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[MorbidBBQ]

Solar panels have just reached a 5 year return on investment in my area, so I'm planning on getting them installed.  One thing that I'm looking at as part of the design process is if I should spend the extra couple thousand $$$ on an off grid inverter.

The Tesla Powerwall is 13.5 kWh, my zero battery is 12.5kWh.  Has anybody tried, or is knowledgeable about the theory of using the zero battery as an emergency house battery tied in to solar?  Twice in the past 4 years I've been without power for more than 7 days; so I'm not worried about battery degradation for such sporadic use.

I'm guessing I would use the accessory charge port underneath, but don't know if it can be discharged through there as well. 

I'm researching the sunnyboy inverters now https://www.sma.de/en/products/battery-inverters/sunny-island-44m-60h-80h.html

[NEW2elec]

I would love to have a female plug on the Zero to power certain things like electric trimmers, pole saws, chain saws and other tools.  It would make yard/estate tasks so much easier. 
Could the Zero battery be set up to do the job you have?  I'd say yes as I've seen people build home made Tesla walls with old 18650 cells.  But after watching this video I saw that "proper" use of a Tesla wall means that the thing you want it for most can't be done.  For safety you can't use it when you lose grid power so it won't zap some lineman working down grid.
Here is the video, it's a bit long but talks about the "fine print".

[Doug S]

I still kinda fail to see the attraction to Li-ion technology for home reserve power use. I mean I love Li-ion batteries as much as the next person, but their claim to fame is extremely high power/energy density. That makes them great for EVs and mobile apps like laptops and cell phones, but I don't really see why you'd want to spend that much money for a home power bank. AGM lead-acid batteries perform very well, have quite a good lifetime, and are far less expensive than Li-ion batteries. Sure, they're a lot bigger and heavier than Li-ion batteries, but who cares if they're just sitting on your basement floor?

And anyhow...if I lost power, the last thing I'd want to do is eliminate my transportation options by discharging my EV!

[MorbidBBQ]

For safety you can't use it when you lose grid power so it won't zap some lineman working down grid.

Thanks for the link to the video, I'll check it out when I have some time.  The lineman getting zapped problem can be avoided with a transfer switch.  Backfeeding to an outlet would be...unthinkable.

I still kinda fail to see the attraction to Li-ion technology for home reserve power use.

The appeal is that I already have it; and don't need to purchase/store/maintain more stuff for the ~4 days per year I might use them.

And anyhow...if I lost power, the last thing I'd want to do is eliminate my transportation options by discharging my EV!

Its about options.  If I only use 20% per day for transportation, and can recharge when the sun is shining, why not use 50% of that battery to keep my fridge running?  Maybe a fan or 2 as well.

[Erasmo]

Solar panels have just reached a 5 year return on investment in my area, so I'm planning on getting them installed.  One thing that I'm looking at as part of the design process is if I should spend the extra couple thousand $$$ on an off grid inverter.

The Tesla Powerwall is 13.5 kWh, my zero battery is 12.5kWh.  Has anybody tried, or is knowledgeable about the theory of using the zero battery as an emergency house battery tied in to solar?  Twice in the past 4 years I've been without power for more than 7 days; so I'm not worried about battery degradation for such sporadic use.

I'm guessing I would use the accessory charge port underneath, but don't know if it can be discharged through there as well. 

I'm researching the sunnyboy inverters now https://www.sma.de/en/products/battery-inverters/sunny-island-44m-60h-80h.html

7 days is sporadic? The average here is 20 minutes per year.

Anyway is you have net metering go for PV asap, power island capable inverters and extra batteries are cool tech to use if you don't have net metering or hourly pricing but for power cuts a generator and a few cans of petrol might still be the best solution.(and a big ol' power bank for your usb powered devices)

[Doug S]

...but for power cuts a generator and a few cans of petrol might still be the best solution....

I think for most of us, I'd agree with that, except I might argue with your choice of fuel. Gasoline is just about the fastest fuel to degrade sitting in a can. I'd probably go for natural gas, on the assumption that the gas lines will still be operational when the power goes out, or propane, especially if you have a decent back yard and can install a good-sized tank. Diesel survives pretty well, too, but diesel motors are usually ridiculously loud and there aren't too many options for small-scale use. I'm not sure I'd want to trust my emergency needs to a Yanmar.

[MorbidBBQ]

7 days is sporadic? The average here is 20 minutes per year.

Yeah, hurricanes are a b*7ch.

Anyway is you have net metering go for PV asap, power island capable inverters and extra batteries are cool tech to use if you don't have net metering or hourly pricing but for power cuts a generator and a few cans of petrol might still be the best solution.(and a big ol' power bank for your usb powered devices)

We have Net metering in Florida, no time of day discounts/surcharges in my usage bracket.  I've always been a fan of the option of grid independence.  Nothing like being able to tell the power company to go packing.  I've got no interest in owning, storing and maintaining a generator; even though it might be the most cost effective.  There's a reason my lawnmower, pressure washer, weed wacker, leaf blower, chainsaw, and motorcycle all have electric motors.  They all just work.

[Doctorbass]

The real solution is here!! a 96Vdc inverter to 120 or 240Vac sinewave: 

looking for any 96Vdc input inverter is the KEY !!

http://www.ebay.com/itm/2500W-Off-Grid-Pure-Sine-Wave-Power-Inverter-Solar-inverter-CE-EMC-Certified-/232508158041?hash=item362290f059:g:NJkAAOSwCXxZqRnI


or for more power!! :
http://www.ebay.com/itm/Inverter-8-000W-16-000W-96VDC-120V-60hz-Off-Grid-pure-sine-Cyber-Solar-Systems-/111395374259?hash=item19efae84b3:g:RyUAAOSwd4tTr0MI

The voltage range it can take at the input is exactly what the Zero 2013+ can do!

Doc

[togo]

Thanks doctorbass.  Looks like those inverters will take DC from a battery and product AC to run your conventional items, like your home.

And you'd need to charge your battery from your solar array, you'd need a MPPT charger/solar controller that can be told to charge to 116.5V and no higher.

I think this is the sort of thing shadow might be interested in.

[togo]

Owning *two* Zero motorcycles would be ideal in this scenario,
one powers your house, one powers your ride, swap at will.

When the sun ain's shining as much, bring home a load of power
from your local J1772 station.

: - )

Disclaimer- I have not tested this configuration but it sounds good in theory.

[Keith]

Also quite practical with one FX and four packs like I have, am I the only one? I've been looking at this idea seriously for a long time. My current hesitation to buy these inverters is that I need enough power to run my well and 2.5kW won't do it. If two units could be phase locked and give me 5kW 240v as well as 120-0-120 split single phase, I would not hesitate. No doubt it is possible to synchronize these inverters, but probably not a simple thing to do. I could buy the 8kW 240v and a 2.5kW 120v but that's more than I want to spend. Interesting that the price per kW goes up with high power, should be the opposite. I don't have solar or a good location for it but even running a gas generator to recharge my batteries would make sense. That would give me power around the clock without noise and fumes. I've run 9 days consecutive without power after a severe snowstorm. Did it by running the generator briefly twice a day and using candles and propane. Batteries are nice, I have 13kWH, would be nice to be able to use it.

[togo]

Yeah you'd need the big one...

"If you need the inverter to run the inductive load (for appliance such as compressor, motor, water pump), please calculate the power of inverter 3 to 7 times higher than the rated power of your appliance."

[Keith]

Yeah transformers could be used but it doesn't help with the cost. The 8000 watt unit is more than twice the $/kW. I should probably just get the 2500 watt size and forget the 240v applications. Kudos to Doctorbass for finding these, the Zero battery DC input voltage range is uncommon in inverters. I notice a lot of the pictures show 72 volt max. The fine print says the 110volt version is 15% more so almost $300, still not bad.

I looked at sunnyboy but it didn't seem right for my non solar needs.

Yes, you can discharge through the external charge port, but it takes some doing. The contactor needs to close so turning the bike on does that. However there can't be any load connected or the precharge will fail, even a 100W light bulb will stop it. So, you'll need another way to connect the load after getting the contactor closed. And switching DC is not to be taken lightly, it wants to arc and burn switches and breakers unless they are properly rated.

[dukecola]

A lot easier to just get some L16 AGMs and keep them charged from your solar. I lose power (seems like its always 7 days) often. Have an off grid inverter and eight L-16's.  I can run off the batteries for days and if there is 2' of snow on my panels, I can recharge the batteries with a small generator in an hour or so.

[Keith]

Well for me it is easier and a whole lot cheaper to buy an inverter and use the four Zero packs that I have. I've ordered the 2.5kW unit, with upcharge for 110v "as the product page shows,we will need 15% additional fee, because the parts of 110V inverter is more durable, powerful, expensive and big than 12V/24V inverter." So I can discharge one pack at a time, keep the lights on, for the price of the inverter, $284 and an Anderson connector, $10. I can recharge all four packs at the same time from the generator I already have. Less than $300 gets me something useful, all the functionality of a Tesla Powerwall with a little juggling of connectors now and then. 13kW of AGMs looks like around $1500. Maybe someday I'll invest in solar.