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Forum Index : EV's : EV's Off grid charging?
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| Godoh Guru  Joined: 26/09/2020 Location: AustraliaPosts: 458 |
We are toying with the idea of having an EV. We live totally off grid at the moment with around 5kw of solar panels. We would add more panels to the system but are wondering what the simplest way would be to charge an EV off a solar system. eg. Could it be charged straight of DC from the panels? Would we need a battery bank and inverter to even out the load variations from the solar panels? We would probably drive around 150 to 200 klm a week. From what I have read on the forum this would mean we would need enough panels to supply around 15 to 20 kwh to the batteries. Of course there are cloudy days to take into account. I am just looking at possibilities at the moment, and interested in the simplest system possible. I would prefer a very simple car too, but the commercial varieties seem overly complicated to me. over to you folk Pete |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1027 |
Usually No For the commercial varieties, Have a read over on the AEVA https://forums.aeva.asn.au/index.php?sid=5ef8c9eedf7ea1b1836b32701da4ffd0 or just ask them. For a home built conversion, DIY home DC charging would be preferable. Edited 2023-07-20 20:21 by Revlac Cheers Aaron Off The Grid |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Thanks for the response and link Aaron. I will check it out. Pete |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1027 |
I was also toying with the EV idea, travel is about 100km a week lately with the occasional 250km or so round trip to go to the doctor and some other places. Also have to include that the return trip to home should still have enough power in reserve (without the need for a charge) for an Emergency trip to the Hospital if needed, Don't think it won't happen because getting older it happens, would not like to be the one with a flat battery in an emergency. Its very quick and easy to drop 10L of fuel into an ICE vehicle from a fuel can and be on your way, an EV electric charge stop along the way (if even possible) is not going to be quick. The conclusion was, it made no economical sense to go with a NEW EV or the cost of building one at this point in time, far better cost savings and environmental savings to be had by adding solar and storage to a house. It may be a different story for those who do a lot more regular travelling. Also I would not want to end up developing the mental insanity and paranoia that some EV owners get, not all of them just some, while others are very helpful to answer any questions, pros or cons about EV's. Had a friend over today and his son had a late model hybrid for work, while I could never afford such a thing it is a better more practical solution at this point in time. I should have asked him if it was a plug in hybrid.  Cheers Aaron Off The Grid |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 651 |
Pete, in your situation I would only consider a plug in hybrid car from what's available today. These you usually can slow charge from a power point. Your solar & battery capacity obviously has to be able to supply this charge, especially if the charging time goes beyond sunshine hours. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Thanks yes it does sound like a plug in hybrid would be a good way to go. Being stuck on the mountain with a flat battery in an EV may not be good as Aaron says. I will have a look at the PHEV range thanks Pete |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
5 KW is a VERY modest amount of panels to live off! I'd be doubling that before you even thought of an EV. You may be able to charge in town while you do the shopping but I'd still put up more panels just for peace of mind. For the limited amount of Miles you do, I cannot see how an EV would make any sense financially. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Hi Davo, we live a very modest life. Our power usage is only around 1.5kwh a day. We don't run our batteries down below 70% full charge, so have three days of storage before they have to be topped up. So far the sun appears or the clouds lighten enough to keep the batteries up fine. I only use heavy loads like power tools when the weather permits and I know that the batteries will be topped up before sun down. We are just trying to get away from fossil fuel usage. So far we have ditched gas, so now are trying to ditch petrol where possible. Considering how complicated car manufacturers want to make their machines these days, we may have to make our own EV. I definitely don't want heated seats, apple or google play, radar sensors, or any other rubbish. I just want a simple car, so far it does not look like any manufacturers are doing that. Cheers Pete |
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Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
Pete, Commercial EV will be very hard to charge direct from solar. Most are running 300 plus volts. The bigger, heavier vehicles are much higher. F150, Rivian and Cyber Truck all run 800v. An inverter to run a wall outlet charger will be the only option. You also need to consider how much power you will use and have to put back in. See the thread on EV consumption https://www.thebackshed.com/forum/ViewTopic.php?FID=15&TID=15357 My EV's are 144v nominal. In EV Hilux I have the main pack in 3 sections of 48v nominal. Each of the 3 sections are connected in series to make the 144v. I have 3 separate solar systems of 48v nominal. Approx 4kW each. On one side of the changeover switch, all 3 solar systems are connected in parallel when charging my house batteries. When charging EV Hilux, the other side of the changeover switch connect each solar system to it's own section of the main pack. The voltage of each pack can get out of balance, but when all done they are all the same voltage. They don't reach full at the same time. Charging in good sun, this can charge around 100km range in a couple of hours. Ok so then to charge T-Rev direct from the solar....... I connect the 3 solar systems to EV Hilux and connect the 2 vehicle packs together in parallel. I can also charge either EV Hilux or T-Rev from the wall outlet powered from the inverter, connected to the house solar battery. Another possibility, if your driving distance is not to high, you can charge an EV at a public outlet, each time your out shopping. I have heard a number of people doing this. They never charge at home. There are still some shopping centers offer free charging. Trev @ drivebynature.com |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Hi Trev, thanks for the explanation of how you charge your vehicles. It gives me a bit to think about. Splitting the cars batteries sounds like a great way to go. Thanks again' Pete |
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pollenface Regular Member  Joined: 01/09/2020 Location: AustraliaPosts: 47 |
I occasionally charge my MG ZS EV from a 6000w inverter @ 1.5-1.8kw during strong sunlight. I have roughly 5.5kw of solar split between 4 victron mppts and 5kwh worth of usable lead-acid batteries. I don't have a lot of battery storage (yet) but also have grid-tied solar available which does most of the work. Charging usually draws about 15-20kwh from the AC side so I imagine 20-25kwh worth of LFP storage in the off-grid system would be great! Edited 2024-02-20 15:54 by pollenface Off grid man caver |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Hi Pollenface, just wondering what sort of inverter you are using, and what battery voltage? I have a 24 volt bank, and now that I have added more solar panels I have around 10kw of panels. They are split into 8 banks so I have 8 controllers and a 14.4kw battery bank. So plenty of solar to charge the car on sunny days, and still enough on cloudy days to keep the house running and put some into the car if necessary. Some more information on what gear you have would be great Pete |
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| pollenface Regular Member Joined: 01/09/2020 Location: AustraliaPosts: 47 |
Hi mate, the inverter is a high-frequency Xijia/CNSwipower 48v model. It's a good quality Chinese one with built in soft start, probably overkill but it does run my 2.5hp belt-driven air compressor. I've added an extra fan to the rear (with a small buck converter) to run a quiet fan 24/7 to help keep the unit cool & quiet in summer. I have a mixture of Victron 100/20s and 150/35s and a few different 1-1.5kw matched panel kits which I've picked up 2nd hand from people upgrading their grid-tied systems. Each panel group to it's own controller. I just need to get my batteries up to speed now, hoping to build a 15kwh lifepo4 bank within the next 12-18months. Edited 2024-02-21 23:52 by pollenface Off grid man caver |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Thanks, good to hear that your HF inverter is doing such a good job. I bought some 2.8mm enamelled wire yesterday to begin winding a bigger transformer for my car charging inverter. Going to be hot here ( for us) so will make a start on the high voltage side today. Pete |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
I have finally finished setting up my system. I bought a second hand Zappi 7kw single phase EVSE. So now I have a home made 8010 4kw battery inverter. Two 5 kw Zeversolar gti inverters AC coupled to the battery inverter. what I am finding is that once the batteries get to nearly full, that the battery voltage rises high enough to cause the battery inverter to shut down due to over voltage. This causes the Zappi EVSE to shutdown and give a message that says "waiting for excess solar" The only way to get it to restart is to put the zappi into fast charge mode which draws power from the battery inverter and lowers the battery voltage. Then I can put it back in eco mode to just use solar power. And once the battery voltage rises we have the same issue. Just wondering can anyone suggest a way that I can prevent the battery voltage from rising too high when the batteries are nearly full. At the moment I have the GTI inverters set to anti island when they see 28.8 volts, and the 8010 inverter does the same. I am open to suggestions from anyone who can come up with a solution, that allows me to have the charger work without too much intervention from me. Thanks Pete |
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| mab1 Senior Member  Joined: 10/02/2015 Location: United KingdomPosts: 210 |
If I'm understaning correctly, you have the gti's and the 8010 inverter all shutting down on overvoltage at 28.8v? If you have miltiple gti's can you not set the gti's to shut down at a slightly lower voltage? Say (if you have two gti systems of different sizes) the bigger one at 28.0v then the other at 28.4v? That way, as the need for power tails off you lose the gti inputs but the 8010 keeps going. If you want the 2nd gti to keep going til the zappi is finished you may need a d.c. diversion controller on the battery big enough to handle most of the 2nd gti's output to keep it <28.8v Edited 2024-09-26 22:11 by mab1 |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Thanks Mab, I was thinking of that idea last night. I will add another Voltage controlled relay for the second GTI and do as you suggest, having them set for different voltages and see how it goes. Supposed to be sunny here today and tomorrow so good days to tinker with the system. Thanks again' Pete |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Hi Mab, I tried your idea today and it works. I added another voltage sensitive relay so I can control the GTI inverters separately. Then I got really brave and switched the changeover switch to back feed through the Latronics 3kw inverter for the first time. And it works great. So now can have one GTI backfeeding the Latronics and one GTI backfeeding the 8010 inverter. Both set to different cut off voltages. I am charging the car off the Latronics and one GTI today. So far everything is going great and I am putting in around 4.5 kw to the car. Up until now I have not been able to charge at more than 3.6kw so the exercise, has been worthwhile. Thanks again for your help Pete |
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| Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 651 |
Good news about your successful charging arrangement. Just make *very* sure you can never accidentally connect the AC from the Latronics and your 8010 inverter to your mini grid at the same time. I did something like that once (unintentionally ) and the result was spectacular  .Just as well I had a spare inverter handy to run the house. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
Thanks Mr Murphy. I have a changeover switch that has centre off on the GTI that is connected to the Latronics. So in one position it connects the GTI to the Latronics inverter. Then when I don't want to charge the car I switch the switch back to put both GTI inverters in parallel and connected to the 8010 inverter. I get the problem with inverters being out of phase. I can only imagine the fireworks display. I have seen a few inverters that I was repairing many years ago, decide to pop all the mosfets. It does look spectacular. It is all a learning curve that gets steep at times but I am getting it all doing what I want now. I did notice yesterday that the solar panels connected to the GTI that fed the Latronics inverter were only outputting around 1600 watts into the car The bank of panels is actually 8 x 320 watt panels so I would have expected a bit more output as it was a clear sunny day. A bit of investigation to to later, Tinkering seems to be a full time job cheers Pete |
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