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Vermont replacing power plants with home batteries

389 points · 304 comments · devonnull

  1. nonfamous · · focus · HN ↗
    I’m in a similar setup where I live in Australia. Our house has solar and battery — unlike the people in the FA, we purchased it directly ourselves, although with a significant government rebate.

    Our battery is under automatic VPP control, but it’s not like it randomly starts exporting when we don’t want it to. When regional demand is high (hot days) or supply is low (no wind or cloudy), our battery might start exporting. But that’s a good thing for us, because our electricity is priced wholesale and changes every 5 minutes, and export rates are high in this situation. A couple of times there have been price spikes and we’ve made a few hundred dollars in under a hour. It’s a win-win for us (making money) and the grid (providing stability). To be fair, those spikes are rarer now than they were a year ago.

    You can always control the battery if you want. Sometimes I’ll manually export even if prices aren’t high if I know I don’t need the power in my battery. Sometimes I’ll prevent export if I know I want to charge the car overnight from the battery. But mostly I let it do its thing.

    From an investment perspective, the battery has been a no-brainer. Even without the windfalls from price spikes, being able to defer grid consumption to daylight hours (when wholesale prices are very cheap or even negative, i.e. we get paid to charge the car) puts the ROI in the 3-5 year range.

    1. fransje26 · · focus · HN ↗
      How is the price system set up when re-injecting to the grid?

      Do you get the full 5 minute spot price, or do they then charge you re-injection costs per kWh?

      And are the grid-costs fixed yearly, or do they also charge you per kWh re-injected?

      1. nonfamous · · focus · HN ↗
        Distribution charges are per kwh and vary by the hour (more expensive in high-demand morning and evenings, lower during the day and at night). The spot price has to be high enough to exceed the distribution charges for net income on export.

        Most of the time, distribution charges are higher than the spot wholesale prices for import and export.

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