I used to think this was an obvious choice but it doesn't make sense because an EV battery would operate very differently to a home storage battery. This link explains better than I could: Tesla CTO JB Straubel On Why EVs Selling Electricity To The Grid Is Not As Swell As It Sounds

EDIT: I'm getting confused as I guess it depends on what you're using it for. If you're using the Leaf to use the excess solar energy from your panels rather than selling it to the grid then great and ignore the above. However, if you're wanting to use the Leaf battery to power your house from then the above is very relevant.

 

I am considering getting a powerwall too. I did consider a Nissan Leaf but felt the powerwall fitted better in my roof space . Seriously I know Nissan have been looking at this for some time:

“Vehicle to Home” Electricity Supply System

However, when you look at the increase in power between the powerwall 1 and powerwall 2 you can see that this technology will be mainstream within a few years both to store solar but also as a back up in case of outages or to even out power surges. As regards your question I too am interested to see if someone is already doing it.

 

There was an interesting discussion about high tec ways to prevent people using such storage to buy E7 cheap electrons overnight, and then sell them back to the grid at high demand times, at a higher price. Begs the question about why the grid isn't doing that itself to level out the demand/supply curves and drive down the overall price in the first place.

 

Begs the question about why the grid isn't doing that itself to level out the demand/supply curves and drive down the overall price in the first place.

Because the amount of energy storage required to achieve this is phenomenally large. Otherwise we would We are working on it, makes good sense to combine storage with renewables but the amount of storage required and the cost of the storage tech doesnt work just yet.

I work with a colleague who lives off grid at the moment. They have a large generator and some solar that also charges a battery bank. She was thinking of a tesla powerwall but a used leaf could do the same thing. Anyone have experiance of this type of setup? Also how cheap can you get a MK1 leaf for? thanks

It almost sounds like she is planning on using the Leaf as just a battery and not a car at all? Basically as a way of getting cheap battery tech. Might not be a bad idea if the battery has enough life left, but Id be amazed if it was a cheap way of doing it. If she plans to use the Leaf as a car as well as a battery storage system, then the juggling of the energy to make sure its charged when she needs to drive it is very difficult.

A true off grid home is really going to need battery storage of some kind, and probably lots of it to cover those worst case days,.

 

It would not be used in any grid connected situation. basically a way of not having the generator run all day.

 

Just FYI, I've been tracking recent news articles on battery storage and filing them here:

Energy Storage | Fuel Included

 

Being from Texas, I do have many options of energy supply contracts that provide some interesting "economics" of V2X. And there are recent commercial offerings of the necessary equipment:

1. Pika Energy and SolarEdge both are seamlessly integrating home solar (both grid tied and off-grid) with similar battery technology to the EVs (LG, Panasonic, Powerwall, etc). The charging/discharging of the ~400 VDC based systems are using power line communications (PLC). The Chevy Bolt also uses PLC in the CCS based charging systems (although not at the 400 VDC bus connection - and NOT seemingly bi-directional energy).
2. The cost of the batteries that are integrated with these systems (based on $$/kWh) appear to be similar to the total drive out cost of the Bolt (60kWh). This will likely change, but for now.....
3. Nissan keeps talking about V2X, however Setec Power appears to be the only US provider of a V2H/CHAdeMO compliant unit - and it is not usable with US power systems without a transformer and is certainly not "smart grid" compliant (totally off-grid). The Leaf already has battery degradation issues - seems reasonable that they would be concerned about additional "cycling".

However, It does seem that as each tech advancement is made, the old paradigms are shifting quite rapidly.

 

Depending on your skill level you'd be better off buying a LEAF or other EV pack or two from a breakers and creating your own "powerwall". Be cheaper and consume a lot less space than having a whole leaf parked there, and will integrate properly in with solar inverters.

 

I think the current solution is to rig your Leaf to the a house inverter using the CHAdeMO plug. V2G DriveElectric vehicle to grid charging service for home and workplace

So it would work like this using current less efficient solutions:
Solar -> inverter into AC -> home AC
<-> inverter into DC <-> CHAdoMO into car and possible to draw from car as well

I'd think a better solution should be (but you won't get feed-in tariff, not that it matters to your off-grid living):
Solar -> smaller home battery
-> inverter -> home
<-> DC directly into larger EV battery, and can also draw from EV if needed.
We move our energy distribution centre to the home battery, into the DC domain. Where electricity only gets converted into AC for home use. Rather than use needlessly charge EV through 2 inverters.

 

I'm very interested in any existing dc-dc solutions that anyone has, being in the very small minority of off grid ev owners.
Currently running solar-inverter - traction cells-inverter- house.
Plan is secondary system with more solar-bms- lithium - inverter- load. Want load to include energy transfer for vehicles so looking at potential dc-dc solutions for this aspect.

 

I'm very interested in any existing dc-dc solutions that anyone has, being in the very small minority of off grid ev owners.
Currently running solar-inverter - traction cells-inverter- house.
Plan is secondary system with more solar-bms- lithium - inverter- load. Want load to include energy transfer for vehicles so looking at potential dc-dc solutions for this aspect.

Most of the systems i've seen use hybrid inverters with a low voltage (eg 48v) battery bank. Cars can simply be charged from the output of the hybrid inverter like any other household load. I dont think many(any?) hybrid inverters exist that will use high voltage DC battery.

You'd need a seriously massive array though if your wanting to charge cars from it.

Take a look at Jason Hughes' build thread on the Tesla forum for some inspiration. He has over 100 435w solar panels and nearly 200kwh of battery.

Plan: Off grid solar with a Model S battery pack at the heart

 

It appears that both Pika Energy and SolarEdge are using high voltage DC bus systems for MPPT and battery charge/discharge systems regulation in their home solar equipment. I believe it is based on power line communications methods along the DC bus. May change the home solar business if EV manufactures adopt PLC for charge (and eventually discharge) integration with a "smart grid" protocol. We'll see if regulatory agencies and EV manufacturers will ever support/allow this to happen.

 

The SolarEdge StorEdge system uses RS485/Modbus, which is pretty much the industry standard signalling system for this sort of stuff. PLT is a horrible bodge, i would personally avoid any system that was using that.

A small number of HVDC systems have popped up after the Tesla Powerwall1 came along (and a few others, like LG Chem RESU7H etc). However they arent particularly DIY Friendly, as the inverters want to talk to the battery over the modbus and its all intended to work together as a kit.

Its not going to work with a recycled LEAF pack.

 

Tongue-in-cheek solution to off grid living.

Used Leaf, troll down to local free charge point, top-up Leaf, come home.
Use Leaf as V to H unit.
Repeat as required.

You are then running off grid, and free - but of course there is someone else who is actually paying!

 

The ever resourceful Jack Rickard goes into his Model S85 battery pack installation in great detail in last month's episode of EVTV. Yes that is an entire 85 pack you see below hanging on a wall taking up negligible floor space

And a very florid description by the man himself on his website:

Canticle of the Sun - EVTV Motor Verks

 

Why not just tie it all together? Surely its better to have one large battery bank with all your panels feeding the pack and inverters?

Otherwise you could end up, for instance, in the situation where one pack is full, and thus its connected panels are going to waste, while simultaneously the other pack is waay down and could be doing with all that extra energy to help get it charged.

Batrium do a pretty interesting customisable BMS as well.

Looking at completed listings on ebay theres LEAF packs sold for as low as £85 per kwh.

 

PLT is a horrible bodge, i would personally avoid any system that was using that.

It's difficult to get details, but from what I've learned the new Bolt (which to me is the non-vaporEV of choice if you want a 200 + mile EV right now) uses PLC to communicate with charging systems. Rumors are that this PLC is actually over the pilot signal wiring. Anyone have confirmation - and details of what standard is actually used to do so?

Personally, I'd like to see reviews of the 2018 Leaf and Tesla Model 3 compared to the Bolt - only after they are actually available to us mortals.

 

Why not just tie it all together? Surely its better to have one large battery bank with all your panels feeding the pack and inverters?

Otherwise you could end up, for instance, in the situation where one pack is full, and thus its connected panels are going to waste, while simultaneously the other pack is waay down and could be doing with all that extra energy to help get it charged.

Batrium do a pretty interesting customisable BMS as well.

Looking at completed listings on ebay theres LEAF packs sold for as low as £85 per kwh.

well- it's a bit more complicated than that. Partly because I have a generation tariff agreement with ofgem, on the existing house system and although it doesn't pay loads it would be a shame to let it go. Partly because the sheds are a few hundred metres down the track from the house, partly because the house system worked very well even in winter until we ran the biomass boiler load in addition to our other loads, partly because the SMA inverter combo that I have on the house doesn't have a lithium enabled canbus type BMS......I came to the conclusion that it was easier to run two systems. The upside being that they are independent, so I can flatten the shed batteries charging a vehicle and choose not to create a gen request, knowing for example that it will be daylight in a few hours, but not affecting the domestic side of things.
Also the 9kw of panels which I have are all the same, and the 2500w of panels on the roof of the house are all the same, but they are not all the same as each other.

 

Stick... with... lead... acid...

Seriously, stick with lead acid for off grid (says the guy who uses wet nicads).

 

I have had a gut ful of lead acid. I use forklift traction cells, have done for years, but I want to try these lithium ones, see what they're like...... have you experience of them then which leads you to say this?

 

Just found a 30kWh leaf pack on eBay for 4500 or best offer... that's actually quite reasonable compared to 30kWh of rolls-surrette or equivalent.

Also found an outlander phev pack for 2.6k ish, that doesn't represent great value.

 

Hugh, forklift batteries are pretty shit. The big difference with lithium to lead is the lack of significant voltage drop with lithium. I have about 12kwh (or 1000ah at 12v) on the house system and I know my biggest mistake was the low dc voltage but changing that requires big hardware expense. But essentially they are decent cells but under a heavy load the voltage drops, it's just what they do, this causes a sequence of events... oh anyway. I'm leaving them on the sma system as if you read what I said earlier, the sma system won't talk to lithium. However an outback or victron energie system will talk to canbus controlled bms. ANyway, I didn't think I'd find another one on here! Pleased to meet you. I'll let you know how I get on.
Cheers
Tom

 

Good to talk too Tom, 12v eh, bad luck. I’m 48 nominal but the wet Nicads really need to be pushed to their upper absorption set point for best capacity and that’s 68v. Luckily the mx60 will do that. 0% soc is at 40v so it’s a really wide range.

I’ve just been doing some research, looks like lithium might actually be a really good option, especially given the price of used packs. Do you have any details of integrating a bms into an outback system? I could be tempted by that outlander pack that’s on eBay.

 

Not specifically, I have been taking advice from a bloke in Braunton called Brad. I run a timber yard and I'm essentially a carpenter sawyer so I must admit the details are a little beyond me. Experience wise I have more of living off grid than on, my adult life has been entirely off grid and I have had, experimented with, and managed many home made systems over the last 25 years.
That's where the 12v comes from, a hangover from the era when I ran two voltages simultaneously. I realised my mistake about 24 hrs into what's so far been a 6 year phase.

Also, does the BMS actually need to integrate fully? So long as it can say "SHUTDOWN" and stop the system if theres a serious issue, surely the BMS can essentially be standalone? It will deal with balancing, and your solar chargers simply need to know the upper voltage cutoff of the pack. A 12S lithium pack has a nominal voltage of 44v, and a maximum voltage of 50.4v. Set your solar charger to shut down at 50v or 49.5v and let the BMS deal with balancing. If any one cell gets overcharged before the BMS can deal with it, it sends the shutdown signal and the chargers turn off. Same story with the low voltage cutout.

Take a look at what Jason Hughes was doing with his Outback system, i posted the link above.

Thanks for the link. I will study it. What you suggest is very possibly true and hopefully in the next 6 months or so I'll have a bit more to add to the mix.

 

Keep your eyes open on ebay. Completed listings show much cheaper packs having sold in the recent past, both outlander and LEAF.

 

Also, does the BMS actually need to integrate fully? So long as it can say "SHUTDOWN" and stop the system if theres a serious issue, surely the BMS can essentially be standalone? It will deal with balancing, and your solar chargers simply need to know the upper voltage cutoff of the pack. A 12S lithium pack has a nominal voltage of 44v, and a maximum voltage of 50.4v. Set your solar charger to shut down at 50v or 49.5v and let the BMS deal with balancing. If any one cell gets overcharged before the BMS can deal with it, it sends the shutdown signal and the chargers turn off. Same story with the low voltage cutout.

Take a look at what Jason Hughes was doing with his Outback system, i posted the link above.