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How We See It - Tesla, EVs and the Grid

Every time Tesla breaks into a new market, the media brings up the same concern: that electric vehicles will overwhelm electric grids, resulting in blackouts. But researchers, analysts, and government officials agree this worry is unfounded.

According to many, including the Federal Energy Regulatory Commission and the Electric Power Research Institute, EVs like the Tesla Roadster and upcoming Model S won’t strain standard electrical grids for several reasons:

EVs don’t use much more power than major electronics. The energy demanded by most plug-in vehicles during charging (about 2 kilowatts) is the same amount drawn by four to five plasma-screen televisions. In just the U.S., 115 million households own televisions, and more than half own two or three -- yet you never hear about consumers and utilities panicking about TVs disrupting the grid. There’s a common misconception that electric cars will double or even triple the amount of power pulled from the grid by the typical home, but this simply isn’t the case.

Electric vehicles will roll out gradually. Analysts predict that only 500,000 EVs will be produced around the world every year, starting in 2015. Continuing with the television comparison, the half million cars added every year to the world’s supply will use about as much power as 2 million plasma TV sets. To put this in context, about 28 million televisions are sold annually in the U.S. alone. Considering that grid utilities are already upgrading local transformers and grid equipment to handle greater loads, accommodating a growing number of EVs shouldn’t be a problem.

Smart grid safeguards are on the way. In addition to adding capacity, utilities are creating incentives and mechanisms to encourage EV charging at night when energy demand is low. Many power companies are planning to introduce discounted rates for EV owners who plug in during off-peak hours. Today, utilities are rolling out millions of residential smart meters and devices that will allow for simple, automated charging. Soon, EV owners will be able to plug in when they get home from work at 5 pm, knowing that their car won’t start charging until cheaper electricity rates kick in at 11 pm. This technology is set to become commonplace well ahead of major EV market share, ensuring a stronger grid for the next wave of transportation.

Tesla is taking grid parameters very seriously as we deliver more cars. The Roadster is designed to consume only as much power as is available. Pair this with the fact that the average Roadster only needs its battery topped off after driving an average of 40 miles a day, and it’s clear that EVs won’t break the grid anytime soon.

I'm not saying solar is wrong for everyone. It works for people who have high electric costs. You have to do the math and figure out if it works for you. There are flexible solar panels you can roll up and put in your trunk.

My company installs solar panels.... rarely.

To get the full efficiency out of a solar panel it must be pointed directly at the sun. For max efficiency (that 20% you are talking about) you need to mount the panels on a tracker that will follow the sun.

Dust, pollen, snow, leaves.... anything on the panels will reduce the efficiency.

Clouds will reduce the efficiency.

The sun does not shine at full strength from sunrise to sunset. At rise and set it is coming thru more atmosphere so the efficiency is less. Best efficiency is when the sun is directly over head.

There are less sun hours in winter than in summer.

That's where the AVERAGE usable hours comes from. In St, Louis, MO there are 5 hours of sun per day on average for the year. There are charts and all kinds of stuff on the web to calculate the pay off. In Saint Louis it's just not there yet.

Sun angle calculator:

This one will give you an idea of solar output if you live in the US.

Also watch the solar panel warranties very closely. The site above has good expensive panels. They guarantee the panel to be at 80% in 25 years. Some panels drop in power on a parabolic curve the minute they see sunlight over the 25 year warranty.

Darn map now shows St. Louis only has 4 hours (or less) now. Well at least they update their web page.

Hello all,
I was always a big fan of Tesla until we had the opportunity to test drive the Tesla Roadster... Now I'm their NUMBER ONE FAN!

Check out our video with and exclusive interview with the Tesla Communications Manager and the representative of ProMotor Romania:

Personally I can't wait for the SUV...

ifilm77, You were posting this same messege on all the threads. As someone pointed out to you not necessry to post same messege on all threads as most of us read them all any way. Some were critsizing you for this. I just thought you might hve not learned the ropes yet and defended you but it was pointed out to me you were likely just advertising you website. Whether just a new kid on the block and not familiar with how things go or someone blantantly advertisising will let you decide. But surely you know now not to put same messege on every thread. I kind of felt ridiculous defending you when it was pointed out why you were posting on all threads. Anyway whatever, glad you like the Tesla's and hope you enjoy an SUV.

I have been researching solar panels for several years now - I plan to use them on the house I will build. The prices for solar have come down enormously over the past 2 years. Yesterday I
priced some panels by BP and Canadian Solar and Evergreen, all with 25 year warrantees and guaranteed output. The price for some were less than $1.60 per watt. I estimate that my house will require about a 6K system, or roughly $9,000 for 30 panels.
Use microinverters - they make the installation a snap and remove most of reduced harvest issues, such as clouding, dirty panels, shadowing, etc. The Feds grant $1000 per kilowatt capacity of your system and the tax break can be spread over 3 years, I beleieve.
My site, in NC, averages 5 suns, from 3.8 in the dead of winter to 5.9 in the height of summer. Tracking mechanisms have never been recommmended - they are simply not cost effective, and even less so today with cheaper panels - simply add more panels. they are far, far more reliable than any tracker machinery, which is mechanical and will always break down. You can construct your array so that it can have its elevation adjusted as the seasons change, but the benefits are not that great. Simply point your panels due south and elevate them at an angle equal to 90% minus your latitude. That will maximize yearly energy harvest for a fixed array.

I looked at the link for Focus Fusion that Brian H posted a while back in this thread. (I am a newcomer to this forum but have been following Tesla for several years.) The article describes a process that sounded so odd to me that I looked it up on Wikipedia, where it is described as being theoretically possible, but extremely difficult, with several enormous technological hurdles and unlikely to come to fruition any time in the near to moderate future. Among the problems are that a much higher temperature is required and much less energy produced, compared with other fusion reactions.

I see no reason that fusion cannot supply energy at some time in the future, but given how far we are from solving the technological problems, I'm comfortable saying that in my lifetime the only fusion power we're going to have outside of minuscule amounts in the lab is that big yellow fireball that rises up over the horizon every morning.

The wiki article is worth about as much as you paid for it. The temperatures involved in the LPP process occur in minute "plasmoids" which are magnetically self-contained, and last microseconds. That's the key to the process; the fusion bursts are short enough not to require "containment", but powerful enough to generate significant ion and electron flows.

Your confidence is based on inadequate investigation.

I have been researching and following solar PV for almost two years
and they have become more efficient and a lot cheaper. Thinfilm
is not what an automaker would likely use and they do not achieve 20% efficiencies. Mono or polychrystaline can achieve close to 20% in commercially available panels. Of course, those stated figures of 20% efficiency are actually exaggerations of what will be obtained in most situations. Expect more like 15 or 16% efficiencies, yielding 300 watts off your 2 square meters. Unfortunately you have made several errors - first you assume that 8 hours of sunlight striking a panel that could yield, realistically, 200 watts (max) would provide 8 times 200 watts. Wrong. The panel rated at 200 watts will only yield that rate for a few minutes per day when the sun is dead overhead, there's no smog, etc. or clouds. All other times the panel will yield less than its maximum. Locales are rated in terms of the number of "suns" they receive, on average, for that date. The sun may actually shine for 12 hours in Arizona, but the number of suns will probably be around 6 or 7. Most locales in the US yield 5 or fewer suns per day during the summer and 3 to 4 per day in the winter months. The number can be obtained from solar irradiance charts and provide data from the past 20 years or so for any locale in the world. The other error you make is asssuming that if a panel produces 200 watts, that the battery will absorb
all 200 watts and none will be lost drawing the power from the
battery , both of which are quite wrong. Expect to lose 25% from the action of putting power into and drawing power out of a battery. And there is yet another error- that 200 watt panel is rated to harvest 200 watts (theoretically, not in actuality) only IF it is pointed directly towards the sun, at all times, which is impossible.
Using this data, for an average day, with 5 suns, expect to harvest not 2000 watthours, but more like 1500, and to lose
25% or 375 watthours, ending up with 1125 watthours per day.
That's enough to travel roughly 4 miles in a Tesla Model S.
And the power is worth 15 cents where I come from. The panels will
probably be a $1000 plus option.

i'm getting solar panels on my roof from this will reduce my costs, and help the environment, and future generations. this will cost me nothing.
my monthly electric bill will be less. solar city has a GREAT lease program. i wish everybody would do this. thanks. peace. :-)
tesla roadster owner number 1229

Powered Highways

Not everyone can afford to buy a 300 mile range battery pack; even if prices come down more than current forecasts, there is an environmental penalty associated with batteries of that capacity. Even worse, when EVs become more than a few percent of total vehicles, the queuing of people and vehicles at roadside charging stations on major highway routes will become an intractable problem. What we need is powered highways that sustain the vehicle charge while underway. The vehicle enters the highway with a particular state of charge, drives a few hundred miles, or even more, then leaves the powered highway with the same or better charge status. While there are challenges in bringing this to fruition, the problems are amenable to engineering.

First, the vehicle needs a computer-controlled pickup arm that optimizes the charge efficiency over the uneven roadway and various driver maneuvers. Equipped with IR, sonar or radar, the intelligent pick up arm will be articulated and powered to maintain the closest possible alignment of the vehicle to the charge element in the roadway. When you consider what Google is doing with self-driving cars, the knowledge base for vehicular software is getting quite mature.

Second, the charge element in the roadway is also a communications carrier; signals are exchanged between the vehicle and a regional traffic control system that integrates each vehicle into an intelligent grid of all the vehicles active on that roadway. Auto-pilot ervices are provided to the driver that surpass what can be provided by cruise control, including possible hands-free driving. The auto-pilot system provides control over the vehicle while it is in the charging lane and controls its relationship to other vehicles in the lane for greatly increased safety. Like the HOV lanes of today, legislation would provide that only EVs could drive in the charging lane. Because the charging element is recessed into the roadway, drivers enter and leave the charging lane at will, just by steering across the lane. The system acquires or releases vehicle telemetry and control automatically. Part of the telemetry system functions will be to steer the vehicle under computer control to also optimize the efficiency of the charging functions.

Third, the vehicle computer provides for payment of the charging toll; use of the charging lane should be something that can be paid in advance for regular users of a particular highway or paid on the spot by "guest" drivers. The tolls should be enough to pay for the electricity used and to retire the capital invested in the charging and computing infrastructure in the roadway. This toll should be favorable when contrasted to the cost of fuel over the same route for a gasoline powered vehicle. For example, I-5 between Sacramento and Los Angeles passes about 105,000 vehicles an hour at peak. If EVs become 3% of vehicles on this route, each one paying about $40 for a 400 mile trip, the peak revenue/hour could be $3,150. The average daily revenue could be in the range of $25,200 and the annual revenue could be over $9 million, or about $100 MM over the life of the infrastructure. At 10% penetration of EVs on a powered highway the annual revenue could hit $30 MM and the lifetime revenue would be over $2 billion.


nice thoughts. Allow me to make some comments on that.

First, a mechanical (conductive) energy pickup is improbable. You don't want voltage carrying metal strips exposed on the tarmac. There is, however, an overhead pickup system well established for vehicle use. It's called electric train ;-)
Seriously, inductive electric charge transfer while-you-drive is in test. Engineering problem solved. Now we need funding...

Second, you want only one communication system in the car and you want it to work everywhere, side roads, city, front yard. It will be wireless. Model S will come with 3G or 4G and an attractively priced data plan.

Third, infrastructure projects paid by future users always run into the chicken-egg-problem: Huge investments prohibit a large-scale roll out, low user numbers prohibit a quick scale up, low coverage prohibits many cars to be fitted with the necessary pickup tech.
Some people won't like charge-per-use since it gives an exact record of whodunnitwhereandwhen.
Since electricity cost is 6c per mile, there is little room for margin to run that business model on. Double it and collect another 6c for every mile...
I'm afraid you need the government to step in there, a no-go for so many US citizens... but might be a possibility in China where the govt sticks at nothing.

At local rates here, home charging costs about 2¢/mi. 10¢ for the privilege of charging on the road is a bit rich!

As someone who spent the last two years of my life designing and building a competition solar car for Iowa State University, I can attest that unfortunately even with the best mono-crystalline silicon solar cells on the market right now, a Model S roof covered in solar panels wouldn't make much of a dent in the overall energy usage of the vehicle. This is not to say that it doesn't make sense to offer it as an option. After all, vehicle's do spend a lot of their lives parked in sunny spots, so why not take advantage of this as much as possible if you can afford the cost?

First a little background. Our 2012 solar car called Hyperion had 6m^2 photovoltaic area using 22.3% efficient cells made by SunPower in California. This is far more area than would be practical for any production vehicle (it barely leaves room for the small cockpit that accommodates a single driver). On a good sunny day with the sun directly overhead, our solar array could produce 1200-1300W. However, over the course of the year in typical Iowa weather, the flat array would only produce an average of 5kWh per day throughout the course of the year assuming that it is never shaded. This is sufficient energy to take the car about 170 per day at a cruising speed of 45MPH. However, the car only weights 660lb with a driver and have an aerodynamic cd of about 0.11. If you'd like more info on the car, check out the fact sheet.

Transferring this solar technology to something like the Model S is certainly possible, but the results would be much less impressive. A quick calculation shows that there is about 1.65m^2 of space available on the Model S roof for a photovoltaic surface. Taking SunPower's latest and greatest C65 cells, this would yield about 350W of power on good day with the sun directly overhead. Again taking Iowa's average solar radiation for a flat panel solar array, this could realistically produce 1.3kWh/day if it weren't shaded. If we assume the Model S can go 3mi/kWh, that would yield a range of nearly 4 miles per day on power from the rooftop solar installation. For the average american that drives 37 miles per day, this would be over 10% of their driving powered on solar energy produced by the vehicle. This could of course be supplemented by an additional home solar installation. In general, a home solar installation makes more sense it me since you could get by with cheaper, lower efficiency solar cells since there is generally a lot more space available on a roof or in a back yard than on a vehicle.

Finally, let's try to gauge the cost of the solar installation described above for the Model S. For our 6m^2 solar car array at Iowa State, we paid $9,000 just for the cells. Hence a Model S installation, the cost of these same cells would be under $2,500. Granted, this cost would likely be a lot lower for mass production due to economies of scale, but then you have to add the cost of the inverter, wiring, and cell mounting/protection. I should mention that there are solar cells on the market that cost significantly less per watt (1/4 the cost), but only have an efficiency of 18-20% and from less reputable companies. My numbers above are intended to show the best case scenario that could be realistically achieved with today's technology (without considering 30% efficient space grade gallium arsenide solar cells which are triple junction and cost astronomically more than silicon solar cells).

Compared to the cost of slightly increased battery capacity, and the electricity required to fill it, solar on cars is insanely expensive, and in practice almost useless. The constraints do not conform in any respect to how people actually use cars.

There is a one use which could be enough for adding tiny solar panel in practical family BEV: all batteries lose energy slowly if left unplugged, so add a solar panel that just big enough to counter that loss + a bit extra and you can leave your BEV in sunny parking lot indefinitely without plugging it in. For that use panel needed would be tiny.

As option of course, here in Finland such solar panel would not make much sense, but if you live in some very sunny place it could be worth the extra buck.

Apparently the Karma solar roof cost $5K (or $5K/W?), enough to run a fan. Is that worth it?

That price has quite a bit "Karma" in it, you can run a fan with panel that costs fifty bucks, not five grand if that is all that it is doing.

Real question here is how much power do you need to maintain battery charge.

... found this "50 percent charge would approach full discharge only after about 12 months.

12 months is about 8600 hours, 50% of charge of 85kWh battery is 42.5kWh. 42500/8600 ~= 5W. Not kW, W. to maintain charge panel needed would be really tiny.

Nice to have some hard numbers Evan, thank you.


"Real question here is how much power do you need to maintain battery charge"

And battery temperature.

Averaged over 24 hrs., say 120Wh, of course, with variable sun hours, intensity, and angle daily, and seasonally. Or none if it's indoors. And assuming it doesn't accumulate a layer of dust or condensed smog. /:p

Smart grid safeguards are on the way. In addition to adding capacity, utilities are creating incentives and mechanisms to encourage EV charging at night when energy demand is low

You make me laught :-)
everything what you need is this
it cost less than 6 bucks
BTW: for night tarif you can make special plug which works only at night tarif. people here usualy have it(czech rep)

you dont need some special space technologies.

1) Smart Grid is the devil. It benefits only the utilities; no one has come up with anything better than feeble hand-wave benefits to the consumer. Internal "smart gridding" of the home so usage per appliance could be tracked would help, but is of no interest to the utilities. They just want to be able to cut off power where and when convenient, to reduce peak load requirements. Bah.

2)Tesla has gone with Solar City in offering free power to all Model S owners (on intercity freeways, etc.) using the best model: power the cars with Superchargers connected to the grid, and generate excess solar power to sell back to the utilities (i.e., more, overall, than the cars draw). Brilliant!

Well, the benefit to consumers is that the grid will go dark less often. Since we aren't used to this happening, I think we underestimate that benefit. Alternatively, we could pay more so that they could just install more capacity, but that's not how things seem to work in the real world.

It certainly serves as extra capacity, but if the FIT is > grid price, consumers are paying too much for it. As is the case with virtually all solar power, except in a few special circumstances of no economic importance.

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