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V2Green Technology to Monitor Performance of 13 PHEVs in Seattle Project

V2Green’s vehicle-to-grid management technology (earlier post) will be used to monitor the performance of 13 plug-in hybrid electric vehicles (PHEV) in a Seattle demonstration project and control their charging.

Under a contract with the US Department of Energy’s Idaho National Laboratory, V2Green will provide a logging system to collect real-time vehicle performance data provided by the V2Green Connectivity Module (VCM) installed in each PHEV. A cellular modem will upload the data to the V2Green server where it is archived and made available for the Idaho National Laboratory’s analysis.

The lab will monitor fuel efficiency, electricity usage and other vehicle performance measures on each of the 13 converted Toyota Prius PHEVs.

Seattle City Light will operate three of the vehicles in the test. The City of Seattle will have one. The Port of Seattle will get two and the Puget Sound Clear Air Agency will get three vehicles. King County will test four plug-ins.

In addition to monitoring vehicle performance, V2Green’s technology also provides the capability of smart charging. By providing intelligent, two-way communication between plug-in vehicles and the electric grid via the VCM, Seattle City Light can control the timing, pace and extent of vehicle charging within driver-specified requirements. The utility can control its load requirements, ensuring that charging takes place during light load hours, protecting the distribution system and avoiding the need to buy power.

We believe this project will show how plug-in hybrid technology can reduce our dependence on oil and cut greenhouse gas emissions that contribute to climate change.

—Seattle City Light Superintendent Jorge Carrasco

Seattle City Light is the city’s municipal electric utility.

V2Green technology also is being used to test two plug-in hybrids in Austin, Texas, and six from the fleet of Xcel Energy, using similar smart charging and data collection capabilities.

Comments

sjc

Spoken like a true capitalist.

This has more to do with the life span of transformers and transmission gear than it does wind power. Transformers have to be replaced on a regular basis, depending on their load profile and running temperature. This becomes very expensive.

vboring

sic,

I happen to work in the substation division of a utility in the PNW and can tell you for a fact that the vast majority of our substation transformers are more than 30 years old. A few of them are over 50 years old. We have plans to improve equipment monitoring, but we have no plans to replace them that I know of.

As for transmission gear wearing out and being replaced, I'd guess that it is the same situation.

Utilities would like nothing more than to increase the capacity factor on their existing equipment by spreading the load more evenly through the day, because it would save our customers money.

We are required by our state gov't to acquire wind power even though we have no use for it and it will increase rates that customers have to pay.

I just wrote a long post on my blog on the subject V2G, smart grid, PHEVs and wind power, if you're interested:

http://vboring.blogspot.com/2008/02/wind-power-mandates-phevs-and-smart.html

John Taylor

Ok Marcus,

You seem to think batteries will not wear out if we subject them to extra duty cycles while we are not driving.
Lets also invent a scheme to let the utility companies use our snow treads in the summer while we aren't needing them. We can pretend there is no real wear and pocket the pittance we get.

Seems logical? No.

vboring
Incorporating wind power into the grid can only be done with tandem power storage, or if there are a great many wind generators in a variety of places. So far, this is not yet cost effective for anyone to do.

vboring

John,

whether or not wind is cost effective is irrelevant. states have mandates. large amounts of wind power will be integrated or heads will roll. the wind generation impact on the grid will be dealt with. it is just a question of how to best do it.

storage is absolutely not necessary and is frequently not the most cost-effective approach. the most cost-effective approach available today is to increase the scheduled spinning reserves. at some % wind generation, that may no longer be the most cost-effective approach anymore. it may become worthwhile to increase our transmission capacity or buy pumped storage. if things work out the way i think they should, market-based PHEV charge scheduling will play an important role.

John: I once attended a lecture on PHEVs and V2G given by Dr. Andy Frank (U.Cal,Davis). When I asked him why I would want to use precious cycles from my BEV for V2G, he told me that they would only ask for discharges of 1 or 2 percent of the batteries capacity at any time. Nobody is left with a drained battery, negligible wear on the battery.

A quote from Motorola:
"The relationship between DOD and cycle life is logarithmic. In other words, the number of cycles yielded by a battery goes up exponentially the lower the DOD." Not fairytale .. fact.

Another one of the beauties of having V2G capability is the security that it gives during power failures.

K

A lot of the V2G advocates seemed to have solid answers to battery durability problems.

And last month I was told that the electronics would be smaller and less expensive than I thought.

So I explored a bit today, reviewed battery chemistry and reliability experience, and read some ideas about how to handle the demand signals and how to estimate the value to the utility.

Conclusions (could even be correct):

1) There will be very little, perhaps no deterioration of batteries when discharge is shallow, no more than 3%. And this is likely to apply to various lithium designs also (lithium facts are hard to come by).

Of course some news bites both ways. The discharge limit means each vehicle can help the grid very little. And it will take a hell of a lot of V2G rolling stock to make a difference.

2) The electronics needed for feeding into the grid put very little weight penalty on the vehicle. And the cost will be low.

3) Bad news. Hard wires from vehicle to grid will be needed. You can charge inductively - the EV-1 did - but feedback into the grid is different.

Not a big deal, but a bit more of a hassle. Even moreso in company parking lots. Vehicles could be wired not to move until the plug was removed. Parking lot spagetti?

4) Figuring out how many $$$ this is worth to the utility will be, shall we say both 'creative' and 'political'. Regulatory laws and rate setting will have to change. But honesty is not required and we aren't short of lawyers.

5) The demand signals must be wireless. No way will it work if the utility is dialing twenty thousand land line phones at 2:10 pm. The cell phone network isn't up to it either but some variety of public wi-fi could. Er, well it could if it existed. Wireless isn't my field.

Summary: Critical mass will be a problem. Perhaps the biggest. You need a lot of vehicles. When you begin you will have few and the grid won't actually be helped.

It will be a political football because subsidies will be needed and rates must be set. The words 'social justice' will be heard.


John Taylor

Ok for proponents ... please remember that my complaint is
Bottom line ...
Will it work? Yes.
Is it a cost effective good idea? No.

There are a great many IF's here ... I shall consider a few of the more obvious ...

IF ... IF we had huge numbers of Li Battery Electric vehicles (BEV) driving around then the idea might be viable. At this point, at least grid load shedding due to home charge timing scheduling would make sense. Here we will have a rather large window where grid load adjustment using charging interruption can easily be done even if we don't make it a 2 way power transfer situation.

IF ... IF we want grid loading to be equalized to the power supply, there are many other loads now in existence that can quite easily be temporally shut down for short periods without any effect on user comfort. Loads such as air conditioning compressors are an existing example. We don't have to wait for the next generation of batteries, and a whole new fleet of cars.

IF ... IF we want to do load management technology, then it does not take a huge mess of fancy two way communications with the utility and a billing nightmare, just a voltmeter to check grid voltage and an interconnect to keep the load from coming on during periods of low voltage. Obviously a slightly more complex energy management system would keep track of the voltage and also not bring on multiple loads at the same time, as well as scheduling such things as laundry dryers or dishwashers. Energy management systems are a useful, proven technology that is common in commercial industrial power usage, and could be made available in homes.

IF ... IF we want to sell power to the grid, then we should be building home power generating capacity. Three sources come to mind, ~> Home source #1 is solar panels. Home source #2 is wind generation. Home source #3 is co-generation from home heating fuel. All work better in home situations with a battery pack. Here the batteries can be cheap heavy led acid ones, not lite expensive Li batteries.


So we see that V2G ( vehicle to grid ) power management technology is a fairy tale. Reality will be quite different. Still, religions* have demonstrated that people will 'buy-into' a fairy tale long before they will accept reality. It seems many green car enthusiasts are just as easily misled as those religious nutters. *(not your religion, the other guys, you know, the totally stupid ones worshiping a god that does not exist).
It is a good idea to be somewhat careful in placing hopes in technology that does not exist, even when we see there is at least a possibility that it could some day become reality.

Neil

oops ... forgot to sign my last post. (two up)

K: what you say rings true.

AFAIK the biggest benefit of intelligent grid connections will be intelligent charging options.

Engineer-Poet

Quoth John Taylor:

If you think tomorrows batteries will be different from today's and not wear out, you have amazing faith
Strawman.  I know that a number of today's technologies have far greater lifespan than the lead-acid cells of 2002, when that report was written.  However, the conclusion was reached for spiral-wound lead-acid cells; even if that's all we have, it still holds.

If we have something like the AltairNano cells which were tested over 15,000 cycles to 100% discharge and back 5 times per hour, we can forget battery wear as a cost.

If utilities are willing to own the pack and lease it at a discount, please let me know
Start writing your business plan, then.  You'll have to arrange for the pack to be available to them (plugged in), so you may want to talk to legislators about tax breaks for charging outlets at work, shopping malls, etc.
This report was submitted in fulfillment of ARB contract number 01-313 by AC Propulsion
Yup.  Way back in 2002.  Do you think that the case for electric vehicles has become weaker since then?

You do realize that AC Propulsion is a creation of EPRI, and its conclusions can be taken as the general position of the electric utilities?  Among those conclusions is this:

Furthermore, since the asset cost of the propulsion system is primarily allocated for transportation, only the incremental cost of battery wear-out and system deterioration need be covered by the vehicle-to-grid functions. Analysis suggests that in many cases,
these incremental costs are well below the market value of vehicle-to-grid services resulting in a new value stream that will attract investment in vehicle-to-grid infrastructure and commerce systems [1].
Later in the document (emphasis added):
The wear-out of the battery generates revenue sufficient to cover the cost of necessary battery replacements for the life of the vehicle. The cost of using the battery for transportation is covered by the revenue generated, creating a real and substantial economic benefit for the vehicle owner.
EVs can increase the market for electricity by more than 40%.  It represents one of the major avenues for expansion of the industry.
(It is great publicity, but will never get implemented).
You can bet the industry is just waiting for public sentiment to turn.
Bottom line ... Is it a cost effective good idea? No.
Directly contradicted by the conclusions above.

Engineer-Poet

Quoth gr:

1)Panasonic lead acid battery pack (EV1 type 2) yields data applicable to BEV Lithium battery packs.
Do you think that cost figures derived from a short-lived pack could not be used as a ceiling for those of a long-lived pack?
Test vehicle assumed connected to grid 23 hours/day @ 80 amp circuit 110-220v.
There are no technical barriers to this, and the cost is paid for out of savings elsewhere.  Here's AC Propulsion's press release of last October on that subject.
First this is a study conducted by an aftermarket EV conversion outfit, AC Propulsion
AC Propulsion is a creation of EPRI.  They have muscle.
Cycling test data was simulated (computer model trap) as real ISO data was unavailable.
From the V2G report:  " sample dispatch profiles were developed from historical ISO data by allocating vehicles a pro-rata share of the total regulation demand."  Real data was used, just not in real time.
what vehicle is connected to a 220 80 amp circuit 23 hours?
One that's used for the typical commute and plugged in when it's parked.  California is an outlier, and I doubt that the conclusions would change much if the vehicle was only on-grid 21 hours/day.
Forget the ISO regulation ... as far too complex with many better solutions.
See opposite conclusion above.  Regulation and reactive power are two things that vehicles can do better than generators, because they are closer to the point of use and the transmission lines can be loaded more evenly and productively.

vboring

@K

Re: demand signals

the PNNL developed a mechanism called smart grid, which sets and publishes a market price for electricity on 5 minute intervals. in response to this information, consumers can choose to set up their devices to respond to market signals.

influencing the battery charger becomes simple. the charger will charge the batteries while the price is below X, do nothing while the price is between X and Y, and sell power to the grid when the price is above Y and the state of charge of the batteries is above Z%. X, Y, and Z will be set by the consumer. this way, the consumer gets the most economical charge and the system gets to rely on the batteries on rare occasions.

Engineer-Poet

Or just sell regulation and spinning reserve for a duration of ~5 minutes.

Spinning reserve could be a biggie.  The local grid needs to have enough extra generation on-line to carry the load if the biggest generator trips off.  Historically, this has been done with actual generators, consuming fuel but producing little or no power so they can be brought up at need.

What if it was all from vehicles?  Suppose you've got 100k cars plugged into 220 V 50 A circuits; that's 1100 megawatts of power capacity.  If they were charging at an average rate of 2 kW but could switch over to delivering 11 kW each within 100 msec, that's 1320 megawatts of spinning reserve without a single thing in motion bigger than a cooling fan.  The near-instantaneous available power would give the utility time to bring up other generation, such as gas turbines.  Within minutes the utility would be paying back the power debt.

The elimination of actual generators for spinning reserve would increase system efficiency and cut fuel use.  This is going to be essential going forward.

K

Yes, Smart Grid is tested. Whenever technology is in flux there will be many good solutions that do not become the surviving one. Something like SG will be used at fixed sites. It may falter for V2G needs.

As I understand it SG has a controller at each device - in V2G the vehicle w/b the device - that can receive price signals and choose whether to draw power. The price changes are sent from the utility on the internet which obviously could mean landline or wireless.

Well and good, but SG was not putting power into the grid, it is managing the house to reduce the power bill. In aggregate that helps a hard-pressed utility too.

When you venture into selling power back the matter changes. How is the utility to set price? Are they forced to buy all power offered or only part? From all of their service area or only some localities? Can they spot sell any excess to neighboring utilities at a profit?

I don't contend those questions can't be answered. But some may prove very tough for a regulated industry. It is really a little worse, we have a half regulated, half free, industry. Depending upon location there can be multiple levels of regulators with conflicting agendas.

When each V2G vehicle has a base - the owners garage - then an intelligent meter can record what was sent back to the grid and handle the accounts.

However it would be much better (for cutting the V2G critical mass) if vehicles also plug in at work.

Then who does the utility pay for the power? Probably the employer who provides plugs in the parking areas.

All dandy and fine for the employer, but the real owner of the batteries is getting nothing for putting power into the grid while at work.

So why donate power? Just set your vehicle to always charge at the employers expense.

Can an employer just settle with the employee? No! Which vehicles provided power? Which took it? No feedback to identify the individual car exists.

Simplistic analysis? You bet! I wouldn't pretend otherwise. But my quick review Saturday concluded that each vehicle in V2G should be able to tell the utility where it is plugged in at the moment and what power it is putting into the grid or taking from it. And it would have to be auditable. Wireless seemed the answer.

Ideas?

K

Oh. Above was intended for vboring.

John Taylor

As K so clearly points out, before this V2G idea becomes useful, we first need a very very large pool of Electric cars (BEV's), and a "smart-grid" ... neither of which exist yet.

Then we can begin talking about political will to make suitable regulations, corporate will to make the idea into a viable reality, and personal will to let individual cars be used as power sources. Again, so far, none of these exist.

We also need technology improvements particularly to batteries and two way battery charging / power inverters, and a "smart" interface for real time and millisecond responding to loads. Again, so far, none of these exist, but some of the technology perhaps is in development.

I predict that long before V2G is possible, we will first see much more "point load shedding" using energy management systems *(EMS) guided by voltage drop. As loads go up the grid voltage goes down, and many loads *(particularly electric motors) can be adversely effected by this. An energy management system that senses grid voltage can shut down loads in time to even out the overall grid loading if a large number of facilities have them. So far, this type of technology is becoming quite popular in commercial industrial settings for reasons that have little to do with altruistically helping the utility.

Reasons energy management systems *(EMS)will be used, and V2G won't.

1 ) There is a useful benefit to the consumer that makes the EMS economically viable, especially when "peak load" metering is introduced.

2 ) The EMS technology is in place and in use and proven to work, and becoming cheaper to install and use.

3 ) The EMS is totally automatic and requires no constant vigilance. By contrast, V2G requires consumers to park in a plug in location, take time to plug in a heavy cord and then disconnect and stow the cord when ready to travel. Sometimes people are in a hurry, and sometimes the weather is bad. A lot of people don't like to fool with high voltage in the rain when they don't have to.

4 ) If you get a Battery Electric Vehicle (BEV), having an on board charging capacity is a fine idea, as is a small inverter to run a small load. However, the penalty price and weight of a large inverter to resupply high capacity high voltage to the grid is quite another bit of unnecessary equipment. I for one would be quite reluctant to get one installed in my BEV.

5 ) A "smart" interface for real time and millisecond responding to loads together with an interconnected billing/rebate system will cost money to build and run, and benefits the utility, not the individual except when financially compensated. The alternative point load shedding using EMS technology is of direct benefit to the consumer for a variety of reasons, and lower net cost to operate is just one of these reasons.


(Incidentally Engineer-Poet, instead of just making various bald faced claims of others being wrong, please address the legitimate objections raised in a way that demonstrates a knowledge of engineering.)

Neil

There is potential for massive amounts of load leveling with the use of commercial scale freezers (a Dutch idea I believe).

If you're curious:
http://www.treehugger.com/files/2007/02/night_wind_proj.php

No doubt this kind of load leveling will happen first, but I see V2G as almost inevitable over the long (possibly very) term.

Here's my scenario:
1) No matter when it happens, sooner or later oil becomes way to expensive for use in transportation.

2) The most likely alternatives are PHEVs, BEVs, and FCVs (including the use of ANG in SOFCs). (If the world goes to ANG ICE, we've missed some huge opportunities.)

3) As the number of EVs grows, so does the likelihood of the utilities implementing smart charging built right into the vehicle. (John: I carry the charger for my motorcycle with me, It's not very big. I also carry a standard extension cord with me everywhere, if you charge at 110 it's not heavy at all)

4) As the number of EVs grow, so to does the demand for "plug-out" capacity. The first demand will be for simple mobile electricity capability for things like camping. Next, people will realize that they can gain a measure of security by having a battery at hand large enough to run much of their house during a power outage. The battery on my bike is big enough to run the sump for extended periods of time to keep my basement dry in a power outage.

5) As smart charging becomes more common the communications become more sophisticated. (It doesn't even have to be wireless because the vehicle will be plugged into a socket anyway, you can run the communications through the same wires)

6) Over time you will have a large number of vehicles with both plug-out and communications capabilities. V2G naturally falls out of that situation even if other methods of load leveling are already in use.

I'm not saying that this is the only way the future will unfold, but it's certainly the path of least resistance and greatest opportunity.

Jeff Baker

SOLARVOLTAIC PANEL on the ROOF of the VEHICLE, for supplemental charging in motion and for feeding the grid while parked. Your future vehicle is a micro power plant. Look beyond batteries for V2G.

vboring

@K,

As I understand it, Smart Grid is just a mechanism for publishing electric rates on a real-time basis from the utility's side. This give customers the opportunity to respond to pricing signals in any way they want.

As simple as this sounds, it is already so complicated (from a regulatory and political standpoint) that many utilities probably won't offer it until they are forced to.

Compared to that, making sure the right person gets billed or compensated for energy flowing in various directions is very simple. The meters could be told whose car is charging, (wirelessly, through the same cable that provides power, through typing a log-in on a keypad on the charger, by scanning a debit card, whatever) then keep track of how much power they use and at what rate, then bill them (either as part of the same power bill as their house or a different one or just charge the debit card. the owner of the meter you interface with wouldn't even have to be the local electric utility).

John Taylor

Neil .. I also have an e-bike. Great machine.
vboring .. I think we are seeing that it could be done, but probably won't done any time soon.

Jeff .. A SOLARVOLTAIC PANEL on the ROOF of the VEHICLE, will at most produce one horsepower using today's solar cells. Don't expect them to become a power fix any time soon. Stationary solar panels, or sun tracking solar collectors are far better at power production.

I expect to have a home energy management system, a home electrical generating system, and a cute fembot android in my home long before hooking up my BEV to the grid for V2G power spike reduction.

gr

@ EP:

Always entertaining. As usual, you defer the cost of a system to some unspecified pool of "savings elsewhere." Your link fails to address WHO PAYS for even a minimum of this new hardware: inverter, comms, CPU, logic, etc.

In fact something all PHEV owners will have to confront is $500.00 cost of running a new 220V 50-100Amp circuit to their garage/parking space (3.5 hours labor @ $100/hr, $150 materials, code certification avg.) Unless they stick with 110V trickle charging.

This applies to the whimsical V2G "employer" who will be expected to pony up this cost for hundreds of parking spaces and then pick up the added charging costs.

The EMS idea seems more logical initially. A Smart Grid publishing real time rates accessed by aftermarket comms hardware also seems reasonable. There is in fact a whole business in educating consumers on how to use their newly acquired 35kW non-interruptible power supplies, aka PHEV. Power and knowledge go hand in hand.

Jeff Baker

To John:

OK, on my solar equipped plug-in hybrid, that is 1 HP for 10 hrs a day times 300 sunny days in Arizona. 3,000 hrs of 1 HP year after year. Every $250 worth of electricity I generate for free will also displace $750 worth of liquid fuel, as I produce no air pollution or green house gases in the process. Most likely, I’ll get more power than that, because solar cells are becoming more efficient at half the price. Global Warming Solutions has a revolutionary double surfaced solarvoltaic panel on a reflector base with almost twice the power per sq ft. There are other solar panels to be announced that are also twice as efficient as they are today. Now, on the roof of my long haul plug-in hybrid truck trailer, I have room for an 8 ft x 48 ft solar panel. And that will supplement my truck batteries as well. When I pull over to rest or park, I will not be idling. I will be running my ac or heater on battery power. I will shut the engine off, save money on diesel fuel, and reduce pollution and green house gases.

vboring

@Jeff and anyone who hasn't heard the "don't bother putting solar panels on the roof of your car argument"

except for putting a very small solar panel on your car for novelty purposes (like preheating it or to run a small fan to keep it cool or to operate a few small lights), solar panels on the roof of your car are almost pointless.

the area of the roof is too small, the orientation of the panels to the sun is rarely going to be optimal, you are too likely to find some shade to put it in (even a very small amount of shade kills PV efficiency), road grime kills efficiency, rattled and shaken solar panels will probably wear faster, you are unlikely to match voltages with your battery pack, so you'll need to add at least one more inverter or booster to your car's payload.

if you live somewhere with a lot of sun and absolutely have to get your own solar panels to charge your EV, you are much better off mounting them on your garage roof, angled towards the south (or wherever the sun spends most of its time in your part of the world).

if you aren't married to PV panels, but still want to capture solar energy, get some solar hot water panels. they may even pay for themselves without the help of government subsidies, unlike any solar panel yet built.

vboring

@Jeff and anyone who hasn't heard the "don't bother putting solar panels on the roof of your car argument"

except for putting a very small solar panel on your car for novelty purposes (like preheating it or to run a small fan to keep it cool or to operate a few small lights), solar panels on the roof of your car are almost pointless.

the area of the roof is too small, the orientation of the panels to the sun is rarely going to be optimal, you are too likely to find some shade to put it in (even a very small amount of shade kills PV efficiency), road grime kills efficiency, rattled and shaken solar panels will probably wear faster, you are unlikely to match voltages with your battery pack, so you'll need to add at least one more inverter or booster to your car's payload.

if you live somewhere with a lot of sun and absolutely have to get your own solar panels to charge your EV, you are much better off mounting them on your garage roof, angled towards the south (or wherever the sun spends most of its time in your part of the world).

if you aren't married to PV panels, but still want to capture solar energy, get some solar hot water panels. they may even pay for themselves without the help of government subsidies, unlike any solar panel yet built.

Engineer-Poet

Trolleth gr:

As usual, you defer the cost of a system to some unspecified pool of "savings elsewhere."
You only think it's unspecified because you won't RTFP.  Savings include fuel for spinning reserve no longer required, fuel in plants used at more efficient power settings, and transformer and power line losses reduced by reduction in reactive power.
Your link fails to address WHO PAYS for even a minimum of this new hardware: inverter, comms, CPU, logic, etc.
It's made abundantly clear in a href="http://www.acpropulsion.com/reports/ACP_V2G_EVS18.pdf">TFP that:

  • the CPU and logic are part of the car

  • the inverter is part of the motor drive electronics and is re-used for the reductive charging system

  • the comms are the only new element required (which experience should tell you is cheap and getting cheaper).

In fact something all PHEV owners will have to confront is $500.00 cost of running a new 220V 50-100Amp circuit to their garage/parking space
Not required for PHEV; adding 70% SOC to a 16 kWh battery (Chevy Volt) can be done using a 14-gauge extension cord (110 V @ 15 A, 1650 W) in 6.8 hours.  If you count the fuel savings at the Volt's consumption of 1/50 gal/mi and 40 miles AER, this saves 0.8 gallons/day or 160 gallons/year at 200 days/year (much more compared to the car the Volt would likely replace).  One year's savings at $3.30/gallon is about $500, which pays for installing the high-power circuit for the next car.

Engineer-Poet

Quoth Jeff Baker:

OK, on my solar equipped plug-in hybrid, that is 1 HP for 10 hrs a day times 300 sunny days in Arizona.
You're not going to get 1 HP out of panels on your car.  Not even close.  If you have 2 m² of active area at 15% efficiency and full sun, you'll get about 300 watts peak or ~2 kWh/day.  That's less than 3 hp-hrs before battery losses.

It's all well and good to be green, but making overblown claims just destroys your credibility.

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