Thoughts:
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Second Sense with main CTs on your 240V generator (mentioned elsewhere right?) … it can be offline (network) if you are offline and still function better than lesser options … you will be online (power) by default if there’s anything worth measuring.
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Existing Sense solar CTs with 240V generator.
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Depending upon the fickleness of your supply I wouldn’t rule out a UPS/PowerWall-like solution that may have the kind of integrated offline power monitoring you want. It could also allow you to have a 120V generator and 240V supply to your panel without a major headache.
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If you have a good generator you might not need anything more than current detection to calculate load. I use Monnit systems for other reasons (risk management) but you can get kWhr readings and it will cache offline. More expensive than a second Sense but sensor options go way beyond current/voltage.
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Look at auto-transfer switches and integrated management options. I would future-proof your thinking and expense by considering that you’ll have solar at some point (unless that’s ruled out for some reason). Get some solar quotes and quiz people about your integration issues?