How Many Solar Owners Charge Their Leafs During the Day?

We've had a 4.3Kw PV array since 2007 in anticipation of buying an EV. However, even though my wife only works half days, we don't charge during the day. Reason being it makes more sense to sell the power during peak times, I don't want to charge the battery pack when it's hot, or outside temps are hot, during the winter, the solar power output is pretty low on many days. Therefore we charge at midnight on the grid.

Would like to hear from other PV array owners and their Leaf charging habits!

I've had my LEAF since April and my PV System since March.

I charge my LEAF off-peak (9 pm - 9 am) due to the extremely low cost ($0.055) per kWh.

Once I have a full year of Solar experience, and have determined how much I generate over what I use, I will probably move my LEAF charging, pool pump usage and some other stuff to on-peak usage.

At this time, it appears that I will generate about 20% more than I use on-peak, over the course of a year.

I am on a net-metering plan (peak and off-peak separate).

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Just as a side note, I am averaging about 90 miles per charge
with 60% highway 65-70 mph, 30% streets 35-40 mph and 10% under 35 mph
all with a/c on auto. I am very impressed with the range.

We are fortunate that the electric utility subsidy for our system allowed us to get quite a large system (6.7 kW). Because of that we generate more electricity than we use and therefore have not bothered to go to TOU. Because we are not on TOU we net kW for kW with the utility because of banking. From a practical standpoint we generate all we need during the day and use very little at night. I was pleased to see that when we received our electric bill for April (the first full month we were charging the car) that we still "banked" a significant number of kilowatt hours. Thus, we charge the LEAF whenever we get back from driving. I have the charging timers set to go "off" at 5:50AM and to go "on" at 6:00AM, thus they, for all practical purposes, are on all the time and I don't have to worry about whether the car will start charging. As soon as I plug it in I can see it start.

On weekdays, the car is out and I couldn't charge at home even if I want to. The car is usually charged after midnight at the low off-peak rate of $0.053/kWh. In the day time, PV generated electricity is sold to the utility at the higher rate.

Leafittome said:

We've had a 4.3Kw PV array since 2007 in anticipation of buying an EV. However, even though my wife only works half days, we don't charge during the day. Reason being it makes more sense to sell the power during peak times, I don't want to charge the battery pack when it's hot, or outside temps are hot, during the winter, the solar power output is pretty low on many days. Therefore we charge at midnight on the grid.

Would like to hear from other PV array owners and their Leaf charging habits!

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I'll charge during the day if I need to, but that's very rare. It's best for the grid to charge off peak at night, and the Time Of Use (TOU) rates take that into account and make night time charging much less expensive.

It's also good to charge when it's cooler. I have a fan that exhausts air from the garage that I start up an hour two before charging at night on the hottest summer days to drop the garage temperature by 10 or 20 degrees when it's getting to the 90's or 100's in the garage from the daytimie heat.

Since we don't have any 'night' rates, I plan on charging my LEAF with our PVs during the day. We're on the 'Basic' plan which is true net metering. On the TOU plan the utility only pays you less than .04/Kwh for on peak or off peak and you have to take a payoff every April 30, then it starts over. So my plan is to use up any 'extra' before April 30. However, I've heard that our utility is going to give us a night time super off peak rate around .04. If they do that, then I'll probably charge at night. :mrgreen:

I produce surplus on my PV and plan to see if I can stay within my surplus with LEAF charging. I just got my LEAF last week and would like to observe for a month or so to get an estimate. Based on that I would decide whether the second meter @0.06c/KWh plus the $5.00 meter rental cost from SDGE is worth. I have a net meter and expect to be paid @0.05/KWh for the surplus. Note than I get to charge at work for free and only need to charge at home during the weekend.

On Net Metering, there is no incentive to charge at night, but I usually do so.

When I had only the L1 charging (the "20-hour" charging rate of the included L1 EVSE), I occasionally had to start charging in the early evening to fill the LEAF by morning.

Now that I have had the "Upgrade Rev1" done to my L1 EVSE (now, a 10-hour charging rate when using 240v), I can start charging in the late evening, before going to bed.

I tried timer-based anytime-charging (Start and End both set at 11 AM) to 80%, and it seemed to work fine. However Carwings is not 80%-aware, so it still shows the 100% charging time estimates.

garygid said:

On Net Metering, there is no incentive to charge at night, but I usually do so.

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To clarify, Net Metering is an addition to your "otherwise applicable rate". So if you have a flat rate, the time of day doesn't affect the cost of electricity, that you pay. Charging during the day does affect and cost us all as a society since the peak power load during the day is met with peaker plants that have higher emissions (pollution) than the baseload plants which run pretty much full output 24x7. Also on peak power is more expensive to the utility and will eventually get reflected in future rate hikes as the utility's costs go up.

Charging during the day often means your EV and it's batteries are warmer or hotter. There may be a slight increase in charging power so for running a fan in the garage, or for EVs that have active cooling for the batteries - fans, liquid cooling, or in the case of the NiMH GM EV1, it actually ran the car's air conditioner to cool the batteries during charging. Never could toilet train that car. It kept peeing air conditioner condensate (water) on the garage floor every time I charged. Some of us resorted to putting a cargo mat on the floor to catch the piddles from the EV1!

Time Of Use (TOU) rate schedules, if they work for you, and they work VERY NICELY for PV + EV let you take advantage of expensive power during the day by reducing your daytime usage with the PV panels and usually driving the meter backwards. At night you consume less expensive electricity with the EV. Having an EV helps to shift most of your power usage to the night. And you learn a few other trivial tricks to save more, like doing laundry off peak.

If you have PV + EV, definitely check out the Time Of Use (TOU) rate schedules, and see if they work for you. For most people who have a utility bill over $100 month the TOU rates should create some substantial savings if it's natural to shift some of your electricity consumption. I still run the Air Conditioner occasionally on peak when I need it. Otherwise there's not much point in buying an AC! At the on peak rates, it costs a few dollars, but the savings from the other summer days when I don't run it, the savings during the winter and the savings for charging the EV at night work out to a large net savings.

I have a 5.16 kW PV system with about 2,000 kWh of net generation annually (in excess of household usage), on Southern Cal Edison with Net Metering and TOU single meter EV charging rates (TOU-D-TEV). I did the math and it is far better for us to reap the benefit of net generation during peak hour rates and EV charging during Super Off Peak hours (midnight to 6 am). My calcs show that we'll be able to turn an annual net generation of 2,000 kWh into 12,000 to 14,000 miles per year of driving free of any fuel cost.

ElectricVehicle said:

Time Of Use (TOU) rate schedules, if they work for you, and they work VERY NICELY for PV + EV let you take advantage of expensive power during the day by reducing your daytime usage with the PV panels and usually driving the meter backwards. At night you consume less expensive electricity with the EV. Having an EV helps to shift most of your power usage to the night.

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Maybe for you in CA, but not for us in AZ with the utility we have. We gain very little with TOU since the utility would charge us .35/Kwh on peak, but only pay us .03/Kwh for all the 'extra'. For example, we generated most of our surplus on peak and had a little over a MWh of electricity extra generated, but only received about $30 on April 30. By switching to the 'Basic' plan, now we have true net-metering and no time restrictions. My wife loves it! :mrgreen:

LEAFfan said:

ElectricVehicle said:

Time Of Use (TOU) rate schedules, if they work for you, and they work VERY NICELY for PV + EV let you take advantage of expensive power during the day by reducing your daytime usage with the PV panels and usually driving the meter backwards. At night you consume less expensive electricity with the EV. Having an EV helps to shift most of your power usage to the night.

Click to expand...

Maybe for you in CA, but not for us in AZ with the utility we have. We gain very little with TOU since the utility would charge us .35/Kwh on peak, but only pay us .03/Kwh for all the 'extra'. For example, we generated most of our surplus on peak and had a little over a MWh of electricity extra generated, but only received about $30 on April 30. By switching to the 'Basic' plan, now we have true net-metering and no time restrictions. My wife loves it! :mrgreen:

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Sounds like you need to make some noise with your utility regulators! Solar PV day generation + EV night load is a huge benefit to the utilities and they need some rate structures that encourage that. It's far more cost effective for the utilities than storing power which some utilities do today, they pump water uphill at night and use it for generation during the day. PV + EV is a much better solution than water storage. Yet, utility rates can be archaic. I think for a while SDG&E rates ended up penalzing solar PV generation for a few years. I believe they finally fixed the rate. Before they fixed it, people would get solar in San Diego and watch their electric bill GO UP! Absurd!

If you do go to the regulators, show them your numbers vs. the rate schedule and how it hurts you - encouraging you to do things that harm rather than help the grid sending you into the past instead of the future by doing better with a flat rate schedule and then charging more during the day since there is no incentive to do so at night.

I'm starting to think we should all move to Smyrna Tennessee where the have numerous green programs, Gigabit fiber Internet, TV and Phone, in addition to the Nissan LEAF factory!

That's also why I recommend to look at your usage patterns, any changes you might make to them, and your utility's rate schedule, since some of their rate schedules are distinclty anti-green - more by ignorance, but the result is the same - rate schedules that promote the use of dirty power, higher prices and more pollution by providing no incentive or even dis-incentives to use and conserve power at the wrong times.

I agree with LEAFfan because we live in AZ and my Electric Co-op's TOU would be inconvenient. It has two peak times per day and then they alter those between summer and winter. Our PV array generates more electricity than we use. For 10 months generation we had an excess of 6 mWh. Although my charging at night may be useful to the utility to be able to sell my daytime power to my next door neighbor at retail ($0.10/kWh) when we were only compensated at wholesale ($0.023). I didn't purchase our system to let my neighbor use clean power during the day. I purchased it so we could use power when we wanted. We use the most power during the day and still have the meter running backward. I know we're a special case as not many have as much generation in relation to usage, but part of that was a thorough analysis of all power uses in the house and getting appliances and insulation everywhere we could to conserve energy. Thus, whenever we pull into the garage with our LEAF, we just plug in and let it charge.