4 ms·

Your car isn't at the house while solar is being produced though for many/most people right? This seems unrealistic.

• eru 10y ago
  A lot of cars sit in carparks during the day.
  • ssmoot 10y ago
    I guess the implication being there'd be a massive number of charge spots and you could swipe your card to pull off the grid what your home is putting on. But this would mean turning a car-park with just 40 plugs into needing 1,600 amps at 240v. With those grid connected homes having modest 2kWh solar installations you're talking 80kw/h. If you only spent 3kWh getting to work on average (double that for the round-trip) you'd fully charge the cars in a couple hours. So I guess the goal would be to run your home off the unused capacity. But then you're putting a far heavier duty cycle on those batteries. Whose going to pay for them when that $10,000 pack needs to be refurbished in five years? Or do we just accept EVs depreciating down to zero when the pack replacement cost exceeds their value? There may well be good answers to all this. Just some things that popped into my head. It would seem at first glance to be very costly for the car park, the grid and the consumer. I'm not sure any technology with the depreciation schedule of lithium batteries makes sense financially or environmentally?
    • eru 10y ago
      Thanks for working through some numbers. My modest intended implication was that if we only care about total sums, where the car is doesn't matter too much, as long as it has access to the grid. The economics could work out, if the car park charges you more for electricity than they pay the grid; and the grid your home less that it charges the car park. The car park and the grid both take a cut. For the home- and car owner, this works out to a slightly less efficient battery cycle. (If you convert the money charged back into the equivalent amount of energy.) Of course, if you are going to use your electric vehicle like as a battery like this, it's going to affect the battery's useful life. The same would happen with the single purpose battery you have sitting in your home. Now, the performance characteristics one looks for in a car battery and a grid storage battery are different. So I don't know whether using the car battery as a home battery even makes sense. (Ie home batteries can be bulky, but better be cheap. Car batteries have to be light and charge fast.) On a more refined note, one can play the same game, but only do it during spikes. Ie the car can stop charging during a spike in demand, and even uncharge if the spike gets big enough or the battery is already full. This won't do much for the diurnal cycle (that we discussed above), but a contribution during the spikiest peaks might already be worthwhile. My gut feeling is that we will see the demand shaping for charging, but I am more doubtful about whether we'll see cars actively feeding back into the grid.
• zaroth 10y ago
  I guess it could drive itself home after dropping its owner off at work, but that's probably too inefficient in most cases to make a full extra round-trip just to charge up with the panels at home.
• toomuchtodo 10y ago
  Its probably sitting at your employer's lot. A lot that that would have charge stations.
  • ssmoot 10y ago
    None that I've worked at. And aren't small businesses the biggest category of employer?
    • eru 10y ago
      I guess toomuchtodo is talking about the future, not the present.
      • toomuchtodo 10y ago
        I am!