, 40 tweets, 7 min read
1. Time to make minor updates to my #solar unpopular opinions thread, since this seems to be a good way to organize thoughts.

If you like these, you’ll like my book, Solar Power Without the Jargon. tinyurl.com/y4bsswty
2. Solar Power Without the Jargon is the book I should have read before seeking a job in renewables, from the perspective of having worked in this for 14 years. It’s short and not too serious; one reviewer said it “made me laugh quite a few times”.
3. It includes interviews with industry legends Professor Martin Green and Dr Zhengrong Shi, who went from being China’s Sun King to learning to cook, as well as Morgan Bazilian, Lucy Hornby, Charles Yonts and others. And what Michael Liebreich was like to work for.
4. To the #unpopularopinions! #Solar manufacturing is a still a terrible business to be in, with vicious price competition and last mover advantage. Most well-known manufacturers are saddled with heavy debt they took on to build their rapidly-becoming-outdated factories.
5. Crystalline silicon technology is good enough and is still achieving major cost reductions, for example diamond wire saws went from new to about 100% of the wafer slicing market from 2016 to 2018. Bifacial modules look likely to do the same, at least for ground mounted solar.
6. Solar is now usually the cheapest source of daytime energy in sunny countries. We don’t need a technology breakthrough in solar to achieve massive adoption, which is happening now in an unevenly distributed, rather messy way.
7. Countries that have built little solar to date are not losing to high-solar countries; they waited for a bargain on price and can now hold an auction to find out how little a solar developer is willing to build it for. These first auctions are getting bigger.
8. In 2017, my analysis team covered 42 countries which were significant solar markets doing more than 50MW/year. Now we cover 122 and keep finding ones we’ve missed. It’s a bit of a pain, honestly, but quite exciting.
9. The more a solar company's pitch is about the enviro-social value of solar in general, the less likely it is to be a good company.
10. I refuse to get excited about perovskites until a perovskite company can disclose a partnership with a named major module manufacturer.

(This was my opinion in 2018. It is my opinion still).
11. Curtailment (cutoff when the grid can’t take all production) of solar is going to be widespread. It's a feature, not necessarily a bug. Grid connections are incredibly valuable (cf Portugal’s 2019 solar auction) and you want to oversize the plant to make the most of it.
12. A lot of current household PV systems are designed suboptimally and may not make economic sense or even perform well. Also, most countries will move to paying a pittance for solar exports, so self-consumption rate is becoming the most important financial parameter.
13. To financially assess a proposed rooftop solar system, you will need at least a year’s data on hourly electricity consumption to estimate selfconsumption. Also, get it built when you have scaffolding up for something else, scaffolding is expensive.
14. Rooftop solar mandates on new construction (like California's) are a good idea. There will never be a better time in the roof's life to add solar than when workers are already on the roof, now the kit is so cheap.
15. Floating solar is a thing, but it’s still not a new technology. It is solar onna boat.
16. In northern Europe, wind is better matched to peak demand times than solar. However, solar is cheaper and may often win tech-agnostic tenders. Increasingly governments will need to stop solar from stealing wind's lunch for this reason.
17. Some solar auction prices below $35/MWh were overoptimistic, which is why Indian solar hasn’t set a new low auction record since May 2017. Some are speculative, eg Portuguese sub 20-euro fixed prices are a flutter on future upside from owning the grid connection.
18. Despite bifacial technology offering 4-9% upside, I don’t think prices below $25/MWh really reflect the full cost of solar except under very unusual circumstances (eg all site work, development and grid connection provided). That is cheap enough though.
19. Auctions and tenders are going to get increasingly sophisticated, driving systems designed to produce power at the best times, or sometimes with a storage/ dispatchability component. Many projects will face west-ish to serve the evening peak.
20. Very few people who are not solar project financiers understand tax treatment for solar projects (I don’t) and it’s important enough to make most calculated LCOEs irrelevant to auction prices.
21. Solar thermal tower and heliostat designs are still not working well, although parabolic trough solar thermal has brought down costs more than expected.

We may even end up using molten salt for multi-day and seasonal storage... but heat it with PV.
22. Utility-scale batteries are likely to have more of a role in bulk storing solar power for the evening than I expected in 2018. There’s a surprising amount of deployment in the U.S., and though this is basically for policy reasons, it will happen elsewhere too.
23. Hydrogen is going to be a thing, but not for transport and probably not for seasonal power storage – exactly. Using renewables when they’re plentiful to make H2, then using the H2 to make steel or fertilizer, looks quite promising.
24. Nuclear is safer than coal and climate change, and probably better than gas unless the gas plants are running very rarely. Batteries might help with the unfavourable ramping economics of nuclear (you *can* turn nuclear plants up and down, but you really don’t want to).
25. Solar is a major part of decarbonizing electricity, but probably not more than 50% worldwide, so we need something else too. Transport will go electric but also we really need to sort out agriculture, shipping and aviation somehow for a sustainably habitable planet.
26. While moving to a circular economy with 100% recycling rates is essential in the long run, it’s not a challenge for PV in particular; few PV panels have been recycled to date only because the vast majority are still in use. It can be done.
27. Solar plant operation and maintenance in desert environments will prove more challenging than PV project stakeholders currently expect.
28. Traded electricity wholesale markets are the worst way of deciding how to dispatch energy resources, except for all the others that have been tried.
29. Many solar project developers complaining their problem is 'finance' are being disingenuous. Their problem is, their project is rubbish and they cannot convince anyone otherwise.
30. Building-integrated PV products are usually attempts to sell bad solar products for premium prices to gullible aesthetes and architects.
31. Job creation from solar will be less than solar advocates forecast. Relatedly, solar cost will be lower than anyone currently forecasts.
32. Offgrid solar is driven more by people wanting TVs than by people wanting their kids to have light to do homework. And that’s absolutely fine.
33. Commercial and residential power pricing structures are going to get more complicated to reflect cheap midday solar. The main role of smart home technology is to take advantage of this. It's not currently doing it very well.
34. There is enough land for lots of solar. There are enough golf courses in the US for about 370GW, ffs.
35. Getting to 100% renewables is really hard, but getting to 50%, 60%, 70% will not be as hard as we think and after that we will have a better toolkit for the rest.
36. ‘Energy poverty’ isn’t a particularly useful term and is too often co-opted by the people who use a lot of energy (ie the rich) to complain that they pay too much. Poverty is bad already and isn’t the same as things being expensive. Cheap energy for poor people is good, tho.
37. If you’re recording PV capacity and only have room for one figure, record MW(DC). It will tell you more about what the project will produce and what it will cost than MW(AC), which is just the size of the wire.
38. Anyone buying a new internal combustion car now is pretty silly. EVs aren’t the answer to everything – especially congestion of cities – but they do use less energy and, with flexibility, can support the grid.
That's it, must cook now. My next book project* is The Solar Powered Home Cookbook: Easy Vegetarian Recipes You Can Cook Before the Sun Goes Down and Eat Later.

*not really.
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