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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. amenghra · · focus · HN ↗
      Orthogonal but related: where I live, homeowners might get charged negative prices at times for solar re-injected in the network. This doesn't make a ton of sense for me since you could just unplug the panels instead of being charged for the production! However, the electric company charges you retroactively (on a 15-min bucket) so you would need an accurate model to "beat them at their game". Negative electric prices in a country with a huge amount of solar/wind/hydro is surprising, since all of these production methods can stopped on demand (and even reversed in the case of some hydro setups).
      1. ZeroGravitas · · focus · HN ↗
        The negative price can either be from subsidized renewables that are passing some of that subsidy onto people who use the power (a good thing!) or remaining coal plants that can't flex fast enough and would rather pay than incur extra costs from flexing (which is good in that they are being effectively fined for lack of flexibility but bad in that they are inflexible and still generating dirty power while more flexible renewables curtail).

        If clean energy is being curtailed increasing usage is a better response which negative prices also incentivize but in many jurisdictions they refuse to pass those price signals onto users because they'd rather waste clean energy so they can sell them dirty energy later.

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