Electric vehicle charging from Solar panels.

Howardvw45Howardvw45 Registered Users Posts: 2
I want to buy an electric vehicle and power the charging system from solar panels.  220volt power supply charges more rapidly than 110-120volts, so I want to be able to get 220 volts.  

I don't want to use installed power as that defeats the purpose of going to electric powered vehicle.  

Voltage draw should be fairly constant without huge surges.  

My site, southern exposure, has near ten hours a day of good, direct sunlight.  

What size system would I need to install in order to charge vehicle? 


  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Most EV chargers require AC voltage, and PV panels provide DC.   So you will have to bypass the AC charger & feedback circuits and figure out where in the DC side to inject the PV power.  Every model of car will be different.

    Many 240VAC chargers are 10kw or more, so you would need at least 10kw of PV panels to make the project worthwhile, and have your car parked there all day.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 33,082 admin
    Most EV's charge from 120 or 240 VAC outlets... And normal utility power supplies 0 amps to "rated for circuit" current at a stable 120/240 VAC.

    Level 1 is 120 VAC at 15/20 amps (normal home outlet)
    Level 2 is 240 VAC at ~30-50 amp circuit (like your home electric dryer--Or larger current draw)
    Level 3 is typically not installed in homes (probably 3 phase @ 480 VAC or more industrial power location--DC voltage/power supplied to your car/bypassing car's internal smaller AC to DC charger)

    A quick (better) idea of how this breaks down:


    The difference between Level 1, Level 2, and Level 3 charging

    The three different levels of EV charging all come down to the power output which flows from the charging station. The power output, in turn, has a direct relationship with charging times. The higher the output, the faster the charge. Similarly, the higher the level, the more power output. Here’s a brief overview of the three different levels of EV charging:

    Level 1 charging

    Level 1 charging is the slowest way to charge an electric vehicle and mainly reserved for home charging. As Level 1 charging works by plugging an electric vehicle into your regular wall outlet, the maximum output for Level 1 charging stations is between 1.3 kW to 2.4 kW, or the equivalent of approximately 3-5 miles (6 to 8 kilometers) an hour.

    Level 2 charging

    A Level 2 charging station can charge an EV faster than Level 1, delivering between 7.4 and 22 kW of power to a vehicle. These charging stations are commonly found in public parking lots and are a great option for businesses offering EV charging or electrifying their fleet. At the maximum output of 22 kW, an hour’s charging will provide roughly 75 miles (120km) distance.

    Level 3 charging

    Level 3 charging stations are the fastest on the market today. Able to deliver between 50 kW and 350 kW power, charging with a Level 3 charging station can add 298 miles (480km) range at the high end and at 50 kW, one hour of charging a passenger vehicle will add approximately 173 miles (278km) of range. 

    If you want a more in depth analysis on the differences between the three levels of EV charging before we get into Level 3 charging, check out this blog explaining EV charging levels.

    Fo And you have to look at when you will be charging... Yes, you can pull power from your solar array--But to get the energy into your car, you need to park next to the array on a sunny day.

    If that works for you--Great. But, at this point, I have not seen any commercial systems that can do this. From what I have seen the present crop of EV cars use "more or less" a "smart" interconnect for the car to pull the "correct" amount of current (Amperes) from the AC power source (120 VAC, 240 VAC 30, 40, or 50 amp circuit), etc. And those chargers "expect/require" stable AC voltage.... But a solar array outputs varying voltage depending on amount of sunlight, current draw by loads, temperature of panel, amount of clouds, etc... Your "car charger" would not like variable AC voltage/frequency, and neither would your TV/Blender/etc...

    You have to tell us what your power needs are (120/240 VAC, 15-50 amps, daytime or anytime charging, amount of storage in your home battery bank (i.e., two days of charging your car without sun...).

    The car "talks" with the AC (or Level 3 DC) system controller and "agrees" to charging current (voltage, etc.). Obviously, my local power company does not have a "black box" to do that communications--The car cable itself/charging outlet box, etc. takes care  this.

    With solar panels, they "do not communicate with anything". We have "things" to take "raw solar" and modulate/convert it for our home's needs (charge controllers, AC inverters, etc.). And we end up with 12/24/48 VDC, or 120/240/230/etc. VAC @ 50 or 60 Hz for our use.

    The "typical" solution for solar charging of electric cars is to convert the solar power to 120/240 VAC @ 60 Hz (North America) and "plug" the car into that.... And there are two "typical" ways of doing this.

    1. This is the "cheapest" and easiest way (low maintenance, reliable, pretty much "transparent" to you). That is to use a Grid Tied/Utility Interactive AC inverter(s) to take DC power from the solar array and convert it to (typical) 240 VAC @ 60 Hz and feed that to your home's electrical panel. And that power is "shared" with your utility power. If you are not generating enough power (loads are more than the solar power--night time, etc.), then the utility supplies the "extra power needed". If your panels are generating power than needed by your home, the extra power is fed back to your utility and (typically) will turn your electric meter "backwards" and put $$$ into your utility account to draw later (night, bad weather, etc.).

    GT systems are cheap and very available. Costco has folks selling these systems in some of their stores (outside vendors). If your local utility allows GT solar--This is usually the way to go.

    You do need to estimate the amount of kWatt*Hours per day your EV Car will need to size the solar array, GT inverter(s), house wiring... But you have to size your loads for the #2 below too--To fit your needs against what solar can provide.

    2. There are utilities that do not allow GT solar on their customers' locations, and/or, some utilities/states charge lots of money for the "service"--Making it uneconomical.

    The other method is to set your home up for "off grid" usage. Solar panels => Charge controller => Battery bank => AC inverter => 120/240 VAC load panel. Essentially, making your home (or specific loads) "off the grid".

    Great if you do not have utility close to your property and/or want "backup solar energy" for power failures (aka replace or supliment a generator).

    Bad because these systems are not cheap and require maintenance and replacement parts of the life of the system (new batteries every 5-15 years, new chargers and inverters every 10+ years, etc.)... And this power will usually "cost you" much more money (say $1.00 to $2.00+ per kWatt hour vs the $0.10 to $0.40 per kWH your local utility make charge.

    If you choose #2--And many people do--You need to understand how much energy your EV Car (and any other loads) will require. You have to size the AC inverter, battery bank, charge controller, and solar array to supply the 120/240 VAC at X kWatts needed to charge the car (and have some extra power in the battery bank to charge the next day when the sun is not up).

    Off grid power systems can be from 1,500 Watts (120 VAC * 12 amps = 1,440 Watts) to 6-8 kWatts (typical "largish" residential system) or ~25 amps to 35 amp @ 240 VAC.

    These systems are not cheap to build (many $10,000's). And much of the money is "up front" (like you are paying the next 10 years of utility bill "upfront" to build the "off grid" power system.

    All of the above are very rough estimates/guesses to help you understand the "scale" of what is involved for different systems.

    If you drive locally/not very much--A small system can take several days to fully recharge. If you drive daily/commute for longer distances, a larger system is required to refill the EV every night....

    I have run across "adapter bricks" that can help you limit power draw from your EV. I have seen some that can be "adjusted" to 10-16 amps, and here is one that (quick look) sets 15 amps @ 120 or 240 VAC... Obviously less load on an off grid AC power system--If you can accept "slow charging".


    But these only "fix/address" the 120/240 AC load draw... Not how fast your need your EV to charge.

    Anyway--What is it you are looking for? Have you seen anyone that offers "solar panel 'direct' to EV car" charging?

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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