Whole house battery backup or natural gas powered standby generator?

[YB88]

In my part of the world the most significant "big disaster that could (but might not in my lifetime) occur" is a major earthquake. In that situation something like a Generac could be a very expensive but completely useless item --- i.e., if natural gas isn't flowing all the way to your house, with your house structure sufficiently intact for that to be helpful.

What I'm suggesting is that it depends on what situation you're (most) concerned about. My personal approach is to have a pretty small propane powered generator with three 40 pound tanks stored under my deck. Wall pass-through unit I installed allows me to plug in on the inside of the house while the generator is running under cover outside. Plan is to use that to recharge multiple lithium battery portable power station units maybe once a day to keep refrigerator, freezer and gas fireplace fan running plus recharge phone, power a couple of DC lights (no inversion loss) and work my garage door opener if needed.

But I'm relatively young in my neighborhood. I have a neighbor who I think needs continuous reliable power for health reasons, without having to personally do something to get/keep that power flowing, so a generac makes perfect sense for him.

 

[Rich]

Until we sold our place on Cape Cod we used a Generac (sp?) whole house generator for over 20 years, using propane fuel (same as for the house heating/water/cooking). Own two Teslas, stated for full disclosure. If you really want security go with a natural gas powered home generator setup. Basically you will have unlimited electrical energy for the duration of any emergency. Battery powered systems are both too limited in duration of power available and very high costs.

 

[ncbill]

In my part of the world the most significant "big disaster that could (but might not in my lifetime) occur" is a major earthquake. In that situation something like a Generac could be a very expensive but completely useless item --- i.e., if natural gas isn't flowing all the way to your house, with your house structure sufficiently intact for that to be helpful.

What I'm suggesting is that it depends on what situation you're (most) concerned about. My personal approach is to have a pretty small propane powered generator with three 40 pound tanks stored under my deck. Wall pass-through unit I installed allows me to plug in on the inside of the house while the generator is running under cover outside. Plan is to use that to recharge multiple lithium battery portable power station units maybe once a day to keep refrigerator, freezer and gas fireplace fan running plus recharge phone, power a couple of DC lights (no inversion loss) and work my garage door opener if needed.

But I'm relatively young in my neighborhood. I have a neighbor who I think needs continuous reliable power for health reasons, without having to personally do something to get/keep that power flowing, so a generac makes perfect sense for him.

no power failure longer than a day here in over 30 years.

but hurricane Helene caused an almost day-long outage.

so I started replacing old UPS units with 1 kWh EcoFlow units, then added a 4 kWH for the gas furnace.

may add a portable tri-fuel generator as well to run directly off natural gas.

 

[skipro33]

I wonder why folks advocate such large generators; 10K and above, some even 22K. I can run my whole house, including two AC units, and stay at 5K max. I have a 7K Honda inverter generator, quiet enough to have a conversation standing next to it while it's running without raising voices. I added a propane conversion kit to it and I have a 500 gallon propane tank. When we have long outages, 4 days or more, I'll turn it off at night to save a little on the propane cost. The generator has wheels and handle, stored in a shed and rolled out when an outage hits or eminent bad weather is forecast. (I hate setting it up in the rain or snow)
Anyways, I recommend looking at your electric meter when considering the size of a generator needed to support your home during public power outages.

In the meantime, I looked into solar and batteries. The battery capacity to even start one of my air conditioners will trip the battery off line, requiring me to physically reset the trip. This is with 2 Tesla power walls. The companies I've talked to about this tell me to plan on not running AC during outages. Right. So check to be sure the inrush current load can be managed by whatever battery plant you plan to use.

 

[NW-Bound]

^^^ My current DIY solar+battery cannot run my 5-ton central AC. I have installed 3 mini-splits with a total capacity of 3 tons to cool the 1st level of my home. They run fine on the solar power 24/7, except on super hot days of 115F, when I run out of battery storage during night time.

What setup is optimal depends a lot on the locality. People without access to natural gas and having to rely on a gas generator will quickly find out that getting gasoline to feed the beast become a real chore for prolonged outages. I never had outages longer than an hour or so, and that happened only once every few years in the 51 years I have been in this locality.

And with the nearly year-round sunshine in the Southwest, I could have gone off-grid by putting up more solar panels if I had more land than this suburban lot. Up in my high-country 2nd home with an acreage lot, I could have gone off-grid easily, but I don't live there full-time to install any system.

And people with a battery backup system can run a smaller generator to charge the battery to supplement the solar panels. The battery will provide the surge power up to the capacity of the inverters, which can be a lot higher than that of the small generator. The battery also allows you to turn off the generator at night and not run it 24 hours. This saves a lot of fuel, because a large generator even when idle, meaning not having a load, burns tons of fuel.

 

[MdaPetralia]

The battery capacity to even start one of my air conditioners will trip the battery off line, requiring me to physically reset the trip.

Have you looked into installing a "soft starter" in your AC unit(s)? IIRC, this device reduces or slowly ramps-up the high power demand at start-up.

 

[monte1022]

I purchased a Cummins 20kw July 2020 for $6300 installed with transfer switch. The same setup is now $11000 from Wiredup Electric, Belpre, OH. They have prices listed if you want to compare with your local dealers. This generator easily handles a 5 ton AC startup.

 

[Jerry1]

And people with a battery backup system can run a smaller generator to charge the battery to supplement the solar panels. The battery will provide the surge power up to the capacity of the inverters, which can be a lot higher than that of the small generator. The battery also allows you to turn off the generator at night and not run it 24 hours. This saves a lot of fuel, because a large generator even when idle, meaning not having a load, burns tons of fuel.

This is my current line of thinking. Get a battery system that will handle minor outages and supplement that with a small generator.

 

[Jerry1]

Here is the label on my AC unit. Can anyone help me understand what it would take to get a battery/inverter to run this? In the big picture, I don't see being able to run my AC but I'm curious and trying to understand. Thanks.

And here's a link to the model of compressor. A 3 ton unit. dn RA14AZ36AJ1NA SEER2 CONDENSER R410A | Rheem Condensing Units | Air Management

 

[NW-Bound]

What you are looking for in the specs is "LRA", for "locked rotor amps". It's the amperage an induction motor draws when it is just turned on and its rotor is not yet spinning. The LRA high current usually lasts just a fraction of a second, but will be enough for an undersized inverter to cry "Murder", then shut down. In the rare case, it may not shut itself off soon enough, and lets the smoke out.

The LRA is not on the label, but is on page 5 of the manual. It says "83 A" for the 3-ton unit. Multiplied by 230V, that is 230V x 83A = 19 KVA! That's big.

PS. The 83.1A LRA is on the label. I missed it. It's on the 6th line. The running current is only 13.1A, or 3KVA.

 

[Jerry1]

Thanks NW-Bound. So I would need something like a 15 to 20 kW generator to run (start) the AC and if using batteries, I'd need a massive inverter and probably need to install a soft start just to make it reasonably practical. I understand better now why even most generators don't run the AC. Thanks.

 

[NW-Bound]

Compared to these archaic induction motors, nearly all mini-splits currently on the market use an inverter motor. This is for the variable speed feature, but an additional benefit is the soft ramp-up in speed. The variable speed allows the smart electronic control to run the compressor only as fast as needed, depending on the ambient temperature. This variable speed plus the higher efficiency of the modern motor means less power usage.

Hence, my 3 mini-splits with 3 tons of total capacity are cruising on my solar+battery all day, and through the night too, as long as it's not 100F at 2AM. When the high is 115+F, my battery runs out of juice at 8PM.

I have more solar panels, more batteries, and more inverters to install. I want more of everything.

 

[Jerry1]

So how would a dehumidifier work? While I could get by without AC, my basement would probably be nasty without a dehumidifier in the midst of summer. I'm assuming it's a lot less than a AC compressor but it still has a compressor. Let's say it has a LRA of 80 (I can't confirm that for my dehumidifier) and multiply that by 115v service, that would be 9200 so 9KVA? Is that a lot for an inverter?

 

[NW-Bound]

There are inverters of 20kW on the market. And many models can also be synchronized and wired in parallel to drive even heavier loads. However, you will need bigger batteries to feed them.

For an idea of the prices, you can look at the equipment offered by Signature Solar.

 

[skipro33]

Have you looked into installing a "soft starter" in your AC unit(s)? IIRC, this device reduces or slowly ramps-up the high power demand at start-up.

Yes I did. I purchased and installed two of these:

SoftStartHome™ 6-Ton – Soft Start For Air Conditioner And Heat Pump Un

The Best Soft Starter For Residential Central Air Conditioners and Heat Pumps Effortless Operation Home 6T is the premier solution for starting and running residential central air conditioners and heat pumps up to 6 tons with limited power sources. Whether you're connected to a standard power...

softstartusa.com

I worked directly with their technician to install. I have two 2-ton air conditioners, not heat pumps. However, they would fail to start the compressor. The way the work is that they slowly (a relative term) ramp up the amperage that the compressor draws. In both my AC units, the soft starts would time out before reaching full operational power, then trip the compressor. The only way to reset is to power off the AC and start over. We worked for days and since I had two of these and two air conditioners, I tried swapping them and still both failed to work reliably. Fortunately the company is legit and gave me a full refund. I was sure hoping they would work so that I could run a 3K generator by powering off one of the AC units and staying in the main living portion of the house during outages. (A 3K genny burns less propane than the 5k does.)

 

[old medic]

but hurricane Helene caused an almost day-long outage.

We weren't so lucky...9 days... but consider ourselves very lucky compared to many others around us.
We have had several multi day outages here since 1985. We have a portable 3400W inverter generator, and made extension cords to run the well, and a power strip in the house with cords to the fridge and freezer. Its a PITA but it works, run 20-30 minutes every couple hours. 5 gallons of gas lasted us through the 9 days.
We also have a portable 3000W inverter with battery pack and solar panels for camping that can be put to use.

 

[finnski1]

We weren't so lucky...9 days... but consider ourselves very lucky compared to many others around us.
We have had several multi day outages here since 1985. We have a portable 3400W inverter generator, and made extension cords to run the well, and a power strip in the house with cords to the fridge and freezer. Its a PITA but it works, run 20-30 minutes every couple hours. 5 gallons of gas lasted us through the 9 days.
We also have a portable 3000W inverter with battery pack and solar panels for camping that can be put to use.

Yeah. We had a 13-day outage several years ago in a heavy ice storm here in Southern NH. I went without for the first 6 days and finally purchased a cheap Home Depot gas generator to get through the next 7 days. Had to fill it often.  Still have the same generator 15 years later and have used it many times for anywhere from 1 hr to 2 days but it's getting very finicky and tired. Think I'll replace it with a better quality, dual fuel version so that I can use an adapter with my 20 lb RV propane tanks.

 

[old medic]

Think I'll replace it with a better quality, dual fuel version so that I can use an adapter with my 20 lb RV propane tanks.

I will recommend a Champion inverter generator. Dual fuel is a nice option but keep in mind that propane doesn't create as much power as gas.

 

[finnski1]

I will recommend a Champion inverter generator. Dual fuel is a nice option but keep in mind that propane doesn't create as much power as gas.

Will check it out thanks. I've run the whole house on a 5500-watt (running) generator for years with gas. Will keep that in mind

 

[Stormy Kromer]

Forget batteries.


Get a Generac and sleep well.

By the way, I don't have either, but if I did I would have an lp fueled Generac.

 

[Texas Proud]

Forget batteries.


Get a Generac and sleep well.

By the way, I don't have either, but if I did I would have an lp fueled Generac.

Just my opinion but Kohler is better built..

Do a little research then decide..

 

[old medic]

Get a Generac and sleep well.

NOPE.... couldn't give me one. Our county has several and nothing but problems. Major power outage and 3 didn't run. My brother and a neighbor friend both had fail to start during power outage last year.

 

[folivier]

About using a generator, I had an idea to build a timer that would run the generator for a set time every few hours. This would minimize fuel usage and allow fridge, freezer, AC to run. This was mainly for when we were out of town and had an extended power outage. This is not unusual for a multi day outage after a hurricane. But abandoned that idea when we sold the house and went full-time in our coach.
I actually contacted a few local companies and generator manufacturers about this and they weren't interested. The best they could come up with was a remote system to turn on/off and monitor the generator. But I told them that probably wouldn't work since internet and phone systems are usually out of service also after a devastating hurricane.
With digital systems out there now it shouldn't be too difficult to cobble together a timer system using relays. One to detect when power is out then another to start the generator. Then a timer.
My main reasoning was if we were out of town and had a longer power outage I didn't want my generator running constantly for a week or more.

 

[old medic]

I had an idea to build a timer that would run the generator for a set time every few hours.

Thats how we deal with long term power outage, but its all manual with pull start generator.
I did run the idea of having a battery backup with solar panels and set a generator up to auto start when the bank got low. We are lucky in the fact we have my brother next to tend to stuff when we are gone.

 

[TripleLindy]

Our area has recent suffered two multi-day widespread power outages.

How often has this happened in the past? I ask because after our snowmageddon a few years ago, where many people lost power for several days, whole house generators were in high demand. I looked into it, and a natural gas generator was a pretty expensive insurance policy for something that had occurred once in my lifetime. And we never lost power for more than a few hours at a time.

I understand the concept and would also like to have backup power, but I’ve chosen not to spend that kind of money for such an unlikely event. As battery capacity grows and costs drop, I may consider that at some point, but for now, I’ll assume the risk.