re: Need help estimating usage cost for a whole house generator

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You dont have to oversize to completely handle starting current of the compressor with rotating generators. They can handle inrush above their amp ratings to an extent.

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I realize this but should’ve done a better job explaining it. The “surge” rating of generators is usually a good bit higher than the base rating. But if you’re talking a 5-ton compressor with an LRA of 150A, you need a lot of surge capacity to get it started. This is where soft starters shine since they can allow you to go smaller on the generator with the large reduction in LRA. If starting directly across the line, most smaller portables can’t handle that amount of inrush current.

For example, my friend asked me to run some numbers for him and his compressor LRA is 152A. With a micro air soft starter, you can expect about a 70% reduction, resulting in an LRA of 45A. But even with that reduction, it’s still a surge of around 10kW.

So one reason home standby units are so big is that it can erase this problem with relative ease. There are still some other things to consider but generally a moderate sized home with a 18-26kW standby unit can power the whole house panel easily.

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I hear you, I'm the same way. But like others are saying, assuming typical use patterns of standby generators, fuel cost is a non-factor. Even if you have a week+ outage every year, fuel will never add up to more than a few % of TCO considering install cost and maintenance and such. Can I ask what alternative(s) you are comparing to?

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I still have a wide net cast and haven’t started narrowing down my choices.

I’ll probably solicit input from various dealers after hurricane season to identify differences in what they recommend, where they recommend it to be installed, initial cost, usage cost, and maintenance cost/effort.

This thread was primarily to expose my limited understanding and identify more of what I need to know in a manner more efficiently than just surveying a few neighbors and other friends who primarily promote their own decision making.

From this thread I learned that while house generators are not much different from portable generators in that there is little to not much correlation between usage and consumption. Seems like the energy production is “use it or lose it.”

I was expecting that there might be options to store energy produced where the generator shuts down if the battery reaches XX% of its charging capacity and restarts once storage capacity drops to YY%.

Anybody know of natural gas burning generators that do that?