this post was submitted on 09 Apr 2024
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I get the sentiment in here, but the poster is missing an important point: there is a reason some group of lunatics (called the TSO or Transport System Operator or in some cases other power producers) are willing to pay for people to consume electricity when there is too much of it; They are not doing it for the sake of being lunatics, the electrical system cannot handle over or underproduction. Perfectly balanced (as all things should be) is the only way the grid can exist.
The production capacity in the grid needs to be as big as peak demand. The challenge we face with most renewables is that their production is fickly. For a true solarpunk future, the demand side needs to be flexible and there need to be energy storages to balance the production (and still, in cold and dark environments other solutions are needed).
In off-grid, local usages we usually see this happen naturally. We conserve power on cloudy low-wind days to make sure we have enough to run during the night (demand side flexibility) and almost everyone has a suitably sized battery to last the night. The price variability is one (flawed) mechanism to make this happen on a grid or bidding zone level.
Thank you, it's very valuable to correct that misinformation.
It seems like an easy mistake to make as the original post being replied to is framing it explicitly in terms of economics.
It's just a bit of shitshow of weird communication. How hard would a tweet like "A problem with solar panels is that they produce too much electricity during the middle of the day, putting strain on the grid and requiring increased power consumption".
That's not as sensationalist but I'm also not a headline writer. It just seems like this shitty piece of journalistic malpractice was made to stir up outrage
https://www.technologyreview.com/2021/07/14/1028461/solar-value-deflation-california-climate-change/
It's MIT, they're not exactly a clickbait source.
The reply is what makes the excerpt seem inflammatory. It's an article about the economics of solar power, so the excerpt is a fair representation of both the article and the real issue it's discussing.
It would be sensationalist if they said "critical problem paying for solar power comes from negative prices, threatening future of solar adoption"
Framing it as though it were a condemnation of solar turns a statement of fact into something different than what it is.
All this time I thought that MIT meant Massive Idiot Team
Solar panels already turn off when grid voltage is too high
This has me thinking
The resurgance of sand batteries has been interesting. While not great for converting back into electricity, it's great for heating and cooling which is a massive portion of our energy consumption. They can also store quite a ton of energy with crazy efficiency, especially when paired with heat pumps. And from what I've been able to deduce, they aren't dependent on beach sand and can use rougher or man-made sand reliably.
First if we could get enough large buildings and neighborhood/home installation sand battery heating & cooling infrastructure operating with heat pumps. Then when during high times of energy production we can dump the energy into the sand battery infra and help keep the grid stablizied and keeping our heat & cooling overall percentage of use down.
In the end, we're going to need tons of solutions and strategies for storing excess production during low demand times. I'm hopeful to see where we go here, the crazy things were seeing in energy storage is extremely interesting. I'm super excited to see the advances were seeing in calcium and sulfur based batteries expand in adoption and the production lines can scale with demand.
I've been really curious about the possibility of a small DIY sand battery type system. I currently store my "negative value" midday solar power by dumping it into a water tank and using it to feed my hydronic heating system.
However as we know that results in a tank containing useless low-grade heat on a cloudy day, where a sand battery would result in a small amount of usable high-grade heat.
The cooling equivalent could actually be implemented fairly easily at home with common consumer ice machines (which are effectively heat pumps). Make ice when there's surplus, dump it in an insulated hopper with a heat exchanger for night-time cooling, recycle the near-freezing melt water to make ice the next day. Water is a lot easier to handle because it can be pumped instead of conveyed, and you get the advantage of phase change storage.
I have been running the numbers on one myself and it seems to me the best case would be to actually have one inside my home, since the waste heat will also end up heating the space. I admit it is similar to just having a lot of thermal mass in the house.
That's really interesting you're storing power. Was it diy??
Entire system is home built and programmed except the inverter which was a surplus rack-mount.
The dump load in the water tank tracks the battery bank voltage, drawing more power as the voltage rises into the float range. This is used to sense available surplus power, which is used to turn on other dump loads, i.e. air conditioning in summer.
I have a couple window units that are cranked to max cooling and come on in sequence as the surplus power rises, on an early summer day with clear skies it can get to the point of needing a sweater in the house :D I'm migrating to a homebuilt multi-stage heat pump this year after the prototype worked quite well last year.
Also seriously considering the ice storage concept for hot nights, though I might need to make an actual ton of ice!
Just made a deal on 8 massive surplus AGM batteries too to refresh my bank
Fucking amazing😮😮 Write a blog if you document things.. Might come handy to beginners
Yes, also it doesnt technically have to be sand, there are concrete mixes and even just bedrock that can be used for similar purposes. I've been looking at sand batteries myself for this reason: run the battery hot when power is cheap, let it cool when not.
This sort of thing is of course why it's useful to have a market mechanism for energy, it can encourage us to build environmentally friendly solutions.
Actually a modern "sand battery" does have to be sand or at least a granular material. The difference between a sand battery and thermal mass is that you use a conveyor to superheat small fractions of the sand, allowing the isolation of high grade heat.
If you have a single kWh to store and 1 ton of sand to work with, you could heat 1kg of sand to hundreds of degrees (sand battery), or 1 ton of sand by one degree (thermal mass).
1 ton of slightly warm sand is useless, while you can extract the high grade heat from the 1kg and get your 1 kWh back.
Interesting, thanks for sharing that!
That is of course absolutely true. But fossil fuels are still a tool of power that is used for political purposes. Of course, this also applies to the metals needed for batteries, for example. However, access to this is not so promising in terms of power, because on the one hand, as you say, you can also live and produce "according to the times of day". On the other hand, there are untapped reserves of these raw materials - such as cobalt and manganese - in the deep sea, i.e. international waters. In short, I do think that some players have an interest in boycotting solar energy and other renewable energy sources in favor of fossil fuels in order to maintain their power base - Russia, for example.
Could they not just install a series of big "resistors" that can be switched on and off to burn off overproduction when necessary?
They can, and they do. They're typically considered safety devices since they can be damaged by having excess load dumped on them, and they either are dumb, in which case they don't act like an actual load the generator is expecting and can maybe cause damage to the generator, or they're smart and can mimic the type of load the grid would actually give, but now they're expensive and need maintenance and testing in excess of what the dumb one needs.
It's something you would need for off grid solar as well, with batteries that can only take so much charge, but at the power grid level it's a much bigger task because you're in the realm of "metal explodes" power, and exploding metal is bad.
i feel like you wouldn't need a dump load for solar, due to how it's setup. At best you just dont do anything, and worst you disconnect the panels entirely, that could be bad for the panels though idk.
It's different with typical generation because it's almost always converting mechanical energy into electrical energy. Which means if you load dump, suddenly the RPM of the turbine driving the generator, and likewise, the generator, is going to vastly speed up. Which given the fundamental mechanics of how those work, is going to fuck shit up. Dump loads exist as a really easy solution there.
But with solid state generation, i'm not sure it would really matter. Unless you're running a decentralized grid maybe.
The panels still generate power even if they're disconnected as long as they're in the sun.
In a home setup they'll probably just get warm, but if you're making a lot of current you'd want it to not do that.
I think a lot of home setups will switch to a water heater, since that's easy and also a potentially useful way to spend extra power.
I did some googling to try to get an idea of what happens if you just quickly disconnect a solar cell, and things seemed to indicate that it's the inverter that switches the DC to AC that likes it the least.
Regardless of the specific reason, I'm quite confident you need something in the mix to eat the excess power from an underutilized solar plant, because otherwise the electrical engineers who built them probably would have taken the seemingly obvious and easy way. :)
solar panels are typically pretty warm already. There are even panels that allow you to push water through them to keep them cool.
I wonder if that would be more effective than dumping resistive heating into water. I suppose it could still be bad for the panel, i would assume panel manufacturers would have data on this, but im too lazy to look it up because whatever site they have is probably a shitfest that i wouldn't be able to navigate easily.
Yeah, when I looked them up they recommended a dump load to mitigate fire risk, since however hot they get normally is the baseline for when all the energy they produce gets turned into heat on the panel as well.
Gotta send extra power somewhere, and better to send it someplace built for it than into the expensive thing that's not.
yeah that checks out i suppose. One of these days i will get around to looking into it out of curiosity.
Those still have to be connected to the grid. be maintained, cooled, controlled, all of which costs money.
Okay? So does the entire rest of the grid.
The point is that those have a cost, so grid has to pay for them, essentially. Hence negative electricity prices.