In MA and a few other states, polluters are also required to buy “renewable energy credits.” Since I have a solar array I can sell my RECs whether I export energy or not. It’s my first year with a solar array, so I’m not sure how much to expect, but neighbors tell me that they earn between $500-$1000 a year.
Rules and regulations could solve that problem (meter not allowed to go backwards, solar companies are forced to pay some kind of battery credit, etc), but the free market will always outcompete.
Therefore, I forsee the future lies in 'smart' electricity meters which can charge different rates at different times of day - perhaps with minute by minute live pricing.
It’s called TOU pricing.
I’m happy enough that a battery will serve me equally well in both modes, but there’s definitely going to be a period where all it does is support self-consumption.
In turn, that means that at times of crisis, prices will be high, but not 1000x high.
Gasoline is another resource with live pricing, and suggesting "I want a subscription where I pay $3 per gallon fixed for a year, no matter how much I use and no matter what happens to the price of oil" wouldn't be something a fuel station would entertain, because they know that when the price was under $3 you'd buy elsewhere, and when the price was over $3 you'd buy millions of gallons and resell at a profit.
It's not latency free to act on price changes. If they spike while people are asleep, what do you expect would happen? And would people get a notification everytime the price changed at all. The logistics are hard.
Minute by minute pricing is not crazy to expect and integration with HVAC, battery systems, and inverters isn’t crazy to expect to occur.
Now every device in your home knows the price. For this to work, everyone must get the same price across the whole grid, and there must be sufficient grid capacity for energy to flow freely which isn't always the case. It will also cause issues with some very old (ie. 60+ year old) clocks with mechanical timers.
All of these issues can be fixed by updating the formula:
price_per_kwh = tan(min(max((-60 + system_frequency + published_offset) * 1000, -pi/2), pi/2))
The published_offset would be unique to each district and adjusted from time to time to keep old clocks working properly, and sometimes to deal with limited transfer properties of the grid...
But the neat thing is that even if you don't take into account the published_offset, you still make nearly optimal economic decisions.
People will choose it based on claims in the shop like "Smart timing cuts energy bills by 25% on average!".
It only takes a smallish percentage of demand to be reactive like that and really big price swings won't really happen.
Somewhere they'll still be grandad manually putting the dishwasher on at a cheap hour or turning the hot tub off whenever he sees the price is high, but I expect most to be automatic.
> I forsee the future lies in 'smart' electricity meters which can charge different rates at different times of day - perhaps with minute by minute live pricing.
That's what I was responding to, not the day/night predetermined pricing.
A max price guarantee would also give the supplier an incentive to have their planning in order.
Seriously though this was a huge issue a couple years ago with the freezing and blizzards that hit Texas.
Not all prime movers are the same with regard to grid dynamics and their impact.
Solar, wind, etc., almost universally rely on some form of inverter. This implies the need for solid state synthetic inertia to provide frequency response service to the grid.
Nuclear, coal, gas, hydropower, geothermal, etc., rely on synchronous machines to talk to the grid. The frequency response capability is built in and physically ideal.
Both can work, but one is more complicated. There are also factors like fault current handling that HN might think is trivial or to be glossed over, but without the ability to eat 10x+ rated load for a brief duration, faults on the grid cannot be addressed and the entire system would collapse into pointlessness. A tree crashing into a power line should result in the power line and tree being fully vaporized if nothing upstream were present to stop the flow of current. A gigantic mass of spinning metal in a turbine hall can eat this up like it's nothing. Semiconductors on a PCB in someone's shed are a different story.
Reddit post by an EE explaining it better than I can: https://www.reddit.com/r/AskEngineers/comments/qhear9/commen...
> There are also factors like fault current handling that HN might think is trivial or to be glossed over, but without the ability to eat 10x+ rated load for a brief duration, faults on the grid cannot be addressed and the entire system would collapse into pointlessness.
I don’t understand what you are talking about here. I don’t work in the utility world, I sell and run commercial electrical work, but handling available fault current in my world is as simple as calculating it and providing overcurrent protection with a high enough AIC rating or current limiting fuses. I don’t see why the utility side would be any different.
There are breakers, of course, but they react slowly enough that there will absolutely be a massive overdraw first. Then the breaker will open. Then, some small number of seconds later, it will automatically close.
It will attempt this two to four times before locking out, in case it just needs multiple bursts. It’s called “burning clear”, and it looks just as scary as you’d think… but it does work.
So, solar suppliers need to also survive this.
The lack of rotating mass in a solar site means the rest of the spinning mass of the generators needs to compensate to maintain frequency and voltage, right? So when clouds roll in and the solar field output drops quickly, it’s a challenge for the rest of the system to compensate since any other generator that spins will slow down much more slowly, giving the grid more time to react.
Also, I was not aware that inverters can only handle fault current that is 1.1x the nameplate capacity, that’s a big limitation. I can buy a 20A breaker with 200kaic, which is 10,000x higher than the breaker ampacity, which is extremely helpful for handling fault current.
I'd argue that nothing that uses semiconductors would be suitable for the task. They get you to maybe 2x rated current capacity for a meaningful duration. A spinning turbine can easily handle 10x or more for a much longer duration.
We could put so many redundant transistors in parallel that we have equivalent fault handling, but then we are into some strong economic issues. There's also no room for error with semiconductors. Once you start to disintegrate, it's all over ~instantly. There is no way to control this. A synchronous machine can trade downstream maintenance schedule for more current right now. The failure is much more gradual over time. A human operator can respond quickly enough if the machine is big enough.
The other trivial solution are synchronous condensers. Or just let the generators and maybe even turbines of future emergency reserve thermal plants spin with the grid without consuming any fuel.
Just ensure the proper margins exist in the grid and call in ancillary services as needed.
No need to make it harder than it needs to be.
One way to think about this problem is that our electrical grids are giant machines—in many ways, the largest machines that humanity has every constructed. The enormous machine of the grid is comprised of many smaller connected machines, and many of those have spinning loads with enormous mechanical inertia. Some of those spinning machines are generators (prime movers), and some are loads (like large electric motors at industrial facilities). All of those real, physical machines—in addition to other non-inertia generators and loads—are coupled together through the grid.
In the giant machine of the grid, electricity supply and demand have to be almost perfectly in sync, microsecond to microsecond. If they're not, the frequency of the grid changes. Abrupt changes in frequency translate into not only electrical/electronic problems for devices that assume 60 Hz (or 50, depending on where you are), but into physical problems for the machines connected to the grid. If the grid frequency suddenly drops (due to a sudden drop in generation capacity or sudden drop in load), the spinning masses connected to the grid will suddenly be under enormous mechanical stress that can destroy them.
It's obviously not possible to instantaneously increase or decrease explicit generation in response to spikes or drops in load (or alternatively, instantaneously increase or decrease load in response to spikes or drops in generation). But we don't need to: all of the spinning mass connected to the grid acts as a metaphorical (and literal) flywheel that serves as a buffer to smooth out spikes.
As the generation mix on the grid moves away from things with physical inertia (huge spinning turbines) and toward non-inertial sources (like solar), we need to use other mechanisms to ensure that the grid can smoothly absorb spikes. One way to do that is via spinning reserves (e.g. https://www.sysotechnologies.com/spinning-reserves/). Another way to do it is via sophisticated power electronics that mimic inertia (such as grid-forming inverters, which contrast with the much more common grid-following inverters).
To learn more about this topic, look up ancillary services (e.g. https://en.wikipedia.org/wiki/Ancillary_services). This Shift Key podcast episode is also a great introduction: https://podcasts.apple.com/us/podcast/spains-blackout-and-th...
This is a solvable problem, but it requires a solution nonetheless.
The frequency (50hz or 60hz) comes from those rotational forces from the generators and until we can eliminate them, we have to play nice with them.
Luckily, we have GFMI’s. Grid-forming inverters that can emulate 60hz push pull but you’re right that it’s more than just voltage since we are dealing with high voltage alternating current.
https://www.energy-storage.news/batteries-are-number-one-at-...
https://arena.gov.au/blog/australias-grid-forming-battery-re...
The issues you describe are from coal, oil, and gas lobbyists saying solar isn’t viable because of nighttime. When the grid is made up of batteries…
If every house had solar and some LiFePo batteries on site, high demand can be pulled from the grid while during low demand and high production, it can be given to the grid. The energy companies can store it, hydropower or batteries, for later. We have the ability. The political will is simply the lobbyists giving people money so they won’t. But we can just do it anyway. Start with your own home.