4 ms·

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

by 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.
      - 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.
      - 13y ago

by criley 13y ago

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.
    - 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.
    - 13y ago