| > 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. |
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.