Generator decision

[R_Holiday]

I’m building a house in central NC and need some help determining what generator to get and at what price point. I’m not trying to break the bank but want one that will be sufficient when a need occurs. The house will have one 400 amp panel. Duke already put a new transformer and poles on the property and plan to use 300 wire or something like that. I plan to use an in ground propane tank for the generator and for the tankless water heater. House will have dual ac units. The other main draw will be my garage where my welders, lifts, compressor, and other tools reside. I would rarely ever have 2 240 volt tools running at the same time since it’s just me there. The question is will a 30kw liquid cooled generator be good enough or will I need more power? The two “affordable” units I saw are the general protector series and Taylor power systems; both units run at 3600rpm. Going up to 40+ kilowatts really jacks the price up and I’m not sure if that much power is really needed but I do like the reliability of an 1800rpm motor.

 

[Firebrick43]

Out of the 100’s of residential generator we deliver fuel to only a few are 31 or 32 KW.

You mention shop equipment, are you making revenue with them? If not do you really have to run the welder or air compressor?

If you have AC going, the well kicks on, plus your in the shop welding and the air compressor kicks on plus all the minor household loads, 30 KW is not enough.

If you can hold off on the shop loads(probably still use the lift) 30kw is usually enough for large houses without much or any change in habits (normal suburbanite)

 

[R_Holiday]

Out of the 100’s of residential generator we deliver fuel to only a few are 31 or 32 KW.

You mention shop equipment, are you making revenue with them? If not do you really have to run the welder or air compressor?

If you have AC going, the well kicks on, plus your in the shop welding and the air compressor kicks on plus all the minor household loads, 30 KW is not enough.

If you can hold off on the shop loads(probably still use the lift) 30kw is usually enough for large houses without much or any change in habits (normal suburbanite)

I don’t have to be in the shop doing any work during a power outage. I figured if I’m home and the power did go out I would like to be able to get some work done in the garage if I wanted to in lieu of just wasting time sitting around watching TV. Fridge, AC and heat are the primary constant loads. I’m not sure what well you’re referring to. I really just wanna have the option of doing work in my garage, purely for my enjoyment, and whether a smaller liquid cooled one would suffice. I hope I’m making sense with what I’m looking for.

 

[Chuckster in NJ]

Since you don’t want to "break the bank"……… I would suggest checking out a KOHLER 26KW LP generator because that would be the most affordable machine and use load sheds on the AC units.

 

[Firebrick43]

I don’t have to be in the shop doing any work during a power outage. I figured if I’m home and the power did go out I would like to be able to get some work done in the garage if I wanted to in lieu of just wasting time sitting around watching TV. Fridge, AC and heat are the primary constant loads. I’m not sure what well you’re referring to. I really just wanna have the option of doing work in my garage, purely for my enjoyment, and whether a smaller liquid cooled one would suffice. I hope I’m making sense with what I’m looking for.

Sorry, water well.

Most around here have access to natural gas if they have city water

 

[theoldwizard1]

You mention shop equipment, are you making revenue with them? If not do you really have to run the welder or air compressor?

CONCUR ! Sizing a generator to run your ACs and your shop will cost BIG $$$ ! It's your money. Maybe consider a second generator just for the shop.

First, look for generator that is water cooled (I doubt anything that big would be air cooled). Second, you want one that runs at 1800 RPM. Most automatic transfer switch have a mechanism that will cut out high loads like AC, is necessary.

Look at Kohler.

 

[75gmck25]

You need to start out with looking at how frequently power outages occur, and then deciding what you really "need" to run during a power outage, and then add on what you "want" to run during an outage.

For example, you could decide to do without A/C if the power outages are usually short and don't happen often. Then all you need is to keep refrigerators going, and maybe a few receptacles for medical devices or other must-have needs. And if you decide you do always need A/C, then maybe you can get by with running only one A/C unit and keeping everyone in that part of the house. However, if you decide you want to run on generator without reducing your lifestyle, then maybe you need to talk to the folks who sell Generac or Kohler whole-house systems.

 

[BillK]

In the last 5 years how many times have you actually lost power and for how long ?

 

[walta]

If you really need the 400-amp service and want uninterrupted operations then you need a 96kW genset.

Note your tankless electric water heater is likely to be 36kW by itself like mine is.

The other big load you may have is backup heating coils that operate when your heatpump enters every defrost cycle.

If you want to run a smaller genset you will need a load shedding plan and you really need it in advance.

Walta

 

[jblnut]

Get yourself a 100hp tractor and a 50kw PTO unit. Then you’ll have plenty of power AND a tractor. Win.

I have a few generators on the farm and dislike all of them except my 40kw Kubota powered diesel. The 80kw GM powered unit in the barn runs on LP and has been a PITA, the 75kw PTO unit works fine but requires a tractor so I usually use the Kubota unit if it’s not too hot or too cold out where I’d need the extra 25kw from the PTO genny to run fans and waterer heaters on the farm.

There are tons of ways to skin the generator cat and it all depends on what you want to spend and how “convenient” you want it to be. The more “convenient” the more expensive. If the power goes out I’d say keep the bare minimum running and go for a walk or paint something and watch it dry like our ancestors did.

 

[mike93lx]

"I don't want to break the bank, so will this $30k generator setup be enough?"

Lol

Either admit that the money doesn't really matter and you don't want any inturruption in your life or come back to reality.

How big are the a/c's? If only two, the house either isn't all that big or this is some ultra complicated system.

 

[wyliesdiesels]

you need to backup and start with the sizing of critical loads, then wanted loads, then size generator from that. picking a genset first is like putting the cart before the horse...

If you want an ATS, you will need load shed modules, unless you buy a genny capable of handling the entire possible load in your panel.

 

[wyliesdiesels]

Most automatic transfer switch have a mechanism that will cut out high loads like AC, is necessary.

no they do not. the load shed modules are separate contactors that go in the electrical panels to cutoff power to individual loads. they dont go in the ATS or even come with most ATSs...

 

[wyliesdiesels]

I’m not sure what well you’re referring to.

do you have municipal water supply or a water well?

 

[mngundog]

I was looking at this one on sale at Costco, 22kw, I'm thinking it may be enough for me:

https://www.costco.com/p/-/honeywell-22kw-home-standby-generator-with-transfer-switch/100767860?langId=-1

 

[mm08822]

I’m building a house in central NC and need some help determining what generator to get and at what price point. I’m not trying to break the bank but want one that will be sufficient when a need occurs. The house will have one 400 amp panel. Duke already put a new transformer and poles on the property and plan to use 300 wire or something like that. I plan to use an in ground propane tank for the generator and for the tankless water heater. House will have dual ac units. The other main draw will be my garage where my welders, lifts, compressor, and other tools reside. I would rarely ever have 2 240 volt tools running at the same time since it’s just me there. The question is will a 30kw liquid cooled generator be good enough or will I need more power? The two “affordable” units I saw are the general protector series and Taylor power systems; both units run at 3600rpm. Going up to 40+ kilowatts really jacks the price up and I’m not sure if that much power is really needed but I do like the reliability of an 1800rpm motor.

Since this house is not built yet, there is some flexibility.

• What is the square footage of the house?
• What are all of the electric loads? Which are critical?
• Who and how was a 320A/400A service determined?
• Assuming the service size is correct, you could possibly split the service up using two 200A panels where one panel is on the ATS ("critical Loads") and the other panel handles the rest of the misc stuff. This could mean that only a 200A xfer switch is required.
• How likely are you going to be in the garage during bad weather/power outage? Not likely everything runs at once either.
• Worst case you need (or want) a 400A xfer switch to handle both panels. Still doesn't mean a 30 or 40KW gen is needed. (Hence, the q's about house size and loads.)

As already asked, what is the outage history and durations?
A bigger gen needs a bigger LP tank. What size LP tank are you planning on?

 

[bob smith1]

Typical OP type post, and accurate responses. OP first needs to figure out IF the power will go out, for how long, and the REAL situation. I treat BFE farmsteads with livestock and/or elderly very different than someone 1mi from their power station in the burbs.

Let me just pop this in here, years ago, we had a once in a lifetime ice storm that took power out for several days. It was Winter but not brutal. I was the only one nearly in the town "with power"....lol Even the POCO asked if I had power. Watching movies in the theater, landscape lights on, furnace rolling. That was all served with a 3KW Honda inverter. I wasn't even prepared! I had to go hack some cords, find some plugs or do what was needed, and just cut the lock and pulled my meter.

I don't feel anyone suffered a bit! I just shut off the furnace for 5min while the other half used the blow dryer...(important).

As for AC loads, I 100% recommend modern soft starts for ACs, using a generator or not! They should be factory. They help protect the compressor, reduce inrush sag, and in all ways are awesome.

If you need to show off for your friends, buy a boat. You will probably get more mileage out of it. Big generators are NOT cheap to run, even unloaded. Some don't care until you puke $500 in a week for it to idle.

I've built several hybrid solar or load shed inverter systems, employing a generator as standby. If you want to spend money, dive into that. The way this works is battery storage carries the house loads until there is a trigger, which is typically only an AC, and that will bring the generator up via AGS to charge batteries and help hold the loads. 99/100, I can get a 10KW to handle it all, but you need to get over the use of the dryer and electric cook top man!

 

[mm08822]

Most automatic transfer switch have a mechanism that will cut out high loads like AC, is necessary.

Generac has two methods for load shed:

• Within the ATS via relay contacts by interrupting the control circuit of the ac unit or furnace
• External load shed modules (50 or 100A contactors) in series with the load's power wiring

Either method is triggered by a drop in gen frequency and then resumes after pre-selected time delays (assuming no further drop in hz)

 

[bob smith1]

Should also be mentioned about 3600r generators. They are generally craptastic primarily due to the sales pitch of running a smaller engine at the peak of the HP curve, NOT the torque curve. This destroys a generators ability to maintain frequency unless running inverter. I do own some Cummins belt drive generators that are non-inverter, but a hybrid to run the engine in the middle of the band, but run the generator head at 3600r. They are exceptional! When you see real specs in the book with base load plus whatever, with x amount of allowable frequency drop, and a tight hz band before they kick out, they are pro goods.

If you have any option at all for LP or NG, I highly recommend!

 

[Stuart in MN]

A reputable dealer of a brand name generator will sit down with you and help you figure out what size you need. Also, the name brands often have a page on their website where you can enter the anticipated loads and it will pop out a number, but that should be considered as a estimate that still needs be confirmed with the dealer.

While you may pay less for an off brand bought online, you also need to consider servicing, repairs, and buying parts in the future, all things easier done if there's a dealer nearby. There's that old saying, buy once cry once.

 

[Lassen Forge]

We went with Kohler, their service was bar none, they replaced their control board under warranty, the system was easy to figure out once we had a copy of the tech's laptop interface. I specced it so that it could handle the full load of our house, our shop, the well, our outbuildings, etc. if we had them all running - ya never know what you're gonna need in a disaster. Plus just running the house, it sipped LPG like a maiden aunt at a tea party, so we went through very little LPG... BUT if I needed to access the shop while the well pump was running and we had some of the baseboard heaters going, peh, not a problem.

BTW - sure, my house MAY have run on less than 1/2 the capacity, but add the well and pressure system, the shop, the baseboard heaters, the shicken farm, the outbuildings.

 

[theoldwizard1]

Duplicate

 

[Metal-Marc]

Typical OP type post, and accurate responses.

This.

Answers are all over the place and OP is gone.

 

[mike93lx]

This.

Answers are all over the place and OP is gone.

Gone? He responded once and only made this post yesterday afternoon.

Hard to believe he might have more going on than a GJ post, eh?

 

[Metal-Marc]

Gone? He responded once and only made this post yesterday afternoon.

Hard to believe he might have more going on than a GJ post, eh?

Once you ask a question here, you have to be committed.

 

[mike93lx]

Once you ask a question here, you have to be committed.

Solid point

 

[R_Holiday]

Sorry for the late reply gents. It got mad busy at the hospital and I was there till late. I appreciate all the insight and clearly I have a lot of things to think about. Here are some answers to some of the replies. The house is 3600sqft and garage is 1600sqft. I have city water with a septic system. Water heater is gonna be tankless gas. I’m not sure about the size of the AC units that are gonna be used as yet. The house is being built on the other side of town which is operated by Duke power. I’m on a different service where my house is currently. Over the past 5 years the power has been erratic with frequent short losses of power, between 10 mins and a couple hours. The longest I’ve lost power for was about 10 hours. The builder determined that a 400 amp service was needed because of the house load and the needs of my garage/shop. I initially didn’t plan to include the garage in the generator plans but changed due to it only being me in the house and wanting the option to finish tig welding an exhaust if I was already in the middle of it or just wanted to do it. Natural gas isn’t available at the location right now and the gas company quoted me for a 320 gallon tank. I think I’ll up it to 500 gallons. Apart from the standard load on the house I don’t have any load specs to give. I keep my thermostat at 74 in the summer and 70 in the winter. It’s constant with no change due to night time or time out the house.

 

[R_Holiday]

I would definitely prefer to buy once and cry once if possible. That’s why I wanted to go liquid cooled. The most “affordable” options for liquid cooled seem to be the generac protector series 30kw and Taylor fortress 30kw. Both are liquid cooled but run at 3600rpm. The 1800rpm motors jump the price up significantly.

 

[wyliesdiesels]

1800rpm gennys are worth it. they last longer, run cooler, consume less fuel....

 

[mike93lx]

For a new 3600ft build that sounds at least somewhat premium, I'd guess a/c's in the 2-3 ton range. My poorly insulated house of the same size has two 2.5's and a 1.5.

You don't need a 30kw genny. Sure, liquid cooled is nice, but a total waste if the power never goes out.

If you do go that big, you certainly won't have to change usage when the power is out, but be ready for the fuel bill.

I'd probably do a smaller air cooled and put in a battery backup to handle the smaller outages

 

[rmanrman]

My home has a 1000 gallon propane tank that I had installed by the propane distributor.
I made a mistake not to buy from propane dealer because I by Nj law must get it filled from the same dealer at their current price per gallon. I cannot remove their tank and replace with my purchased tank because I would ruin my septic field running a large machine to dig out the old tank. Something to think about placement on your property.

 

[manwithtools]

I'd probably do a smaller air cooled and put in a battery backup to handle the smaller outages

I like this approach too. Add solar to the battery system and it's even better. It can be used all the time for peak hour offset and then power outages when needed. I've been seriously looking at the Anker Solix E10 system.

OP what is your power cost in the new home area?

 

[Stuart in MN]

I'd probably do a smaller air cooled and put in a battery backup to handle the smaller outages

I did a lot of standby generator design when I was working but I've been retired for 5 years and haven't really kept up with the latest offerings for battery backup. I do know the smaller portable power stations (like from Jackery, there's a number of other brands) have become pretty affordable. For short power outages I think they'd be a great option for plugging in a few essentials.

 

[mike93lx]

I did a lot of standby generator design when I was working but I've been retired for 5 years and haven't really kept up with the latest offerings for battery backup. I do know the smaller portable power stations (like from Jackery, there's a number of other brands) have become pretty affordable. For short power outages I think they'd be a great option for plugging in a few essentials.

No, I mean something bigger like a tesla power wall or anker e10. Real, automated backup capability

 

[manwithtools]

No, I mean something bigger like a tesla power wall or anker e10. Real, automated backup capability

Yep an E10 system can be outfitted with real backup capability. A single inverter can handle 30kW of batteries and 9kW of solar input. 20ms of switch over time when power is lost. You can use up to 3 of the inverters for up to 90kW total storage and up to 27kW of solar. There is no way I would use a dedicated generator today when you can buy batteries, inverter, ATS, generator and solar for nearly the same money.

 

[mike93lx]

Yep an E10 system can be outfitted with real backup capability. A single inverter can handle 30kW of batteries and 9kW of solar input. 20ms of switch over time when power is lost. You can use up to 3 of the inverters for up to 90kW total storage and up to 27kW of solar. There is no way I would use a dedicated generator today when you can buy batteries, inverter, ATS, generator and solar for nearly the same money.

Generators solve for long outages far better than a battery and not every house is a good candidate for solar.

Plus a generator is a lot cheaper

 

[R_Holiday]

Yep an E10 system can be outfitted with real backup capability. A single inverter can handle 30kW of batteries and 9kW of solar input. 20ms of switch over time when power is lost. You can use up to 3 of the inverters for up to 90kW total storage and up to 27kW of solar. There is no way I would use a dedicated generator today when you can buy batteries, inverter, ATS, generator and solar for nearly the same money.

I’ll have to look into this. The power cost is $13-15 per kilowatt hour.

 

[mike93lx]

I’ll have to look into this. The power cost is $13-15 per kilowatt hour.

Just a FYI it's 13-15 cents, not dollars.

That's pretty cheap and will be hard to justify a solar setup

 

[manwithtools]

Generators solve for long outages far better than a battery and not every house is a good candidate for solar.

Plus a generator is a lot cheaper

Generator is not a lot cheaper, go price out a system. Also they offer a DC generator to couple directly to the E10 system for efficient charging during power outages. Minimal solar will top up the system enough that coupled with the generator will get you thru long power outages.

This is not like the typical solar calculation. Low power costs do have a longer payback, but ...

I think you will be surprised how the price compares to a generator that will set for 11.9999 months of the year unused.

 

[wyliesdiesels]

for nearly the same money.

I dunno about that... and gennys can sustain someone thru longer outages that happen with very large emergencies such as hurricanes and ice storms. GL with the solar when there is no sun