Time to make 2025 updates to my annual “opinions about solar” thread.
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28. ...but sometimes net-zero electricity models want to put in hydrogen to cover weeks of low renewables just because the model isn’t given any other option. Deep decarbonization models do weird things. It may turn out there are easier pathways in practice.
29. Electrification of transport is far better than biofuels; solar plants can run an electric car on a small fraction of the land used to grow fuel to run a biofuel car.
30. Decarbonizing aviation is hard. The CEO of Lufthansa said in 2023 that running its fleet on sustainable aviation fuel made from electricity would take half Germany’s current electricity demand. BNEF thinks this an underestimate.
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29. Electrification of transport is far better than biofuels; solar plants can run an electric car on a small fraction of the land used to grow fuel to run a biofuel car.
30. Decarbonizing aviation is hard. The CEO of Lufthansa said in 2023 that running its fleet on sustainable aviation fuel made from electricity would take half Germany’s current electricity demand. BNEF thinks this an underestimate.
31. Direct electrification of aviation would be better. BNEF research did track orders for 989 electric aircraft (mostly small ones) as of early 2022, but this is a long term project. Fingers crossed. (www.bnef.com/insights/30267 ).
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31. Direct electrification of aviation would be better. BNEF research did track orders for 989 electric aircraft (mostly small ones) as of early 2022, but this is a long term project. Fingers crossed. (www.bnef.com/insights/30267 ).
32. Heatpumps are better for heating homes than hydrogen, but in seasonal climates like northern Europe will exacerbate the seasonal demand and supply mismatch for solar. We need to build wind and probably nuclear as well.
33. How mismatched is European seasonal solar supply and electricity demand? Well, here is the situation for my fully electrified house in Switzerland with 13.2kW of solar, a heatpump and an EV. I would have needed about 122kW of PV to be self-sufficient across December.
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32. Heatpumps are better for heating homes than hydrogen, but in seasonal climates like northern Europe will exacerbate the seasonal demand and supply mismatch for solar. We need to build wind and probably nuclear as well.
33. How mismatched is European seasonal solar supply and electricity demand? Well, here is the situation for my fully electrified house in Switzerland with 13.2kW of solar, a heatpump and an EV. I would have needed about 122kW of PV to be self-sufficient across December.
34. Europeans shouldn't feel guilty about using electricity for airconditioning, it'll all come from the sun anyway by 2030. Solar generation times and seasons match airconditioning demand pretty well, which is good news for really hot countries.
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34. Europeans shouldn't feel guilty about using electricity for airconditioning, it'll all come from the sun anyway by 2030. Solar generation times and seasons match airconditioning demand pretty well, which is good news for really hot countries.
35. Nuclear is safer than coal and climate change, and better than gas unless the gas plants are running very rarely. Batteries should help with the unfavourable ramping economics of nuclear (you *can* turn nuclear plants up and down, but you really don’t want to).
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35. Nuclear is safer than coal and climate change, and better than gas unless the gas plants are running very rarely. Batteries should help with the unfavourable ramping economics of nuclear (you *can* turn nuclear plants up and down, but you really don’t want to).
36. We’re finally getting serious about net zero carbon. Getting that last 5-20% of carbon out of power will be hard, and require some expensive solutions. The first 80-95% is easy-ish but we're getting on with it.
37. You can be cynical about government and corporate net zero emissions targets if you like, but they're a lot better than no net zero emissions targets.
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36. We’re finally getting serious about net zero carbon. Getting that last 5-20% of carbon out of power will be hard, and require some expensive solutions. The first 80-95% is easy-ish but we're getting on with it.
37. You can be cynical about government and corporate net zero emissions targets if you like, but they're a lot better than no net zero emissions targets.
38. Ordinary people have no idea how much progress we’ve made. Tell people at parties that UK carbon emissions in 2023 were at their lowest level since 1879, for example. Most developed economies are now reducing carbon emissions without lowering quality of life.
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38. Ordinary people have no idea how much progress we’ve made. Tell people at parties that UK carbon emissions in 2023 were at their lowest level since 1879, for example. Most developed economies are now reducing carbon emissions without lowering quality of life.
39. …It would still really help if rich people would stop pissing carbon into the atmosphere for no reason.
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39. …It would still really help if rich people would stop pissing carbon into the atmosphere for no reason.
40. There are signs that solar is reducing fossil fuel burn in poorer countries, for example Pakistan — which has no significant government support for solar but has built over 25GW just in response to high prices for power and fuel for irrigation.
41. This has interesting and not uniformly positive side effects. Pakistan may be the first market to see a true 'utility death spiral' where customers who can go solar do so, leaving other customers to pay for the grid, raising power prices..
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40. There are signs that solar is reducing fossil fuel burn in poorer countries, for example Pakistan — which has no significant government support for solar but has built over 25GW just in response to high prices for power and fuel for irrigation.
41. This has interesting and not uniformly positive side effects. Pakistan may be the first market to see a true 'utility death spiral' where customers who can go solar do so, leaving other customers to pay for the grid, raising power prices..
42. Annual build volumes of solar are rising, but they are not guaranteed to rise forever. This is a symptom of solar starting to actually make a dent in power demand, with negative feedback effects such as power price cannibalization.
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42. Annual build volumes of solar are rising, but they are not guaranteed to rise forever. This is a symptom of solar starting to actually make a dent in power demand, with negative feedback effects such as power price cannibalization.
43. Data centers are increasing power demand, but let's keep a sense of proportion. BNEF estimates total electricity demand from data centers of 373TWh in 2024 (1.2% of global generation) and expects this to increase to 1,596TWh (4.4% of global) in 2035.
This is a source of some disappointment to renewable energy project developers.
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43. Data centers are increasing power demand, but let's keep a sense of proportion. BNEF estimates total electricity demand from data centers of 373TWh in 2024 (1.2% of global generation) and expects this to increase to 1,596TWh (4.4% of global) in 2035.
This is a source of some disappointment to renewable energy project developers.
44. Demand for solar panels to sub-Saharan Africa is also strong, measured by Chinese exports, though the total was still less than 13GW in 2024 (it's hard to sell to poor people). Nigeria, Ethiopia, Congo, Kenya, Senegal and Zambia are the largest African markets in 2025 to date.
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44. Demand for solar panels to sub-Saharan Africa is also strong, measured by Chinese exports, though the total was still less than 13GW in 2024 (it's hard to sell to poor people). Nigeria, Ethiopia, Congo, Kenya, Senegal and Zambia are the largest African markets in 2025 to date.
45. Some governments are definitely out to fight against a better future.
46. Achieving a net-zero energy transition, for most countries, will not look like winning a war or marching into a capital waving flags. It will be the ability to say "no thank you, we do not want what you are selling" to the petrostates, and walking (or cycling, or taking an electric bus, or driving an EV) away.
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45. Some governments are definitely out to fight against a better future.
46. Achieving a net-zero energy transition, for most countries, will not look like winning a war or marching into a capital waving flags. It will be the ability to say "no thank you, we do not want what you are selling" to the petrostates, and walking (or cycling, or taking an electric bus, or driving an EV) away.
47. 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, and is, done.
Volumes are still tiny compared with most things we also have to recycle.
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47. 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, and is, done.
Volumes are still tiny compared with most things we also have to recycle.
48. Floating solar, agrivoltaics, balcony solar: yes you can put solar panels on anything that stands still long enough. If you have a lightweight encapsulant, you can also put them on something that moves.
The decision comes down to: in this use case, will the solar panels get in the way, and will they get broken by normal activities?
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48. Floating solar, agrivoltaics, balcony solar: yes you can put solar panels on anything that stands still long enough. If you have a lightweight encapsulant, you can also put them on something that moves.
The decision comes down to: in this use case, will the solar panels get in the way, and will they get broken by normal activities?
49. 'Agrivoltaics' is defined as 'solar that gets preferential legal / permitting treatment applying to agrivoltaics projects' and therefore the definition is local. It's not really a different technology and so a general statement on it is not really possible.
It's harder to harvest crops and work land under solar panels, so many owners may quietly drop the farming bit once support is secured.
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49. 'Agrivoltaics' is defined as 'solar that gets preferential legal / permitting treatment applying to agrivoltaics projects' and therefore the definition is local. It's not really a different technology and so a general statement on it is not really possible.
It's harder to harvest crops and work land under solar panels, so many owners may quietly drop the farming bit once support is secured.
50. Grazing sheep under solar panels should not qualify them for agrivoltaics support. Solar subsidising sheep farming is not particularly an environmental plus.
(Some crops do seem to work well with PV, for example shade-tolerant berries, and in some climates, vegetables for which growth isn't limited by light availability. Farming involves a lot of optimising for local conditions and so often the answer to 'what works?' will be 'it depends....').
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50. Grazing sheep under solar panels should not qualify them for agrivoltaics support. Solar subsidising sheep farming is not particularly an environmental plus.
(Some crops do seem to work well with PV, for example shade-tolerant berries, and in some climates, vegetables for which growth isn't limited by light availability. Farming involves a lot of optimising for local conditions and so often the answer to 'what works?' will be 'it depends....').
51. For 6 years I have been refusing to get excited about perovskites until a perovskite company can disclose a commercial partnership with a named major module manufacturer. They have now. Still not excited.
Crystalline silicon is honestly good enough.
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51. For 6 years I have been refusing to get excited about perovskites until a perovskite company can disclose a commercial partnership with a named major module manufacturer. They have now. Still not excited.
Crystalline silicon is honestly good enough.
52. Get your rooftop solar system built when you have scaffolding up for something else, 'cos scaffolding is expensive. Ideally build it when you’re building the roof, there will never be a better time. Rooftop solar mandates are good but don't do much unless you are adding a lot of new buildings, which most developed countries aren't.
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52. Get your rooftop solar system built when you have scaffolding up for something else, 'cos scaffolding is expensive. Ideally build it when you’re building the roof, there will never be a better time. Rooftop solar mandates are good but don't do much unless you are adding a lot of new buildings, which most developed countries aren't.
53. Anyone buying a new internal combustion car now is silly. EVs aren’t the answer to everything – especially congestion of cities – but they do use much less energy, it's relatively easy-to-decarbonise energy, and, with flexibility, they can support the grid.
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