Would like to charge my EV off solar panels :) Need help on battery bank size!

lolcashcow · November 2015

Hi Guys,

I have a 2013 Nissan Leaf and would like to charge it off Solar Panel Power. The car comes with a plug for Lv1 Charging which is Level 1 charging 1.92 kW (120 volts x 16 amps = 1920 watts or 1.92 kW). In the Nissan LEAF the battery is 24kWh capacity, with about 21kWh usable. It gives you 80 miles at full and usually I drive 40 or less miles, so I used about half the capacity. What kind of battery size bank would be suggest for this? My guess would be at least twice as big? Is this a crazy thought?

oil pan 4 · November 2015

You are looking at spending some where around $10,000 to replace $1.50 worth of power.

MarkC · November 2015

You are simply 10 (20) years ahead of your time! Incentivized PASA installations (parking area solar arrays - grid tied - shaded parking areas) that are installed at malls and businesses would allow you the get into your cool, air conditioned Leaf every day after work (or heated) and drive home with a full battery. Put a hybrid solar/wind system at home to power both your home usage and a "powerwall" (Leaf equivalent) to recharge your Leaf at home - no more dirty stuff from the grid - well almost.

Current (no pun) disadvantages are massive $$$'s ($10,000 for this is only a down payment), only a few PASA's exist (Fed subsidized), expensive commuter EVs (Wheego?), big oil, new hi-tech stuff for a low-tech consumer (lots of new apps!), etc. etc. Big advantages - a new trillion dollar business and the US consumer becomes totally energy independent. Big challenges - efficient solar panels (or equivalent) and inexpensive energy storage.

All I can recommend is to keep working on this one - it's a pragmatic approach to preventing this administration's (and likely the next) carbon tax and allow us all to drive (solo) to work and back every day. You gotta pay the Piper!

lolcashcow · November 2015

Well, wow. I thought it would be expensive, but not as expensive as $10,000 +. I mean, I knew that the most expensive part in an E-Car was the battery, but I think I underestimated the cost

. Thanks Mark and oil pan for your input. Currently I just charge the leaf at malls and other places I visit (Which works just fine, but sometimes I stay a little longer just to get that extra charge). I'm a fan of solar power and thought charging the EV at home from very clean solar panels would be a great idea. Speaking about battery costs do you think once the tesla giga factory is up and fully operational they will sell lithium ion battery packs (Tesla power wall???) at really cheap and reasonable costs? Seems to be a big thing and musk already said he wants to build a few more Giga Factories to help bring down the cost.

Interestingly you can get a salvaged leaf battery pack for about 4-7k in a junk yard. If I had the engineering skills this seems like the best way to get a cheap battery pack that could work as a battery bank....

http://www.summet.com/blog/2015/03/26/how-to-purchase-a-leaf-battery-pack-and-surrounding-car/

solar_dave · November 2015

The best way to use solar to charge an EV is to grid tie you house and work against all your consumption. We have 2 Chevy Volts and our annual electric bill in AZ (with high AC loads) is still only about $500. BTW one volt has about 36K miles on is and only used about 110 gallons of gas the other has less miles and only used about 30 gallons of gas. The cars are solid as a rock, very low maintenance ( both coming up on the second oil change) and with solar that has met its ROI cheap as it gets to drive them.

oil pan 4 · November 2015

Oh yeah, 10,000 is a down payment if you are not DIY.

Lithium batteries are ridiculously expensive. The LiFePO4 battery I made my self out of raw cells costs around $500 for 0.6kwh. Scale that up and 10,000 wont even pay for the battery alone.

The supply push created by the giga factory will not make them noticeably cheaper.

If you could find a used EV battery you would not be able to get a charge controller. EV batteries are typically well over 200 volts and solar power systems are typically under 48 volts. You could invert the power then convert it to EV voltage with huge inefficiency and cost.

MarkC · November 2015

lolcashcow said:

Well, wow. I thought it would be expensive, but not as expensive as $10,000 +. I mean, I knew that the most expensive part in an E-Car was the battery, but I think I underestimated the cost . Thanks Mark and oil pan for your input. Currently I just charge the leaf at malls and other places I visit (Which works just fine, but sometimes I stay a little longer just to get that extra charge). I'm a fan of solar power and thought charging the EV at home from very clean solar panels would be a great idea. Speaking about battery costs do you think once the tesla giga factory is up and fully operational they will sell lithium ion battery packs (Tesla power wall???) at really cheap and reasonable costs? Seems to be a big thing and musk already said he wants to build a few more Giga Factories to help bring down the cost.

Interestingly you can get a salvaged leaf battery pack for about 4-7k in a junk yard. If I had the engineering skills this seems like the best way to get a cheap battery pack that could work as a battery bank....

http://www.summet.com/blog/2015/03/26/how-to-purchase-a-leaf-battery-pack-and-surrounding-car/

lolcashcow;
Grid tied solar can make economic sense in selected areas. As a member of an electrical cooperative, I can get a significant installation subsidy AND Fed tax rebate $$'s (now at least). My co-op also pays me 9 cents for every KWH returned - and charges 11 cents. Under these financial conditions, plus contracting the installation (and my own labor!), I estimate the payout to be 5-7 years. If I'd had NO incentives and paid for a turn-key installation, the system would never pay out - at such cheap energy costs anyway.

However, IF I could buy a commuter EV for less than $15,000 that could get me back and forth to work every day, get free recharge every day, (under the shade of a parking area solar array - in (hot) Texas!!!) that is provided by my employer (major Engineering and Construction Company), it is conceivable that EV's could become the normal, thus bringing all associated costs due to the phenomena of mass production. So, could Tesla (or similar) mass produce an affordable energy storage system that integrates a whole house solar/wind system for it's entire energy source? I hope so, but likely too old to ever see it!!

So, if the DIY'ers, entrepreneurs, blog experimenters that share their experiences, the individual geniuses out there that make the true break-troughs in technologies, and IF FREE MARKET SURVIVES, it will happen (apologize for injecting politics, but it will NOT happen by force of the FEDS). All I can recommend is try your best to meet some affordable goals of self- energy production, do as solar_dave suggests to minimize your consumption, and start getting some pragmatic experience to share.

Solar2 · December 2015

First, you don't want to charge your EV using your house battery.
It is too expensive.
Battery wear, best case, is about 18 cents to put a KwHr in a battery then draw it back out.
Depending on the battery it can be as much as 50 cents.
But using the solar panels direct is a great idea.

We also have a Leaf and love it.
It is the first choice by our family if the trip is 100 Mi or less.
It charges from our solar panels if we have enough sun that is.
If not enough sun, we do have grid @ 8 cents per KwHr incremental thanks to the Grand Coolie dam being near by.

I would recommend getting a decent high speed charger.
The charger they supply with the car is too slow.
The Juice Box 40 by Electric Motorwerks is a good choice and most reasonable cost too.
It allows you to vary the charge rate from about 1.2 to 10 Kw/Hr.

When I charge the Leaf back up I take a look to see how the sun is doing and how many KwHr the Leaf needs.
Then set the charge rate, keeping in mind it needs to be done before the sun goes down.

MarkC · December 2015

Solar2 said:

We also have a Leaf and love it.
It is the first choice by our family if the trip is 100 Mi or less.
It charges from our solar panels if we have enough sun that is.
If not enough sun, we do have grid @ 8 cents per KwHr incremental thanks to the Grand Coolie dam being near by.

I'm seriously considering purchasing a 2012 Leaf with low "bars" and possibly having the battery replaced under warantee. Seems like a good deal - even if the replacement doesn't happen. Since I have to haul large, heavy loads about 100 miles each way, my Suburban is a necessity. I'd like to figure a way to extend the Leaf range to use it when no loads are required (100 miles). Any ideas?

I believe your's is the best solution currently (grid tied?). I do hope that at some point, a combination of many charge stations (at least level 2 - and solar powered), PV panels much more efficient and cheap enough to compete with grid power, combined with the home energy storage compatible with the EVs (for real off-grid emergency use during our hurricanes), will self promote massive shift of transportation energy to solar.

Probably too old to see it!

Solar2 · December 2015

MarkC said:

I do hope that at some point, a combination of many charge stations (at least level 2 - and solar powered), PV panels much more efficient and cheap enough to compete with grid power, combined with the home energy storage compatible with the EVs (for real off-grid emergency use during our hurricanes), will self promote massive shift of transportation energy to solar.
I believe the time is here now.
It does take a different mind set than the traditional solar array
Even though fuel is low cost right now, you know that is not going to last.

You are correct in noting the battery is critical.
As arrays get bigger and bigger you can't just keep increasing battery capacity.
There is not enough lead in the world to give everybody a 100 KwHr bat.
Alternative battery technology just is not here yet.

You need to develop ways of using solar power without running it through a battery first.
Grid tie is great if you can get it.
Priority control is another way.
In this case an EV is an assistance since you can use it to limit the current you feed to the house battery.

We have grid available but are not grid tied.
I started out planning a grid tie but the local utility is not helpful.
They have jiggled their rules such that grid tie is of no benefit.

As for extending the range of an EV;
You can get a Tesla (100 K$ and two years lead time)
The 2016 Leaf is said to have 18% more range.
They are getting reasonable price.
They actually do not let you buy them.
You have to lease them.
You can after a few months pay off the lease however.
But they give you incentives and tax breaks on a lease plan.

For now I think the best plan is to just use them for what they are.
You are going to need another car/truck anyway.
For most people, the majority of their runs are trips less than 100 mi.

Brock · December 2015

Mark I am not sure where you are but without using any AC or heating 100 mile would be pushing it even on a new battery. If you can charge at the destination or 50 mile mark even for a few hours at 120 you should make it. We have a similar trip (90 miles round trip) and I can do it in summer by taking an "old highway" running parallel to the highway cruising about 50 mph either on the way there or back, but not taking the highway (65 mph) both ways.

I do charge our leaf in summer or any time it is sunny via our array, I have a second EVSE that can accept anywhere from 120 vac at 8 amps to 240 vac at 30 amps, I typically leave it set to 10 amp at 240vac which is about perfect on a sunny day to use up the panels producing full power with small house loads.

solar_dave · December 2015

If your looking for a cheap EV and still have all your range, look to a Chevy Volt. In 36,000 miles My volt has only used 110 gallons of gas, all the rest of the miles were EV based around town trips. Used ones are pretty cheap as lots of them are starting to come off lease. Easy at about $15K. A good grid tie setup and a decent net metering plan can reduce your cost of consumption pretty good. My experience has lowered my annual electric bill to $500, that's about 10% of my bill prior to the solar install and all the conservation efforts taken here.

Now in AZ with 2 electric cars and pretty steep summer consumption for AC I think that is pretty damn good. No batteries to buy, replace or maintain, low maintenance setup are all good attributes to justify grid tie where feasible.

MarkC · December 2015

Solar2 said:

You need to develop ways of using solar power without running it through a battery first.
Grid tie is great if you can get it.
Priority control is another way.
In this case an EV is an assistance since you can use it to limit the current you feed to the house battery.

We have grid available but are not grid tied.
I started out planning a grid tie but the local utility is not helpful.
They have jiggled their rules such that grid tie is of no benefit.

Interesting concept of priority control. Have you designed a reliable system that is somewhat automated and does a good job protecting the house batteries? For many people (not me - retired), the EV is not at the house during peak solar production => the need for a companion EV battery - which sort of defeats the purpose.

My grid tied system is at a rural cabin and has essentially negated electrical energy usage except in the winter during really cold weather - since I have electric heat. In South east Texas, not so much of a problem. My electric co-op has a great deal for us renewable guys - writes me a check for $1/watt installed and buys back any excess energy at 80% of cost. On top of that is the Fed subsidy.

Would like to charge my EV off solar panels :) Need help on battery bank size!

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