Affordable battery storage (used electric car batteries)
 

Hi folks,
I don't get around as often as I used too, but had recently been thinking about repurposing EV batteries for PV storage systems. Now I knew I couldn't have been the first to think of this so I did a little research and found this write up.

Use of Nissan Leaf battery in Solar installation. - My Nissan Leaf Forum

Early disclaimer: All the things written below are just ideas. No plans to implement at this time.

I have been reading about various people buying used leaf battery packs in the $2000-2500 range. IIRC the leaf has 24Kwh pack. this puts the cost of storage at about $100/kwh not including controls. That's not too bad. Obviously you would have to derate the pack based on age and mileage and the inevitable losses related to charging the pack, but still not terrible.

In my own case,I use 10-15 Kwh/day. I figured with 5kw of panels and 50 Kwhrs of battery that I could likely go offgrid for $10-15,000. The 50kwh should give 3-5 days autonomy. I'd probably use a car to charge the battery pack if things got desperate but could just pick up an inexpensive generator.I'm in central CA so we average 6-6.5 hours of good sun/day. Of course I would do all the installation myself. Used to do a bit of electrical work and picked up a EE along the way so I'm ok working with power and did enough construction work to build about anything I need.

You may think this is really low priced. It probably is. But I regularly see surplus panels for sale in the area for 50-70 cents/watt. So 5Kw might put me in the $3500 range. As I said before I see the battery packs go for say $2500 average. I would need two of them so call it $5000. I'm guessing I could come up with the controllers,chargers ,wiring, mounting supplies,etc. for under $5000. So that's about $13,500 with a couple grand of slop money.

Anyway, I mainly posted this for the article I linked to. Enjoy.
JJ

Though I can really offer no advice, I am thinking about doing just about the same thing you are. It had been suggested to me to use the new Tesla batteries but I haven't gotten around to looking into them yet.

I'll be following this closely. Thanks you posting!

Thanks for posting that project I really love reading about projects like this.

Check out this project it might interest you. he is using a Tesla battery pack.
Plan: Off grid solar with a Model S battery pack at the heart

I would love to do this someday but this winter we used 100KW one day now this was a Max usage day. We charged our car three plus times. But you have to plan for the worst day.
I think a EV car is great with solar but it makes it harder to go off grid.

I am hugely under impressed with what Tesla is marketing for storage batteries. The $350/kwh is not terrible for new batteries but still is a bit high to be really cost effective. Also from what I read about the power output from the packs they seem kind of dismal. I have heard that they will be announcing a new pack in the near future. Again, mine is simply a good theoretical study. I don't plan on doing it any time soon, but thought it might give others a good idea of what is possible at current prices and with current technology.

Thanks for the link. Looks like it could take a few days to read.
I would actually use a gas powered car to charge the house batteries if it came down to it. CA cars already have the strictest emission standards in the US, so I would guess that I'd actually be polluting less than most of the power plants that provide energy to the state. Although as I understand it we are powered by a good number of natural gas powered plants.

Wow! A hundred Kwh in one day.I think the worst I've had in years is close to thirty on a roasting summer day. Still I guess electricity is still cheaper than gas to power your car.

We make all the power we use with our 12.5KW array. We make more power in the summer than we use and bank that to use it in the winter to charge our car and heat our house.
I have a grid tied system.
http://ecorenovator.org/forum/solar-...lar-array.html

Why would you want to use super expensive lithium batteries?
Lead acid is cheaper and they can be recycled (unlike lithium).
Why not just go grid tie and save your self a few thousand dollars?

Don't bother. Like all of teslas products they are over priced toys for the rich.
If money is no object, then go for it.

Nope not even close.
Per kilowatt hour of production your car is far worse all around than all but the worse coal burning plants found in china.
Once you average in the states cleaner sources such as nuclear, wind power, hydro electric and natural gas, its no contest.

EnPhase makes a very interesting battery. A client of mine in Australia is uses these to load shift.

https://enphase.com/en-us/products-a...age/our-system


Very easy to set up and a lot of ability to control where excess PV energy goes and at what cost. The Australia farm first fills up batteries and then sells excess power to utilities. They then can sell excess kWhrs at peak time back to the utility - or save it for on farm use.

All controlled by smart phone . . . .

Tesla is no where close on performance, cost or utility. But BIG on publicity.

Steve

That Enphase module looks very enticing. 96% efficiency, 95% depth of discharge, a 4 module rig would give you ~5KWH of storage at up to 1KW discharge rate. Not too shabby for a few wall-mounted boxes on a modest array. That's enough storage to run all the TV's, fans, and lights all day and night in a typical single family home. Plus maybe a computer or two. Any info as to the price?

The system I am aware of was part of a large PV system, so it is impossible to break out the unit costs for just the batteries.

EnPhase is really big in Australia due to their widespread time of use (TOU) metering policies. Load shifting is quite common as net metering is not.

This system has over 500 PV panels and has not had one microinverter failure. Admit it has only been on line for just under two years, but that rate is nothing short of remarkable.

The new EnPhase microinverters (S300) will be available this fall and will support large watt panels in both 60 and 72 cell configurations - and about the size of a smart phone.

A little bird told me that "used" battery packs from EVs will be a snap to hook up to an EnPhase system as it will be open to almost any type of battery back.

Time will tell.


Steve

Because even if the used lithium batteries were 25-30% depleted from new they would still have more cycle life than new lead acid batteries. Again, I would repurpose used cells at approximately $100/kwh. You can just barely buy new lead acid for that price and used lead acid will have no where near the life expectancy as most lithium batteries. Additionally the lithiums weigh half as much and take up less storage area.

Not sure where you get the idea that lithium batteries can't be recycled. the articles I read say they can. I will give you that there aren't a lot of lithium recycling plants yet since massive production is still in its infancy, but that will come around.

As for the grid tie, were I to start this project, I would no longer wish to be attached to any power company. That's a personal choice.



Ah, I was making a guess. You appear to be stating fact. Could you provide sources to check those facts.?

Thanks,
JJ