5 ms·

It's interesting that they are selling the excess to the local supplier as they will be able to offset the cost faster, and start making a profit from it sooner

by rhdunn 3y ago

It's interesting that they are selling the excess to the local supplier as they will be able to offset the cost faster, and start making a profit from it sooner. That is, the point at which the amount of money saved from not paying for the electricity and the amount gained from selling the excess balances the cost for the installation.

PaulKeeble 3y ago
This happens in residential solar a lot. During the Spring/Summer/Autumn you will produce 1.5x - 2x what you consume on any given day but the peak of the power all comes at 9-10am to 2-3pm. You need large amounts of battery to move that power to cover the house for the other 2/3 of the day and that adds a lot of cost and is often similar price to the solar array. One of the best ways to deal with the problem is selling it back to the grid but how that is done vastly changes the payback period. Some states do it as a unit exchange so you sell 1KWh to them then you get that back later when you want it for no cost. Whereas many do a sale price with a price half or worse. Which price you can get for that power and whether its following wholesale (which tends to be peak early evening and be more during the day than night) can drastically change the pay off period.
- ajsnigrutin 3y ago
  So, power when you're not at home, the house is empty, it's warm, and your electric car is with you at work, and no power at night, when you need to cook, heat and charge your car.
  - Syonyk 3y ago
    Yup. This is one of the reasons I've argued in favor of "slow, at work charging" as the default for EVs. If you put in a bunch of 240V/16A chargers (3.8kW), as people show up in the 8-9 timeframe, they start charging, and the bulk of the charging happens in the ~10AM-2PM window that's after the morning peak, as solar is ramping up, and before the afternoon cooling/evening peak. You can even restrict the chargers a bit more in the morning if needed until off peak, though I'm not sure this is worth much over just using dumb chargers that are cheap to install. An average 35 miles a day driving (in the US) requires ~10kWh, so you've got a few hours of charging that can swallow an awful lot of power during the time nothing else is using much of it. It's far better than having to deal with evening and overnight charging.
    - ajsnigrutin 3y ago
      But for that you need every parking space in every office building equipped by a charger, and somehow have the grid strong enough to power all that from solar cells which need to be installed somewhere further away, since an average office building does not have enough roof space to charge all those cars. The hours you mentioned are usually spent at work and the cars are parked there (and not at home).
      - Syonyk 3y ago
        Who said every parking space? I didn't. Even at the coastal FAANG offices, EVs are still the minority. And not everyone will be charging every day. It's still fine to have a lot of non-charging spots - some people have short commutes and can be perfectly fine charging for 8-9h once a week (at 3.8kW, that's around 100 miles in 8h of charging). My experience from the early to mid teens is that the Leafs fought for charging, and the longer range BEVs charged if they could, and otherwise didn't get in the (damned near literal) fistfights over charging, but if someone showed up early, they'd plug in for the day. If you look at grid demand curves, that "late morning, early afternoon" time spot is the mid-day low for most grids. So there's excess capacity anyway, and if you look at the "duck curve" sort of graphs, there's a ton of solar on the grid then anyway. This is only increasing with time. So we may as well make decent use of it. You could also have some lower power, 1440W charger slots (15A @ 120V) for those who don't need much power - it'll still make up an average day's driving in 8h of charging, but since it's literally the same wiring cost and such to run 120V as 240V, I'm not sure you gain much with it, and it's now perfectly valid for chargers to coordinate regarding total circuit demand anyway.
        lucb1e 3y ago
        > Who said every parking space? I didn't. Even at the coastal FAANG offices, EVs are still the minority. Might just be me, but I read any comment talking about an ideal future scenario for charging vehicles (if not otherwise qualified) as being for the ideal world where the 99% switched to electric vehicles. If you're talking about planning for the situation that we have today... that doesn't seem too useful and would be outdated in two-odd years.
  - morsch 3y ago
    Your house can act as a thermal battery and draw power to heat or cool it while there is a surplus. You can also have a hot water reservoir as another large thermal battery for showering etc.
bjelkeman-again 3y ago
Where I am, Sweden, last year I got 3x the price during the day for my sold electricity, than what I paid at night. So car charging at night and selling electricity during the day.

by rhdunn 3y ago

PaulKeeble 3y ago

This happens in residential solar a lot. During the Spring/Summer/Autumn you will produce 1.5x - 2x what you consume on any given day but the peak of the power all comes at 9-10am to 2-3pm. You need large amounts of battery to move that power to cover the house for the other 2/3 of the day and that adds a lot of cost and is often similar price to the solar array. One of the best ways to deal with the problem is selling it back to the grid but how that is done vastly changes the payback period. Some states do it as a unit exchange so you sell 1KWh to them then you get that back later when you want it for no cost. Whereas many do a sale price with a price half or worse. Which price you can get for that power and whether its following wholesale (which tends to be peak early evening and be more during the day than night) can drastically change the pay off period.

ajsnigrutin 3y ago
So, power when you're not at home, the house is empty, it's warm, and your electric car is with you at work, and no power at night, when you need to cook, heat and charge your car.
- Syonyk 3y ago
  Yup. This is one of the reasons I've argued in favor of "slow, at work charging" as the default for EVs. If you put in a bunch of 240V/16A chargers (3.8kW), as people show up in the 8-9 timeframe, they start charging, and the bulk of the charging happens in the ~10AM-2PM window that's after the morning peak, as solar is ramping up, and before the afternoon cooling/evening peak. You can even restrict the chargers a bit more in the morning if needed until off peak, though I'm not sure this is worth much over just using dumb chargers that are cheap to install. An average 35 miles a day driving (in the US) requires ~10kWh, so you've got a few hours of charging that can swallow an awful lot of power during the time nothing else is using much of it. It's far better than having to deal with evening and overnight charging.
  - ajsnigrutin 3y ago
    But for that you need every parking space in every office building equipped by a charger, and somehow have the grid strong enough to power all that from solar cells which need to be installed somewhere further away, since an average office building does not have enough roof space to charge all those cars. The hours you mentioned are usually spent at work and the cars are parked there (and not at home).
    - Syonyk 3y ago
      Who said every parking space? I didn't. Even at the coastal FAANG offices, EVs are still the minority. And not everyone will be charging every day. It's still fine to have a lot of non-charging spots - some people have short commutes and can be perfectly fine charging for 8-9h once a week (at 3.8kW, that's around 100 miles in 8h of charging). My experience from the early to mid teens is that the Leafs fought for charging, and the longer range BEVs charged if they could, and otherwise didn't get in the (damned near literal) fistfights over charging, but if someone showed up early, they'd plug in for the day. If you look at grid demand curves, that "late morning, early afternoon" time spot is the mid-day low for most grids. So there's excess capacity anyway, and if you look at the "duck curve" sort of graphs, there's a ton of solar on the grid then anyway. This is only increasing with time. So we may as well make decent use of it. You could also have some lower power, 1440W charger slots (15A @ 120V) for those who don't need much power - it'll still make up an average day's driving in 8h of charging, but since it's literally the same wiring cost and such to run 120V as 240V, I'm not sure you gain much with it, and it's now perfectly valid for chargers to coordinate regarding total circuit demand anyway.
      - lucb1e 3y ago
        > Who said every parking space? I didn't. Even at the coastal FAANG offices, EVs are still the minority. Might just be me, but I read any comment talking about an ideal future scenario for charging vehicles (if not otherwise qualified) as being for the ideal world where the 99% switched to electric vehicles. If you're talking about planning for the situation that we have today... that doesn't seem too useful and would be outdated in two-odd years.
- morsch 3y ago
  Your house can act as a thermal battery and draw power to heat or cool it while there is a surplus. You can also have a hot water reservoir as another large thermal battery for showering etc.

bjelkeman-again 3y ago

Where I am, Sweden, last year I got 3x the price during the day for my sold electricity, than what I paid at night. So car charging at night and selling electricity during the day.