19 folding project. Only addition is a small fan which looks to be keeping temp around 52-55.

I agree my 20W mains draw is being unfair to the (official) PSU I am using as I'm sure it's probably at least 80% efficient or better. Sounds like a mains draw between 10-15W would be more accurate which in turn would drop the annual cost towards £15.

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dickon
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 9:06 am

Using an RPF Pi <4 PSU and a booting Pi 3, I'm seeing 2-3W at the mains input. A Pi 4 on a RPF Pi 4 PSU, playing 4k HEVC, is sitting at 3.8W at the mains ATM. 3.8W*86400*365.25 = 33.3kWh, which is ~£5. Or, as I like to think of it, a nice sunny day in May, for my roof.

20W seems awfully high to me. But yes, it will very much depend on the workload. That was driving 4kp60, decode and display 4kp2410b H.265 (albeit with broken colours), with a keyboard plugged in.

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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 9:22 am

This is the published spec of the Pi4 official PSU showing the efficiency etc:

https://docs.rs-online.com/b3ba/0900766b816fdf82.pdf

For many (most?) people the running cost is low enough that the Pi gets left on 24/7 permanently.
(A fraction of the cost of running an x86 based PC).
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 9:25 am

About a year ago I checked secondary power consumption on the RPi4 and the maximum I saw during a "make .-j 4" kernel build was about 5.7W (this was well before all the power/thermal optimizations we've seen in the last year).

So a rough estimate of max 7-10W primary/mains power consumption seems more realistic. That'd be about 10-15 ponds per year then.

so long,

Hias

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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 2:07 pm

dickon wrote:
Tue Apr 14, 2020 9:06 am
A Pi 4 on a RPF Pi 4 PSU, playing 4k HEVC, is sitting at 3.8W at the mains ATM.
That initially felt a little low to me but does look to be right.

The 3A rating of the Pi PSU includes 1.2A of USB supply giving about 1.8A max draw for the Pi itself. Say it's half of that doing moderate tasks and that's about 1A.

For e-on's normal tariff with VAT added that's about £8 a year -

5v @ 0.5A = 2.5W = £4.12
5v @ 1.0A = 5.0W = £8.24
5v @ 1.5A = 7.5W = £12.36
5v @ 2.0A = 10.0W = £16.48
5v @ 2.5A = 12.5W = £20.60
5v @ 3.0A = 15.0W = £24.72

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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 2:24 pm

dickon wrote:
Tue Apr 14, 2020 9:06 am
Using an RPF Pi <4 PSU and a booting Pi 3, I'm seeing 2-3W at the mains input. A Pi 4 on a RPF Pi 4 PSU, playing 4k HEVC, is sitting at 3.8W at the mains ATM. 3.8W*86400*365.25 = 33.3kWh, which is ~£5. Or, as I like to think of it, a nice sunny day in May, for my roof.

20W seems awfully high to me. But yes, it will very much depend on the workload. That was driving 4kp60, decode and display 4kp2410b H.265 (albeit with broken colours), with a keyboard plugged in.
My back of an envelope maths is much the same. If I use the Royal Institute method of doing that maths from Rob Eastaway https://www.youtube.com/watch?v=-_-Vg_B3nzM

My easy way is assume £1 per WattYear and start from there. This year is costing a micro penny more because of the leap year.

There's lots of info about current (excuse the pun) power costs for the EV car owners (which will be me "next month" +/- covid19 delaying the delivery of my new Kia Niro on a long range car ferry into Southamptom) as sites like https://evchargingsolutions.co.uk/ev-charging-costs/

I don't have PV on my roof, but I may do if it's a good option for the new car.
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dickon
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 2:53 pm

hippy wrote:
Tue Apr 14, 2020 2:07 pm
That initially felt a little low to me but does look to be right.
Me too, frankly, as my (six-year-old) Intel Core i7-4771 with quad 3.5GHz amd64 cores can't manage to decode and play that particular stream with its 84W TDP in real-time. It seems to manage about half that. Admittedly that's a software rendering, but nevertheless: a 2013-$350 84W CPU is being thrashed by a 2020-$35 SBC with a decoder block on it. Still impressive stuff.

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dickon
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 3:09 pm

DougieLawson wrote:
Tue Apr 14, 2020 2:24 pm
My easy way is assume £1 per WattYear and start from there.
I tend to assume much the same.
I don't have PV on my roof, but I may do if it's a good option for the new car.
Today is looking likely to have generated around 23kWh by the end of it, which is enough to power that Pi 4 continuously for 250 days or so. To my mind, that's well within the noise margin of my electricity consumption, and is less than a couple of pints in the pub. Back when pubs were a thing, of course.

royhenderson
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 8:01 pm

My thanks to all for responses - most appreciated!

I particularly like the WattYear approximation which is excellent for getting a ballpark.

It's evident that my initial mains draw assumption was wide of the mark.

The conclusion looks to be that, for sensible (?) quantities, the annual running costs are irrelevant.

ejolson
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 8:22 pm

royhenderson wrote:
Tue Apr 14, 2020 8:01 pm
My thanks to all for responses - most appreciated!

I particularly like the WattYear approximation which is excellent for getting a ballpark.

It's evident that my initial mains draw assumption was wide of the mark.

The conclusion looks to be that, for sensible (?) quantities, the annual running costs are irrelevant.
How many Pi 4B computers do you have doing Rosetta@home? Do you also have a number for work units per hour that could be used to make a folding-compute per watt efficiency comparison?

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bensimmo
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 8:55 pm

ejolson wrote:
Tue Apr 14, 2020 8:22 pm
royhenderson wrote:
Tue Apr 14, 2020 8:01 pm
My thanks to all for responses - most appreciated!

I particularly like the WattYear approximation which is excellent for getting a ballpark.

It's evident that my initial mains draw assumption was wide of the mark.

The conclusion looks to be that, for sensible (?) quantities, the annual running costs are irrelevant.
How many Pi 4B computers do you have doing Rosetta@home? Do you also have a number for work units per hour that could be used to make a folding-compute per watt efficiency comparison?
the Pi run different and specific work units, you could compare the RAC (recent average credit) as a starter, but if they are not in the pool with the x86 machines, then the RAC cannot be checked properly.

ejolson
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Re: Annual running cost of RPi4?

Tue Apr 14, 2020 10:40 pm

bensimmo wrote:
Tue Apr 14, 2020 8:55 pm
ejolson wrote:
Tue Apr 14, 2020 8:22 pm
royhenderson wrote:
Tue Apr 14, 2020 8:01 pm
My thanks to all for responses - most appreciated!

I particularly like the WattYear approximation which is excellent for getting a ballpark.

It's evident that my initial mains draw assumption was wide of the mark.

The conclusion looks to be that, for sensible (?) quantities, the annual running costs are irrelevant.
How many Pi 4B computers do you have doing Rosetta@home? Do you also have a number for work units per hour that could be used to make a folding-compute per watt efficiency comparison?
the Pi run different and specific work units, you could compare the RAC (recent average credit) as a starter, but if they are not in the pool with the x86 machines, then the RAC cannot be checked properly.
Thanks for the clarification.

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