I used to design all of Cummins Natural gas stand-by gensets from 150kw to 1.2 MW (2003 - 2005) as well as custom mobile gensets. the standard power gen offering was developed in either Fridley or Daventry. Lived and breathed gennys for 5 years, must have designed about 200 plus products including a member of the NFPA standards committee. not worth the headache of maintenance for a residence. dont really know anyone who was in the power-gen field that actually owns a genny.
automatic switchgear for emergency backup is 10 seconds from line-loss to full load - requires a monthly exercise run
residential switchgear is 20+ seconds. recommended monthly test. minimum requirement is a semi-annual run.
if I really wanted a genny, I would get one (probably build it myself or have it built). they dont really add much to the value of a house other than to add a line-item on the purchase contract. no-one maintains or exercises their residential gennys, so when it comes time to rely on them, they usually fail. fuel is usually stale and the starting batteries have been boiling on the maintenance charger for 4 years and wont turn it over.
regarding fuel consumption. internal combustion spark ignited engines require 0.4 #/hp / hr or fuel to run. so doesnt matter if I am running a 20hp V-twin or idling my truck. same amount of fuel is being used. Compression ignition engines burn 0.34 #/hp / hr.
knock yourself out getting a genny.
Sweetie and I are over 75 and back in 2014, when cows were high, sold off our herd. I had been dragging the portable 6500W out of the shop and hooking that up with gas cans and extension cords and all and figured it was time to do better. With about $4500 of the cow sale, I bought a 11kW Generac with switchbox and 250 gallon propane tank full of gas.
I did the Gen. installation and the propane co did the tank installation and hookup. I just topped off my tanks for the winter yesterday and I used 10% (of 80% max fill) over the year for the automatic, once a week runups, and the power outages we had over the year. Propane is neat as you can store it in a large quantity onsite, it's safe, relatively cheap ($1.50 a gallon), engine runs clean on it, and it doesn't go bad over time. Between that and Mobil 1 10w-30 oil stays clean and changes are like every 300 hrs......of run time not calendar time. The machine tells you when to do it. There is a drain hose that you just put over your catch pan, pull off the cap and let her go. Spin on filter is right there. Battery is maintenance free. I have changed the oil once since obtaining. That's not what I'd call a problematic piece of equipment to have at your disposal.
It kicks on once a week and runs for 15 minutes. If power goes out, it immediately kicks on the V twin 4 stroke engine (of their own design) and after running for a couple of minutes, the switch box "slams" the contactor to the gen position and away we go. Satellite receivers, computers and TV are on Cyber Power (brand) battery power supplies so they don't know that the switch took place. It's all automatic as are the status lights on the side which tell me when it's time to change the oil and perform battery checks. I run half the house with it, just like running coop power from the power company, eliminating non essentials like the wash room and some of the other rooms of no consequence. I deliberately did it this way as the smaller sized unit runs on less propane and the tank would last longer in an emergency. After having it, I wouldn't be without it.
Since Texas is into power rationing during peak load periods, like really hot summer days, they may cut your power for several hours and move the blackout around the state to let all share in it to keep things running on existing resources. Not a fun thing to have to go through if you don't have to. That was one of the reasons for the purchase along with ice storms that come most every winter knocking power out, and then there is the outage every time we have a thunderstorm which is often in the spring and fall and on and on, or some goon on the highway runs into a power pole, or a storm knocks trees down over lines.
Certainly something to think about if you worry about power outages, regardless of the reason.
