5 ms·

Yes! But in that paradigm, where you generate 80%+ of your needed energy and rely on the grid for the rest, how does that affect the utility? The only differen

by criley 13y ago

Yes! But in that paradigm, where you generate 80%+ of your needed energy and rely on the grid for the rest, how does that affect the utility? The only difference to them is that you draw less power than you used to. Sure, it would benefit them to learn your habits so they can manage steady power delivery at scale, but they don't get a say in your solar rollout. They don't get to prevent it. They don't get to be skeptical (or if they are, they can't act on it). The person I'm replying to seemed to say that the engineers at utilities are skeptical of this technology and honestly I don't understand how they're relevant, since utilities aren't rolling out the technology, maintaining the technology, etc.

sp332 13y ago
But what if you generate 110% of your electricity needs? You would push out more power than is coming in, sometimes literally running the meter backwards.
- criley 13y ago
  Are we saying that there is no way to prevent power from going backwards back to the utility? I figured what you generated went directly to your storage system, you drew from your storage system OR the grid, or some third part intelligently drew from the grid or your system as necessary. Is it functionally impossible to have solar panels that don't "run the meter backwards?" Because I can see how that would threaten the infrastructure that wasn't designed for it. I mean, I see places like Apple generating all their electricity on location for their new planned office and using the grid as backup. Is Apple sending their excess power back to the utility? Totally different scale, I'm well aware, but just curious.
  - toomuchtodo 13y ago
    Yes, you can configure inverters to not dump excess current back to the utility. You either charge batteries or you dump the power into a load like an electric water heater. In almost all grid-tied scenarios though, you want to sell the power back to the utility. I'm not familiar with commerical operations, as they would fall under power purchase agreements (PPAs), but with residential installations your meter quite literally does spin backwards or a separate meter is used to determine how much power you've sent back to the grid. This is dependent on how the utility compensates you for the power you generate (spin the meter back if its a credit or the same price as what your purchase it from them at, separate meter if the pricing paid to you is different than the retail rate). As the article states, we don't have the issues in the US that Germany has yet, because Germany produces so much more solar energy than in the US. At some point though, questions will need to be answered about who is going to pay for the spinning capacity (likely natural gas generators) that isn't used except for those rare times when the wind isn't blowing, the sun isn't shinning, and you can't drag enough power in from another geographic region over HVDC transmission lines.
    - marshray 13y ago
      > who is going to pay for the spinning capacity (likely natural gas generators) that isn't used That doesn't sound like a bad problem to have. Fukushima showed us how hard it is to turn a nuke on and off quickly, but I would think most hydrocarbon burning and other generation systems could be throttled according to demand. If you really have a problem with too much energy, well, smelt some aluminum or electrolyze water or something.
      - ramchip 13y ago
        "Spinning Reserve is the on-line reserve capacity that is synchronized to the grid system and ready to meet electric demand within 10 minutes of a dispatch instruction by the ISO. Spinning Reserve is needed to maintain system frequency stability during emergency operating conditions and unforeseen load swings." http://www.caiso.com/docs/2003/09/08/2003090815135425649.pdf http://www.caiso.com/docs/2003/09/08/2003090815135425649.pdf The poster isn't saying they're producing energy, just that they must be ready to do so at any time.
        toomuchtodo 13y ago
        Correct. You're not paying for that field of gas turbines to run. You're paying for them to sit in the field warm until issued to run, because if they're not there, hello blackouts.
        jnw2 13y ago
        Spinning reserve ought to be replaced with batteries. I bet some of it could be replaced with batteries today with the utilities' customers saving money, aside from the sunk costs not then providing the proper return on capital to their investors.
        NickNameNick 13y ago
        Do you have any idea how big and environmentally unfriendly those batteries would have to be? Ready reserve is generally provided by peaking generators (the aforementioned natural gas turbines) and by hydro dams. There aren't many batteries that can provide hundreds of megawatts for hours at a time.
- Negitivefrags 13y ago
  I don't know how it works elsewhere, but in New Zealand at least, power going each way is metered separately. Power is sold to the electric company at a much lower rate than the power that is bought from the electric company. So you might buy power for 27c/kwh and sell it for 3c/kwh.
  - ensignavenger 13y ago
    In the US it depends on where you are at and who your power company is. Some times they do it the way you describe in NZ, but in many areas it is more the way the OP describes, where there is one meter, and sometimes it literally runs backwards- only if there is an excess at the end of the month is it credited at the lower rate.
snowwrestler 13y ago
> The only difference to them is that you draw less power than you used to. That is not the only difference; the pattern of your load changes too. With 100% grid-supplied power, changes in load are driven by slow-moving, predictable systems like sunrise/sunset, weather, and seasons. If you are running your own solar array, though, you will vary your grid load on much shorter time scales unless you invest in a big battery pack to smooth out the variations in insolation from clouds and storms. And even the normal daily variation will be stronger, since when it gets dark you'll not only be increasing your load (turning on lights, TV, cooking, etc), you'll also be losing your local generation. The current electric grid is not built to handle such large changes in load on such short timeframes.
- kalleboo 13y ago
  Example of dealing with load patterns: Handling when 1.75 million britons make tea after a popular soap opera ends http://www.bbc.co.uk/britainfromabove/stories/people/teatimebritain.shtml http://www.bbc.co.uk/britainfromabove/stories/people/teatime...
- gngeal 13y ago
  With 100% grid-supplied power, changes in load are driven by slow-moving, predictable systems like sunrise/sunset, weather, and seasons. If you are running your own solar array, though, you will vary your grid load on much shorter time scales I'm not so sure that these latter variations are significantly less predictable than what you mention in the former paragraph. Isn't the output of a solar array dependent on the insolation? Isn't the insolation dependent on the cloud cover? Can't you predict the cloud cover in any single place simply by taking advantage of real-time meteo satellite data? A similar feedback could be established for wind power. Given enough data, I'm reasonably certain that models could be established that would allow you to predict how the solar and wind power generation distribution is going to change in the next hour(s) so that you could prepare for it.
  - akiselev 13y ago
    The problem isn't the prediction, full solar is probably only slightly more volatile than full grid on a large scale. Maybe not hourly but the companies would still be able to work out the supply side. The issue is that the supply side and supporting infrastructure is built for an entirely different system where power leaves the power plants and goes through the grid to consumers. Now people are adding solar panels which generate a ton of electricity during the day (when everyone is largely at work/school) that must then be fed back into the grid, opposite the direction of normal flow.

by criley 13y ago

sp332 13y ago

But what if you generate 110% of your electricity needs? You would push out more power than is coming in, sometimes literally running the meter backwards.

criley 13y ago
Are we saying that there is no way to prevent power from going backwards back to the utility? I figured what you generated went directly to your storage system, you drew from your storage system OR the grid, or some third part intelligently drew from the grid or your system as necessary. Is it functionally impossible to have solar panels that don't "run the meter backwards?" Because I can see how that would threaten the infrastructure that wasn't designed for it. I mean, I see places like Apple generating all their electricity on location for their new planned office and using the grid as backup. Is Apple sending their excess power back to the utility? Totally different scale, I'm well aware, but just curious.
- toomuchtodo 13y ago
  Yes, you can configure inverters to not dump excess current back to the utility. You either charge batteries or you dump the power into a load like an electric water heater. In almost all grid-tied scenarios though, you want to sell the power back to the utility. I'm not familiar with commerical operations, as they would fall under power purchase agreements (PPAs), but with residential installations your meter quite literally does spin backwards or a separate meter is used to determine how much power you've sent back to the grid. This is dependent on how the utility compensates you for the power you generate (spin the meter back if its a credit or the same price as what your purchase it from them at, separate meter if the pricing paid to you is different than the retail rate). As the article states, we don't have the issues in the US that Germany has yet, because Germany produces so much more solar energy than in the US. At some point though, questions will need to be answered about who is going to pay for the spinning capacity (likely natural gas generators) that isn't used except for those rare times when the wind isn't blowing, the sun isn't shinning, and you can't drag enough power in from another geographic region over HVDC transmission lines.
  - marshray 13y ago
    > who is going to pay for the spinning capacity (likely natural gas generators) that isn't used That doesn't sound like a bad problem to have. Fukushima showed us how hard it is to turn a nuke on and off quickly, but I would think most hydrocarbon burning and other generation systems could be throttled according to demand. If you really have a problem with too much energy, well, smelt some aluminum or electrolyze water or something.
    - ramchip 13y ago
      "Spinning Reserve is the on-line reserve capacity that is synchronized to the grid system and ready to meet electric demand within 10 minutes of a dispatch instruction by the ISO. Spinning Reserve is needed to maintain system frequency stability during emergency operating conditions and unforeseen load swings." http://www.caiso.com/docs/2003/09/08/2003090815135425649.pdf http://www.caiso.com/docs/2003/09/08/2003090815135425649.pdf The poster isn't saying they're producing energy, just that they must be ready to do so at any time.
      - toomuchtodo 13y ago
        Correct. You're not paying for that field of gas turbines to run. You're paying for them to sit in the field warm until issued to run, because if they're not there, hello blackouts.
      - jnw2 13y ago
        Spinning reserve ought to be replaced with batteries. I bet some of it could be replaced with batteries today with the utilities' customers saving money, aside from the sunk costs not then providing the proper return on capital to their investors.
        NickNameNick 13y ago
        Do you have any idea how big and environmentally unfriendly those batteries would have to be? Ready reserve is generally provided by peaking generators (the aforementioned natural gas turbines) and by hydro dams. There aren't many batteries that can provide hundreds of megawatts for hours at a time.
Negitivefrags 13y ago
I don't know how it works elsewhere, but in New Zealand at least, power going each way is metered separately. Power is sold to the electric company at a much lower rate than the power that is bought from the electric company. So you might buy power for 27c/kwh and sell it for 3c/kwh.
- ensignavenger 13y ago
  In the US it depends on where you are at and who your power company is. Some times they do it the way you describe in NZ, but in many areas it is more the way the OP describes, where there is one meter, and sometimes it literally runs backwards- only if there is an excess at the end of the month is it credited at the lower rate.

snowwrestler 13y ago

> The only difference to them is that you draw less power than you used to. That is not the only difference; the pattern of your load changes too. With 100% grid-supplied power, changes in load are driven by slow-moving, predictable systems like sunrise/sunset, weather, and seasons. If you are running your own solar array, though, you will vary your grid load on much shorter time scales unless you invest in a big battery pack to smooth out the variations in insolation from clouds and storms. And even the normal daily variation will be stronger, since when it gets dark you'll not only be increasing your load (turning on lights, TV, cooking, etc), you'll also be losing your local generation. The current electric grid is not built to handle such large changes in load on such short timeframes.

kalleboo 13y ago
Example of dealing with load patterns: Handling when 1.75 million britons make tea after a popular soap opera ends http://www.bbc.co.uk/britainfromabove/stories/people/teatimebritain.shtml http://www.bbc.co.uk/britainfromabove/stories/people/teatime...
gngeal 13y ago
With 100% grid-supplied power, changes in load are driven by slow-moving, predictable systems like sunrise/sunset, weather, and seasons. If you are running your own solar array, though, you will vary your grid load on much shorter time scales I'm not so sure that these latter variations are significantly less predictable than what you mention in the former paragraph. Isn't the output of a solar array dependent on the insolation? Isn't the insolation dependent on the cloud cover? Can't you predict the cloud cover in any single place simply by taking advantage of real-time meteo satellite data? A similar feedback could be established for wind power. Given enough data, I'm reasonably certain that models could be established that would allow you to predict how the solar and wind power generation distribution is going to change in the next hour(s) so that you could prepare for it.
- akiselev 13y ago
  The problem isn't the prediction, full solar is probably only slightly more volatile than full grid on a large scale. Maybe not hourly but the companies would still be able to work out the supply side. The issue is that the supply side and supporting infrastructure is built for an entirely different system where power leaves the power plants and goes through the grid to consumers. Now people are adding solar panels which generate a ton of electricity during the day (when everyone is largely at work/school) that must then be fed back into the grid, opposite the direction of normal flow.