Is Renewable Energy Reliable?

In this guide we outline whether renewable energy is reliable or not.

We look at the general reliability of renewable energy sources, as well as looking as real world examples of how renewable energy is being used, and the impact it is having on reliability of energy supply.


Summary – Is Renewable Energy Reliable?

It depends on the type renewable energy source 

It also depends on how each renewable energy source is used as part of overall energy and electricity systems (to supply an electricity grid) – with other renewables, or with other energy sources like fossil fuels and nuclear.

Renewables don’t function individually, but with other renewables or other energy sources as a part of a whole grid or system

Solar and wind in particular are seen as variable and intermittent/variable sources of renewable energy on their own, but can perform well in a flexible and diverse energy system.

When people talk about unreliable forms of renewable energy, solar and wind are usually what they are talking about due to this variability and intermittency

Hydro and geothermal (along with bioenergy) are seen as more reliable and consistent sources of renewable energy on their own, but particularly hydro, as long as there is adequate water storage or running water sources (from a river for example)

But, each of these energy sources are used differently in different States and countries around the world, with different levels of reliability, in different energy grids

For example, one country may have a different energy mix and electricity systems than another, along with a more reliable electricity supply.

Further to that, energy mixes and reliability of electricity systems can vary from State to State within one specific country

It also depends how you define reliability

Renewable energy can be reliable in some specific ways, but unreliable in other broad ways (and cause other reliability related problems)

There can be side effects to increasing renewable energy supply, such higher electricity prices.

So, this must be considered along with reliability (reliability is not the only consideration)


Definition Of Reliability In Relation To Electricity


Security and reliability are terms used to discuss the strength and stability of the electricity grid, also known as an electric power ‘system’.

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 such events include generators breaking down or transmission lines failing.

Reliability is the ability of an electric power system to deliver electricity in the quantity and quality demanded by energy users.


The Reliability Of Real Life Electricity Grids Using Renewable Energy – Germany, Denmark, Australia

Germany and Denmark both use an increasing amount of renewables for their electricity.

Both are said to have reliable and secure electricity grids according to some reports.



Germany’s annual power supply interruption has decreased from 2006 to 2017:

When systematic monitoring started in 2006, average outage times exceeded 20 minutes. 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

[In 2016, interruptions have decreased all the way down to 12.8 minutes]

[Germany still has one of the most reliable electricity grids in the world in 2016, along with Denmark, Switzerland, Luxembourg and the Netherlands]




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



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.

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.

They have nothing to do with renewables



South Australia

[Over the last summer in 2017], with 50 per cent wind and solar, South Australia can lay claim to having the most reliable grid in the country.

Unlike the previous summer, with severe weather events and mis-steps by the market operator, there were no major outages

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



The % Of Solar & Wind Supplying Electricity Can Matter When It Comes To Reliability outlines that different studies have found that different regions, individual States, and the entire country of the United States as a whole can take on different % shares of solar and wind making up their electricity supply, while still maintaining reliability.

For example, that number for California might be 40 to 50% by 2030, and for the United States as a whole, that number might be 80% by 2050.


Reliability Is Only One Feature, Or Consideration To Make, With An Energy Or Electricity System (& When Adding More Solar & Wind)

Reliability of electricity supply is only one feature to consider when incorporating and adding more solar and wind to an energy system or electricity grid.

Adding more solar and wind can impact the overall cost of electricity generation.

It also has the ability to increase electricity prices fairly significantly.

And, there are social and environmental consequences of adding and reducing different energy sources in an energy mix. 

Germany for example has reportedly dealt 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.

The infrastructure and funding has to be there to make a renewable transition smooth and not laden with problems.

Denmark also has some of the highest electricity prices in the world.

So, reliability is only one of many features, and overall pros and cons to consider, with changing any energy or electricity system.


How Solar & Wind Are Growing, While Maintaining Reliability Of Electricity Supply

There are a variety of practices that are being implemented by utilities and grid operators to maintain the reliability of solar and wind for a steady electricity supply:

Spreading wind farms and generation sites out across a broader geographic area, so that there isn’t a reliance on one site or geographic location for it’s wind conditions

Forecasting solar and wind output with better accuracy so energy sources can be adjusted as required (depending on forecasted output)

Drawing on other energy sources like hydro and natural gas (which is quick starting/ramps up quickly) when wind and solar supply diminishes [these are known as backup sources of power]

Designing the electricity grid to deal with variability in supply and demand from all energy sources.

Even coal and nuclear experience interruption sometimes due to different factors



On top of these things, other ways to address the variability of solar and wind might include energy storage batteries, and complementary energy storage sources like pumped storage hydro.

For example, emerging energy storage technologies are … poised to make it possible to store electricity for use when the wind does not blow and the sun does not shine (


Renewable energy opponents love to highlight the variability of the sun and wind as a way of bolstering support for coal, gas, and nuclear plants, which can more easily operate on-demand or provide “baseload” (continuous) power. 

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

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



ARENA is working on solutions in Australia to deliver reliability to the electricity system.

These solutions may include:

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

… reducing or shifting energy demand to meet supply, improving information about electricity production and use, and developing ways to access or store renewable energy for use when it is needed.

… they may also include collaborating on projects with energy businesses to examine new ways to empower energy consumers that will deliver reliable renewable energy, and with policy makers to determine whether laws governing the electricity market should be changed to encourage reliable supply.



Also in Australia, ways to deal with intermittent solar and wind energy might include:

a ‘dispatchable’ generator that can increase or reduce its output as required

develop a coherent emissions and energy policy

… In South Australia [which 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 – for the first time in the recent heat-wave that hit South Australia in late January – the use of the emergency back-up generators



Responding To Common Reliability Claims Against Renewables clears up some common reliability claims about renewables:

– Reliability is not a function of individual generation technologies, but a function of the electricity system as a whole 

[how an individual renewable energy functions on it’s own doesn’t matter as much as how it functions as part of an overall electricity system] … “renewable energy” is not a single energy source, but roughly speaking six: solar, wind, biomass, geothermal, hydro, and ocean.

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

[Also,] 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


– Base Load Is Not Essential

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

What we do need are power systems that can match supply and demand in a more concerted and flexible way.

Flexibility is key.


– Supply From The Grid Always Has To Match Demand From Consumers

[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] 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.


Is Solar Energy Reliable?

Solar is generally seen as an intermittent and variable energy source.

It can be reliable in an electricity system that is set up the right way with the right infrastructure, design, and balance of other complementary energy sources. says solar is not a reliable energy source though.


Is Wind Energy Reliable?

Wind is generally seen as an intermittent and variable energy source.

It can be reliable in an electricity system that is set up the right way with the right infrastructure, design, and balance of other complementary energy sources. says wind is not a reliable energy source though.


Is Hydro Energy Reliable?

Hydro is generally seen as a reliable energy source as long as there is stored water or running water to draw upon. says hydro energy is generally a reliable energy source, but there can be challenges to using it.


Is Geothermal Energy Reliable? says that geothermal is physically reliable and more environmentally friendly than fossil fuels, but it is not economically reliable without government subsidies in many cases


Is Bioenergy Reliable?

There are many different types of bioenergy. says that biomass is expensive, inefficient, and environmentally damaging.
















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