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I misread that as "hospital" instead of "hospitality" on my first read, which actually brings up an interesting tangent. If the Tesla stations make use of and

I misread that as "hospital" instead of "hospitality" on my first read, which actually brings up an interesting tangent. If the Tesla stations make use of and store solar power, would they be a viable backup power source for hospitals? Or are the power requirements for a hospital on backup energy way too large for that sort of thing?

chaz 13y ago
Aren't these stations just connected to the grid and any power is just put back into it to help offset charging costs? I don't think there's any actual storage. Not every Supercharger station has solar panels.
sp332 13y ago
I think solar is too unreliable to be a backup power source for much of anything, especially something like a hospital.
MiguelHudnandez 13y ago
The amount of solar panels you'd need to charge a Tesla at supercharger rates would be ridiculous. They may have solar panels, but that is just something cute that might make a small dent in the installation's grid power consumption. However, you are on to something [1], though it's more for cars that are parked for long periods during the day. The point of a supercharging station is contrary to donating your vehicle's power to the grid. 1: http://www.scientificamerican.com/article.cfm?id=how-to-sell-power-from-electric-cars-back-to-the-grid http://www.scientificamerican.com/article.cfm?id=how-to-sell...
- pbreit 13y ago
  Are you sure? "plans are to install on-site grid storage to make them self-reliant with their own energy supply"
  - icegreentea 13y ago
    Well... let's do the math! Incident solar radiation is about 1 kW per meter squared. Assume 10% end to end efficiency (including solar -> electric, storage, and actual charging efficiency... this is optimistic, but doable... certainly not the cheapest though). You now need 10 square meters of panel to supply 1 kW. Assume sun is out for 12 hours a day, and for the full 12 hours you get all 1 kW/m^2 incident radiation (this is very very generous). The car has a 60kWh battery. So if we want to find out how much panel it takes for one station to charge one car a day... 60kWh to charge, but 12 hours to charge it up, so you basically need 5kW, which is 50 m^2 of panel. Which honestly isn't -THAT- big. Its a 7 meter square. Now... from my random snooping around, and my own impressions, I would say that a 'large' gas station typically covers something like... 500-600 meters squares (thats 5300 to 6500 square feet). That would be enough to super optimistically charge 10-12 cars a day. I saw optimistic, because incident solar radiation is not that kind. Can take a looksey here: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/ http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook... If you pick average, annual, and single axis east-west tracking (which I believe is the best bang for the buck), you see on the solar map, the BEST places in the US gets 5-6 kWh/m^2/day, compared to our assumption of 12 kWh/m^2/day. The feasibility of superchargers being even 90% off the grid is of course completely dependent on the ratio of size of supercharger panel array and rate of cars charging. But given the above, I'm inclined to believe that it is highly impractical for the majority of super charger stations to become actually self reliant, especially in high traffic areas.
    - btilly 13y ago
      A supercharger network is going to have a lot of stations on lonely stretches of highway. Given how few Teslas there are being taken on those trips, you're going to want charging stations in places where there will be very, very little usage. I can easily see a random station on I-10 near the CA/AZ border being entirely self-reliant...

chaz 13y ago

Aren't these stations just connected to the grid and any power is just put back into it to help offset charging costs? I don't think there's any actual storage. Not every Supercharger station has solar panels.

sp332 13y ago

I think solar is too unreliable to be a backup power source for much of anything, especially something like a hospital.

MiguelHudnandez 13y ago

The amount of solar panels you'd need to charge a Tesla at supercharger rates would be ridiculous. They may have solar panels, but that is just something cute that might make a small dent in the installation's grid power consumption. However, you are on to something [1], though it's more for cars that are parked for long periods during the day. The point of a supercharging station is contrary to donating your vehicle's power to the grid. 1: http://www.scientificamerican.com/article.cfm?id=how-to-sell-power-from-electric-cars-back-to-the-grid http://www.scientificamerican.com/article.cfm?id=how-to-sell...

pbreit 13y ago
Are you sure? "plans are to install on-site grid storage to make them self-reliant with their own energy supply"
- icegreentea 13y ago
  Well... let's do the math! Incident solar radiation is about 1 kW per meter squared. Assume 10% end to end efficiency (including solar -> electric, storage, and actual charging efficiency... this is optimistic, but doable... certainly not the cheapest though). You now need 10 square meters of panel to supply 1 kW. Assume sun is out for 12 hours a day, and for the full 12 hours you get all 1 kW/m^2 incident radiation (this is very very generous). The car has a 60kWh battery. So if we want to find out how much panel it takes for one station to charge one car a day... 60kWh to charge, but 12 hours to charge it up, so you basically need 5kW, which is 50 m^2 of panel. Which honestly isn't -THAT- big. Its a 7 meter square. Now... from my random snooping around, and my own impressions, I would say that a 'large' gas station typically covers something like... 500-600 meters squares (thats 5300 to 6500 square feet). That would be enough to super optimistically charge 10-12 cars a day. I saw optimistic, because incident solar radiation is not that kind. Can take a looksey here: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/ http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook... If you pick average, annual, and single axis east-west tracking (which I believe is the best bang for the buck), you see on the solar map, the BEST places in the US gets 5-6 kWh/m^2/day, compared to our assumption of 12 kWh/m^2/day. The feasibility of superchargers being even 90% off the grid is of course completely dependent on the ratio of size of supercharger panel array and rate of cars charging. But given the above, I'm inclined to believe that it is highly impractical for the majority of super charger stations to become actually self reliant, especially in high traffic areas.
  - btilly 13y ago
    A supercharger network is going to have a lot of stations on lonely stretches of highway. Given how few Teslas there are being taken on those trips, you're going to want charging stations in places where there will be very, very little usage. I can easily see a random station on I-10 near the CA/AZ border being entirely self-reliant...