Home Battery Storage to EV Charging Problem Explained. Can a Tesla Powerwall Charge A Tesla Car? 

Fake 🕷️ to make sure we were paying attention in class ?!? 😝👍

Its important not to overthink things and make life complicated. At home I just limit my EVSE to a charging rate that my solar generally keeps up with (net). Which for me is roughly 4kW. Most of the time I plug in during the day to directly offset my solar. If I have really depleted the EV battery, which is rare but does happen sometimes, I just plug in overnight and use the grid. Trying to be perfect winds up being too much work. Even EVSEs that have mains current monitors and try to match what you would otherwise export aren't really all that useful in my opinion because it is important to know just how many miles you are putting into the vehicle. The non-determinism can catch you off-guard. I don't use those gizmos for that reason. For me, personally, I usually only have 20kWh/day of net export during summer anyway. And for someone with batteries (I don't on the main system but do on a secondary system)... for someone with batteries, you still want to make sure that the batteries can zero you out or even be net-export during the peak pricing period (4-9pm in my case) (depending on the utility tariff you are on). That doesn't leave a whole lot for the car anyway so I just don't sweat it too hard. A battery doesn't really help charge the vehicle at all. -- I have a little off-grid charging setup on an off-grid property that is fairly cheap... a few thousand dollars worth of gear (cheap as solar goes anyhow). Roughly 2kW worth of panels ($2000), two Victron charger controlllers ($200), 10kWh worth of LiFePO4 batteries (200Ah @ 51.2V nominal) ($2400), a small 3000W inverter ($200), and an EVSE configured for roughly 8A @ 120VAC ($200). Roughly speaking, not including wiring, fusing, and such. Call it $5K. That setup can put 30 miles/day into my EV in the summer... which is far better than nothing at all! Multi-use of course. Lights, cooking, other things as well. Its actually a bit of a bigger system but 2kW worth of the panels is ear-marked for the EV. -Matt

Great Info as always. Thx Man👍

I'm definitely one of those who thought I could go by an Anker F3800 with extra batteries and 4x 400w panels to charge my EV, not to full capacity but to add some easy and cheap range on the daily in my garage. I think I'd rather just find a soloar solution to reduce my daily cost of electricity and charge my car from the grid. Thanks for posting this video.

I think something people forget is to calculate the cost of using the battery. Just simplifying the numbers here, $10,000 for a 10kwh battery rated for 5000 cycles. That's 50,000kwh/$10,000 or an additional 5¢ per kwh. (I've seen real world calculations of 20¢ or more just to use the battery) And thats not including conversion losses. Almost definitely cheaper to charge from the grid at night or from solar during the day if possible.

That fake spider is back….lol…

I have 60 KWH of LFP storage but wouldn’t charge a car off batteries as a rule. Most households have multiple cars ,one of which is usually sitting at home for short runs. By alternating the stay-at -home car, you can self consume all the solar excess without cycling the house battery so much. If you are driving the full range of your EV daily,and driving isn’t your job,you have a lifestyle issue more than charging challenge. My motivation for getting an EV is,for a large part,expansion of battery storage since I am retired and don’t have to go to work. My battery assist bicycle is all I can afford at the moment since I don’t want credit purchases.

Excellent very clear info! The solution to this problem is bidirectional charging. Car batteries are cheaper because they don't have to be installed. Once bidirectional charging is an option, you can just buy a new Tesla and park it in your garage, even if you never drive it, and get storage equivalent to 5-13 powerwalls. It really makes sense if you don't need to drive your car as much during daylight hours when solar can charge up the battery. Tesla has said 2025 for bidirectional capability, just waiting for this to buy my first EV!

The battery is a buffer for the sun and, for most, a full electrical grid. No one comes home with an empty battery. Most people's cars are home at least 15% of daylight hours. Charging at work during the day and allowing your car to help the grid stay balanced is a profitable option.

Makes total sense Thanks for sharing The spider was cool

When heading off yesterday morning I drained my 9.8kW LG Chem battery into my M3 Long Range increasing the car to 55%, knowing that the LG Chem battery would charge while I was away from home. Apart from when staying away from home, all of my EV charging comes from my 15 kW pv via my Zappi EVSE. If charging at a friend's house I use her free power between 11.00 am and 2.00 pm courtesy of her power company, Ovo Australia.

My dog was watching tat spider the entire time

Exactly, EV are supposed to fill at home at night when power is cheaper.

It’s also important to remember that most people are not fully charging up each day. Often at most it’s 10-15 KWh of power each day for the car. Sometimes less. So you CAN get away with just one power wall. I know, because I do.

What the heck was that crawling up the wall?

Luckily I only use 1 cup a day versus a full bucket.

Charge your car when it is the highest production of solar and charging your power at the same time ya you may be taking from the grid and the power wall is there if you go past and into peak power but on the power your still cool

well currently all of Australia gets between $0.05-0.12/kwh for solar feed in tariff. but we get charged at $0.35/kwh to take from grid so its either 1:3-1:7 ratio if not using a battery to store power. but still on 25% of new solar installs get batteries. so how does cali compare since have the new net metering 3? because some people and companies are installing solar plus ev chargers and offering cheap charge rates higher than the utility is offering for feed in tariff. but is only pulling the excess of the solar array that be sent to the utility. maybe worth a look at the IOT with some solar inverters and options for ev charger to only use what is solar excess

1st thing i see is the consumption is not averaged out and same for production and yes jul/aug have highest production plus mar>jun are fairly even plus sept but consumption is all over the shop so need to show a bar where leveled out for the year on production and making the assumption may heve been travelling as well in some of those periods

Well, we need to look at not just the total kWh ratings of the respective devices, but also how much power can be transferred at any moment in time. These calculations assume that you can dump an entire PW3 as fast as you can possibly refill an EV, and that’s just not true.

I charged my vehicle from the sun 300+ days a year.

California is a muppetshow

Your math sucks - are you depleting these batteries every day (300-500 miles) ?! Go back to the drawing board.

Nobody and I really mean nobody charges from 0 to 100 %. Most people charge from 20% to 80% at the extreme. This fact just makes your video totally worthless.