GREAT video - I've been trying to understand this for a while now. One figure I've stumbled across during my research is that "it takes ~1.3-1.6 kWh to initiate a charge on an EV battery.." Is this true? Can you explain why?
Somebody did a test on RU-vid, and it turned out to be more efficient to charge at a higher current. So I assume lower power will be less efficient or just not enough.
Thanks :) i charge from off grid solar i only have a Nissan with 35kwh useable, i only need around 2-3kw to drive from work and back 30km distance, my solar setup is very small 800w panel and 135ah 48v batteries. im in Australia.
Well I'm assuming that you're not using the solar panels to fully charge your car, instead of replacing plugging it into the power grid. The idea is to allow your car to recharge the batteries while it's sitting there in a parking lot while you're working. Most people work in 8 to 10 hour shift daily. So why not have your car sitting there regenerating your batteries, making up for the loss of electricity from traveling to and from your destinations. It's not the idea to fully recharge your vehicle.
i have a 2013 chevy volt which i put 2x 100w flexible solar panels on. they feed directly into the 12v system which imo is the most efficient way to do it. almost all EV's have about a 200-500watt loss through the 12v system when turned on, mostly to run the big beefy high voltage contactors, lights, infotainment, ect. they just go straight through a PWM charge controller for now, im pretty sure at low voltages a pwm is actually more efficient since the voltages are already at the right value. I added a 4kwh lifepo4 battery, which normally would be a bad idea. it has a little 15w heater and thermostat wired directly in to keep it above freezing, and no BMS, just an active balancer. the chevy volt is one of the only cars that uses a high voltage battery to start its engine so no need to worry about starter surge current. the volt doesnt do a good job of matching the lifepo4 battery since it looks like a floating lead acid most of the time, which is actually a feature. the solar panels keep the lifepo4 topped up and avoid the ~15% loss from stepping down from high voltage to low voltage (350v high voltage battery to 12v system) this being said, they only add about 4 miles of range per day (unless i drive much longer and start using up the lifepo4 battery which is rare). the thing is, the volt normally gets about 30mpg, and that's equal to about 8kwh. so by saving about 800watts per day= 0.13gal gas saved = $0.54 in my area. the solar panels cost 70$ and paid for themselves in about 4 months. now theyre just free and keep saving me gas.
I was thinking of doing the same thing, would you think about posting a video about your setup? Did you end up using a Mppt controller for the battery? Doing the calculations for using an inverter to plug in the car.
I didn't see a link to a sun hours chart for different locations, such as northern California. Also, my Bolt can charge on L1 (120 volts at 8 amps) at about 88% efficiency, so that might change the calculus. I pay about 41.724 cents per kWh of grid electricity here. I'm interested in the math for a suitable portable system.
so if you have a 5kwh solar system at home, then you can expect about 15-20KW of power per day stored. And if the car has a 60KW battery , then you need at least 3 days to charge it.... just a waste of time and money if you ask me. you can forget about putting solar panels on your car roof, another waste.
Home grid tie systems are priced over $20,000. So you'd have to do it all yourself. And there would be nothing left to power your home, either, since it's all going to the car. Have to go up to 10 kilowatts + batteries to do both. Double the size and expense. Didn't they say renewables were going to be so much cheaper than 'fossil fuels'?
If you intend to charge an EV with a standalone (off grid) or emergency backup power solar system. It's important to consider the technology that's used in the inverter. High frequency, transformerless inverters provide a much lower surge capacity and a shorter life expectancy than heavy duty, low frequency, transformer-based inverters. Additionally. high frequency, transformerless inverters do not provide any galvanic isolation between its DC boost stage circuitry and its AC output which can allow high amperage DC current to pass through to your EV's onboard charger and damage it. You may be able to use a high frequency inverter to charge an EV short term, but it would just a matter of time before the MOSFETs or IGBTs in this inverter fail and you can kiss your EV's onboard charger goodbye. A much better and safer choice if you want to charge your EV with solar is to use an inverter or power station that uses low frequency, transformer-based technology in its design. Low frequency inverters can handle high surge loads for at least 3x their continuous rated capacity and they can do this repeatedly, without sustaining damages to their MOSFET transistors, for minutes, rather than the milliseconds that a high frequency inverter offers. And because low frequency inverters use a transformer, they provide galvanic isolation which protects your EV's charger. That's why the big-name brand inverter manufacturers like Schneider Electric, Outback Power, Sigineer Power, Magnum Energy and Victron Energy and others, all use a low frequency topology in their design.
For charging an EV, there is no surge needed. There is no need for galvanic isolation between system and charger, why would there be? Low frequency is indeed good for lifespan and surge power, but i don't believe you need them to charge an EV if you don't have the budget.
@@cleversolarpower Why would there be a need for galvanic isolation? Because no inverter on the market is immune to failure and a high frequency inverters have a much high failure rate than low frequency inverters. Google it if have doubts. All it would take is for a MOSFET or IGBT to short to ground in the H-Bridge circuit, and without an isolation transformer, the inverter can pass high amperage, DC current through to your EVs onboard charger which would not only damage it, but can also set the onboard charger on fire. I have spent the past 24 years in the inverter repair industry and I have examined thousands of inverters with FETs and IGBTs that have shorted to ground.
@@cleversolarpower Why would there be a need for galvanic isolation? Because no inverter on the market is immune to failure and a high frequency inverters have a much high failure rate than low frequency inverters. Google it if have doubts. All it would take is for a MOSFET or IGBT to short to ground in the H-Bridge circuit, and without an isolation transformer, the inverter can pass high amperage, DC current through to your EVs onboard charger which would not only damage it, but can also set the onboard charger on fire. I have spent the past 24 years in the inverter repair industry and I have examined thousands of inverters with FETs and IGBTs that have shorted to ground.
@@cleversolarpower I'm not saying that there needs to be galvanic isolation between the system and the charger. I said that their should be galvanic isolation between this high frequency, transformerless inverter's high voltage DC boost stage and it's AC about which is connected to the EVSE and then to the EV's onboard charger. Without galvanic isolation in the inverter, during a catastrophic failure of the inverter's H-Bridge circuit, high voltage DC can pass through the EVSE and damage the EV's onboard charger and void your EV's warranty. Search for the video by Red Hill Labs titled "Solar Inverter Catastrophic Failure" to learn more about inverter design and why you should never charge an EV with an EG4 or any brand of high frequency, transformerless inverter.
Hi from New Zealand. Found your channel when figuring out a solar system for our new small house (84 meters) in the Waikato district of North Island. Thanks for Pv watts site- we get 4.63 sun hours per day. Or if we install a 8 kilowatt system as planned, we get 10,602 per year. With the exchange rate differences our power is the same price as yours- 20 US cents or NZD 33 cents from the grid. A reasonable 8 kilowatt grid tied WITHOUT batteries is around $10k NZD or $6k USD. Add batteries 15 kilowatt 200 amp and your at another $6 NZD or $3,500 USD. So now, we are not going to purchase batteries and instead sell back surplus to the grid at $0.10 NZD per KW. Thank you for you channel and help in working out the economics of vehicle charging.
I would say that you don't need to get a 15kw batteries, you can always buy a small battery and add more (and batteries have a life span of about 3 years after which they start holding less charge). You can start with a (random number) 1kw battery but then again, what's the use of the battery/ies for?
I have a model S with the upgraded charger 72 amps at 240 volts it charges about 60 miles per hour it would take 43 panels 😮😮😮😮 to charge at that speed
Damn, 60 miles per hour is fast. However, this would be useful for on the road. If you are at home, best not to charge so quickly to save the battery a bit.
I use a 4kw grid tied system on a zappi… charging at an average 3kw… it gives me 25 miles of daily driving for my needs… But a PowMR hybrid inverter with 10kw output and a decent battery should allow me to use a regular 7kw ev charger…
Additional weight would indeed be another factor + aerodynamics. I don't think it would be better on a bus, because the bus also weighs more, thus using more electricity per mile. Solar panels on vehicles are to 'look good' for the environment.
How many 500w panels do you need for a 100mw solar panel field Assume 6 hours sunlight How many 4mwh mega batteries do you need to supply power for 6 hours
These are strange questions. You would need 200,000 500W panels to create a 100MW solar array. 6 hours of sunlight is not relevant to your questions. The answer to your last question depends on the power consumption of whatever you are supplying the power to.
We should think very differently regarding charging our cars. The usual power use cycle at home is that most power consumption is at 7-8 AM and 5-7 PM. But the sun generates best at ~9 AM to 15 PM, when most people (and cars) are not at home. The obvious smart way is to have direct charging from solar at work, and then use/sell most of that electricity during the next evening and morning peak hours. Modern (and cheap) LFP batteries last 5000+ cycles till they degrade to 80% of their capacity, while an average car needs only about 1000 cycles for its lifetime (1000x300km=300 000km range). So it is a waste not to use that extra battery capability for trading electricity and balancing the grid. But to use it this way, you want a car with LFP batteries, a model with vehicle-to-grid capability, and I'd say at least a 11kW charger at home, as you will want to offload the battery during ~4 peak hours. If you choose to cycle your ~60 kWh car the battery from 20% to 90% to maximize its life, and use 10kW to drive to/from work, that is 70%x60kWh=42kWh-10kWh=32kWh, which need to be offloaded in ~4 hours= at ~8kW. 5000 cycle LFP batteries allow doing that for 5000/365=13.5 years every day if you discharge fully every day, or 20+ years if you save your battery a bit, like I described.
Thanks for your comment. Tesla uses NCA (Nickel-Cobalt-Aluminum), not LFP. If we use it as you describe, from 20 to 90%, we can get 1,000 cycles from it at 80% capacity left, and that is from a conservative perspective. Cars with LFP batteries will have a shorter range because the energy density is not that high. LFP: 160Wh/kg and NCA 260Wh/kg. Charging at work will definitely help.
@@cleversolarpower Tesla use LFP too, theis Model 3 is offered with a 57.5kWh usable LFP battery. Many other new cars also offer it. And by 2030, it is expected from sodium batteries to reach the same energe density, but even more cycles (8-10k). So I really hope, that car batteries and capabily with so many cycles will help with grid balancing and energy trading too.
Just thought: the average household has about 5KW? But do you think that this average household has a Tesla? Isn't it one of the most expensive electric cars?
@@cleversolarpower I was not assuming that, but asking. Probably I misunderstand you. I think a household with a Tesla is not average and probably would use more solar panels than the average user to have enough electricity to charge a Tesla faster. 4.3 days seems very long to charge a car. I don't want to be smart, just try to understand.
@@SjaakSchulteis so if you have a 5kwh solar system at home, then you can expect about 15-20KW of power per day stored. And if the car has a 60KW battery , then you need at least 3 days to charge it.... just a waste of time and money if you ask me.
@@cleversolarpower that’s probably ok, most people who own a tesla probably have a climate controlled garage. You make great videos, this video here was informative, thanks
The cost for grid electricity when charging a Tesla is the cheap overnight rate. The overnight grid rate is likely the cheapest option. Solar & battery combination make more sense compared to the dinner hour expensive electricity price. Solar with minimal batteries could make sense for daytime power consumption, such as air conditioning or a heat pump.
I have a Counterpoint for you, by looking at the image of the car I see multiple spots you could have Collective solar panels. You prefer to have the roof of the car, and I can see you can place a lot of miniature solar panels up there including the flat part and the corners of the roof. You could have transparent solar panels instead of Windows and mirrors, lights so on. And you could also have solar panels attached to the doors and the other panels of the exterior of the vehicle. And if it's weight that's the issue, just use more smaller lightweight panels.
Horribly bad math and wtf do you mean 25KW... 1500w idle is an asinine claim. Bad component selection, arbitrary location and season but no angle data, and you assume a 4 hour day? WTF? I get peak power for 4 hours in the winter. 8 hours of light. My 2kw system generates 25kwh winter nearly 40 summer... I literally track it in real time.
Apparently I didn't do a good enough job explaining sun hours for you. If you don't know the difference between Watts and watt hours I recommend watching my video about solar basics. After viewing that video, get a current meter and measure the current draw from your batteries when there are no loads. Then multiply by your battery voltage. You're welcome 🤗.
