by Slartie | 2025-10-07 08:34:08+00:00
> 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.