Taming the Sun: Innovations to Harness Solar Energy and Power the Planet

by Varun Sivaram

How solar could spark a clean-energy transition through transformative innovation--creative financing, revolutionary technologies, and flexible energy systems.

Solar energy, once a niche application for a limited market, has become the cheapest and fastest-growing power source on earth. What's more, its potential is nearly limitless--every hour the sun beams down more energy than the world uses in a year. But in Taming the Sun, energy expert Varun Sivaram warns that the world is not yet equipped to harness erratic sunshine to meet most of its energy needs. And if solar's current surge peters out, prospects for replacing fossil fuels and averting catastrophic climate change will dim.

Innovation can brighten those prospects, Sivaram explains, drawing on firsthand experience and original research spanning science, business, and government. Financial innovation is already enticing deep-pocketed investors to fund solar projects around the world, from the sunniest deserts to the poorest villages. Technological innovation could replace today's solar panels with coatings as cheap as paint and employ artificial photosynthesis to store intermittent sunshine as convenient fuels. And systemic innovation could add flexibility to the world's power grids and other energy systems so they can dependably channel the sun's unreliable energy.

Unleashing all this innovation will require visionary public policy: funding researchers developing next-generation solar technologies, refashioning energy systems and economic markets, and putting together a diverse clean energy portfolio. Although solar can't power the planet by itself, it can be the centerpiece of a global clean energy revolution.

A Council on Foreign Relations Book

Genres: Science, Nonfiction, Environment, Economics, Climate Change, Technology, Business

371 pages, Hardcover

First published January 1, 2018

About the author

Dr. Varun Sivaram is a physicist, bestselling author, and clean energy technology expert with experience spanning the corporate, policy, and academic sectors—most recently as Chief Technology Officer of ReNew Power Limited, a multi-billion dollar renewable-energy firm that is India's largest. He is currently a visiting senior fellow at the Columbia University Center for Global Energy Policy and was formerly fellow & director of the energy program at the Council on Foreign Relations, senior energy advisor to the Los Angeles Mayor and New York Governor, professor at Georgetown University, and consultant at McKinsey & Co. TIME Magazine named him to its TIME 100 Next list of the next hundred most influential people in the world. His books include "Taming the Sun: Innovations to Harness Solar Energy and Power the Planet," "Energizing America: A Roadmap to Launch a National Energy Innovation Mission," and "Digital Decarbonization: Promoting Digital Innovations to Advance Clean Energy Systems." A Rhodes and Truman Scholar, he holds a Ph.D. in condensed matter physics from Oxford University and undergraduate degrees from Stanford University

Reviews

[Mario the lone bookwolf · Rating 5 out of 5]

Varum is an expert in his field and describes the state of the art technology, its possibilities, possible dangers and some alternative, pessimistic future timelines.

Always there, always shining, giving so vast amounts of energy that we should better power everything that way, using advanced and subsidized technology, so that it´s completely logical that humankind is using it as the main energy source. Not.

Be it in deserts, mountains, in space, wherever there is room for building any kind of solar energy collecting or sun focusing machinery, all energy problems could easily be solved. With battery technology getting better and better or just using the daily generated power to pump water to higher storage reservoirs to generate electricity at night or to just physically heat energy storages during the day so that they can give it up during the night or to use a global power grit to send the power of the sun from where it is shining to any place on earth.

A very utopic approach might be to start collecting sunlight directly in space to produce 24/7/365,25 forever and store and beam it wherever needed.

Add a bit of hydrogen, microgrids, wind power, bioenergy from bioreactors, some conventional, carbon-based energy sources and the one or other nuclear plant to the mix and a nearly carbon-free and CO2 neutral or even CO2 negative emission rating could easily be reached. As long as the political will isn´t there, the subventions flow in the same ways as usual, CO2 emission markets are a joke and old industries are sitting everywhere possible, but at least every small community, each roof, electric car and all the other great alternatives, finding more and more use in the civil society, can make the crucial difference.

And the great thing is, as slow and incompetent the state may be, the big companies and big money will have to begin to leave the sinking boats of coal and nuclear energy (nuclear energy is carbon neutral, but uranium won´t last forever and final disposal is a tricky, expensive thing), giving oil still some time to chill and invest massively in anything that could become the next new big thing. Be it controlling the infrastructure, production or distribution, nothing more than the endless money printing option of an endless energy source is waiting to be exploited and the first global market leader may have an unassailable advance.

Some lengthy and too specific parts may be better skimmed and skipped, although one has the theoretical background to find it entertaining.

A wiki walk can be as refreshing to the mind as a walk through nature in this completely overrated real life outside books:
https://en.wikipedia.org/wiki/Solar_e...
https://en.wikipedia.org/wiki/Renewab...
https://en.wikipedia.org/wiki/Electri...

[Chris Fleischman · Rating 5 out of 5]

I have been reading a lot about renewable energy recently, and this is by far the best book I have read to understand the entire solar energy landscape and limitations. Thank you!

[Charlene · Rating 5 out of 5]

I didn't realize how much I didn't know about harvesting the energy of the sun. Without exaggeration, my very favorite thing in the world to think about and study is how forms take in, circulate, and expel energy. It's an obsession really. People, especially people in my family, are sick of me talking about it. I want to think about it and talk about all day.

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Sivaram started off by providing a history of how human's tried to harness solar energy:

- Mostly civilizations focused on using the sun to heat water.
​- ​3000 years ago​, the Chinese used mirrors to ​direct sunlight to start a fire​, which is the oldest known form of solar energy.
​- ​​In the ​7th​ century ​B​CE The Chinese also had summer and winter houses with different pitched roofs to either block out the sun or let the sun​ ​come in and warm everything​, which is an indirect way of trying to harness solar energy or shield oneself from too much of that energy​.
​- ​The Romans used a glass​ to build their buildings​​ ​called bathhouses because the glass allowed fairly effective capture of the sun's heat.
​- Eventually, civilizations ​began to ​learn how to convert solar energy into mechanical work​. In the ​1st​ century CE​, Hero of Alexandria built ​a​ solar siphon that heated air​, which expanded to propel water from one Chamber to another. ​I read about this in Smil's Energy and Civilization and this engine has been my cover picture on Facebook ever since. It's beautiful. I recommend searching images. ​
​- ​Leonardo da Vinci ​built​​ a 4 mile long mirror to heat a factory​'s​ ​b​oiler. He never finished it.
​- ​August ​Mouchot made the most progress ​when​ envisioned three uses of solar power that are still being used today​; driving a heat engine, generating electricity, and producing portable fuel​s. ​ In 1874 he built the first solar engine using 8 foot mirrors to focus the suns energy on a boiler that drove a half horse power engine . That is roughly enough ​energy to run a machine in a woodworking shop.
​- ​In 1879 ​Mouchot​ figured out how to convert solar ​radiation​ into electricity​ by​ reflecting sunlight to heat the junction of two metal​s soldered together, generating and electric ​current​. He​ used this electricity to split ​water​ atoms ​into hydrogen and oxygen, and ​planned​​ to use the hydrogen as fuel. ​None of his applications were cost effective, but they served to inspire modern uses ​of ​solar energy (this reminded me of Elon Musk).
​- ​First solar panel, was developed 60 yrs ago but it’s been in the making for centuries​.​

​-------------​

After recounting the history, Sivaram examined the practical nature of solar panels:

-​ It is not enough to really produce more solar panels. We need a lot of other aspects to fall into place for solar energy to really take off and become more officiant, and reduce our reliance on fossil fuel’s.
​- ​There was a solar war but ended in bankruptcy or some pretty important companies in 2013. China one out with their cheaper solar panels. And amid this disruption solar power came of age
​- ​There are two ways in which solar panels work. One way is to heat up water and produce steam​. The other way is to convert the suns energy directly into electricity​.
- Rooftop solar panels overloads the grids in local neighborhoods, the local grits.
​- ​Utility scale solar ​might be helpful​

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How do solar cells work and how effective can they really be?: (this is the stuff I LOVE. I did know the following, but it fills me with sheer bliss every time I read about anything that resembles the process that generates ATP)

(I am trying to quote page 148, but I took the notes by dictation on my phone, so forgive any typos)
"Silicon​ cells convert sunlight into electricity​ by using two particles​, the photon and the electron​. ​Photons are wispy particles of light with different wavelength​s. ​Energy is directly related to what color the photon is. For example​, blue photons are a shorter wavelength and have more energy than red ​photons​ . Invisible ultraviolet photons have even higher energies​,​ but infrared photons​, which are​ also invisible​,​ are low energy . ​.......​

The electron is ​negatively ​charged and surrounds the positive protons . A solar cell recruits both particles by transferring the energy from each incoming photon to an electron​ (remind anyone of the awesome electron transport chain?:)​. Once endowed with an ​energy​ boost, the electron can break free from its atom end can leave the solar cell. The stream of electrons leaving the solar cell represents the electricity​,​ and the amount of energy pumped out by the solar cell depends on two values​. First, the 'electric voltage​" is tied to how much ​energy is in each electron that flows out of the solar cell​.
Second, the "electric current" depends on ​the total number electrons leaving the solar cell each moment. The power output of a solar cel​l - how much ​electric energy is pumped out every second​ -​ is just the voltage multiplied by the ​current.

If a solar cells could transfer all of the energy from every single ​incoming ​photon to an electron​,​ and make sure that every ​energized ​electron could leave the cell and do useful work​, it would maximize its ​e​lectric voltage, current, ​and p​ower output ​to be 100% ​effective. ​​But, even the very best silicon cells can muster only 25% because they are a semi conductor , A material that can toggle between acting as an insulator and a conductor. This allows electrons to switch between staying put and mov​ing​ around when photons strike them . And semi conductors have a fundamental feature that limits their efficiency. The more photo​n​s ​t​he cell absorbs the less energy Per for time it can transfer to electrons . In other words​,​ there is a trade off between The maximum current in the voltage that a solar cell can produce, even though both quantities matter for the cell power output.

The more current there is the less voltage. The more voltage the less current. Because electrical outlet is simply voltage times current, you can never reach 100% proficiency​.​

The voltage current trade off stems from the semiconductor property called the band gap. The amount of energy and electron needs to break free from its post at him and contribute to the cells Electric output . A photon with less energy than the band gap will flow right through A solar cell. A photon with more energy than the band gap will transfer only a band gaps worth of energy to the electron , thus wasting the rest of the photons energy because it is released as heat and does not transfer to the electron .

Think of the band gap in a solar cell as the amount of energy needed to get the flow going, just as you would get ketchup flowing. If you hit the ketchup with just the right force it will start the ​ketchup flowing out of the bottle. If you hit the ketchup bottle with two little force, you won’t get the catchup flowing. If you hit it with just the right force you will get the ​ketchup flowing (this reminds me of action potentials in the brain). If you hit the ketchup with a sledgehammer, you will still get the catchup flowing but you will have a high cost of waste for that energy. That is like a high energy ultraviolet photon transferring its energy to an electron. There is a lot of waste . To make affective solar cells that can transfer a high percentage of the suns energy, researchers need to choose materials with the right band gap. If the band gap is too high, most photons Will lack the energy needed to eject photons from the cell and generate a very low current . If the band gap is too low, most photons will set electrons free but they only transfer a dribble of energy to each one resulting in a low voltage. Silicon happens to have a decent band gap somewhere in the middle, although it is a little lower than some ideal materials such as gallium arsenide which is used to make more efficient solar cells but unfortunately it’s too expensive to have commercial success. So you have to weigh your options with cost and ​efficiency​.​"​

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News from Caltech:

Nate lewis is looking into how to create a machine that would convert the suns energy just like plants do by taking in water and sunlight and spitting out gaseous oxygen and hydrogen. “No bugs, no wires“ meaning that unlike plants in nature it would outperform natures best plans.

Plants are shockingly terrible at converting the suns energy into work. Photosynthesis is in efficient . For example black leaves would be far better at absorbing the suns rays. Yet, a plants leaves are green. Plants turn carbon dioxide into sugar. Even the most efficient plants convert less than 1% of the suns energy. Early on in photosynthesis plants split water and release oxygen to the atmosphere and hydrogen that goes into reactions.

Nature is not a pyromaniac and has found a brilliant way to stop combustion. First, it separates the two reactions into different photo systems, photosystem one and photosystem two. This design keeps hydrogen from combusting in the presence of oxygen . Second, Also each of the photosystems where light is absorbed, also contains catalysts , which are molecules that speed up the respective Half reactions. In fact we can thank the manganese catalyst that speeds up accelerates the plants production of oxygen for all of the oxygen in the earths atmosphere. (Wow, I never thought of the manganese catalyst as producing all of the oxygen in our atmosphere). Third, plants separate the 2 half reactions with a membrane that not only keeps hydrogen and oxygen apart, but also allows charged ions to pass through it , which is important to avoid an imbalance in charge that would halt the 2 half reactions. ( I love this!) Constantly creating this equilibrium to create energy potential‘s. (Nature is the fucking bomb!)

To mimic this, Nate lewis wants to create a solar fuel generator /hydrogen generator with two photo electrodes immersed in water. to absorb light energy to perform each of the two half reactions to split water. Two catalysts would speed up each of those half reactions. And, and a membrane stops the whole contraption - called a photo electro Chemical cell (PEC) - from exploding.

But the similarities and there.... Just like when we invented flight we modeled birds but far surpassed them by constructing planes. Nate Lewis thinks we can model our generators from plants and surpassed them. PECs of the future probably will not use two green photo electrodes that compete with each other to absorb the same part of the sun spectrum. Rather, one of them, the anode , which creates oxygen from water, should harness high energy photons, leading Low energy photons pass through it to be absorbed by the other One below, the cathode , which produces hydrogen. (I was unaware of Nate Lewis and want to keep following it.)

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Be carful! Think about safety:

PEC’s are not very safe . To keep oxygen and hydrogen from combining an exploding, a PEC needs a membrane to keep them separated. But the half reaction that produces oxygen from water, of course leaves a lot of hydrogen. We know that hydrogen makes that water very acidic . Where as the half reaction that produces hydrogen turns the water basic. Acids are what digest food in your stomach and bases are what clean your drain . If safety were not a concern and the membrane could be eliminated, the acids could combined with the bases and neutralize each other . But with the membrane in place scientists have to find materials for electrodes and catalysts that do not get Dissolved or corroded in acidic or base conditions . That rolls out the many cheap materials that would not survive these conditions .

A PEC could actually achieve 30% efficiency if you can buy the right parts for the membrane .

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Are microbes the answer?:

Can genetically modify microbes act as catalysts. If so, using GMO microbe/catalysts could really raise efficiency, but some organic catalysts were incompatible with inorganic catalysts, which produced forms of reactive oxygen that destroyed the bacteria's DNA. So, it took some pretty ingenious work to find appropriate catalysts. Finally they found a phosphorus cobalt catalyst that seem to work very well - this catalyst not only left the bacteria unharmed, but also self assembled out of solution, mimicking The self healing catalysts found in nature. (That is amazing !) The catalyst and bacteria working together in harmony has boosted efficiency to 10%. That is actually an incredibly high efficacy rate in converting sunlight into alcohol fuels . With this bacteria and in organic catalyst combination, we might be able to fix nitrogen! Which means that sunlight instead of fossil fuel’s could fix nitrogen. This would be huge . But biological things tend to be sensitive and difficult to work around. Bacteria is sensitive to acids and other things in the environment.

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The author also discussed, at length, the super grid pros and cons, which led nicely into discussions about the pros and cons of decentralized grids.


​

[Mark · Rating 4 out of 5]

This book paints a very bleak picture of the future, and I found myself walking away from it doubtful that the nations of the world would be able to make their commitments to the Paris Accord.

Namely the deficiencies to the current status quo are as follows:
- Nuclear power investment and research are floundering. Paradoxically, Fukushima has made most nations and companies involved in pushing the envelope on newer safer reactor designs retreat and disinvest. Nuclear power is the only base power that is carbon neutral. Natural gas, oil, and coal all contribute carbon to the atmosphere.
- In the absence of some type of base load technology to cover nuclear's gap, insane amounts of investment need to be made in power storage technology and/or Solar technology generally.
- Solar technology is the only renewable energy source capable of meeting earth's needs given how much potential the sun gives us --right now, very efficient PV panels let us capture only 20% of the suns energy.
- Nevertheless, while power companies and nation states are doubling down on silicon PV and incentivizing installs, very little to no money is going toward research on critical solar technology that would allow us to harvest more of that energy at off-peak hours --e.g., concentrated solar arrays.
- Every day we delay this critical research, we are one day closer to irreparable harm to the planet
- Absent US leadership on this front, the world will likely miss its targets, or China will fill in the vacuum and profit immensely from whatever it discovers along the way.

I think that about sums it up. But basically the main take-away is this: while PV is the new hotness, it can't solve the climate crisis in its present form. Looking at the California energy market gives us a taste of the future, where so much PV has been installed that new peak hours emerge in the evening when the sun has set and people continue to use electric. Google "CAISO Duck Curve" to see this graphically. As long as humans continue to use and demand electric at all hours, without the ability to scale up clean power to meet that evening demand, the ice caps are toast.

By the way, the author repeatedly states that decarbonizing the electric grid is the easiest task humans face with climate change. Other areas such as transportation policy are even more baffling --e.g., how do you manufacture and replace all the forms of transit with electric and battery technology without releasing still more carbon? (Nevermind the technology for electric trucks, planes, and buses aren't even fully baked.) If we fail this basic test, how much more will we fail the others.

[Andrea · Rating 2 out of 5]

My rating might be a little harsh. This book is a comprehensive and technically detailed survey of large-scale solar power generation and grid-based distribution. I also work in the tech industry where it touches renewable energy and preventing future catastrophe, and from this perspective I have a few issues:

First, the writing style is a bit tedious. I don’t mind the technical details but I do mind when the author alternates between arguments, repeats himself, or tries to add dramatic flair. Too many sections read like: This will be the future! Unless it isn’t. We have the potential to do this! But there’s a long list of challenges. Of course they can be overcome! Or maybe not.
I suppose also I was personally hoping for a bit more on what my options might be for a private residential system. Fair enough if that wasn’t the intent of the book, but I’m not sure I need all the info on what types of capital need to be raised through private portfolios for financing state- or country-wide grid systems. But I will keep the book around in case I’m ever the CEO of a utility conglomerate, or a venture capitalist.
Finally, the author seems to have bitten hard on the political aspect of climate change. It is a solvable problem from many angles, solar being only one small niche. Maybe there is an element of the “either/or” future envisioned here, but most likely the years ahead will be filled with diverse forms of adaptation, a mix of some predictions panning out while some being proven incorrect. Solar can contribute, but the book seems inconclusive on where the industry overall is headed.

[J.P. Ashman · Rating 5 out of 5]

Listened to on Audible.

Very informative and fascinating, whether you're interested in renewables, technology and innovation or the environment (and where it's going), or for those with business/entrepreneurial interests.

Highly recommended.

[Ramnath Iyer · Rating 4 out of 5]

Much more innovation required for the solar revolution to succeed

“Taming the Sun” is an excellent survey of the current state of play in the solar industry, written by a US based energy expert Dr. Varun Sivaram. By discussing the challenges, potential and pitfalls facing the industry, the book provides a relatively dispassionate analysis of a field which while full of either true believers who aver that renewable energy-based future is the only possible one, or sceptics who don’t wish to see beyond carbon.

Sivaram is an optimist, and also a realist. He starts the book by painting two alternate futures, one which is dependent on carbon and essentially an extrapolation of current trends – which predictably does not end well. The alternate future mitigates the fallout from climate change by a global transition to a carbon free energy system.
So far, this is standard stuff coming from all who say renewable energy is the only solution to avoid doomsday. What makes Sivaram different is that unlike the majority, he doesn’t take it as a given that solar energy will win in the end. While he would like to see that outcome as one good for the world, he does an excellent job of pointing out the pitfalls and challenges to this scenario eventuating.

The main issue pointed out by the author is that although solar panels look like an attractive and competitive source of energy today based on their niche deployment, a more pervasive usage of solar energy can very quickly destroy the overall economics. This doesn’t seem obvious until the examples of California and parts of Europe are examined more closely, as the book does.
To deal with this, more technological innovation is required to better harness more of the sun’s energy more cheaply. This calls for more investments in technology, which so far has remained focused on polysilicon panels. However, as the author points out, polysilicon only translates about 8% of the sun’s energy into usable power, and its improved economies of scale have meant that its falling prices have reduced the room for investment in research in innovation into other chemicals and coatings that may be more efficient.

It is this kind of innovation that is needed to keep the industry moving forward, the author says, as he uses the decline in the nuclear industry as an example of what happens when technological progress stalls. As he explains, the heavy water processing reactors saw only incremental improvements, and no step change in the past 50 years. This lack of investing in research is probably what has led to the nuclear industry failing to stay ahead of the curve, and led to its seeming decline. The author feels that the solar industry, which is currently having its heyday (much as nuclear energy had in the 60s), should keep this example in mind.

The second issue is the incommodious fact that solar power can only be produced when the sun shines, which makes it imperative for more research and innovation into batteries and other storage to enable this to be available for use when required. Until this happens, solar energy if more than a niche source plays havoc with other sources of energy on which modern systems typically depend on, by reducing their cost competitiveness while not enhancing the availability.

A related issue is the unpreparedness of grids currently to handle the surges and drop downs that are associated with solar power, as the sun rises and sets. This places tremendous burdens on the grid systems which then need to switch quickly to other sources. Sivaram therefore believes that technological innovation is also needed in systems that transport power, the grids, to make them better equipped to handle the surges and slumps that occur naturally in solar energy generation.

Many of these potential innovations and technologies are highlighted in the book, as is the need for financial innovation. The episode of Sun Edison’s attempt to use a yield co structure to raise financing for its projects, which ended with its spectacular bankruptcy in 2015, is held out as a cautionary reminder for policymakers to enable better financial structures. The fact is that while investments in oil transportation is encouraged by the tax advantages given under the “Master Limited Partnership” framework, solar energy has been excluded. Sivaram is also critical of the current Trump administration, which has significantly cut f=down the funds available for research and innovation into solar by government labs, which have been the drivers of much basic technological developments.

All in all, a good and comprehensive read for anyone with interest in the subject.

[Omar · Rating 5 out of 5]

An excellent book with great insights into the state and possible futures of the solar industry. Very well researched with around 60 papers/references per chapter.

The book is accessible to both industry insiders and novices as it introduces concepts clearly before elaborating. It starts by imagining different future outcomes then describes the current context and history of the solar industry. I have appreciated, in particular, the analysis given of the silicon valley clean-tech boom and bust of the late 2000's.

The author does a great job of clarifying why it will take a 3-axis approach to innovation (business model, technological, and systemic innovation) to achieve solar's true potential.

The arguments are facts and data-based and the author's viewpoints are justified, balanced, and ideologically neutral.

[Sannu · Rating 4 out of 5]

From the outset, one thing is clear. Varun loves going solar. Who doesn't? It's cheap (~now), it's carbon free, and it's everywhere. Just install lot of solar panels and let the markets figure out rest of the stuff. Like all the questions in life, the answer is not so simple. Imagine having an erratic partner who can only shine love on you for half of the day, who brings a set of additional problems to you in mingling with your family and whom can't trust because you can't seek help when you most need it. That partner is very much like solar energy.

Solar energy brings a multitude of problems, but taming them in a timely manner is our last shot at saving the planet from global warming. Varun doesn't want solar to become another false hope like Nuclear energy. Scaling up without innovation, with cheap inefficient panels, wrong policies and expecting invisible hand of markets to do things right is surely going to fail.

Although it didn't feel like it was the intention of Varun to explain solar energy in detail, the book actually ended up as a nice contemporary introduction to current state of affairs in solar. A must read for everyone interested in renewable energy, policy makers and investors.

[lando roberts · Rating 4 out of 5]

For utility / energy / solar nerds. Discusses next steps in solar. Great read if that's your thing.

[Ahmed · Rating 3 out of 5]

I really tried to enjoy this book, but I couldn’t. Although it is very informative and an important topic to tackle specially with our current issues on climate change. I liked the different ideas on how to invest/finance solar/clean energy projects and how sad that we are very far away from achieving huge milestones in replacing fossil fuels.

[Abhimanyu Bhargava · Rating 5 out of 5]

Great inspiring book about the latest advances in solar but importantly clearly outlining few paths that for the future - which is a first in this literature done at such a technical level.

[Bernat Ayneto Gimeno · Rating 5 out of 5]

Molt necessari per entendre el present i el futur de l'energia solar i les renovables. La veritable manera d'aconseguir la transició energètica, més enllà de les polítiques i subvencions que només miren en el curt termini i en els objectius de creació d'ocupació dels curts mandats polítics.

Fa falta invertir en Innovació i no en subsidis. Innovacions Financeres, Tecnològiques i Sistèmiques.

[Madi Nally · Rating 4 out of 5]

3.5 ⭐️

I read this book for my Energy Supply Chain Management course, and while very informative, I didn’t find it to be as accessible as some other reviewers did. Some chapters felt relevant only to policymakers and other chapters only to energy scientists.

Overall, I understood his main ideas and enjoyed the summaries he prepared to make the information more digestible.

[Dean · Rating 5 out of 5]

Really well researched, doesn't feel dated. Just a bit too much policy wonkery for my personal taste, but understandably necessary.

[KarlInSanDiego · Rating 4 out of 5]

Varun Sivaram delivers a wealth of information on the subject of current solar energy in this extensive and topical book on the subject. Plucked from his final year in a Ph.D. program studying an esoteric new solar cell technology at Oxford University to help advise Mayor Villaraigosa's energy policy team in 2012, Sivaram shows no shortage of knowledge about the potential and also the potholes that the future of solar energy encounters. His book is a great read for those interested in energy, but maybe more specifically for policy wonks. Probably important to note, this is not a 65 year old college professor, but at the time of writing this book, he is 28 years old.

Unfortunately, his work after college has been totally about policy, and oddly in a position of dictating to others what is good strategy, which I found unsettling. In my reading, I found his attitude about the pros and cons, needs and wants, successes and failures withing the industry to be told from the perspective of a technocrat on Wall Street. That's not to say you won't learn a lot reading his book; however, the strategies for financing solar's rollout, the pessimism about solar's ultimate role in the future of energy, his willingness to accept the tired strategies of "no bad solutions" energy mix, and his discounting of silicon solar as positive force left me disappointed as a reader. If this "Hamilton of the Solar Industry" can't see today's solar as tomorrow's holy grail, we might need to keep looking for a better "thought leader in the solar industry". Instead, he seems to believe that perovskite or another breakthrough solar cell tech will bring cheap solar to the masses, and without government investment in such technologies (which he admits in 2018 is in its infancy) we will miss the solar boat. Paradoxically, he describes a counter intuitive concept of solar value deflation that occurs with solar's inescapable time-of-day delivery nature and how adopting too much solar as its prices continue to decline, leads to its devaluing during daylight and the increased value of competing energy sources beyond that time.
Of course you'd expect him to attack that problem with storage, which he does address, but perhaps not in ways that I found appealing. He describes at length the use of hydrogen as a form of potential energy storage of electricity originally harvested by solar (or other means) and ties that to still nascent technology (PEC). This appeals to his sense of technocrat, I believe. He leaves pumped hydro storage as a yesterday's technology, despite admitting it currently represents 95% of the world's storage.

On balance, I learned about a lot of specific examples of successes and failures in recent solar tech and other renewable aspects of clean energy. I had a hard time slogging through the chapters on attracting private investment dollars and the supergrid.

[Jay French · Rating 4 out of 5]

I was pleasantly surprised by the width of topics covered in this book. It isn’t aimed at individual home owners, but describes the technology and its use at a high level. I found the discussion on the economics of solar in comparison with other energy sources, and the outcome that wasn’t black or white, but gray, was refreshing. The author explains how solar works well with other sources of energy filling in when the sun’s down. Obvious, yes, but it leads to conclusions that aren’t always talked about when talking about solar. The author also provides some background into the march of solar technology into more efficient materials and more usable substrates on which those materials can be used as a coating. I haven’t kept up with the solar industry in decades, so this was a good update.

[Johann Fernandes · Rating 3 out of 5]

Review of Taming the Sun (Heard on Audible)
* Might not be the perfect book from a technical perspective but does balance some technical pieces. (Tech part wasn’t fun while listening to it) Multiple repetitions at the start of the book.
* Germany and Japan are huge players who took the baton from US when they wanted to focus on nuclear. 
* Solar became a dirty word in Silicon Valley after most companies filed for bankruptcy.
* Mention of the company sun power from the US that still manufactures efficient panels.
* Different governments played around with subsides right from production to the deployment.
* China pays more for giving solar to the grid than India does. 
* The industry will improve as low purity silicon becomes high purity and cell architecture improves. 
* Value deflation of solar as long as the cost of electricity continues to fall. Solar brings the price of power very low hence other generators suffer. 
* Three kinds of innovations are required to cure problems of solar
* Financial
* Technological
* Systemic Innovation
*  Rooftop solar is more expensive than mass solar plants because of the instability it causes on the grid. 
*  15% adoption so far has been driven by public capital but the private sector will need to invest more
*  Chapter 6 speaks about the benefits of off-grid solar. Off-grid solar has not caught up very much in India because kerosene has a subsidy and the prices have been kept artificially low. 
* Pay as you go is limited by mobile banking. Secondly, the upfront capital cost is also high
* The debate between DC and AC. DC is a cheaper alternative in the 21st century. As AC grids lead to energy loses and will be more unreliable as city's grow in size.
* Bottom up electricity - depending on the demand, micro grids have come up and peer to peer transactions take place.
* Excess energy from a photon here gets converted into heat. A material with an optimal band gap needs to be chosen.
* Two layers gives you 44% and 3 gives you 50% where as the highest that silicon can give you is 26%
* Plants convert just 1% of solar to energy. 
* Hybrid grids - keeping a balance between centralised and decentralised grids. A super grid might not be the answer as political relations between countries will matter. 
* 95% of storage of energy is not lithium ion but hydro storage.
* Flow batteries
* Last chapter - funding gaps can be filled by the government and involve the pvt sector. The military has played a role for adaptation of riskier tech all along
* Focus on innovation

[Kathleen · Rating 4 out of 5]

Taming the Sun's singular purpose is to convince you of the necessity of investing in early-stage solar energy technologies, but in the process, Varun Sivaram delivers a simply-stated and comprehensive summary of the intertwined issues solar faces in scaling to a level that will deliver global carbon benefits. The second chapter - which sets out the stakes for a solar plateau mid-century - is a must-read for everyone in the energy industry; even oil & gas analysts will find their concerns fairly considered and addressed. Subsequent chapters you can probably pick & choose depending on your relative level of expertise. I enjoyed learning about the history of PV cell development, design & deployment of high voltage transmission lines, and networked energy storage strategies. But I found that even the chapters on solar business model development, financing, and rural solar mini-grids - where I have more direct experience - covered the key issues succinctly. At his best, Sivaram clearly links the need to push the envelope in technology, financial, and systemic energy innovation all at once so that solar can deliver on the goals we've implicitly set for it in demanding a low-carbon future. In other places, the primacy that he places on increased investment for academic R&D projects (Sivaram started out as a solar materials researcher) can seem repetitive and self-serving. I'd judge the weakest chapter to be the last one on policy solutions, which isn't framed so much as an area for potential innovation as one where we just need to put down more money (easier said than done). But this assessment could also be due to the fact that after 11 hours of listening, I was very ready for the book to be over! All in all, I'd recommend - correction, I already have recommended - this book as required skim reading for those working in energy issues, as it's a great primer on today's most relevant solar energy topics across a range of disciplines.

[Austin Hinkel · Rating 4 out of 5]

Excellent insight into the workings of the energy sector and the challenges facing deep decarbonization. The author very clearly presents the problems, potential solutions, and potential pitfalls in a relatable manner, though seems to enjoy taking shots at academia and heaping adulation on Elon Musk whom he mentions in the book more than any other person or thing other than solar power.

I’m not sure how much of Sivaram’s vision/timeline still holds now that the Trump administration has set US energy policy back by years; perhaps more urgent action will be needed now - beyond the author’s sunny optimism for free market forces. I’d be interested in learning how Sivaram’s predictions have changed given the US setbacks.

A must read book for anyone interested in renewable energy and energy policy. The book offers a hefty dose of realism when discussing the problems, a huge does of optimism when discussing solar’s role in a future clean energy economy, and heaps skepticism on nearly all other solutions despite outlining extremely complicated solar solutions. Perhaps the skepticism is well-founded, but the book lacked significant context as to why other (non-solar) solutions wouldn’t work, despite dedicating a huge amount of text to convoluted solar solutions. The author simply wrote off other areas with a few sentences. (I don’t mean to cast doubt on the solar solutions - if they weren’t complicated or convoluted they would have been done by now - but why not spend more real estate in the book giving the reader context as to why other ideas won’t work?) Surely there are solutions which are just as complicated in the other subfields.

Either way, this book is very well-sourced and is an excellent resource to return to, despite the stylistic issues I personally had with it.

TL;DR: Excellent insight into the energy economy, well-sourced, weird amount of Elon Musk worship.

[Kee Onn · Rating 3 out of 5]

The challenge of incorporating renewable energy (solar and wind, for example) is a business challenge as much as they are a technological challenge. Here the book focuses on solar energy, which holds more promise in penetrating the energy market with its many forms including solar panels, solar thermal, and solar fuels. Varun outlines that the greatest threat to the future of the solar industry right now is actually silicon solar panels - their low-cost brings risks of locking in the industry and stifle required innovations for renewables to further penetrate into the energy market. The fluctuating nature of solar and wind energy also requires backup sources such as nuclear and clean-burning natural gas, and this becomes more important as the share of solar power increases in an electricity supply system. Alarmingly, these facts have been overlooked by most researchers and the industry is bound to face a bottleneck if these issues are not addressed.

On the business side, Varun provides an insider view on the dynamics of the utility market and how certain dynamics could be tweaked to better accommodate renewable energies in the mix. The book provides an interesting history of renewable energy funding, from the government-backed ARPA-E agency to the spectacular crash of private efforts such as SunEdison's to fund renewable energy projects. Modest successes comes mainly from state utilities, such as Iowa and Texas, that are slowly incorporating renewables into their portfolio. Finally, considering the technological limitations and the nature of business funding, Varun proposes an utility system consisting of multiple small renewable power plants connected regionally, but backed up by large-scale renewable plants as a way to increase the share of renewable energy in the grid, and ultimately cutting down on greenhouse gas emissions.

[Joris · Rating 4 out of 5]

Great book about the state of solar energy, looking at the topic from many angles, focusing primarily (but not solely) on the US.

The main premise is that solar energy, surging in supply due to cheap silicon PV panels from China, is on a path to hit a ceiling at ~20% of total energy production because of value deflation: intermittent production will mean that the value of energy at times that the sun shines will go to zero, being in oversupply. The book argues innovation is needed in technology (e.g. perovskite solar, solar power towers, fuel production, etc.), financing (making it easy and attractive to invest in traditional solar projects, and in helping test and scale novel solar concepts) and grid systems (smarter local grids, long distance transport). Long term energy storage looks impractical (prohibitively expensive for cross-season storage at grid scale), and more flexible sources of supply (e.g. nuclear power) and demand (e.g. transportation, heat, freshwater production and agriculture) are needed in addition to solar.

Overall it's a great, in-depth, deeply researched overview of the solar energy sector touching on many dimensions (technology, policy, financing, market dynamics, etc.). With the industry evolving fast, at 4 years old the book is slowly nearing its shelf life, but as of today it's still highly relevant.

[Bill 3 · Rating 5 out of 5]

This book provides prospective on solar power and its realistic role in power generation for the future. It discusses the limitations of the system (the electric grid, other power plants, storage, how the grid is used) and solar itself. He outlines how to achieve better improvements in efficiency, cost, and storage. Varun isnt afraid to highlight the shortcomings of solar and the diminishing return that solar panels offer above a certain saturation point ~30%. He does this with examples of areas already inundated with a high penetration of renewable power. He also details the difference in economics for installation or solar fields (acres of solar panels) vs relatively expensive small roof top applications.

My favorite part about the book is how it explains the NEED for basic and applied research. He further explains how government can and should help take on risk with newer technologies that may have a larger impact than silicon solar panels. Currently the private sector is leaning too heavily on silicon based solar panels and it is a detriment to future innovation in the solar space.

Overall this was a great read for someone interested in the facts behind why solar energy is important and the issues surrounding deep de-carbonation of the power sector.

[Ted · Rating 3 out of 5]

Overall it was a worthwhile read. He definitely knows the topic. I think some of the ancillary non-solar stuff is better covered in other books/papers, but that's understandable, skip those sections if you already know that stuff.

Chapter 1-Skip.
Chapter 2-interesting technical details on types of solar
Chapter 3-solar and the current grid. Chapter 3 introduced the concept of 3 types of innovation required- financial, business model, and systemic.
Chapter 4- history of investment in solar projects, utility impacts, and future financial requirements
Chapter 5 about solar power in Africa and Asia. Lots of bottom up opportunities for growth and new businesses. I have no idea what it takes to succeed there so I wonder what business models will actually succeed. Interesting few pages about how super small individual household solar systems are really just kerosene replacements and not advancing the economies.
Chapters 6-7 about future solar technologies.
Chapter 8 all about the grid and storage and such, but better to read any in-depth articles about some recent model studies. The author actually quotes Jesse Jenkins who’s recent work is very worthwhile to read about.

[Mahamid Ahmed · Rating 5 out of 5]

A detailed, visionary and complete book on the potential of solar energy to provide the world with its energy needs.

Sivaram goes into detail on the various elements of the solar supply chain that need investment and innovation; from materials such as pervoskite to Concentrated Solar Power (CSP) systems that provide both electricity and heat.

The book also explores the need for the technologies and innovations that are needed to enable the growth of solar to offset the issue of intermittency, such as HVDC, Lithium-ion storage, compressed air storage and localised energy grids. In particular, I found the pages on a globalised UHVDC grid linking thousands of mini local grids visionary.

In 2026, Solar PV for electricity generation is mutiplying globally on a GW scale with the other uses of solar such as combined heat and power, producing fuels through solar energy and solar powered desalination investment being negligible or non-existent. This is why the message of the book holds today in 2026 as it did in 2018 when this book was released; invest in further innovations to capture the full potential of energy from the sun.

[Brian Campbell · Rating 4 out of 5]

The author covers solar energy up to 2016 including technologies, economics, financing and policy. Contents are both broad in scope and fairly deep in detail. Author includes many personal experiences which keep the text interesting while staying relevant to innovation to advance solar energy. His treatment of innovation is extensive including financial, business model and systematic innovation. He clarifies the distinction between invention and innovation. A helpful insight for me is electric grid improvements to modularize local grids so that each one has smarts to match demand and supply and ability to isolate itself from remote failures. Another insight for me is that new technology will be needed to effectively bring solar energy up to 50% of the energy supply mix. He also promotes global electric grids to facilitate supply sharing with supply including fossil fueled generation (with carbon capture and reuse or storage) and nuclear generation to supply electricity during periods when the sun is not reaching the solar cells. Some text about U.S. public policy is,”The goal of solar policy should be to encourage financial, technological and systematic innovation that enables a sharply rising share of solar energy to decrease customer costs and carbon emissions . . .” Later he writes, “a carbon tax would need to be paired with support for new technologies to stimulate innovation most effectively.” Given the rapidly changing energy picture, this text could quickly become dated, but in 2021 I found it very insightful and a welcome view of the big picture of the challenge of harnessing solar energy to meet customer and climate saving needs.

[Pat Rolston · Rating 4 out of 5]

This book is the opportunity to get an interesting and informative overview of the technical and economic challenges of rebalancing our energy system from carbon to solar and alternative options. There is more detailed economic rationale presented than I expected, but the reality is economics combined with technology will determine the fate of mankind. We are beyond the precipice and experiencing the incremental impact of the anthropogenic age changing the earth’s climate. Bending the curve from cataclysmic to sustaining requires a global reset that can happen only with the most profound realignment of energy and economic priorities. The author details the use of solar as well as other alternative technologies allowing for the positive outcome. He also graphically illustrates life in in a world if we fail or succeed. I highly recommend the book for everyone wanting to be informed regarding what may be the most critical issue determining the fate of the earth.

[João Arsénio · Rating 4 out of 5]

Very insightful book! It gives a good perspective on what innovation means for solar sector and a simple and brilliant, overview of cost vs value evolution.

Also interesting is the comparison between solar and nuclear technology lock in, they definitely have some common patterned and if nothing changes, that might well be the next step into solar PV.

Nevertheless, and as much as PV should be focused, other technologies we’re mentioned , even if they are a bit far from commercial stage, competing with chinese solar behemoths.

So many things can be said about the author, the book, the ideological references, but one thing remains, solar is not here to stay, is here as long as we know how to use it and improve it.

Thanks for this truly smart, farsighted and interesting perspective !!!

P.s. I’ll not talk about the new solar panels power output and bla bla, since it’s very well explained in this book what that is, read carefully the cost and value opinion

[Zo · Rating 4 out of 5]

Lots of information almost none of which I was familiar with beforehand concerning the state of solar power and different difficulties/opportunities it faces in the future. A book I somewhat wish I had read because it was a lot to process over audio without background familiarity, but also felt somewhat repetitive, so maybe would have gotten too bored reading. I'm struck by the potential solar seemingly has to transform energy usage, and if his arguments are believed, how silly it is that the type of funding for R&D he advocates for is not being undergone. All the questions about balancing between supergrids & microgrids were interesting, and there were a number of points where specific solar debates seemed to reflect larger philosophical/ideological debates about the best governance strategies for managing complex systems and encouraging innovation. Interesting stuff.

[Qmmayer · Rating 4 out of 5]

This book is essential for anyone trying to understand how the U.S. energy grid operates (as in, the generation, transmission, and distribution of electricity) as well as how it *needs* to operate in order to decarbonize our electricty use, an essential element in our ongoing climate change struggle.

Sivaram is persuasive in arguing that some current trends that favor solar energy are not unequivocally moving us in the right direction: 1) the production of cheap, silicon PV panels risks technological lock in, crowding out potentially better-performing technologies and 2) increasing solar penetration will eventually hit a ceiling if there are not deliberate efforts to integrate solar into the grid (ie, developing complementary zero-carbon flexible energy sources and improving transmission).

Sivaram makes clear that a comprehensive effort is required for solar energy to truly reach its potential. It will require significant public and private investment, thoughtful, forward-thinking policymaking, and global cooperation. The good news is that these are largely political, not technological problems (although there are certainly technological hurdles along the way). The bad news imbedded there is unfortunately obvious: Politics have bedeviled nearly every major U.S. and international effort around climate change. We have yet to commit to the policies and prescriptions that have to happen in the coming decades.

This is a heavily footnoted, thoughtful overview of solar energy. It is engagingly written, even for liberal arts majors like myself. There are a couple of chapters on solar financing that I finally gave up on, but otherwise I would recommend this book for anyone looking for deeper dive into renewable power. It is well paired with Our Renewable Future, a short but dense overview of the road ahead.