A few years ago, solar power became the “cheapest electricity in history”, but it still lacked the ability to meet demand 24 hours a day and 365 days a year.
Since then, there have been significant improvements in the cost and performance of batteries, making it cheaper than ever to pair solar with energy storage using batteries.
In our new Ember “white paper”, we present modelling showing that solar with batteries in major sunny cities, such as Las Vegas or Mexico City, can now get more than 90% of the way to continuous generation, at costs below those of coal or nuclear power.
Even in cloudier cities away from the equator, such as Birmingham in the UK, it is possible to run on solar plus storage across the majority of hours in the year.
The white paper sets out how near-continuous “24/365” solar power has become an economic and technological reality in sunny regions.
Solar and storage ‘gamechangers’
A solar panel generates most electricity when the sun is shining, meaning it cannot provide constant power throughout the year. Put another way, 100 watts (W) of solar capacity only generates around 20W on average – and that output will be concentrated in daylight hours.
Our report shows that battery energy storage can unlock solar’s full potential, by turning daytime generation into around-the-clock electricity.
Indeed, when paired with sufficient battery storage, that same 100W of solar capacity can provide electricity around the clock – up to 100% of the time.
This also means up to five times as much solar generation can be delivered using the same connection to the electricity network, reducing the need for costly grid upgrades.
Battery energy storage is now cheaper than ever, with global average prices falling by 40% in 2024 alone. The cost of a full battery system fell to a record-low $165 per kilowatt hour (kWh), according to BloombergNEF.
Additionally, there have been a number of technological improvements boosting battery energy storage.
Recent innovations mean almost all grid batteries are now cobalt- and nickel-free, reducing the need for so-called “critical minerals”. They are longer-lasting than ever, with some batteries now having 20-year warranties. And they are safer than ever – with fire risk improving by a hundred-fold since 2019.
Improved container design has also cut maintenance and installation costs.
Our white paper shows that supply is ready to scale, with manufacturing capacity already exceeding demand. There is also significant new production capacity under construction outside of China.
The next frontier is sodium-ion “salt” batteries, which would eliminate the need for lithium and drive prices down even further. One large salt-battery plant has already been commissioned in China.
These technological advances and declining costs mean the world’s first “24/365” battery and solar plants are now coming online:
- In Hawaii, several solar-plus-battery projects are providing electricity through the night after the decommissioning of the last coal power plant in 2022.
- In the United Arab Emirates (UAE), at 100 megawatt (MW), Moro Hub is the world’s largest 100% solar-powered data centre, commissioned in 2022.
- In Saudi Arabia, a tourist mega project, including 16 hotel resorts that are all powered entirely by solar electricity, was completed in 2023.
- The first gigawatt-scale 24-hour solar project is already under development in the UAE. Emirati state-owned renewable energy company Masdar is leading the project, which was announced in January 2025 and will consist of a 5.2 gigawatt (GW) solar photovoltaic (PV) plant coupled with a 19 gigawatt hour (GWh) battery storage system to provide 1GW of uninterrupted solar electricity supply to the grid.
These examples show that 24/365 solar electricity has already been supplying customers and that it will increasingly start being used to power parts of the grid.
Cheaper in the sun
In order to investigate the potential for 24/365 solar, Ember’s white paper modelled a hypothetical system, using real weather data, for a series of cities around the world.
The modelling is based on a system with 6GW of solar capacity and 17GWh of battery storage, because there are roughly 15 hours of darkness in winter in the mid-latitudes.
The modelling shows that solar and battery in the sunniest cities could already get more than 90% of the way to 24/365 solar generation, covering almost every hour of every day in the year.
For example, Muscat in Oman could draw on 1GW of continuous solar electricity for 99% of hours in the year, if it paired 6GW of solar panels with 17GWh of battery capacity.
Las Vegas in the US, Mexico City in Mexico and Johannesburg in South Africa could all rely on such solar-plus-storage systems for at least 95% of hours in the year.
Even Birmingham in the UK could achieve 1GW of solar output for 62% of hours annually. (This is lower than for sunnier cities due to a stronger seasonal cycle and cloudier weather.)
In the sunniest places, solar and storage could generate reliable output, close to 24/365, for around $100 per megawatt hour (MWh), based on average global costs for solar and batteries in 2024.
For each city, the yellow shading in the figure below shows the share of hours each year that it could rely on 1GW of solar output if it installed a 6GW solar plus 17GWh battery system, given historical weather conditions.
Over the past year alone, the levelised cost of electricity (LCOE) for solar-plus-storage systems fell by 22%, driven by a 40% fall in battery prices. This is based on $165/kWh, which was BloombergNEF’s assessment of the global battery pack price at the end of 2024. The LCOE of solar and battery had fallen by 28% over the previous four years.
This makes solar with battery storage cheaper than both coal and nuclear when compared with US-based LCOE, as shown in the chart below.
There is evidence that 2025 solar and battery prices will continue to fall again. Already in early 2025, tenders for large-scale battery storage projects in Tabuk and Hail, Saudi Arabia, reported battery prices as low as $72/kWh.
Cloudy day challenges
Our modelling shows that the greatest challenge to generating constant, year-round electricity from solar plus storage is not nighttime, but clouds.
In the mid-latitudes, with around 15 hours of darkness in winter, around 17 hours of battery capacity is sufficient to bridge the period from sunset to sunrise.
This is because batteries typically do not fully charge and discharge to maintain high performance over time.
However, getting to 24/365 solar is harder, as while every day has daylight, not every day has full sunlight. Even though clouds do not reduce solar generation to zero – and despite batteries being cheaper than ever – extra battery storage is still not an economical option for bridging cloudy periods across multiple days.
The graphic below illustrates this, based on the same 6GW solar plus 17GWh storage system as described before, generating electricity under the weather conditions and seasonal cycles of the same 12 cities around the world.
The chart for each city runs from January to December on the horizontal axis and across 24 hours of each day on the vertical axis. Direct use of solar power is shown in orange, with stored solar from the battery shown in yellow and periods with a shortfall in dark blue.
The figure shows that, even on the cloudiest day of the year in Muscat, this solar-plus-storage system would generate constant electricity for 18 hours. Madrid in Spain would see lower output on some shorter and cloudier days in November, December and January. In contrast, Hyderabad in India would be impacted in the summer by cloudy monsoon days.
Overall, the figure shows that the sunniest cities would only fall slightly short of 24/365 solar electricity, but clouds would have a larger impact elsewhere.
The trade-off
The International Energy Agency (IEA) has described solar power as offering the “cheapest electricity in history”.
For example, solar power costs just $41/MWh in Las Vegas, according to Ember’s calculations using average global equipment and borrowing costs. However, this is only delivering electricity through daytime hours. As a result, on average around the world, solar has a “capacity factor” of 21% – meaning each unit of solar capacity generates 21% of its maximum theoretical output.
Raising this all the way to 97% raises the price to $104/MWh. However, this also substantially improves the value of solar, now that it is delivering close to 24/365. However, as the chart below shows, meeting the last few percent of demand from solar and storage alone significantly increases the price.
The best value between solar alone or solar with plentiful storage depends on the use case.
It may be optimal to build solar without a battery, so long as a factory can access cheap grid electricity when the solar panels are not generating, for example.
On the other hand, it may be optimal to build solar and batteries to get to 99.7% for an off-grid data centre that values reliability over price. Even in the most sunny places, exactly 100% supply will generally be uneconomic – but it is possible to get very close.
For many cases and based on current prices, the sweet spot may be to size the system for a constant supply of solar electricity for 60-90% of the time, our modelling suggests.
This provides cheap, low-carbon solar power most of the time. It would enable electricity to be used flexibly through the night or during high-price hours.
If widely deployed, such systems would allow for a significantly downscaled need for grid investment, whether they are large-scale solar farms exporting more electricity to the grid or industrial sites drawing from public supplies less often.
The post Guest post: How solar panels and batteries can now run ‘close to 24/365’ in some cities appeared first on Carbon Brief.
Guest post: How solar panels and batteries can now run ‘close to 24/365’ in some cities
Climate Change
States Say They Need More Help Replacing Lead Pipes. Congress May Cut the Funding Instead.
The U.S. House voted to cut millions promised for the work this year. The Senate will vote this week, as advocates and some lawmakers push back.
The Senate is taking up a spending package passed by the House of Representatives that would cut $125 million in funding promised this year to replace toxic lead pipes.
States Say They Need More Help Replacing Lead Pipes. Congress May Cut the Funding Instead.
Here are 6 inspiring books discussing oceans, critiques of capitalism, the Indigenous fight for environmental justice, and hope—for your upcoming reading list this year.
The Deepest Map: The High-Stakes Race to Chart the World’s Oceans
by Laura Trethewey (2023)
This book reminds me of the statement saying that people hear more about the moon and other planets in space than what lies beneath Earth’s oceans, which are often cited as ‘scary’ and ‘harsh’. Through investigative and in-depth reportage, ocean journalist and writer Laura Trethewey tackles important aspects of ocean mapping.
The mapping and exploration can be very useful to understand more about the oceans and to learn how we can protect them. On the other hand, thanks to neoliberal capitalism, it can potentially lead to commercial exploitation and mass industrialisation of this most mysterious ecosystem of our world.
The Deepest Map is not as intimidating as it sounds. Instead, it’s more exciting than I anticipated as it shows us more discoveries we may little know of: interrelated issues between seafloor mapping, geopolitical implications, ocean exploitation due to commercial interest, and climate change.
The Code of Capital: How the Law Creates Wealth and Inequality
by Katharina Pistor (2019)
Through The Code of Capital, Katharina Pistor talks about the correlation between law and the creation of wealth and inequality. She noted that though the wealthy love to claim hard work and skills as reasons why they easily significantly generate their fortunes, their accumulation of wealth would not last long without legal coding.
“The law is a powerful tool for social ordering and, if used wisely, has the potential to serve a broad range of social objectives: yet, for reasons and with implications that I attempt to explain, the law has been placed firmly in the service of capital,” she stated.
The book does not only show interesting takes on looking at inequality and the distribution of wealth, but also how those people in power manage to hoard their wealth with certain codes and laws, such as turning land into private property, while lots of people are struggling under the unjust system.
The Intersectional Environmentalist: How to Dismantle Systems of Oppression to Protect People + Planet
by Leah Thomas (2022)
Arguing that capitalism, racism, and other systems of oppression are the drivers of exploitation, activist Leah Thomas focuses on addressing the application of intersectionality to environmental justice through The Intersectional Environmentalist. Marginalised people all over the world are already on the front lines of the worsening climate crisis yet struggling to get justice they deserve.
I echo what she says, as a woman born and raised in Indonesia where clean air and drinkable water are considered luxury in various regions, where the extreme weather events exacerbated by the climate crisis hit the most vulnerable communities (without real mitigation and implementations by the government while oligarchies hijack our resources).
I think this powerful book is aligned with what Greenpeace has been speaking up about for years as well, that social justice and climate justice are deeply intertwined so it’s crucial to fight for both at the same time to help achieve a sustainable future for all.
As Long As Grass Grows
by Dina Gilio-Whitaker (2019)
Starting with the question “what does environmental justice look like when Indigenous people are at the centre?” Dina Gilio-Whitaker takes us to see the complexities of environmental justice and the endless efforts of Indigenous people in Indian country (the lands and communities of Native American tribes) to restore their traditional cultures while healing from the legacy of trauma caused by hundreds of years of Western colonisation.
She emphasizes that what distinguishes Indigenous peoples from colonisers is their unbroken spiritual relationship to their ancestral homelands. “The origin of environmental justice for Indigenous people is dispossession of land in all its forms; injustice is continually reproduced in what is inherently a culturally genocidal structure that systematically erases Indigenous people’s relationships and responsibilities to their ancestral places,” said Gilio-Whitaker.
I believe that the realm of today’s modern environmentalism should include Indigenous communities and learn their history: the resistance, the time-tested climate knowledge systems, their harmony with nature, and most importantly, their crucial role in preserving our planet’s biodiversity.
The Book of Hope
by Jane Goodall and Douglas Abrams with Gail Hudson (2021)
The Book of Hope is a marvelous glimpse into primatologist and global figure Jane Goodall’s life and work. The collaborator of the book, journalist Douglas Abrams, makes this reading experience even more enjoyable by sharing the reflective conversations between them, such as the definition of hope, and how to keep it alive amid difficult times.
Sadly, as we all know, Jane passed away this year. We have lost an incredible human being in the era when we need more someone like her who has inspired millions to care about nature, someone whose wisdom radiated warmth and compassion. Though she’s no longer with us, her legacy to spread hope stays.
Ocean: Earth’s Last Wilderness
by David Attenborough and Colin Butfield (2025)
“I could only have dreamed of recording in the early stages of my career, and we have changed the ocean so profoundly that the next hundred years could either witness a mass extinction of ocean life or a spectacular recovery.”
The legend David Attenborough highlights how much humans have yet to understand the ocean in his latest book with Colin Butfield. The first part of it begins with what has happened in a blue whale’s lifetime. Later it takes us to coral reefs, the deep of the ocean, kelp forest, mangroves, even Arctic, Oceanic seamounts, and Southern Ocean. The book contains powerful stories and scientific facts that will inspire ocean lovers, those who love to learn more about this ecosystem, and those who are willing to help protect our Earth.
To me, this book is not only about the wonder of the ocean, but also about hope to protect our planet. Just like what Attenborough believes: the more people understand nature, the greater our hope of saving it.
Kezia Rynita is a Content Editor for Greenpeace International, based in Indonesia.
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