Charging a Tesla with a completely off grid solar/battery/inverter system

[Cujet]

This video shows a completely off grid system that is absolutely capable of charging an EV at fairly high rates. He uses inexpensive used solar panels, imported LiFePO4 batteries, assembled into battery packs and a pair of inverters. A system like this can easily power the daily needs of average drivers. The interesting part is that the battery is large enough to charge the car overnight. Of course, it's a bit more efficient when charging the car during sun shine. However, the LiFePO4 batteries he uses are capable of 2000+ cycles or about 500,000 miles, and the claim is that "IF" properly managed, those batteries could last a lifetime. Also of note, the proper temperature for the batteries is about or around 90 deg F.

I'd very much like to build a system like this. What's interesting is that while there are a stack of losses and necessary compromises, such inefficiencies are easily overcome by, for example, adding one extra solar panel or battery.

 

[Cujet]

This video addresses the possible costs, depending on component choices.

 

[UncleDave]

Fun experiment for a temporary and unpermitted solution.

 

[Snagglefoot]

I thought that was well done. Jeff K will be all over this. Like the fellow on the video says it depends largely on where you live. Also, I’m not sure if it’s valid to be talking about used stuff, because I can buy a used Ford Fusion for $3000 and put $17,000 into the S&P 500. Maybe the satisfaction is from sticking it to the Man.

 

[JeffKeryk]

Thanks Cujet. So interesting. I know so little about electricity. Kinda scares me...
He hit on a few points that sold me on installing solar 3 years ago.
Cost was down and Silicon Valley electricity is some of the most expensive in the nation.
I MAY upgrade to an off grid system, but for now I am 100% satisifed with the decision to do the solar project. The numbers were just too compelling. A true no-btainer.
And I used very conservative calculations. Little did I know we would be buying a Model 3 later that year, but having the panels made it more doable. I would hate to pay CA energy prices to fuel an EV. Nearly as bad as CA gasoline...

 

[Cujet]

Also, I’m not sure if it’s valid to be talking about used stuff,

There is no question that used is used. However, as always with solar panels, it's the cost/output/lifespan calculations that matter. Solar panels have come down in price and that's driven the cost of used panels down to about half that of new. Remember, the used panels generally have about 10% lower output than the new rating (and, yes when they were brand new, probably put out slightly more than the rating) . However, solar panels typically degrade at just under 1% per year forever (some manufacturers claim 0.5% and others 0.8%). This means that one must simply account for this during design. Whether new or used, that degradation must be accounted for. If space for panels is an absolute premium, then pick the most efficient new panel possible. If not, it may be worth considering used.

The used panels don't come with warranty, and there may be a bad one in the bunch if one is not careful. However the economics can work out.

 

[Cujet]

Fun experiment for a temporary and unpermitted solution.

I do have to wonder just how much higher the costs would be to "install" that properly on and in my garage. Many areas of the country require electrical inspection of high voltage installations (the part between the inverters and the circuit breaker box) However, it's good to know that permits may not be required depending on geographical location and of course, panel placement.

For example, my property in TN has no permit requirements. But they do require an inspection of the high voltage installation. I could install the inverters, high voltage wires and breaker box with outlet for the EV's charger, pass inspection and do the rest at any time, without need for further inspection.

The thing that warms my heart with such a system is just how many "self powered" miles I could drive. I'm not convinced the savings are valid, especially when compared to a modern Honda Accord Hybrid that will return 40MPG all day long, or cost about 8 cents per mile. Or $8,000 to drive 100K miles.

 

[UncleDave]

I do have to wonder just how much higher the costs would be to "install" that properly on and in my garage. Many areas of the country require electrical inspection of high voltage installations (the part between the inverters and the circuit breaker box) However, it's good to know that permits may not be required depending on geographical location and of course, panel placement.

For example, my property in TN has no permit requirements. But they do require an inspection of the high voltage installation. I could install the inverters, high voltage wires and breaker box with outlet for the EV's charger, pass inspection and do the rest at any time, without need for further inspection.

Would be interesting to know.

If you are only connecting to your own stuff the worlds your oyster you can do what this guy is doing.

If you are going to net meter in any way you need a permit or permits, this is why Im surprised when he says he runs his air conditioner from any excess-Im pretty sure he isnt running a central air off that, but the way to do it is to net meter.

Your two step approach is probably the most economical way.

 

[JeffKeryk]

The thing that warms my heart with such a system is just how many "self powered" miles I could drive. I'm not convinced the savings are valid, especially when compared to a modern Honda Accord Hybrid that will return 40MPG all day long, or cost about 8 cents per mile. Or $8,000 to drive 100K miles.

Curious... Can you show me your 8 cents per mile calculation? Just for fun, I wanna plug in CA gas, oil, etc. cost numbers...
Thanks Cujet!

 

[loneryder]

I do have to wonder just how much higher the costs would be to "install" that properly on and in my garage. Many areas of the country require electrical inspection of high voltage installations (the part between the inverters and the circuit breaker box) However, it's good to know that permits may not be required depending on geographical location and of course, panel placement.

For example, my property in TN has no permit requirements. But they do require an inspection of the high voltage installation. I could install the inverters, high voltage wires and breaker box with outlet for the EV's charger, pass inspection and do the rest at any time, without need for further inspection.

The thing that warms my heart with such a system is just how many "self powered" miles I could drive. I'm not convinced the savings are valid, especially when compared to a modern Honda Accord Hybrid that will return 40MPG all day long, or cost about 8 cents per mile. Or $8,000 to drive 100K miles.

It might work for you in FL but TN is too cloudy.

 

[ron17571]

I keep reading how there are no issues with a future of EV, s plugging in and overwhelming the electric grid. But the idea of providing ur own power seems like a good idea. Not to mention helping keep electric bills down. That William Prowse knows his stuff.

 

[tshephard]

Kinda scares me...

Master Electrician, scares me too, that is the proper response!

 

[JeffKeryk]

I keep reading how there are no issues with a future of EV, s plugging in and overwhelming the electric grid. But the idea of providing ur own power seems like a good idea. Not to mention helping keep electric bills down. That William Prowse knows his stuff.

"overwhelimg the grid" is another word for opportunity. Heck, Musk built and continues to expand his own Supercharger network around the world. People should stop sniveling. Flame suit on!

 

[Nick1994]

I'm so glad I got the LFP battery Tesla. I need to do some more research on how to take care of the battery properly.

 

[Mikek13]

As far as solar panels go, look at what you pay. I pay less than 12 cents per kilowatt hour so it would take over 20 years to buy all the equipment. Don’t believe those solar calculators that the manufactures have on their sites. They will inflate the kWh price to make it look like the payback period shorter. The calc I used more than doubled the kWh price so they can claim it takes seven years.

Liars and Thieves.

 

[PandaBear]

I've watched his video a while ago. It basically sums up to 1) having lots of space, 2) having the know how, 3) having a lot of used stuff (panels), 4) having a way to use the output.

I would say this is a good DIY project like how people have been building new bathroom in their home with their power tool, pickup truck, landing a good deal on surplus building supplies, and a lot of free time. It is likely not scalable to everyone and if everyone does it then it won't be "cheap" anymore.

Nonetheless it is a great idea, he is a great guy in this domain, and he probably also wasted a lot of money early on to learn what to do and not to do today. With the amount of battery and solar he has he can probably run a crypto farm (or host crypto farm) instead of charging his EV and make way more money.

 

[PandaBear]

Fun experiment for a temporary and unpermitted solution.

Oftentimes permitted permanent solution is so expensive, it is better to be temporary forever even if efficiency is lower. This is one of the reason we use buses instead of light rail / train / subway in a lot of places, as well as restaurants using disposable plates and utensils instead of ceramic plates and metal utensils.

I keep reading how there are no issues with a future of EV, s plugging in and overwhelming the electric grid. But the idea of providing ur own power seems like a good idea. Not to mention helping keep electric bills down. That William Prowse knows his stuff.

The #1 reason a grid is overwhelmed, is population growth and real estate development. If you are building new division and creating jobs in the area you will use up some of the capacity. You need to increase the capacity of the grid no matter what but people are happy to pay for it.

There is no question that used is used. However, as always with solar panels, it's the cost/output/lifespan calculations that matter. Solar panels have come down in price and that's driven the cost of used panels down to about half that of new. Remember, the used panels generally have about 10% lower output than the new rating (and, yes when they were brand new, probably put out slightly more than the rating) . However, solar panels typically degrade at just under 1% per year forever (some manufacturers claim 0.5% and others 0.8%). This means that one must simply account for this during design. Whether new or used, that degradation must be accounted for. If space for panels is an absolute premium, then pick the most efficient new panel possible. If not, it may be worth considering used.

The used panels don't come with warranty, and there may be a bad one in the bunch if one is not careful. However the economics can work out.

For many commercial infrastructure (say servers), a lot of the time they are replaced near the end of life not because they are less efficient or less powerful than needed but because they have calculated the failure rate is starting to creep up to a meaningful cost. Say for hard drives, if you have labor that will replace 1% of them every year and then they start failing after warranty at 5%, 5%, 8%, 10%, 12%, 15% then it make sense for them to replace it. The site is also a huge part of the cost so replacing old stuff to save space / increase capacity is a no brainer.

This is usually not a problem for residential setup, but I guess for utility scale or commercial solar they likely upgrade and toss out still good enough panels for the same reason as data center upgrade servers. Many server chips get 2nd life when Chinese remove chipsets and build new motherboard for gamers on the cheap, just like how this YouTuber reuse commercial retired panels for his project, not going to scale for everyone but it is good fun on the cheap.

 

[UncleDave]

Oftentimes permitted permanent solution is so expensive, it is better to be temporary forever even if efficiency is lower. This is one of the reason we use buses instead of light rail / train / subway in a lot of places, as well as restaurants using disposable plates and utensils instead of ceramic plates and metal utensils.

If one understands and accepts the tradeoffs of that decision go for it.

I admire and understand the guy.

In this case unpermitted and or temporary means non grid tied - so its not ever going to be taken advantage of fully.

Its just a big battery charger and inverter - which is Ok, but without the ability to offset the rest of your electrical spend - somewhat wasted - to the extent of maybe 40-50% of it based on his own information.

 

[PandaBear]

If one understands and accepts the tradeoffs of that decision go for it.

I admire and understand the guy.

In this case unpermitted and or temporary means non grid tied - so its not ever going to be taken advantage of fully.

Its just a big battery charger and inverter - which is Ok, but without the ability to offset the rest of your electrical spend - somewhat wasted - to the extent of maybe 40-50% of it based on his own information.

I do remember seeing some of his video showing the redundant AC he installed, 1 set of mini-split for using his backyard panels + inverter and 1 set for his utility grid tied electrical.

However for the grid to be able to work efficiently with net metering they also need to have a lot of waste due to duck curve, and they also would end up paying for the waste indirectly. Whatever he didn't use during the day time (i.e. his main AC) will end up bumping out the equivalent amount of power of unused capacity / demand from the grid and also amplify the duck curve problem.

In the end there is only so much a home user can do to shift load. He can charge his EV, dry his clothes, cool his house, make ice, heat water for night time shower, etc, but the amount of work and waste will definitely add up, both in cost of equipment and efficiency loss. Maybe he can fish a wire through a hole in the window to the garage so he can use his solar panel to power a dryer and a freezer filled with water jug and use the frozen jug to cool his house when the sun is down.

 

[UncleDave]

I do remember seeing some of his video showing the redundant AC he installed, 1 set of mini-split for using his backyard panels + inverter and 1 set for his utility grid tied electrical.

However for the grid to be able to work efficiently with net metering they also need to have a lot of waste due to duck curve, and they also would end up paying for the waste indirectly. Whatever he didn't use during the day time (i.e. his main AC) will end up bumping out the equivalent amount of power of unused capacity / demand from the grid and also amplify the duck curve problem.

In the end there is only so much a home user can do to shift load. He can charge his EV, dry his clothes, cool his house, make ice, heat water for night time shower, etc, but the amount of work and waste will definitely add up, both in cost of equipment and efficiency loss. Maybe he can fish a wire through a hole in the window to the garage so he can use his solar panel to power a dryer and a freezer filled with water jug and use the frozen jug to cool his house when the sun is down.

Im a bit unsure what you mean by waste due to the duck curve. (I understand the duck curve otherwise)

If you are going to bother with a big battery one of the best uses is to offset peak time load.

- but you cant unless the whole thing is grid tied.

For sure he can run some stuff from a big disconnected system, but a maze of wires and extension cords all over the yard and house are going to be a hassle over time.