Talk:Capacity factor

Load Factor
The Load factor and the Capacity factor are not the same thing. The difference is in the difference between the supply and the use. I agree that the concepts are similar but the only proper discussion of load factor is in the Demand Factor page. If I knew how to fix a redirrect I would make the Load Factor page myself. Can somebody fix this? — Preceding unsigned comment added by 76.10.188.142 (talk) 18:39, 5 December 2012 (UTC)

Wind Energy
Perhaps some discussion needed on the misconceptions equating capacity factor with efficiency as often seen in the popular press. Something along the lines of how a wind turbine could theoretically run just off rated power for a year, and thus have a capacity factor of zero, yet still be generating a substantial amount of energy, etc, etc. Davagh (talk) 22:59, 30 June 2008 (UTC)


 * This is a good point particularly as some parts of the media are prone to quote the typical capacity factor of wind turbines and name it as efficiency. I don't think the turbine you describe would have a capacity factor of zero though, it would be low. Biscit (talk) 14:54, 4 March 2011 (UTC)

Power capacity
We should have an explanation of power capacity and how it's derived, but I don't think it deserves its own article. Can we rename this article to cover both? — Omegatron 10:24, 16 March 2008 (UTC)

Time period
"The capacity factor of a power plant is the ratio of the actual output of a power plant over a period of time and its output if it had operated a full capacity of that time period."

All of the power-plant articles casually mention capacity factor, referring to this article. But, the relevant time period is not stated! I would assume that the implicit time period is "one year", generally. This article should address this issue. -69.87.203.158 13:38, 5 November 2007 (UTC)


 * The time period doesn't matter. It's a ratio.  — Omegatron 10:24, 16 March 2008 (UTC)

I think the time period matters specially when you taken into consideration power generation sources like solar. If you take a 1 month time period in summer your capacity factor might be higher when compared to 1 year time period (because spring and winter seasons will effect the fuel availability). So do we expand the article to include time period. Does industry follow specific time periods? —Preceding unsigned comment added by Nemanij (talk • contribs) 18:34, 15 March 2010 (UTC)

Typical Capacity Factors
In this section, nuclear power is claimed to be able to generate over 100% of its capacity factor:

"Nuclear 60% to over 100%, U.S. average 92%.[3]"

The source doesn't go into any detail about these numbers.

It might be useful to explain how this is possible - does the over 100% factor imply that some nuclear plants are generating power in excess of their nominal capacity? Frekja (talk) 13:51, 23 October 2008 (UTC)
 * I wondered that myself. I don't see any other explanation for it, so I think it does imply that.  The source is supportive of wind though, so it seems unlikely that they would be mangling facts to make nuclear power look better than it is.  I just noticed that there are other data on nuclear over in Intermittent power sources that I haven't added here. Mishlai (talk) 14:02, 23 October 2008 (UTC)

>>The reason you can get over 100% CF for nuclear is because the capacity of any generator is set at manufacturing. If a generator is rewound in order to increase the capacity as many/most nuclear generators are...as high as 15% above the origanal capacity, the CF can then generate MORE than the original name-plate capacity. A nuclear plant whose name plate capacity is, say, 1000MW can now producte 1080MWs is now producing "108%" of capacity...becasue the generator was upgraded. — Preceding unsigned comment added by 73.71.218.216 (talk) 13:19, 11 July 2017 (UTC)


 * Nameplate capacity should be upgraded too in that case though. --Ita140188 (talk) 03:08, 12 July 2017 (UTC)

Dubious solar capacity factors

 * Thermal solar power tower 73% [6]
 * Themal solar parabolic trough 56% [6]

Okay, the source does have those numbers, but — the transparency of the Earth being what it isn't — I don't see how ground-based solar can have a capacity factor over 50%. They must be using some oddball definition of capacity factor, but what? Average power divided by peak power for the ~8 hours/day it's working? Dividing average energy generation per year by the maximum possible in a year of perfectly clear weather? Whatever it is, it needs explaining. —WWoods (talk) 18:12, 14 November 2008 (UTC)

I concur. I considered deleting the entry altogether, but instead added the comment that it is unlikely to be accurate. If a solar power tower ever delivered a 73% capacity factor our energy woes would be over, as would global climate change. I wish it were true, but wishing wont make it happen. Rod Sullivan —Preceding unsigned comment added by Rod Sullivan (talk • contribs) 20:09, 20 July 2009 (UTC)
 * The reason CSP plants can reach these high capacity factors is the assumption that the system stores energy during the day, by heating tanks of water, and using that water to during a part of the night to drive turbines. See . GNOJED3891 (talk) 04:41, 3 December 2009 (UTC)

I have to disagree. However, it should be noted that these plants have thermal storage and that the high capacity factor is due to thermal storage.

However, this:

"However, according to the SolarPACES programme of the International Energy Agency (IEA), solar power plants designed for solar-only generation are well matched to summer noon peak loads in areas with significant cooling demands"

is basically bunk because the peak usage does not occur at noon in the summer. The peak load due to air conditioning occurs in the after noon. Probably at 4:00 PM or possibly later in really hot climates.

Tyrerj (talk) 16:21, 19 July 2011 (UTC)

The key here is to realize that the people in that link with the 73% and 56% capacity factors are playing games with the definition of nameplate capacity If you reduce your nameplate capacity then of course your capacity factor will go up. Essentially those concentrated solar plants are designed to produce a low amount of power all the time, as opposed to other solar plants which produce varying amounts, sometimes large and sometimes zero. So the maximum output of a concentrated solar plant is lower but it runs more often, compared to conventional solar. You are producing the same amount of total electricity, just changing when that energy is put out into the grid. Which is actually really useful. BTW they use molten salts, hydrocarbons and other exotic fluids, not water, as the medium for heat storage. It is pretty efficient and neat, but some of them are toxic or flammable and ironically bad for the environment.

Anyway, the real question here is "when is the power produced?" Like a conventional solar plant, a concentrated solar plant will only absorb the sun's energy around 20% of the time, so by one standard they have a 20% capacity factor. But a concentrated solar plant can store that light as heat, and by hoarding that heat for later, they can produce a lower level of electrical output 56-73% of the time, even at night. Which is where that higher capacity factor comes from...

It is misleading though, since it implies that the CSP plants are producing more electricity, which is not the case. — Preceding unsigned comment added by 99.152.114.72 (talk) 02:48, 5 February 2012 (UTC)


 * Well put 99.152.114.72, we need more experts such as yourself to stick around and improve this place.
 * Boundarylayer (talk) 02:44, 26 February 2013 (UTC)

Wind power
It's interesting. Some people say "wind power is the epitome of intermittency" (see ); others say that large-scale wind power cannot be accurately described as being intermittent (see Greenhouse Solutions with Sustainable Energy). Johnfos (talk) 07:23, 21 December 2008 (UTC)

Capacity Factor VS Load Factor
In this article, Capacity Factor == Load Factor

In my lecture however, we define

'''load factor = average demand/maximum demand  capacitor factor = average demand/installed capacity '''

Obviously it always depends on definition but the above definition makes more sense to me...

--IluvatarTheOne (talk) 19:19, 27 December 2011 (UTC)

You are right, they are two completely different concepts. I'm changing the article. — Preceding unsigned comment added by 99.152.114.72 (talk) 02:49, 5 February 2012 (UTC)

Conversion to MWh from MW
1000MW *30 days * 24 h/day = 720,000 MWh. the article says 648,000MWh. Can someone clarify 115.186.48.195 (talk) 17:22, 15 February 2012 (UTC)

Background, and explanation for, the varying values from different countries
I included the sentence below to convey to readers why the UK have a lower nuclear power capacity factor than the US, which boasts a much higher value. Sadly this pertinent piece of background info was deleted.  It is worth noting that the UK is unique in not operating a nuclear power plant fleet dominated by the most common nuclear reactor design, in the form of the Light water reactor, but that the UK operates a fleet dominated by Advanced gas-cooled reactors, which is not reflective of the dominate reactor technology used by the rest of the world.: Boundarylayer (talk) 02:41, 26 February 2013 (UTC)

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Capacity factor for fossil fuels
This article strangely leaves out any discussion of fossil fuel capacity factors, although they make up most of the grid. — Preceding unsigned comment added by 2A00:AB60:21E:D601:B913:F730:252C:BC3C (talk) 15:47, 4 October 2020 (UTC)


 * Fossil fuel power plants are generally dispatchable load following power plants, so their capacity factor depends on external factors mostly independent of the technology (such as the composition of the rest of the grid, the total grid demand, etc.). This is in contrast to renewables such as solar and wind, whose capacity factors are quite consistent over a year for a specific location, or nuclear power, which tend to run at maximum capacity all the time so the capacity factor is actually a measure of their availability factor. --Ita140188 (talk) 01:26, 5 October 2020 (UTC)

Confusing table dynamics
On the table under United Kingdom heading, what are the up and down arrows in the column headings? They seem to scramble it. Need some explanation please.Ian R Bryce (talk) 12:13, 21 October 2020 (UTC)