They are worth the money, whether it's a portable or whole house. Better to have one & not need it than to need it & not have it.
We had no power for 5 days when Hurricane Ike went through Ohio. The next day after loosing power I found a portable gasoline generator that handled everything we needed power in the next county north of us who didn't loose power as much power. We ran it in the morning before work & turned it on as soon as we got home in the afternoon until 9 PM. We lucked out with the weather so we didn't need the heat or A/C. We used it to keep the freezers, fridge, water pump, tankless water heater, basement lights & TV going.
After it was over, we redid some wiring to make hook up the next time easier for us. We also found out how often we needed to fill it up with gas. All of the local town was out except for a small pocket which had the gas station so we had a local supply for that. We didn't use it after that time, but we decided to get a whole house.
There are certain things we want to be able to run like the A/C, water pump, water heater, oven, washer, dryer, basement lights, garage lights/door, barn lights & heated water buckets/tank for livestock in winter. We've always had the wood stove for heat so that was covered. Everything would not be on at the same time, but we wanted to know what the max usage would be if we had everything on in the house.
Our neighbor had has electrician buddy come over with a meter that he hooked up to the panel to measure the usage when we turned on everything in the house at one time. Once we had that number, we knew the size of the generator we needed to buy.
We bought a 20KW Kohler LP gas generator which our electrician installed & the plumber ran the gas pipe for power. We replaced our 500 gallon LP tank with a 1,000 gallon which allowed more gas to be on hand. We can also turn it off if we think we need to conserve the LP gas.
We have had it now for 5 years & only used it twice. Once for over 6 hours when the construction crew at a neighbors cut the main power cable digging until the power company could fix it. The second time was after a car hit a power pole in the area during the heat wave this summer for several hours.
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@gamboolman, we don't want to loose the food in our freezer & we need our well pump. We also can't leave & go any where else because of pets & horses if it's an extended outage. We learned during Hurricane Ike that some people had to drive a fair distance to find a room.