Around here I have a backyard washing machine, a backyard grill, a backyard clothesline, and my neighbors have backyard childcare, backyard parking, and a backyard motorcycle. And actually inside my house I have a flush toilet and an oven.
Your assertion seems to imply that if instead I had to wash and dry my laundry at a coin-operated laundromat, eat at a cafeteria table with all my neighbors, and piss in a portapotty down the street, and my neighbor's kids were taken away to live at a boarding school, while he had to ride the bus to work instead of driving, that would be evidence of successful policy!
We clearly have radically different definitions of success. Yours seems not to be well thought out.
The problem with backyard furnaces was that the steel they produced was not just expensive but also inferior. If you could plug in a Tabletop Minimill that produced ingots of specialty precision steel alloys to your order, ranging from maraging steel to tool steel to nitinol, and which was also cheap to operate, that would not be an economic policy failure. That would be an enormous success!
Your generalization that any kind of decentralization amounts to collective action failure is wrong. Some kinds of decentralization do; my household water pressure tank is decentralized because of collective action failure, for example, as I explained in https://news.ycombinator.com/item?id=45487610. Others don't. We have to analyze the particulars of each case. I've written at https://news.ycombinator.com/item?id=45487051 a bit about the particulars of this case.
> Your generalization that any kind of decentralization amounts to collective action failure is wrong. Some kinds of decentralization do; ... Others don't.
That's correct, yes. I too prefer a decentralized washing machine to coin-operated laundromats which are very common in France where I live nowadays.
However I still believe that electricity generation has more in common with steelmaking than with laundry. Today solar panels make sense in terms of money ROI but not in terms of KWh ROI, they're largely enabled by economical disbalances around the world and not by their long-term value. The long-term solution in my view is nuclear which coincidentally the French do rather well, it's not all laundromats.
> Today solar panels make sense in terms of money ROI but not in terms of KWh ROI
That is clearly wrong. Even the worst-case embodied energy assumptions for solar panels estimate the cost of producing a square meter of solar panel area at 2000 kWh (the best cases are around 300, see https://en.wikipedia.org/wiki/Energy_return_on_investment#Ph... ). A square meter of solar panel area produces an average of 200 kWh of power per year in Germany (which implies a pessimistic assumption, more sunnier countries can get a multiple of that). This means that even in the worst case, the solar panel has amortized itself from the perspective of embodied energy after 10 years. On average it will be more like below 5 years. Solar panels however have an expected lifetime of well over 30 years and require no maintenance if installed correctly.
30 years lifetime (if there are no heavy storms), 5-10 years to recoup energy, that's 3-6 EROI. Then you also need to include inverters which are energy-heavy. If we're talking of any meaningful scale, then you also need to include batteries because without them panels get shut down during sunny hours lowering the EROI even further.
In the end you're lucky if you get EROI of 1.5-3. That's an extremely bad deal. All other sources of energy, renewable or not, are in the 20-100 territory. The purpose of the energy production system is not to barely sustain itself but to actually produce usable electricity for everything else you want to do. It's the means, not the ends.
Solar panels have very solid benefits of course, you can buy them for your house to be more autonomous -- I would do that if I had a house. But from the energy/CO2 perspective what you're doing is buying a sort of "battery" that was charged with cheap coal-based electricity in China and shipped off to US/Europe. This makes sense in certain situations but presenting this as a green solution or as future of humanity is just delusional.
> Then you also need to include inverters which are energy-heavy.
Scientific publications say otherwise. It's quite hard to come by any numbers, but page 11 of https://www.wisdomlib.org/uploads/journals/mdpi-sust/2025-vo... says that typical solar inverters require about 15 MJ/kW of power for their production in total, which would amount to approx. 4 kWh per kW of inverter power. A solar panel square meter produces about 200-250 watts of peak power, so it needs inverter power that cost about 1 kWh to build. Let's triple that, because inverters have a typical lifetime of 10 years in contrast to the 30 years of solar panels. 3 kWh for the inverter is negligible when compared with 300-2000 kWh for the panel itself. So we can just ignore that.
Batteries are interesting. According to https://www.mdpi.com/2076-3298/12/1/24, it takes about 35 kWh in total to produce 1 kWh of battery capacity. Let's say we'll need 250 Wh of capacity for our 250 WPeak solar panel square meter (the rule of 1 kWh capacity for each 1 kWp is a typical estimate applied when sizing solar installations for residential homes). That makes up about 8 or 9 kWh to produce this battery capacity. Admittedly that doesn't include the raw materials, of which the cell requires quite a few expensive ones. Unfortunately I wasn't able to find a good resource on that, so I resorted to asking ChatGPT for a rough calculation, and it came up with about 140 kWh for our 250 Wh LFP cell, which doesn't sound entirely wrong, as it assumed a cell weight of 1,5 kg and splitted that up into different materials. The weight matches what I would expect from personal experience with LFP batteries.
Basically, we can just ignore the inverter and must add about 150 kWh for the battery to our 300-2000 kWh for the panel. That does not substantially impact an EROI calculated from a 1000 kWh assumption for the panel alone.
And this is a calculation based on Germany. Again: weather conditions are far from optimal for solar in Germany. It's much better in many regions in China, where solar panels are made. They can easily achieve EROIs of 20+ with solar there, which is probably the reason why China installs absolutely HUGE numbers of panels. But according to you, they must be "delusional" over there.
> > This makes sense in certain situations but presenting this as a green solution or as future of humanity is just delusional.
> which is probably the reason why China installs absolutely HUGE numbers of panels. But according to you, they must be "delusional" over there.
State-run economies get delusional pretty easily, but in this case China is safely on the "makes sense in certain situations" side:
* keep electricity prices low
* invest heavily in nuclear
* install solar within reasonable limits (currently around 8% of the grid)
* for better or for worse they burn more and more coal every year
They certainly don't make insane green commitments and they don't say solar is the future of humanity. I don't like China much, but I don't see how they can fall into "delusional" category according to my criteria above, they have none of it.
Now Germany's policy is the complete opposite of China's, except for the "burning coal" part. Germany killed their own economy over high electricity prices because they wanted to go green, but then somehow they've got almost 2x CO2 emissions per capita compared to France.
If someone says "I sacrifice A to get B", but then never get the B and still lose A, and then insist that the plan was a great success -- he's certainly delusional, that's like the definition of the word.
Maybe you can explain in more detail what you mean by "enabled by economical disbalances around the world and not by their long-term value", but on my assumption that you're talking about EROEI and energy payback time, your assertion is profoundly incorrect.
> Just on an economic basis we can bound the energy payback time to about four years
If you use electricity prices to make that calculation, you need to take in account that solar panels are produced in China off cheap coal-based electricity. If you produce a panel in Germany it would take much longer to break even economically (if ever). That's what I mean by "enabled by economical disbalances around the world".
> we found a Fraunhofer report by Simon Philipps and Werner Warmuth with a more detailed estimate arriving at a 1.1-year energy payback time in Northern Europe, 0.9 years in Southern Europe
This article doesn't explain how they make their calculations and I struggle to replicate them. The usual estimate to produce a PV panel is 600-1000 kWh per 1sqm. Measured (not projected) yield in Germany is 160-180 kWh per 1sqm per year. A balcony solar panel will yield even less than that because it's not positioned optimally. Then you won't consume all that it produces because you're at work during the day and there are no appliances running except the fridge maybe. In the end you may get anywhere between 10 and 100 kWh per 1sqm per year (would love to see some real measurements by the way, not projected ones).
So my view is very simple: these balcony panels make sense economically because German economy is cooked. However from the physics/ecology perspective they make no sense at all and many of the panels installed today will never recoup the electricity used to produce them, making them a net-negative impact for the environment. Which by the way could be a reasonable price to pay for autonomy in case of power failure but these balcony setups can't run when the grid is off.
> A balcony solar panel will yield even less than that because it's not positioned optimally.
Non-optimal positioning is already included in your "Measured (not projected) yield in Germany". Because that is the difference between a projected yield (under optimal conditions) and actual measurements of actual panels, which are practically never optimally placed.
> Then you won't consume all that it produces because you're at work during the day and there are no appliances running except the fridge maybe.
That is relevant for an economic calculation, but it is entirely irrelevant if you want to determine the point after which the panel breaks even regarding the energy used for its production vs. the energy produced by it. In that case, every single kWh counts, whether the owner of the panel economically profits from it or whether he or she just donates it to the grid without compensation.
And clearly, we are discussing the energy break-even here, as indicated by "The usual estimate to produce a PV panel is 600-1000 kWh per 1sqm."
> However from the physics/ecology perspective they make no sense at all and many of the panels installed today will never recoup the electricity used to produce them, making them a net-negative impact for the environment.
As I've demonstrated with concrete calculations, that you seemingly accept as valid as you perform the same calculations with roughly the same numbers, the EROI of solar panels even in Germany over their lifespan is clearly in the positive range. Maybe they "only" recoup 3x or 5x their investment, and not 20x, but they are a net positive regardless. Any number above 1x is.
In addition to this, as I've described in another posting here (https://news.ycombinator.com/context?id=45490555) there's the psychological side of things, where cheap and easily profitable balcony panels for everyone are a gateway drug for "normal people" to get actively involved in the field of renewable energy and must not be underestimated in their ability to open the minds of people for other, more efficient actions to get closer to a carbon-neutral energy economy. Since those activities tend to be heavily inhibited by broad refusal that's often not based on factual arguments, but simply on inertia in people's minds ("we've always done it the other way") and a certain lazyness to actively grapple with new technologies and developments, this effect is at least as important as the actual impact on the energy grid. Just like on the stock market, the raw numbers are only half of the story. Psychology is the other half.
> Non-optimal positioning is already included in your "Measured (not projected) yield in Germany". Because that is the difference between a projected yield (under optimal conditions) and actual measurements of actual panels, which are practically never optimally placed.
No, because the figure I have was for normal solar panels, not the balcony ones which are even worse. I haven't seen anyone reporting real yield for balcony panels yet, would be interested to see the numbers.
> That is relevant for an economic calculation, but it is entirely irrelevant if you want to determine the point after which the panel breaks even regarding the energy used for its production vs. the energy produced by it. In that case, every single kWh counts, whether the owner of the panel economically profits from it or whether he or she just donates it to the grid without compensation.
No, because when you get any significant amount of solar installed you start to get negative prices on sunny hours and need to shut them down. If home solar setups won't shutdown then some other panels in the grid would. This is a fundamental tradeoff with solar: it's either too small to make any difference or you never get your projected EROI because you have to shut them down during the very time they produce maximum energy.
> I've demonstrated with concrete calculations, that you seemingly accept as valid as you perform the same calculations with roughly the same numbers, the EROI of solar panels even in Germany over their lifespan is clearly in the positive range. Maybe they "only" recoup 3x or 5x their investment, and not 20x, but they are a net positive regardless. Any number above 1x is
You confuse the "maximum possible outcome" with real life. No one knows if these $300 setups will last 30 years, that was never tested because that requires well 30 years. My estimate is they won't because electronics from the lowest price range very rarely do. Then even if they could last that long, half of them will end up in a dumpster after a few years because people move and can't always take their panels along.
I'm extremely sceptical of all these "concrete calculations", not because they're mathematically incorrect but because they are detached from real life. It's like when they sell you a timeshare cottage on a ski resort and mathematically it's profitable, but in reality it's a huge liability.
> No, because the figure I have was for normal solar panels, not the balcony ones which are even worse. I haven't seen anyone reporting real yield for balcony panels yet, would be interested to see the numbers.
„which are even worse“ is an assumption you make, you do not have any data to back that up. From what I regularly see, they are not worse at all. People without sun on their balconies do not buy balcony solar kits in the first place. Also there’s the fact that people can spend time to meticulously optimize every single panels’ location (which they usually don’t when someone places 30 panels on a roof in a single day, it’s just about getting them up there quickly). If you are interested in numbers, browse https://www.reddit.com/r/Balkonkraftwerk/ - it’s German language but Reddit does quite well with auto-translation as far as I know. Every month, people post their yield numbers for comparison there.
> No, because when you get any significant amount of solar installed you start to get negative prices on sunny hours and need to shut them down. If home solar setups won't shutdown then some other panels in the grid would.
You are equating the time during which a home solar owner cannot use his own solar power with the time during which there are negative electricity prices. This is grossly wrong. In 2024, Germany had 457 hours of negative power prices (see https://www.pv-magazine.de/2025/01/03/bundesnetzagentur-457-...). That’s roughly 5% of the year. Typical home solar power usage if no battery at all is installed is about 50%. If we talk about batteries, which are increasingly getting common in balcony solar installations due to significant price drops, it’s more like 80-90% of power that the owner can use directly.
> You confuse the "maximum possible outcome" with real life. No one knows if these $300 setups will last 30 years, that was never tested because that requires well 30 years. My estimate is they won't because electronics from the lowest price range very rarely do.
The panels are the exact same panels used for large-scale solar installations. These are tested and guaranteed by the manufacturer for 30+ years. Nobody doubts that they’ll reach that lifespan in most cases.
The inverters are a negligible amount of kWh invested, as I pointed out in the parallel threads’ posting. So you can easily buy one or two replacements over the 30 year timespan without impacting the EROI of the panel at all. Also, a lifespan of 30 years does not mean that the panel fails after 30 years. It just goes below a defined point of efficiency (80% of original peak power). You can very well use it for another 10 or 20 years, you just have to accept that it produces only 80% of the original output.
> Then even if they could last that long, half of them will end up in a dumpster after a few years because people move and can't always take their panels along.
That’s not what I see, because it is surprisingly hard to dispose of solar panels in practice. They do not fit into the typical „dumpsters“ people use to dispose their regular trash. You would be able to dispose of them for free at the next recycling center in Germany, as they are mandated to take them, but most cars cannot be used to transport solar panels as they are too large, so it’s not trivial to get them there. From what I observe, people therefore simply sell or donate the panels to the next renter/owner when they move, which is obviously a good idea as they are usually installed on a balcony or garden house or whatever and you usually buy the matching installation equipment for a particular situation which you wouldn’t be able to use at your future home anyway.
I find it quite interesting that you did not object to my second argument about the psychological impact/use of this technology.
Your assertion seems to imply that if instead I had to wash and dry my laundry at a coin-operated laundromat, eat at a cafeteria table with all my neighbors, and piss in a portapotty down the street, and my neighbor's kids were taken away to live at a boarding school, while he had to ride the bus to work instead of driving, that would be evidence of successful policy!
We clearly have radically different definitions of success. Yours seems not to be well thought out.
The problem with backyard furnaces was that the steel they produced was not just expensive but also inferior. If you could plug in a Tabletop Minimill that produced ingots of specialty precision steel alloys to your order, ranging from maraging steel to tool steel to nitinol, and which was also cheap to operate, that would not be an economic policy failure. That would be an enormous success!
Your generalization that any kind of decentralization amounts to collective action failure is wrong. Some kinds of decentralization do; my household water pressure tank is decentralized because of collective action failure, for example, as I explained in https://news.ycombinator.com/item?id=45487610. Others don't. We have to analyze the particulars of each case. I've written at https://news.ycombinator.com/item?id=45487051 a bit about the particulars of this case.