6 ms·

3. It's solar-powered. I wonder if they have a electricity backup... It's grid electric powered. The canopy doesn't do much. Let's calculate: Guess that th

by jws 14y ago

3. It's solar-powered. I wonder if they have a electricity backup... It's grid electric powered. The canopy doesn't do much. Let's calculate: Guess that the canopy for each bay is 7 by 4 meters, 28m^2 Sunny spots receive about 4kWhr of solar power per square meter per day. Solar panels might be 25% efficient. Total daily power: 28m^2 * 4kWhr/m^2/day * 0.25 = 28kWhr/day Model S has an 85kWhr battery, half charge is 42kWhr. It is going to take about two days to charge off the solar.

uvdiv 14y ago
The press release makes a seemingly absurd claim: Each solar power system is designed to generate more energy from the sun over the course of a year than is consumed by Tesla vehicles using the Supercharger. wtf?
- notJim 14y ago
  They're presumably assuming that the station will not constantly be charging a car. ChuckMcM (your sibling) explains in greater detail.
- deleted 14y ago
  [deleted]
schiffern 14y ago
>It's grid electric powered. The canopy doesn't do much. They're sizing the installations in partnership with SolarCity, one of Musk's other start-ups. They claim they'll be sized such that it will generate as much energy over the course of the year as the vehicles consume. Meanwhile, you're estimating power output from a CG rendering on a marketing page. You could argue whether or not they're lying, but they're certainly not incompetent. SolarCity's sizing calculators take these (and many more) variables into account.
- sbierwagen 14y ago
  generate as much energy over the course of the year as the vehicles consume Yeah right. At what utilization rate? A single charge is ~90KWh, and takes half an hour. Two charges back to back are 180KWh. jws guesses that each slot generates 28KWh/day. A ten slot charging station would only be able to charge three cars without going into the red. Tesla would have to build a lot of very oversized installations in a lot of sunny, rural locations to hit breakeven.
  - timdorr 14y ago
    They could have solar only at some locations and excess capacity to make up for the locations without solar.
    - 001sky 14y ago
      Ok, but prob with solar is it does you no good if its not connected to anything. And if they are just putting it into the grid what is the point other than PR?
      - jlgreco 14y ago
        Well for one, you presumably get paid to put power back into the grid. Secondly, is there not value in putting as much power into the grid as you consume anyway?
        001sky 14y ago
        The problem is, in the case you propose, Tesla would be creating installations in urban environments. This type of "development" kills their credibility on "green" or environmentalism, etc. Is this kind of thing better than hydropower?
        jlgreco 14y ago
        Hydropower is pretty gnarly from an environmental standpoint. And I doubt the land they are using would otherwise remain undeveloped.. it is an urban area after all. Perhaps solar in previously undeveloped areas would be better? I doubt that. Developing solar plants in undeveloped areas only to put the charging stations in urban areas (that is where the market demands them after all) hardly seems better than putting charging stations in urban areas and sticking some solar there too. What is there to be gained from not putting solar wherever you can?
- jws 14y ago
  The source I worked from, http://www.teslamotors.com/supercharger http://www.teslamotors.com/supercharger , contains only this about solar power… And, at many locations, solar cells mounted on the weather canopy charge your Model S with solar energy. I'm sure SolarCity projects will be supplying more power than Teslas use, but not from these charging stations. (Unless virtually no one uses the stations, which is probably not the plan. There'd be no reason to install 4 parallel charging stations if you were charging less than one car a day. Another possibility is that they build car ports that cover many parking spaces in a lot to support each charging bay. That's not what the picture shows, but it would work.) I can't find an original source for the idea that the stations will produce more power than they consume, but it appears, attributed to Musk, in both Engadget and Huffington post. Most other articles on the event don't have it. It seems to have come from an oral presentation. The good news is, if a Tesla S goes about 2 miles on 1 kWhr of power and if an average person drives about 10k miles per year, that is only 14kWhr/day. Each bay would supply the typical power requirements of two Tesla S cars. Update: The press release is out now, http://finance.yahoo.com/news/tesla-motors-launches-revolutionary-supercharger-032000226.html http://finance.yahoo.com/news/tesla-motors-launches-revoluti... It clearly says the stations will make more power than they consume. So either they are huge compared to the picture, or Tesla S drivers aren't much for road tripping.
ChuckMcM 14y ago
Right, so if you think of it as a grid tied system it will generate power when ever it can, and people will charge on it. I've got 5.2kW of panels on my roof and can verify attest to the fact that even though I might use 28kWh in a day I can generate 34kWhr (during the summer, during the winter my best days are about 20kWhr) I would guess that as long as the duty cycle on the fill up is small they will consume net zero power. The SunTech panels [1] produce a nominal 295W and are 2 x 1M so in your 6 x 4M square you can put 12 panels, nominal output 3.5Kw, my system is 90% "efficient" (5.2 kW Panel rating, 4.7kW delivered to the grid) assuming the same that is 3.15kW delivered to the grid. over a nominal 6 hr solar 'day' that is about 18kWhr/day. So the duty cycle on a power station would need to be one fill up every 3 days. If the travelling is mostly on weekends I could see the stations getting a couple of fillups on the weekend and having 5 days of no visitors. Time will tell. It is handy that Elon's the primary stockholder of Solar City :-) Good discount on panels. [1] http://www.solarsystemsusa.net/solar-panels/by-brand/suntech/stp295-24-vd/ http://www.solarsystemsusa.net/solar-panels/by-brand/suntech...
- rustynails77 14y ago
  I support your figures. However, my efficiency of my inverter is 98% rather than 90%. I'd also clarify that the average during winter is a lot less than 20kWhr/day ... I know you said it was a maxinum :) It's most probably about 14kWh for me.
sbierwagen 14y ago
You'll only collect the total insolation if you use two-axis solar panel pointing. Fixed panels are less efficient. Depending on latitude, sometimes much less efficient: http://physics.ucsd.edu/do-the-math/2012/08/solar-data-treasure-trove/ http://physics.ucsd.edu/do-the-math/2012/08/solar-data-treas...

by jws 14y ago

uvdiv 14y ago

The press release makes a seemingly absurd claim: Each solar power system is designed to generate more energy from the sun over the course of a year than is consumed by Tesla vehicles using the Supercharger. wtf?

notJim 14y ago
They're presumably assuming that the station will not constantly be charging a car. ChuckMcM (your sibling) explains in greater detail.
deleted 14y ago
[deleted]

schiffern 14y ago

>It's grid electric powered. The canopy doesn't do much. They're sizing the installations in partnership with SolarCity, one of Musk's other start-ups. They claim they'll be sized such that it will generate as much energy over the course of the year as the vehicles consume. Meanwhile, you're estimating power output from a CG rendering on a marketing page. You could argue whether or not they're lying, but they're certainly not incompetent. SolarCity's sizing calculators take these (and many more) variables into account.

sbierwagen 14y ago
generate as much energy over the course of the year as the vehicles consume Yeah right. At what utilization rate? A single charge is ~90KWh, and takes half an hour. Two charges back to back are 180KWh. jws guesses that each slot generates 28KWh/day. A ten slot charging station would only be able to charge three cars without going into the red. Tesla would have to build a lot of very oversized installations in a lot of sunny, rural locations to hit breakeven.
- timdorr 14y ago
  They could have solar only at some locations and excess capacity to make up for the locations without solar.
  - 001sky 14y ago
    Ok, but prob with solar is it does you no good if its not connected to anything. And if they are just putting it into the grid what is the point other than PR?
    - jlgreco 14y ago
      Well for one, you presumably get paid to put power back into the grid. Secondly, is there not value in putting as much power into the grid as you consume anyway?
      - 001sky 14y ago
        The problem is, in the case you propose, Tesla would be creating installations in urban environments. This type of "development" kills their credibility on "green" or environmentalism, etc. Is this kind of thing better than hydropower?
        jlgreco 14y ago
        Hydropower is pretty gnarly from an environmental standpoint. And I doubt the land they are using would otherwise remain undeveloped.. it is an urban area after all. Perhaps solar in previously undeveloped areas would be better? I doubt that. Developing solar plants in undeveloped areas only to put the charging stations in urban areas (that is where the market demands them after all) hardly seems better than putting charging stations in urban areas and sticking some solar there too. What is there to be gained from not putting solar wherever you can?
jws 14y ago
The source I worked from, http://www.teslamotors.com/supercharger http://www.teslamotors.com/supercharger , contains only this about solar power… And, at many locations, solar cells mounted on the weather canopy charge your Model S with solar energy. I'm sure SolarCity projects will be supplying more power than Teslas use, but not from these charging stations. (Unless virtually no one uses the stations, which is probably not the plan. There'd be no reason to install 4 parallel charging stations if you were charging less than one car a day. Another possibility is that they build car ports that cover many parking spaces in a lot to support each charging bay. That's not what the picture shows, but it would work.) I can't find an original source for the idea that the stations will produce more power than they consume, but it appears, attributed to Musk, in both Engadget and Huffington post. Most other articles on the event don't have it. It seems to have come from an oral presentation. The good news is, if a Tesla S goes about 2 miles on 1 kWhr of power and if an average person drives about 10k miles per year, that is only 14kWhr/day. Each bay would supply the typical power requirements of two Tesla S cars. Update: The press release is out now, http://finance.yahoo.com/news/tesla-motors-launches-revolutionary-supercharger-032000226.html http://finance.yahoo.com/news/tesla-motors-launches-revoluti... It clearly says the stations will make more power than they consume. So either they are huge compared to the picture, or Tesla S drivers aren't much for road tripping.

ChuckMcM 14y ago

Right, so if you think of it as a grid tied system it will generate power when ever it can, and people will charge on it. I've got 5.2kW of panels on my roof and can verify attest to the fact that even though I might use 28kWh in a day I can generate 34kWhr (during the summer, during the winter my best days are about 20kWhr) I would guess that as long as the duty cycle on the fill up is small they will consume net zero power. The SunTech panels [1] produce a nominal 295W and are 2 x 1M so in your 6 x 4M square you can put 12 panels, nominal output 3.5Kw, my system is 90% "efficient" (5.2 kW Panel rating, 4.7kW delivered to the grid) assuming the same that is 3.15kW delivered to the grid. over a nominal 6 hr solar 'day' that is about 18kWhr/day. So the duty cycle on a power station would need to be one fill up every 3 days. If the travelling is mostly on weekends I could see the stations getting a couple of fillups on the weekend and having 5 days of no visitors. Time will tell. It is handy that Elon's the primary stockholder of Solar City :-) Good discount on panels. [1] http://www.solarsystemsusa.net/solar-panels/by-brand/suntech/stp295-24-vd/ http://www.solarsystemsusa.net/solar-panels/by-brand/suntech...

rustynails77 14y ago
I support your figures. However, my efficiency of my inverter is 98% rather than 90%. I'd also clarify that the average during winter is a lot less than 20kWhr/day ... I know you said it was a maxinum :) It's most probably about 14kWh for me.

sbierwagen 14y ago

You'll only collect the total insolation if you use two-axis solar panel pointing. Fixed panels are less efficient. Depending on latitude, sometimes much less efficient: http://physics.ucsd.edu/do-the-math/2012/08/solar-data-treasure-trove/ http://physics.ucsd.edu/do-the-math/2012/08/solar-data-treas...