But what I don't get: the electricity producer has to pay someone to take the excess electricity off their hands? The producer can't route the excess to, well... nowhere?
If we assume the numbers for a sort of medium-size nuclear plant, we've got a total power generation of 500MW.
Dumping that kind of power is... hard.
If I haven't missed an order of magnitude, that's enough to boil an Olympic-sized swimming pool in about 25 minutes (500MW to boil 2.5ML of water, assuming STP).
So you'd either need to build and maintain the infrastructure to burn that kind of energy when it isn't needed (not cheap) or just sell the power at a loss (likely cheaper).
This is in a country that — as I understand it — could definitely do with more desalinated water. How capital intensive can putting a huge kettle element in the sea with something to catch the vapour be?
Why not route it to a nearby neighborhood? It's free it doesn't matter if a lot is lost in transmission and you don't need to pay somebody to take it.
This would be the case, what's wrong with this? It's better than paying people to take your electricity and isn't this how business works? I don't see why they shouldn't be able to increase supply (And hence reduce other suppliers) just because it would ruin the profit margins of others. Unless there's something I'm missing here or not following correctly.
And once you're generating there's no great way to just "disconnect" in many cases. If you disconnect the load, the charge still has to go somewhere. Preferably not into nearby equipment. Even the safety switches are non-trivial when dealing with high power - if you break a cable connection, the electric arc will still keep them connected.
I guess the process is somehow invertible, and once reached a certain static charge each panel stops absorbing energy?
In which case you're sort of already dumping the (non)produced energy in the environment- as heat, on each single panel?
> Electric power is the product of voltage and current. If there is no external circuit, there can be no current and thus no electric power can be delivered by the panel, i.e., the "electricity" is never developed and thus, there is no need to consider "where it goes".
There's also an interesting discussion in the linked post in more depth about electron hole-pairs.
My takeaway is that the temperature in the panel will not rise due to it absorbing any power that would otherwise go down the wires were the circuit complete.
"The equilibrium temperature of the connected panel should be slightly lower than the disconnected panel, because those hole recombinations introduce heat. But the efficiency is only something like 12% to begin with. So the temperature difference isn't like the difference between a white and black surface. More like the difference between a dark and slightly darker surface"
In practical terms the energy has to go somewhere. Maybe they could build massive dump resistors to burn off the energy that way but doing so would only increase load on everything (shortening component lives) for no gain.
(The heat being dumped is usually low-temperature waste heat, not final output.)
The negative bids aren't coming from suppliers who can easily turn off, they have already turned off at this point.
And, cooling towers don't work by pumping hot water back into a lake. No need for a tower for that. They work by evaporating it, which lets you dump both the heat up to 100C, plus the latent heat of liquid -> gas.
There is a bit of leeway in that turbine power stations will run a little bit slower or faster depending on exact use (resulting in a grid frequency a little bit faster or slower than 50Hz) but the difference has to be made up quickly.
(not an expert, this is badly remembered from Internet articles so probably hurts to read for real experts, I'm sorry. But I hope I got the gist sort of right.)
In a wholesale electricity market we have a market operator who estimates the demand for the near term future and opens the market up to bids for supply.
Suppliers bid a certain capacity for each period, with the operator typically accepting firm supply offers, contingency supply offers, and ancillary service offers in advance. Since some suppliers are “baseload” (ie: unable to adjust output to suit the current level of demand) they will typically bid low to always be paid for their supply. Everyone else will be affected by these bids because the “baseload” operators are typically not only inflexible but also have huge capacity.
In periods where total demand is low relative to total supply capacity, the wholesale bids will drop to low prices. For the baseload suppliers, they would prefer to pay for someone to use their excess power rather than damage their equipment by either turning it off or reducing output below certain minimums. A baseload supplier might, for example, be facing a maintenance cost of a million dollars versus paying the market a hundred thousand to create extra demand for surplus energy. So rather than turn off equipment they will bid negative prices on the wholesale market.
A second cause of negative wholesale prices is established players with large war chests waging economic war against new entrants. They know solar farms have razor thin margins, so it is worth spending a few tens of million dollars to drive the solar farm bankrupt. Enough negative pricing periods during peak solar capacity means the solar farm is not making any money. If the baseload operator knows roughly the breakeven point for the solar farm, they will know how much they have to spend in order to shut the solar farm out of the market and bankrupt them. There are no rules against this kind of activity in the Australian energy market.