Battery based electric vehicles of today and tomorrow.

[Grumpycat]

In the drive through?

8 years ago all the academic intellectual armchair engineers who have never really done anything were saying we would have smart roads to charge EVs while they drive.

Never mind the inconvenient physics of a moving coil over a stationary coil. Ever seen that before? (Hint: In an electric motor? Or consider how one coil field pulls the other along? Perpetual motion, anyone?)

 

[Grumpycat]

Next we will see Hooters Carhops on roller skates plugging in your EV before they take your order. All while you drool,,,, I mean dine in your car.

The other thing in addition to powered roads was the no-touch wireless charging as has been popularized by Qi for cellphones. Terribly difficult, heavy, and expensive to get better than 90% efficiency vs 99.95% of a plug-in cable. But so what if charging 240V at 40A (9600W) that 960W is heating your garage? Right? "It is futuristic! No price is too great for the future!"

Note the wireless car charger must jump a 4"-8" gap between the floor and the bottom of your EV. The greater the gap the greater the losses.

 

[Grumpycat]

Well said, all of this post of yours.

You'd have no way of knowing it, but you are Preaching to the Choir.

Late '80s, I worked for a company that designed and built PV production equipment. Our major clients were in India, and China - even back then, they wanted to own their own PV supply chain, top to bottom, but most importantly, their own energy production. I've been following HomePower for about that long too.

PV energy has come a very long way since then, and I welcome it - as one option in the energy toolbox.

Remote area, high line-in cost (as you personally described) has always been a top reason for going PV. Cost efficiency is now driving it into broader applications.

For many people, the grid is kinda like being a tiny kid with two parents - they are just "there", and what they do day-to-day and the fact that one day they won't be there, never crosses your mind...

I lobbed in a softball with my recent post, and you knocked out at least a 2-base run with it.......... And, that was exactly where I was trying to go with my point....... The grid has more vulnerabilities than most people realize.

I don't think it was in this thread, but ultrarunner has posted about surgeons coming up to him at the hospital he engineers for, asking for advice. They were wealthy enough to afford multiple Teslas (only) at home, and large PV arrays on their expensive houses.

What they didn't know (it obviously was not an issue of affordability), was that the grid-tied arrays they liked to gloat about not costing them anything to drive with could be set up in Island mode.

When Cali did the lengthy preemptive Safety Shutdowns, these surgeons had Teslas sitting in their driveways and large PV arrays on their mansions, but no (turn-key) way to charge the vehicle.

Advance knowledge - presents opportunity for better personal outcomes.

Rgds, D.

Even considering the widespread ignorance that abounds is disappointing surgeons with large PV installations and multiple Teslas did not have Tesla Powerwalls. The first Powerwall is $10k installed, $7k for each additional. The Powerwall is a 13 kWh battery and inverter in one package which will keep grid-tie PV inverters operating during an outage.

 

[3930dave]

I swear i drove by "teardrop" camping trail, and saw 4 of those on the top trailing part of it. It caught my attention as it was not a flat shape, but followed the slight curve of the roof.

Flexible solar panels have been around for a while.

I've seen them used on watercraft - nice for something where you don't have a lot of roof to play with. Relatively low output, but convenient for draping over a rolled up sail to hopefully give you some offset for what sleeping or idling electronics chews up.

They are fairly thin and light, so would be perfect for a teardrop's roof - a good quality silicone would likely be enough to bond them on, and you wouldn't have to worry about roof leaks.

We'll get the roof on Gale's Leaf converted yet !

Rgds, D.

 

[3930dave]

Next we will see Hooters Carhops on roller skates plugging in your EV before they take your order. All while you drool,,,, I mean dine in your car.

Are we talking about re-charging batteries, or some other function ?

Rgds, D.

 

[3930dave]

Found this new potential battery tech.

I understood the gains they were going for, and why.

Even with a lottery win in-hand, I'd want to understand how changeable that structural battery is.

I've made it a priority to not buy a cell phone, with a welded-in battery...

Rgds, D.

 

[Jchonline]

6.2 Grid-Tied Solar System with SolarEdge and 16 Heliene 390 watt Panels

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Sorry try again.

First you would need actuated mount to optimize solar gain with varying seasons to get close to 6kW. In the Winter (depending on location) you are around 55 deg. In the Summer around 35 deg. That means a ground based array. Now if you just want to throw them on your roof…well you are at the mercy of your roof angles and direction so your actual solar output goes down considerably. Lets say you get a max of 4kW in the Summer when the sun is directly overhead. In the AM when the sun is coming up you are getting far less, in the afternoon also less. Overall you would get about 25kWh at best. You can check specifics here. Depending where you are in Madison county it might be worse. If you have shade on your property it would be much much worse.

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So you have a 75-90kwh battery that you can only charge 25kwh a day Max. That means the car has to be sitting at home every single sunny hour of the day while the sun is out to even get that much.

Next you haven’t even included installation, which will cost you probably $8-10k. Add insult to injury…all of that nice solar you put on your roof to reduce electricity bills from your AC running in the summer? It’s being pumped into the car now. So your bill goes back up!


Thus you have a car you cannot drive during the day. I guess you will need to work the night shift?

 

[Jchonline]

Even considering the widespread ignorance that abounds is disappointing surgeons with large PV installations and multiple Teslas did not have Tesla Powerwalls. The first Powerwall is $10k installed, $7k for each additional. The Powerwall is a 13 kWh battery and inverter in one package which will keep grid-tie PV inverters operating during an outage.

I agree some grid down back up would have been a much smarter investment than an EV. Especially living in CA.

However what is seldom understood is just how much power the typical on-grid house uses. 13 kWh will get you a few hours, and there are loads in a normal house it will not power. Such as your HVAC. Just not enough current surge to kick it on. You can probably get 2 Powerwalls and it will kick on the HVAC , but this system depending on size could pull from 5-10kwh…so your batteries run out very quickly.

Sorry but a Powerwall really isn’t a viable option to power a normal house for any significant length of time. Now if one were willing to substantially reduce loads while the powerwall was running (no AC, no electric heat at al) then you can stretch it further. An electric hot water heater (non heat pump) pulls like 5kwh an hour…..it adds up so fast. Maybe you have NG instead? It certainly helps. Well? 240v well pump? Bad news. Hopefully one has city water.

So many things to consider when you are running off of batteries With current technology.

 

[Grumpycat]

Sorry but a Powerwall really isn’t a viable option to power a normal house for any significant length of time. Now if one were willing to substantially reduce loads while the powerwall was running (no AC, no electric heat at al) then you can stretch it further. An electric hot water heater (non heat pump) pulls like 5kwh an hour…..it adds up so fast. Maybe you have NG instead? It certainly helps. Well? 240v well pump? Bad news. Hopefully one has city water.

No one suggested a single Powerwall would let a surgeon's house stay off-grid. It will keep the PV system running which was the original prompt of this discussion, the surgeons' surprise their homes' PV shut down when the grid shut down.

"5kwh an hour"? An hour squared?

Electric water heater elements are typically 3500W-5500W, 4500W is most common. Two per water heater but only one runs unless demand is heavy. One element would be about 5kW for estimating purposes and 5kWh if left on for an hour.

A Tesla Powerwall 2 is rated for 5.8kVA (kW but allowing for power factor) continuous output.

The first Powerwall costs $3k extra for the installation of a Tesla Energy Gateway. This monitors the flow of power in/out and disconnects from the utility in the event of an outage. And reconnects when the grid resumes. Controls are added for things such as water heaters and slow starts for HVAC so as not to slam the Powerwall(s). The Energy Gateway can automatically disable the hot water heater.

The original discussion was of California surgeons disappointed their elaborate PV systems did not keep their home running during CA rolling brownouts. Tesla recommends 2-3 Powerwalls for 12kW PV systems. The Powerwall serves to bank PV power if your grid-tie pays less for your PV power than it sells its power to you. For those with aggressive T.O.U. pricing the Powerwall can charge off the grid at night to provide lower cost power during the day, no PV system required. The Tesla Energy Gateway is where these decisions are made. Tesla subscribes to weather forecasting services and will alter your energy schedule accordingly.

My modest home in northern Alabama can consume 1800 kWh on a hot summer or cold winter month. Or 700 kWh on a mild month. Call it 60 kWh/day. Have been pleasantly surprised at how little power friends' homes in California consume. The difference here is no developer will build more than stick walls with brick veneer and insulation blown in the attic. In CA friends' walls were 18-24" thick and roof was ceramic tile.

 

[Grumpycat]

Sorry try again.

Ok. I'll prove you wrong.

First you would need actuated mount to optimize solar gain with varying seasons to get close to 6kW.

Every never-done-anything armchair PV engineer says that. In the real world a static mount costs less than 5% of the capacity of the system. Is much cheaper to add more PV panels than to articulate the mount. Almost no PV system uses an articulated mount.

I have a big flat south-facing roof perfect for PV but for it's 12° slope. The annual difference between my suboptimal 12° and optimal 30° is 5%. Not worth the space and effort to add 18°. Not worth one row shading the row above. But considering 12° is near optimal during the summer, its even easier to mount panels simple and flat.

So you have a 75-90kwh battery that you can only charge 25kwh a day Max. That means the car has to be sitting at home every single sunny hour of the day while the sun is out to even get that much.

Now you are fabricating additional conditions. The original statement was "$10,000 will charge an EV" and now you want unlimited daily mileage?

My locale has an average annual daily 4 solar hours. That means a 6kW PV system will produce 24kWh/day. My power hog Tesla Model S will drive 63 miles according to the EPA. A newer Model 3 will go 92 miles.

Car doesn't have to be connected full time. I'll grid-tie and use the utility as my power bank. Give them the excess power during they day when they need it then take it back at night when I need it.

Next you haven’t even included installation, which will cost you probably $8-10k.

Nope. I get to make up rules too. I didn't include the cost of the driveway, the garage, the real estate to put the PV system. The increased cost of homeowner's insurance. I didn't select a system size for maximum value or optimal size for the home. This is TractorByNet so all of our project labor is free.

Tesla's online fixed-price quote for complete installation is $24,600 for 12.24 kW of generating capacity. Also wants to add $17,000 for 2 optional Powerwalls. That is $2/kW for PV, or $12,000 for the $9600 system I referenced. Then -26% Federal tax credit puts us well under $10k, full professionally installed price.

Design your Solar + Powerwall system | Tesla

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Add insult to injury…all of that nice solar you put on your roof to reduce electricity bills from your AC running in the summer? It’s being pumped into the car now. So your bill goes back up!

Nope, PV runs the HVAC saving me the cost of electricity during the day that I can use those funds to buy electricity for the car at night.