I am (finally) looking seriously at a backup generator for my house, plus panel replacement.
Current panel is 2 fuse boxes + an 8-space breaker panel (installed with kitchen upgrade in 2000). Rule of 6, just barely enough capacity for everything, no AFCI, various other "because it is all old" issues, but no real problems. Been thinking about a full replacement for years, now is the time.
Not sure what size the current service is (probably 100A), though my electrician told me that current county rules are that with any change like this an upgrade to 150A will be required. Should not require a new line to the house as all the outside service lines in the neighborhood were upgraded several years ago after numerous outages.
Thanks to the smart meter, I know my usage.
Top usage for the last year (hourly readings, not sure why they can't give homeowners industry-standard 15-minute readings, but then again, the average homeowner has no idea what any of this means) is 9.98 kWh, so just under 10 kW. Dropping down to 99% of hourly readings gets to just under 7 kW.
Low usage is 0.41 kWh - in fact, 46% of usage hours < 1 kWh and 71% < 2 kWh.
With current usage, and not planning on major new equipment (no Bitcoin mining, no grow lamps), an 8,000W - 10,000W (more or less) generator will do just fine. So not planning on a true "whole house" permanently installed generator but rather a "portable" to be used when needed. That also means that except for making sure I don't run air conditioner, electric oven and electric dryer at the same time, I really can run everything without too much worry. FYI, water heater, furnace and cooktop are all natural gas.
- Since I really can power everything from a 50A (electrician said probably even 30A) inlet from a generator, is there anything wrong with simply having 50A generator breaker on one side, 150A utility breaker on the other side with an interlock and always switching everything? Having to install two panels and then be limited in what I can power (power out on a hot day and I'll want to run the air conditioning at least for part of the day) doesn't make sense to me.
- Is there anything else I need to consider in sizing a generator, or is the peak usage enough?
- Is the low usage going to be a problem or do typical generators run OK (if not quite as efficiently) at low load?
I will likely have more questions after electrician does a site visit. He has worked on my house before but hasn't been here in a few years. Work will be coordinated/permitted/etc. with utility and county as needed.