First world problem: backup power

[vavet]

We have a propane powered 22kw generator.
we also have a 10kw roof mounted solar array.
we have no battery backup.
when the utility power goes out, the house goes dark. Some amount of time elapses, maybe 15 seconds. The generator starts. Depending on ambient air temp, the auto transfer switch flips 5 to 30 seconds later and we have power back in the house.
if we had a battery backup, Tesla powerwall or similar, would we still have that lag between the power failure and backup power?
is there anyway to eliminate it? Basically, I want a giant UPS for my house.
is that possible? What would it take and how much would it cost?

 

[Walkers]

It is my understanding that you would experience any power outage.

 

[BillK]

A true UPS would switch over instantly just like a small one does for a computer. I have no idea what a large one would cost and how much battery space it would need.

I just Googled "whole house ups" and found plenty of information.

 

[MileHighRover]

Tesla Powerwall 2 for your existing solar. Check out their website for more info.

Powerwall

 

[Kezorm]

No lag with my battery-backed grid-tied solar. I have an Enphase micro-inverter system. Solar and batteries feed to my backup loads panel (essentially everything except for heavy-loads that are too big for the solar/battery). Small downside is that the battery inverters are always idling even when not charging / discharging - ready to take over in an instant. My 20kWh battery system consumes about 120W continuous even when it's not doing anything.

 

[dcg9381]

if we had a battery backup, Tesla powerwall or similar, would we still have that lag between the power failure and backup power?

You would have some lag. Apparently switching can begin in as fast as 50ms after the gateway detects a grid outage.
The devil is on those details though, because not all failures are hard down of the grid. There can be frequency variations, voltage variations, even failure of a single leg. But lets just say that it's "simple case" and the grid goes down. You're probably looking at a total of 200-500ms, per what owners are saying.

So that's enough to blip things that are sensitive.. And it's fast enough for other things not to notice at all.

is there anyway to eliminate it? Basically, I want a giant UPS for my house.

Apparently there are solutions that are faster than Tesla.. I assume you could set more aggressive "grid down" detection also.
IMHO, the big advantage for your situation might be that with a power wall you can leverage your solar power when the grid is down.... Perhaps... For sure if you use a Tesla inverter, not so sure if you stick with the existing inverter.

What's critical use on your house? For me, it's internet, internal network, wifi, and a few electronics. I cover those with UPS systems and a POE network. HVAC systems and accessory building are all on "delayed start" after the generator is doing it's thing.

is that possible? What would it take and how much would it cost?

Traditional early data centers had a large mass spinning flywheel UPS'. Zero switch over really requires that you're on secondary generation all the time.


I think you're after something like what Telsa is offering, but there are (perhaps) faster switching options if 1/2 second isn't fast enough. You'll need to determine how much power you need on the battery side/inverter side, because that's really going to set your cost.. It's largely a factor of how many amps you're using at peak if you want to back up everything. May take 2-3 power-wall like inverter/battery setups.

 

[wyliesdiesels]

tesla PW FTW

 

[Stuart in MN]

Do you lose power often? Is a 15 to 30 second delay before the generator kicks in that big of a problem? A point of use UPS for your computer so it doesn't have to reboot is about the only thing I can think of that would be affected by a temporary loss of power.

 

[2Rocky]

Do you lose power often? Is a 15 to 30 second delay before the generator kicks in that big of a problem? A point of use UPS for your computer so it doesn't have to reboot is about the only thing I can think of that would be affected by a temporary loss of power.

It's a real PITA when the Automatic Coffee timer gets reset....

 

[rharman]

So....
A regular computer UPS has, essentially, no lag time - realistically it likely does have but so short as to be imperceptible to the attached devices.
Does a Tesla Powerwall work the same way (Uninterruptible?) or is it considered a "stand-by" device that has to do a longer cutover to the attached devices which may be impacted by the delay?

 

[theoldwizard1]

is there anyway to eliminate it? Basically, I want a giant UPS for my house.
is that possible? What would it take and how much would it cost?

Yes ! Modern UPS try to "catch" the power as it goes out by very quickly switching to the batteries and inverter. Most of the time this works, but it is not 100% perfect !

The only "true", 100% "uninterruptible power supply" is an "on-line" "double conversion" UPS. Technically, you are running off the batteries and inverter 100% of the time. Incoming power (from whatever source) just recharges the batteries.

Very expensive ! Probably tens of thousands of dollars. Also requires a huge amount of space for batteries (the one in the computer room I used to run had 6 cabinets, each the size of double door refrigerators !)

 

[LopezBart]

We have a few short duration outages here every year in the PNW, usually caused by trees, winter storms and power lines. My home network uses POE (power over Ethernet) so an old computer UPS in the basement keeps that running for a while. The most critical device is my CPAP machine, however - I hate waking up trying to breath with the device turned off. I am fortunate enough to have a CPAP that runs on 12V, so my solution was a 20AH gel cell and a 3A Battery Tender. I always have power, and simply don't notice power outages anymore.
Everything else seems to do fine w/ occasional outages.

- LopezBart

 

[wyliesdiesels]

Yes ! Modern UPS try to "catch" the power as it goes out by very quickly switching to the batteries and inverter. Most of the time this works, but it is not 100% perfect !

The only "true", 100% "uninterruptible power supply" is an "on-line" "double conversion" UPS. Technically, you are running off the batteries and inverter 100% of the time. Incoming power (from whatever source) just recharges the batteries.

Very expensive ! Probably tens of thousands of dollars. Also requires a huge amount of space for batteries (the one in the computer room I used to run had 6 cabinets, each the size of double door refrigerators !)

tens of thousands of dollars? yeah maybe for a very very large one.

the Eaton 9PX double conversion UPS i have in my shop wasnt tens of thousands of dollars (less than $2K), its 2U, 2200VA & can have 4 addl external battery units attached to it which are also 2u...

BTW it has a bypass feature where you can run the connected equipment off the utility power

 

[theoldwizard1]

tens of thousands of dollars? yeah maybe for a very very large one.

the Eaton 9PX double conversion UPS i have in my shop wasn't tens of thousands of dollars (less than $2K), its 2U, 2200VA ...

His generator is 10 TIMES that size !

The other question is "ride through time" !

 

[dcg9381]

Does a Tesla Powerwall work the same way (Uninterruptible?) or is it considered a "stand-by" device that has to do a longer cutover to the attached devices which may be impacted by the delay?

It does a switch over. It's "very fast" - but it's not a "double conversion". It may be fast enough that for most devices you never know that power dropped.. It's going to depend on your use case.

One thing that make seem a little odd to some people (I've largely got the same setup as the OP) is that when the grid is down and he's on generator power, his solar is offline. It does absolutely no good without the grid... Modern inverters (including Teslas) will allow some charge function from those panels with the grid offline. To me, this is a big advantage. But I haven't moved to a modern inverter yet either.

I don't know the "configuration" of Tesla's system, but I know it can be setup to "buy power low" and "sell power high" - meaning that it can be set to discharge battery power during peak rates. If there was to be a grid failure and he's already on battery power, there is no switch over time. The disadvantage of that setting (perhaps) is that you're charging and discharging batteries every day and like all batteries they have a cycle lifetime.

In terms of cost of scale - it costs us about $20k for enough inverters and batteries to provide 50A of 240V power for about 2.5 hours (about 30kWh of battery). And that's as cheap as you're going to get it (no labor). So when you need to cover 100A at 240V, or move up even higher, things get real expensive...

 

[rharman]

Yes ! Modern UPS try to "catch" the power as it goes out by very quickly switching to the batteries and inverter. Most of the time this works, but it is not 100% perfect !

The only "true", 100% "uninterruptible power supply" is an "on-line" "double conversion" UPS. Technically, you are running off the batteries and inverter 100% of the time. Incoming power (from whatever source) just recharges the batteries.

Very expensive ! Probably tens of thousands of dollars. Also requires a huge amount of space for batteries (the one in the computer room I used to run had 6 cabinets, each the size of double door refrigerators !)

That's what we had in the computer room at a previous employer. 3-Phase. About 7' tall and 6' wide. And, yes, a bypass to use PoCo only for live maintenance. We also had a connection to feed it from a (rented) generator when they took down one of our on-site power distribution closets. Eventually, we got our own permanent Generac so we were self-sufficient.

When I took over the department, I discovered that the batteries had not been replaced in YEARS. Management was not happy when I submitted a budget request to replace the batteries - "We've never done that before!" They looked like regular car batteries. When we actually opened it up, a fair number of them had collapsed inward on themselves. Fortunately, we had never needed battery power - Don't think it would have been much help.

 

[theoldwizard1]

That's what we had in the computer room at a previous employer. 3-Phase. About 7' tall and 6' wide.

Similar height, but almost 20' long !

When I took over the department, I discovered that the batteries had not been replaced in YEARS. Management was not happy when I submitted a budget request to replace the batteries - "We've never done that before!" They looked like regular car batteries.

Exact same scenario ! The only difference was we were able to significantly downsize the battery bank because much of the equipment had been removed.

When the Northeast blackout of 2003 I was not in the building. When I got back, the building safety lights were on. Luckily I had a key to the computer room (ID card reader was non-functional). Safety lights were on and all the equipment was humming away. Network equipment was running, but there was nothing outside of our room to talk to. We immediately started shutting down "auxiliary" equipment. We did not complete our shutdown for probably 30 minutes AFTER the blackout started.

 

[durk_2007]

What brand of solar inverters do you have? No, your lag will barely be noticeable. my system will switch over in 50ms and I have enough battery to run essential loads for 4 hours. Running off 6kw solar and when batteries get below 50% generator with start up to recharge batterys. Not Tier 1 equipment but 5k invested before panels.

 

[cdoublejj]

We have a propane powered 22kw generator.
we also have a 10kw roof mounted solar array.
we have no battery backup.
when the utility power goes out, the house goes dark. Some amount of time elapses, maybe 15 seconds. The generator starts. Depending on ambient air temp, the auto transfer switch flips 5 to 30 seconds later and we have power back in the house.
if we had a battery backup, Tesla powerwall or similar, would we still have that lag between the power failure and backup power?
is there anyway to eliminate it? Basically, I want a giant UPS for my house.
is that possible? What would it take and how much would it cost?

look up Will Prowse on youtube, also look up Lifepo4 Server Rack batteries. Tough chemistry, i once saw a 13 years old Lifepo4s that weren't charged for 8 years run circles around traditional flood lead acid. i had always heard Lifpo4 was rated at 10 years but, never seen any past that till recently.

 

[Mr onetwo]

The EG4 battery I just bought is rated for 8000 cycles down to 20% https://eg4electronics.com/categories/batteries/wpower-16-280-aw-powerpro-wallmount-all-weather

 

[dcg9381]

The EG4 battery I just bought is rated for 8000 cycles down to 20% https://eg4electronics.com/categories/batteries/wpower-16-280-aw-powerpro-wallmount-all-weather

That's pretty much what they say about all of this technology. And that may be true of the base materials, but there is more in play than that.

I'm interested to see how this works. These are "straight off the boat" and the inverters that I've had function, but lets just say they are more like a late-beta product. Prose has good reviews on the stuff, but he does not cover all use cases.

Did you buy their 18k inverter?

Which vendor are you buying from? The guys from Signature have been out to my shop... Good local business, but they've had trouble keeping up on the support side.. Finally seeing some documentation on firmware changes.. so they're moving in the right direction for sure.

 

[Mr onetwo]

I got the EG4 6000XP https://signaturesolar.com/eg4-6000xp-off-grid-inverter-split-phase/ the battery is supposed to ship in a couple of weeks

 

[cdoublejj]

That's pretty much what they say about all of this technology. And that may be true of the base materials, but there is more in play than that.

I'm interested to see how this works. These are "straight off the boat" and the inverters that I've had function, but lets just say they are more like a late-beta product. Prose has good reviews on the stuff, but he does not cover all use cases.

Did you buy their 18k inverter?

Which vendor are you buying from? The guys from Signature have been out to my shop... Good local business, but they've had trouble keeping up on the support side.. Finally seeing some documentation on firmware changes.. so they're moving in the right direction for sure.

signature solar and current connect are the talk of the town but, is also whatever gold and ecoworthy for the even cheaper stuff. whatever gold makes me thinkg of harbor freight and eco worthy of ebay or aliexpress but, i've never looked up thier customer satishfaction.

you might also look up mr prowse, he not beats on the equipment but ,the phone support and help agents too. as in consdering the whol experience not just the specs when he reviews.

 

[dcg9381]

signature solar and current connect are the talk of the town but, is also whatever gold and ecoworthy for the even cheaper stuff. whatever gold makes me thinkg of harbor freight and eco worthy of ebay or aliexpress but, i've never looked up thier customer satishfaction.

SS is in Sulphur Springs, Texas near where I grew up. They are an off-the-boat importer of goods from China. I'm not being critical as I've run the same business in a different vertical (theirs has been much more successful). With respect for their business, I will not indicate who they are importing from, but for a quantity of 50 units and the applicable BS that goes into bringing things over in a boat from China, I can have it branded "GJ Superheros" and we can all go into business.

That being said, I use and have built the engineering side of a business around what they have imported. SS is expanding rapidly and giving "corporate" customers advanced tech support and engineering support.

I've had 4 of their inverters running in my shop for over a year, more than 12 of their 5500 kWh batteries and can make these things do what they should do...

you might also look up mr prowse, he not beats on the equipment but ,the phone support and help agents too. as in consdering the whol experience not just the specs when he reviews.

I blame Prose for me saying "I can build that". He's "independent" but like the NASA guy with squirrels, he probably makes a lot of income off the reviews and people are throwing hardware at him. Prose does not review all situations (grid tie, mobile, grounding, etc) - so YMMV (as I found out) but I generally trust him....

What I can tell you is that vendors are going to give him "substantial" support over you and me in a one-off situation.

EG-4 has largely been "internet help" unless you're Prose or have a high visibility business.

 

[cdoublejj]

indeed! i also like that he is mention the OEMs that these places are using to slap their name on and whos doing the firmware updates. i haven't found any channels that are as savy, well there is the boat guy

but, he doesn't do so much hardware coverage.

btw that is pretty interesting a know a few guys who were selling chinese scooters back in the late 00's but, you sounds make your sounds like a home grown harbor freight.

 

[dcg9381]

you sounds make your sounds like a home grown harbor freight.

I'm not good with calling it "Harbor Freight" - their stuff works and seems to be reliable.. But it's not well supported (by the actual engineers building it) unlike other much more expensive brands.. But the cost difference is fairly shocking, so you'll be seeing more of this stuff. My guess is that it will continue to improve and the DIY guys who are essentially "beta testing" this stuff will continue to be vocal about what's broken and how to work around it.

And then there is the whole certification thing that some states are requiring for grid tie, I've seen a little wavering on that...

Long term, this is good for the consumer... The market for off-grid seems to be pretty massive.

 

[cdoublejj]

I'm not good with calling it "Harbor Freight" - their stuff works and seems to be reliable.. But it's not well supported (by the actual engineers building it) unlike other much more expensive brands.. But the cost difference is fairly shocking, so you'll be seeing more of this stuff. My guess is that it will continue to improve and the DIY guys who are essentially "beta testing" this stuff will continue to be vocal about what's broken and how to work around it.

And then there is the whole certification thing that some states are requiring for grid tie, I've seen a little wavering on that...

Long term, this is good for the consumer... The market for off-grid seems to be pretty massive.

i meant more in volume than big picture. last few prowse videos i've seen was lauding the pre certifications as folks were having PnZ/inspectors sign off on it with little to no fuss since it's already meets state certs.

people are tired of getting you know whatted. checkout

for a long time here outages were a regular thing. oncei bought my big boi metal cased 24v 150ah Lifepo4 to run my APC back the power company must have got scared straight, we even got new poles, guess they are watching my amazon purchase history

 

[Just_Steve]

I got the EG4 6000XP https://signaturesolar.com/eg4-6000xp-off-grid-inverter-split-phase/ the battery is supposed to ship in a couple of weeks

what was the $$ for the battery?

 

[dcg9381]

what was the $$ for the battery?

Their 6500 watt inverters really need 2 x 48V batteries to be able to handle any sort of decent load.. This inverter apparently has lower idle draw - so might be better at starting loads. EG-4 Batteries are BMS limited to 100A output anyway.

Basically I think 2 x $1300 batteries minimum... Some people roll their own battery packs.

 

[Just_Steve]

what was the $$ for the battery?

Looking at their site, battery set ups are priced good. I would have to figure out if it is compatible with my system

EG4 WallMount All Weather Lithium Battery | 48V 280Ah | 14.3kWh

Power your home with the EG4 14.3kWh AllWeather Battery. Outdoor-rated, self-heating 48V lithium storage built for reliable backup in any climate.

signaturesolar.com

 

[Mr onetwo]

I bought the battery on their free shipping deal...$4218. It's on it's way... just got this email last evening.
The video above can be watched free on VUDU.