We have purchased a 9000 watt generator to run some items during a power outage. We have gotten estimates from two electric companies so far and they are doing it different ways.
The first one gave us a higher quote but is adding a additional panel. We currently have 2 200 amp panels for our house. he told use we could pick 10 switches for the new panel and he was using a 50 amp circuit to the generator.
The second one wants to keep the 2 panels and run a 30 amp interlock off each panel into another interlock switch to the generator and said we could turn off the high circuits and use the lights and stuff in the house as needed. This was much less expensive.
Money is not our deciding factor as we want it dome the right way. If both are good, is there any information that would help us decide?
Thanks,
Jim

On mine, the electrician just mounted a box on the house near the generator, and put an interlock on my existing panel.
I think the whole deal was a couple hundred bucks.
Oddly, my well pump runs off a separate box (main house service), which I didn't know at the time.
So, even if the gen is supplying the house, it's "after" the well pump.
Not a big deal for me, though I wish I'd known that; I just keep water (5-gal bucket) to refill the toilet and keep a few gallons of drinking water.
My main service would be a pain to get to in a decent snowstorm anyway,

The first guy should also have an interlock but you didn't say.

how I would want it run would be
3rd panel with an interlock between the genset and main panel.
Everything on the 3rd can be run by the genset.
1 of the mains feeds the 3rd panel and you can't have both the genset and mains powered on the 3rd panel. Ie the interlock on the 3rd panel.
the other 2 mains stay on city power full time.
a few reasons.
only 1 interlock to deal with.
no mistakes on leaving too many things hooked to the genset.
can tell when city power is back on.

I would add a small panel between the meter and the two other panels with an interlocking breaker.

Sounds like you are smart enough to manage the loads without restricting yourself to ten circuits.

I have a "smart" meter at my house and I can look at it and tell if I have utility power or not.

Portable generator? Or is this a fixed location for a residence? 9 KW is about 50 amps, hence the 50 amp breaker for the generator feeder. For my money I'd regroup your critical loads into a new panel making sure you don't overload the generator. I'd then use one transfer switch in the feed to that panel so that when a power loss occurs, your critical loads are switched from your utility to the generator. Your first option sounds a lot like this and is the one I'd go with.

This is a portable generator, the cost difference between to 2 is about $1,800. I don't mind paying the r
higher price , but if the other option would work? It's just 2 of us in the house, our well pump and minimal electricity is all we will need.

The well pump is run separately so you can fight a fire if your house (panel) is burning. Probably for an equal amount of time you are more likely to burn your house down during a power outage (using candles, too much power for the generator...) and even if they were the same risk you still want to have your water to fight a fire, so it would be a good idea to do something about it. I have a slow well (2GPM) and an 1850 gallon cistern, I like having a gasoline powered pump handy to pump right out of the cistern in a total loss of power.

My well isn't run separately as I have a 500 gallon tank with a pump for my sprinkler system. Not sure how that would work during a fire that may affect my electricity not to mention during a power outage.
I am still trying to decide. I have emailed the electrician wanting to add a third panel about doing it the other way. In the meantime, any input would be appreciated.

Factor in if you have electric a/c, water heater, heat pump/base board heat, think about the seasons and what you use as well during said season, year round. In my mind, thats what a generator should handle. Anything you use normally so you don't have to wander from your normal. An extra fridge, an extra freezer, over build so you don't get caught crying.

Also if you over build, if you ever sell the house, it will be a great item of leverage in negotiating price if you can show you stand independently from the grid during an outage. I know I would pay for that insurance

First question to the OP why two 200 amp panels? If it was me I would run a bigger generator and an automatic transfer switch. I was looking at a 20kw setup. Generator is big enough to run everything. Sometimes a smaller generator may use just as much fuel as a larger unit.

My neighbor has a whole house generator that runs on natural gas. It comes on every Sunday to run for awhile. Power goes off it automatically starts.

Just be careful, this past winter we had a multiday electrical outage so I drug out the portable generator, it's a generac. Went to put fuel in the tank and it was full of rust. I had only ever ran it once when I first bought it and I put it way empty and sealed. That is not the time to find out your portable generator, or fire fighting pump, will not work. In my case I ended up using fabbing a temporary gas tank by using a plastic one, putting a nipple in the bottom and adding a long fuel hose. Tied it all down with a bungee cord. Looking for a good plastic replacement for the original metal one.

For those of us that have generators for standby use at our homes, we need to drag them out every thirty days or so and run them, preferably under load.

I shoot for 30 days, probably make 60 and run my generator with an electric heater hooked up.

This is really the only way you know its going to work when you need it.

Data centers will typically run their generators without load once a week and under load once a month.

Good advice, which I also fail to follow on a regular basis

When sizing a generator, keep in mind that a large one will use considerably more fuel than a small one, even when lightly loaded. If you just have 500 watts of lights and TV on, the whole-house unit will be expensive to operate.

I have a remote-start 2.5 kw Onan in a hut the size of a large doghouse with two 6-gal. outboard motor tanks. It will run lights, TV, furnace, and my CPAP machine and sips fuel... the thirsty 10 kw Onan rarely is needed except to recharge the well tank and run the water heater.

If we had natural gas, we would have a whole house generator. We have propane, so we went with portable. We have a gas stove and a gas fireplace and we are not worried about heat. The well, fridge, kitchen, fireplace fan, and sump pump are all we really need. Anything else is a bonus.

Having natural gas service to the house and an existing easy to access port and valve inside the fireplace
has made me think about buying a kit to convert my 10 HP Briggs & Stratton powered Troy built 7500 watt gasoline portable generator to natural gas
and keeping it on hand “just in case.”

If anyone knows the best kit to buy for this please comment.

I have now been through ice storms and Hurricanes that kept the electric service off for more than 7 days numerous times.

I don't know of a kit but beware that changing it over to NG will likely reduce its output. Costco was selling a tri fuel generator that ran on Gas, NG, or Propane. It had different output ratings for each fuel, the highest being gasoline and I think proane was next.

If your buying a portable to use for the house as a stand by get an Inverter Generator, often used in the RV world. They produce clean electric that you can run the fridge, TV, router, and other sensitive electronics with, the contractor grade generators will damage sensitive electronics.

And buy a Honda! The small Generac units are absolute garbage, everything vibrates of them and when you need a repair, no one will do it as you can't get parts for them.

I have a smaller home than most on here I am sure 1500SF but 2600 under roof.
Had an electrician put an interlock on my existing panel. Have a 9000-watt Blackmax with 13 hp Honda. We have a gas water heater, furnace, fireplace, drier, and range/oven.
with everything on the gen is putting out at 28% of the available total 100% load. with the microwave off using 16-18% and at that rate tank of fuel last 15 hours.
I have some smaller VP racing fuel 15-gallon drums and a hand pump. But will one day convert it to NG as we have it. I simple kit is not much $ but running the gas line is $
Note that we had a Briggs powered 4000watt that was using more fuel with the 8HP cast-iron sleeved engine
We run it every 30 days under load and keep all gas with stybil in it. Gas has never been a problem going bad. even used 3-year-old sealed drum gas no problem. Stybil also sells 360 so it coats the inside the tank to prevent rust.
In the past, my old Generac with Briggs (1992 they do not make them like they used to) ran all the 110 for 7 days after a hurricane and the same goes for the Honda-powered but the Honda engined one way outperformed the smaller one and used less fuel.
I saw someone posted larger uses more fuel that was not the case for our use of a larger one less taxed used less fuel
In addition to the every 30 days run with load, I do oil changes with Mobile One
We sized Larger since the NG Conversion will put out less BTU and put out less

See if your local utility offers something like this - http://www.generlink.com/ or http://www.generlink.com/generlink.html - that is what we used works great - simple and safe but the utility has accept/support the installation.

Just grab the handle, what could go wrong....

https://medicalxpress.com/news/2021-08-portable-recalled-amputates-fingers.html

Quote

An unlocked handle can trap users' fingers against the generator frame when the generator is moved, posing a risk of finger amputation and crushing,

Having spent several years in engineering some of which involved "idiot proofing" convinced me that no matter how much time & effort was put into the concept, the the first person to walk up would think of something we didn't. And the above article is another example.
It also reminds me of a ex co-worker that had his fingers in a MANUAL sheetmetal brake like the one shown and managed to fracture all 4 of them. WHAT PART OF STOP PULLING ON THE HANDLE WHEN IT STARTS HURTING didn't he understand???
Evidently the same part that the above idiots didn't while lifting the handle to move their generator while it was unlocked. Wonder why the MFR. went to the expense of putting a lock on the handle
Proof that Darwin's offspring walk amongst us and are breeding

If you can afford a Cummins Standby generator, they power the entire house.

Yeah the gasoline units really are crap. There's no NG in my neighborhood so I try to periodically run the generator as well and not allow old fuel to sit in it. I guess the next best would be a propane powered unit.

We only have propane available, so I went with a gas unit that will do what we need. I will be running it every 30 days under load, use Staybil 360, and run it dry each time.
Thanks for all the ideas and suggestions.

I plan to use my large stand by to run the air compressor to keep it fresh and cycling on a regular basis with fresh gas.