4 ms·

Building a solar-only grid is hard. People don't realise that it's a huge challenge kepping the whole grid synced at 50/60Hz when there's a large amount of sola

Building a solar-only grid is hard. People don't realise that it's a huge challenge kepping the whole grid synced at 50/60Hz when there's a large amount of solar being exported, never mind the entire grid.

eqvinox 1y ago
Why would anyone build a solar-only grid?
- pydry 1y ago
  Nobody would, but the nuclear and carbon lobbies like to use straw men models - combining things like laptop batteries with solar to "prove that you cant live without them" and these models leak into public discourse. A fully green energy grid would most cost effectively comprise of: * Solar (generally strongest when wind is low, ~5x cheaper per kwh than nuclear power) * Wind (generally strongest when sun is low, ~5x cheaper than nuclear power) * Large scale interconnected grids to offset intermittency. * Batteries and pumped storage for short term storage (~90% roundtrip efficiency but expensive to store long term) * Syngas for seasonal storage (~50% roundtrip efficiency but cheap to store long term).
delusional 1y ago
My understanding is that this is mostly a technology problem. Current solar does a lot of grid-following. If solar instead did some sort of "grid driving" with an external synchronizer I would expect this to be a fairly solvable problem.
- mousethatroared 1y ago
  Put a motor-generator pair next the solar or wind farm and the problem of frequency stabilization is largely solved. Adds a big flywheel for more initial mass. But now you've changed the economics by adding a big, inefficient (0.95*0.95%), and expensive piece of equipment.
  - Calwestjobs 1y ago
    flywheel nonsense, just add battery.
    - JumpCrisscross 1y ago
      > flywheel nonsense, just add battery Flywheels are batteries. If your model is predicated on a particular chemistry of battery, it’s overfitted.
    - mousethatroared 1y ago
      Which requires inverters, which are a huge problem. Riddle me this, what instantaneous voltage should an inverter target if the grid's at a fault condition? Stated another way, how do you define the frequency of a non-sinuoid? Careful, get the wrong answer and you get a short and you help melt millions of dollars of equipment, some with year old lead times.
      - Calwestjobs 1y ago
        it is no riddle. you are asking questions from 1942. except you put inverter into it. so you either think about current technology or go spark some wires. you can island and not island at same time. decentralized grid means DECENTRALIZED grid. every renewable needs battery next to it.
        mousethatroared 1y ago
        Indeed, not a problem to solve if you have all day to measure it. The trick is measuring a frequency in the 60s of Hz of a non-sinusoid within a thousandth of a second. Otherwise you get a short.
  - rcxdude 1y ago
    You don't need that, though, the problem is entirely solvable through the inverters. Having some batteries also helps. Combined it's much better grid intertia than spinning motors.
- zidel 1y ago
  The term of art you are probably looking for here is grid forming inverter. The ENTSO-E class list on Wikipedia is probably a good starting point for some of the problems that one might want to handle: https://en.wikipedia.org/wiki/Inverter-based_resource#Grid-forming https://en.wikipedia.org/wiki/Inverter-based_resource#Grid-f...
Havoc 1y ago
Fast response battery systems largely solve the frequency issue. Unfortunately there is a lot of incentive to put solar on the grid by individual players, while the cost to do the frequency response is collectivized so tends to lag behind what is needed. Bit surprised countries aren't just legislating this away. For every MW you put on the grid that doesn't have rotational inertia you need to contribute X money to a fund that builds stabilization capacity.

eqvinox 1y ago

Why would anyone build a solar-only grid?

pydry 1y ago
Nobody would, but the nuclear and carbon lobbies like to use straw men models - combining things like laptop batteries with solar to "prove that you cant live without them" and these models leak into public discourse. A fully green energy grid would most cost effectively comprise of: * Solar (generally strongest when wind is low, ~5x cheaper per kwh than nuclear power) * Wind (generally strongest when sun is low, ~5x cheaper than nuclear power) * Large scale interconnected grids to offset intermittency. * Batteries and pumped storage for short term storage (~90% roundtrip efficiency but expensive to store long term) * Syngas for seasonal storage (~50% roundtrip efficiency but cheap to store long term).

delusional 1y ago

My understanding is that this is mostly a technology problem. Current solar does a lot of grid-following. If solar instead did some sort of "grid driving" with an external synchronizer I would expect this to be a fairly solvable problem.

mousethatroared 1y ago
Put a motor-generator pair next the solar or wind farm and the problem of frequency stabilization is largely solved. Adds a big flywheel for more initial mass. But now you've changed the economics by adding a big, inefficient (0.95*0.95%), and expensive piece of equipment.
- Calwestjobs 1y ago
  flywheel nonsense, just add battery.
  - JumpCrisscross 1y ago
    > flywheel nonsense, just add battery Flywheels are batteries. If your model is predicated on a particular chemistry of battery, it’s overfitted.
  - mousethatroared 1y ago
    Which requires inverters, which are a huge problem. Riddle me this, what instantaneous voltage should an inverter target if the grid's at a fault condition? Stated another way, how do you define the frequency of a non-sinuoid? Careful, get the wrong answer and you get a short and you help melt millions of dollars of equipment, some with year old lead times.
    - Calwestjobs 1y ago
      it is no riddle. you are asking questions from 1942. except you put inverter into it. so you either think about current technology or go spark some wires. you can island and not island at same time. decentralized grid means DECENTRALIZED grid. every renewable needs battery next to it.
      - mousethatroared 1y ago
        Indeed, not a problem to solve if you have all day to measure it. The trick is measuring a frequency in the 60s of Hz of a non-sinusoid within a thousandth of a second. Otherwise you get a short.
- rcxdude 1y ago
  You don't need that, though, the problem is entirely solvable through the inverters. Having some batteries also helps. Combined it's much better grid intertia than spinning motors.
zidel 1y ago
The term of art you are probably looking for here is grid forming inverter. The ENTSO-E class list on Wikipedia is probably a good starting point for some of the problems that one might want to handle: https://en.wikipedia.org/wiki/Inverter-based_resource#Grid-forming https://en.wikipedia.org/wiki/Inverter-based_resource#Grid-f...

Havoc 1y ago

Fast response battery systems largely solve the frequency issue. Unfortunately there is a lot of incentive to put solar on the grid by individual players, while the cost to do the frequency response is collectivized so tends to lag behind what is needed. Bit surprised countries aren't just legislating this away. For every MW you put on the grid that doesn't have rotational inertia you need to contribute X money to a fund that builds stabilization capacity.