Is Renewable Energy Reliable?

Below, we outline whether renewable energy might be reliable or not.

We do this by outlining what reliability means, looking at how different renewable energy sources might be reliability or unreliable, as well as providing examples of how electricity grids might be performing in places where renewable energy is used.


Summary – Is Renewable Energy Reliable?

What Does Reliable Mean?

We outline what ‘reliable’ and also ‘secure’ might mean in the context of energy sources and electricity grids in the guide below


Is Renewable Energy Reliable?

Overall, it depends on a range of factors

Firstly, there’s different renewable energy sources.

Some of them might be identified as being less reliable than others for different reasons

We identify those energy sources and the potential reason in the guide below


Reasons Why Solar & Wind Energy Might Not Be As ‘Unreliable’ As Some Reports Claims

Whilst some reports indicate that solar and wind contribute to ‘unreliability’ in an electricity grid, others indicate that this might not be the case

The various reasons that solar and wind might not be as ‘unreliable’ as some reports may claim, might be:

– There are cities, regions and countries in the world using notable %’s of renewable energy in their energy mix

Some reports indicate that either the electricity grids of these places are reasonably reliable, or, the issues that are experienced in these places may not be caused solely (or at all) by renewables

We list some of these places and provide more information on this point in the guide below


– There might be a range of ways that the variability of solar and wind might be managed within an energy system/electricity grid


– There are factors other than the energy source used in an energy mix that can contribute to an unreliable power supply

So, there may be factors other than the renewable energy sources being used that can contribute to an ‘unreliable’ electricity grid


– The traits and shortcomings of individual energy sources might matter less in some power grids than how all energy sources work together in a power grid, how the power grid is designed, and how the entire energy system works together

So, the electricity grid and local energy system as a whole has to be analysed for poor performance or potential problems, rather than just looking at an individual energy source

Each city or town ultimately has different a different power grid and energy system too (useing different energy mixes, have different power grid designs, and ultimately have different levels of power supply reliability and quality)

So, each city or town might need to be analysed separately


Reliability Is Only One Factor To Consider When Assessing The Impact & Capability Of Different Energy Sources

Reliability is only one of a range of performance factors for the different energy sources used in an electricity grid


Each Energy Source Might Have Different Benefits & Drawbacks To Consider

Renewable energy sources specifically may have different benefits and drawbacks when used within an electricity grid

For example, renewable energy may cause or contribute to some technical issues, and increased electricity prices

But, it might also be more sustainable in some ways, of have other benefits that other energy sources don’t have


Definition Of Reliability For Energy Sources & Electricity Grids

Below, outlines the difference between ‘security’ and also ‘reliability’ in the context of an electricity grid.

Reliability essentially refers to the ability of energy sources to deliver the quantity and quality of power demanded by the users of an electricity grid.


Security, & Reliability Of An Electricity Grid

Security and reliability are terms used to discuss the strength and stability of [an] electricity grid … (


What The Security Of An Electricity Grid?


The security of an electricity grid is its technical resilience (or strength), namely its ability to quickly respond and remain stable when unexpected events occur [. Examples of this are] generators breaking down or transmission lines failing …


What Is the Reliability Of An Electricity Grid?

Reliability is the ability of an electric power system [i.e. the electricity grid] to deliver electricity in the quantity and quality demanded by energy users (


So, Is Renewable Energy Reliable?

To provide some type of answer to this question, the following points might need to be addressed:

– The individual renewable energy sources being referred to

– Of these renewable energy sources, which ones might be less reliable, and why

– Why these same renewable energy sources might not always be as unreliable as some reports claim

– How do non renewable energy sources compare in terms of reliability?

– What are the considerations other than reliability that have to be taken into account with different energy sources?


We’ve tried to address these points and provide other relevant information below …


What Are The Different Renewable Energy Sources, & Which Ones Might Be Less Reliable Than Others?

The Different Renewable Energy Sources

We list the different types of renewable energy in this guide.

Solar, wind, hydro, geothermal, and bioenergy might be some of the main ones.


Which Ones Might Be Less Reliable Than Others?

Some types of hydro energy using stored water, and geothermal might be examples of renewable energy sources that deliver a reasonably consistent power supply

For this reason, they might be seen as somewhat reliable

Solar and wind energy on the other hand are the two main renewable energy sources that are variable/intermittent (because they rely on the weather to capture energy)

This variability/intermittency is sometimes reported as being a main cause of unreliability, or creating other issues with the electricity grid and power supply of a city for example mentions that (paraphrased) both solar and wind can be unreliable energy sources


Also from

… sun and wind [have variability as energy sources, compared to …] coal, gas, and nuclear plants, which can more easily operate on-demand or provide “baseload” (continuous) power …



… only wind and solar are “variable;” the rest are capable of being dialed up or down when needed – “dispatchable” in industry parlance … mentions that:

Denmark … derives nearly half its electricity from wind, and [it] can only do this because it can import or export electricity from neighbours to match demand …


The Reliability Of Electricity Grids In Different Countries That Use Significant Renewable Energy

Below, we look at the reliability of electricity grids in different regions of the world that use a notable amount of renewable energy.

Some data suggests that some existing cities and towns may have reasonably reliable electricity grids (even whilst using renewables).

A summary of the findings is:

– California

In California some data might suggest that solar and wind have ‘enhanced grid reliability’


– Germany

In Germany, in the period that renewable electricity production significantly increased, average outage/electricity interruption times (in total minutes) for the electricity grid may have decreased

Germany may have also had one of the most reliable electricity grids in the world and in Europe in 2016

Other reports though indicate that Germany’s energy transition may have resulted in a range of issues


– Denmark

Denmark has a high renewable energy share, and one report indicates that both coal and renewables have proved to generally be ‘reliable’

Denmark may also have one of the best rated electricity supplies in the world, and in Europe

Having said that, Denmark may have high electricity prices – this might be a potential issue that renewables contribute to


– Australia

In Australia, power outages may be caused by factors other than renewable energy sources

However, renewables may contribute to technical issues that arise in Australian grids

South Australia in particular may use a notable amount of wind and solar, but have a reasonably reliable grid


– Future Forecasts For The US

Some studies indicate that the US can introduce more renewable energy in the future whilst maintaining electricity grid reliability


More information on the above points …



Tests performed in California, which has some of the highest rates of renewable electricity use in the world, provide real-world validation for the idea that solar and wind can actually enhance grid reliability (



[When monitoring average outage/electricity interruption times in total minutes …] Germany’s annual power supply interruption has decreased from 2006 to 2017 … [and in the same period …] the share of renewable electricity production in Germany rose from 11.3 to 33.1 percent, mostly from fluctuating sources such as wind and solar power stations (


However, other reports indicate that Germany’s energy transition has resulted in issues to do with overcapacity, high electricity prices, blackouts, increased carbon emissions in some years from the use of gas plants to provide electricity when solar and wind are not producing, and various other issues.




Coal fired generation has proved to be reliable, but so has renewable energy.

Denmark has just about the highest renewable share and the most reliable supply in Europe.



Whilst households in Denmark pay some of the highest electricity prices around, the electricity supply is ranked as one of the best in the world with an index score of 6.8 out of a possible 7 [and] Only Scandinavian neighbor Norway, Singapore and Switzerland had a higher ranking than Denmark in 2018.




… the overwhelming majority of [power] outages in Australia – more than 97 per cent – are caused by faults in the local network, such as transformers failing or trees falling on wires [and] They have nothing to do with renewables


The growing share of renewable energy in the [Australian] national electricity grid is producing technical challenges that must be overcome … [but there are solutions] (


From, specifically in South Australia:

[Over the summer in 2017], with 50 per cent wind and solar, South Australia [had] the most reliable grid in the country [but] Unlike the previous summer, with severe weather events and mis-steps by the market operator, there were no major outages …


Most Reliable Electricity Grids In The World

[Germany, Denmark, Switzerland, Luxembourg and the Netherlands had some of the most reliable electricity grids in the world in 2016] (


Most Secure Electricity Grids In Europe

In 2016, Switzerland, Germany and Denmark has some of the most secure electricity supplies in Europe (


Future Projections On How Much Solar & Wind The US Can Hand Whilst Still Maintaining Energy Grid Reliability outlines (paraphrased) that different studies indicate that different energy markets (in cities and countries) can introduce different %’s of solar and wind to their energy mix, while still maintaining reliability.


Practices & Solutions That Might Help Address The Variability Of Solar & Wind

There might be various ways to address the variability of solar and wind.

Paraphrased from reports from, and, whilst adding some of our own information and comments, some practices that might be implemented to address the potential variability of solar and wind might be:


– Reducing or shifting energy demand to meet supply


– Increasing energy supply to meet demand

This can include having more total energy generation capacity

It may also involve having dispatchable energy sources (and dispatchable generators) available that can ramp up quickly, can be adjusted (in terms of their power output), and can be turned on and off, to meet energy demand 


– Spreading out wind farms over wider/broader geographic areas

This may reduce reliance on the wind conditions in one geographic area


– Using solar and wind in a complementary way to one another

For example, solar might be used more in hotter months, and wind more in colder months


– Using complementary backup energy sources around variable solar and wind energy sources

Hydro and natural gas might be examples of energy sources that can start up quickly/ramp up quickly when wind and solar output drops

Hydro and natural gas might therefore make good backup energy sources


– Incorporating the variable power supply from solar and wind into the design of the electricity grid 


– Using energy storage batteries

They can store surplus energy when there is surplus supply, and, this energy can be used later on when supply is not enough to meet demand mentions that South Australia in Australia has incorporated this solution:

[South Australia has seen …] the introduction of Australia’s first, and the world’s biggest, utility scale lithium-ion battery … which has demonstrated speed and versatility unseen before in the grid …


– Using other forms of energy storage to access or use energy at a later time when it’s needed

Pumped storage hydro energy may be able to store energy from renewable energy sources in some circumstances 


– Improving collection of, and access to information about electricity production (and power output) and energy use across the energy system and electricity grid

This can help decision makers and energy producers make better informed decisions about energy


– Trying to forecast solar and wind output in advance with better accuracy

This may help with the adjustment of other energy sources around the output of solar and wind


– Consider how energy policy and lawmaking can contribute to reliable electricity grids


– Collaborating with energy related businesses to better understand how to deliver reliable power with the energy sources that are in use


– Other information on potential solutions



There are many ways of managing variable electricity technologies within the broader mix.

This is hardly surprising given that grid operators have been dealing with variability since the birth of electricity distribution over one hundred years ago, for the simple reason that demand always varies …



Solar and wind are highly predictable, and when spread across a large enough geographic area—and paired with complementary generation sources—become highly reliable. 

Modern grid technologies like advanced batteries, real-time pricing, and smart appliances can also help solar and wind be essential elements of a well-performing grid



… In South Australia [, which uses a high % of solar and wind, and experienced a blackout …] – management practices were changed to better suit the changing shape of the energy system, and a combination of regulatory obligations and market mechanisms are being applied to support grid stability as the system continues to evolve … [This] involved a combination of demand management, battery storage, and … the use of the emergency back-up generators …


The points above might be considered in an overall strategy to use renewable energy more effectively in a city’s energy system/electricity grid.


Factors Other Than Renewable Energy Sources That Can Contribute To Unreliable Electricity Grids

We mentioned some of these factors in this guide already.

Some examples might include:

– Faults in the local network

– Poor grid design

– Infrastructure and transformers failing

– Trees falling on wires

– Extreme weather

 – And more


Reliability Might Be Impacted By The Grid And Energy System As A Whole, & Not Just Individual Energy Sources

An important point about reliability is that it might be impacted by the electricity grid and local energy system as a whole, and not just the individual energy sources (in the local energy mix) that make it up.

One way to explain this succinctly might be – how an individual renewable energy functions on it’s own might not matter as much as how it functions as part of a whole grid or energy system … because, in reality, energy sources don’t function on their own.

Solar and wind for example might be able to perform well in a flexible and diverse energy system (with a good design, good infrastructure, complementary energy sources, etc.) goes into more detail about this point in their guide


Other Potential Misconceptions Relating To The Use Of Variable Renewable Energy Sources That May Impact Reliability

There may be some misconceptions about using variable energy sources like solar and wind.

We’ve paraphrased some information below from that goes into these potential misconceptions in more detail:


– Base load might not be essential

[It is often said that we need baseload from energy sources like nuclear and coal]. [But, baseload is not always necessary].

[Flexibility might be more important … and] What we do need are power systems that can match supply and demand in a more concerted and flexible way.


– Supply from the grid might not always have to match demand from users/consumers of the grid

[This may not always be the case as in the future the power grid could act as a backup to] individual households, communities and global companies producing and managing their own electricity supply and demand.

[Several countries around the world are already producing electricity from renewables without battery storage].

[As an example of this,] 41 per cent of Danish electricity demand was met with wind (roughly 39 per cent) and solar (2 per cent) last year [in 2016], and expectations are that this number will rise to nearly 90% in the next nine years.


Non-Renewable Energy Sources May Experience Power Interruptions Too

Electricity grids with using fossil fuels and nuclear as energy sources may experience power interruptions for various reasons.


Even coal and nuclear experience interruption sometimes due to different factors (


Reliability Is Only One Performance Indicator To Consider For Energy Sources – There Are Other Indicators

Reliability of electricity supply is only one performance indicator to consider when incorporating different energy sources to an energy system or electricity grid.

Other indicators that might be considered might include:

– Impact on electricity prices

– Contribution to technical issues

– Impact on sustainability

– And more
















13. Various ‘Better Meets Reality’ guides


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