The Nissan Leaf can be charged at Level 1 (110V, 12A) or Level 2 (220V, 16A), both using on-board 3.6 kW (max) charger, or Level 3 (440V, 50A 3-phase DC requiring optional $700 charging port direct to Li-manganate carbon battery pack, to maximum 80% of 24kWh capacity). The level 3 public charging stations are not yet available. The challenge in operating a car like this with a nominal 100-mile range is getting to and from work reliably when you have an 85-mile roundtrip as I do (Laguna Niguel to Santa Fe Springs, CA). The range can be more like 70 miles under non-ideal conditions.
Why not save the approximate $2500 cost of a 220V home charging installation at level 2 if one can get 6 hours of solar power (plugging into Edison at 110V if cloudy or raining) at work. Knowing little about solar other than a typical panel is 200-240 watts, my question: is it not feasible to set up a dedicated system of 8 panels of total 1.6+ kW, wired to provide enough voltage for charging the approximately 350V battery pack at relatively low amperage (4-5A) through the level 3 charging port, and get about 8-12 kWh charge when the sun is shining? It's already DC from the solar panels, but I'm not sure about Nissan's reference to 3-phase, whether this is just due to the method of getting 440V from the grid, and would not be necessary if charging directly from solar. Alternatively, send it at 110 or 220V (inverted to AC) and use the built-in charger, but isn't this a lot less efficient?
I read an earlier post about this subject (solar carport for Leaf) and the responses, but it seems like the efficiency could be much greater than suggested there. If the connection is direct from panels to car using the level 3 port, would an inverter or some type of 3-phase conversion be necessary? If the total cost were $5000 or so, it could make economic sense due to the high cost of peak-demand electricity ($0.25-0.60 / kWh). Southern California's cloudy summers of late notwithstanding, an optimistic estimate of saving $2.50 per day (10kWh x $0.25) is $500/yr for 200 days of charging; that's a 10-yr payback.
Please point out any weaknesses in this admittedly back-of-the-envelope estimate by a solar novice, car power inverter especially my assumptions about voltage and current available from solar panel outputs and conversion to usable battery charge.
Any comments on feasibility of a conventional small to medium sized solar setup to charge one or more EV's? Plenty of roof space on a leased 40,000 sq. ft. building, flat roof tilt-up concrete, we lease about 60% of it. I'm a senior employee of a 40-person unit of a worldwide materials testing company with major manufacturing (pharmaceutical, electronics, etc) clients, so it would be good PR to have a solar story on the website, but having the company install commercial solar with net-metering to utility would take a major decision in corporate and take up to year or more with big chance of no project.
I want to buy a Nissan Leaf for delivery early next year, need to charge at or near work (will use 10-15 kWh of a 24 kWh capacity battery pack driving 40-45 miles to work). I can ask the company to plug in, but company or I will pay $2.50/day or more depending on rate and it's peak time of day solar pv system for utility rates.
The car charger accommodates 110V/12A, about 8 hr to get 10kWh; or 220V/16A, about 3 hr charging, but this requires installation of approved EVSE unit costing $2000-3000 with install by Nissan contractor and local permit. The DC quick charging port on the car ($700 option) is for use at future commercial installations, currently none available, so I need to plug in at work. Longterm, it is advantageous for battery pack lifetime to limit the discharge as much as possible. Charging at work means I can probably eliminate the EVSE at home and use 110V only during the night at low rates with time-of-use metering.
I plan to talk with some Modified sine wave power inverter local solar installers, but before I do, is it too expensive for a one-car solar setup because of fixed costs besides panels (inverter, etc.)? What's the ballpark cost for 1.5 kW, 3.0 kW, and 6.0 kW systems supplying at 110V? I don't want to waste the time of installers if they would only be interested in a big commercial install using most of the roof space.
I presume the idea of going direct DC to battery pack is not feasible, but why--expensive custom charger or limitations of the commercial panels to supply high voltage/low amperage? Power inverter
Ok I have a little more time to walk you through this.
First the internal
solar inverter charger cannot work directly with a solar panel. It has to have either a dedicated 120 VAC 20 amp or 240 VAC 20 amp circuit. You cannot just take say 2000 watt solar panel and connect it directly to say a 12 or 24 volt inverter to plug the car charger into. Nor will a grid tied inverter work in a dedicated fashion There are multiple reasons but the big one is a 2000 watt solar system does not deliver 2000 watts when the sun is shinning. At around 12 noon it can deliver say up to 1800 watts, but the rest of the day much less.
The problem is the internal charger must have the power it demands, otherwise it will see an undervoltage condition and shut down.
The work around is you would have to build a full blown off grid battery system. So looking at your solar insolation of the Luguna CA area in winter is roughly 4 hours, and your Leaf battery pack is 24 Kwh worse case. So in solar panel wattage you would need (24 Kwh x 1.5) / 4 sun hours =
9000 watt solar panel array. 900 wat of solar panels will cost you roughly $2 to $3 per watt or $18,000 to $27,000
You would also need a minimum 75 Kwh lead acid battery bank to store and buffer the energy. The amp ahour capacity needed depends on th evoltag eof the battery but at this huge power level you would want to run 48 volts or more, but that is irrelevent in this discussion because all that is needed is the 75 Kwh reserve capacity to determine cost, weight, and space required. At $140 per Kwh the cost of the batteries is $140 x 75 Kwh = $10,500. Weight = 60 pounds per Kwh = 60 pounds x 75 = 4500 pounds.
Then you will need a few charge controllers. At 9000 watts and 48 volt batteries you would need 3 60 amp charge controllers at $500 per unit.
As for the inverter, no off the shelf solar unit is going to do the job. You will need an industrial inverter. At this price level you just as well get a 3-phase 480 volt 25,000 watt inverter. That is going to set you back another $50,000.
So by the time you are done you are pushing $70,000 to $100,000 to generate 24 Kwh of electricity per day to fuel your car. So if you spend 20 cents per Kwh to your electric company a charge cost you 24 x $.6= $14.40 per day. How many days would it take you to break even to pay back $70,000? I come up with 13.5 years. But here is the fun part. Remember those $10,500 batteries. Using such a small 75 Kwh stack and draining them 40 % each day means you get to replace them in about 2 to 4 years at even higher cost. So in reality a solar battery system would never pay off.
I cannot believe you guys pay such high electric rates in CA. Well actually I can since you guys decided to quit building power plants and depend on most of your power coming from neighboring states, you will get taken to the cleaners for that energy policy and always be dependent on others to supply you with energy. Here in TX we get all the power we want for 10-cents per Kwh
Now what you can do and feasible in CA is have your neighbors buy you a grid tied system and let them eat most the cost with their tax and electric rate dollars. To generate 24 Kwh in your area with a grid tied system only takes roughly 4500 watt solar system and a
4000 watt inverter. Grid tied power inverter After your neighbor pay their fare share your out of pocket cost will be around $9000 to $10,000. At your electric rates it will pay for itself in less than two years. While the electricians are there instaling the system you can have a 240 VAC 30 amp circuit installed on an outside wall to plug you car into. Sweat huh?
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