Americans basically live like energy is unlimited, free and has no side effects, the rest of the world doesn't have that chance, last time I checked the average US household used anywhere between 3x and 4x more electricity than the average EU household

They tend to prefer huge houses with relatively complex designs (less optimal in term of area/volume ratio) / poor insulation, they make up for it by relying on tech for heating/cooling pretty much year round.

Your tankless water heater is a good example of something that is completely inadequate for solar setups, they draw insane amount of energy over very quick period of time. But I think that's the core of the issue, if you want to keep all the nice things modern American houses have you're going to need a lot of money and a lot of sun. On the other hand if you're a bit more frugal, with so called "passive house", you can get by with a much smaller setup.

> I will note in passing that both our dishwasher and our microwave oven require 20A circuits

And a tankless heater will need 5 times that, unless you're using gas but I wouldn't count that in a "modern first world 21st century home".

You should still probably add a hot water tank to that setup, just put it in front of the tankless heater. It is a like a battery that is 100x cheaper. You could go high tech and run the tank heater when you have solar excess, or low tech and just put it on a timer to run for a few hours around noon.

Everyone should calculate how much is consuming in kWh, recalculate gas into kWh, wood into kWh, propane into kWh.... then it starts making sense for ordinary people. Even for how much energy leaves their house. To use kW / kWh for everything.

" 1)- tankless"

more than half of USA has water tanks. both water tanks and tankless heaters have expected working life, after taht they have to be replaced either way.

Tankless heaters are more efficient if you think only about AMOUNT of energy, but water tanks are there to lower your PRICE of hot water. (or spread load over longer time for usecase as your offgrid) So yes, with tankless you are doing best in standard "old" grid situation, where price for electricity for customer was same throughout day, (some tariffs can have different price in night) (or when you ask Ask This Old House)

AND with PV! on roof and tank in basement, households are providing service for utility because A) they do not export solar at noon, they are putting that energy to water tank, B) they do not import energy during evening peak hours. so less generation / "base load" needed to exist, to operate, service, manufacture.

but there are new things like solar export which will change grid. and people have to adjust, or they can just install expensive battery paid with gov subsidies (by "utility")... residential customer can either use cheap electricity during day to heat water tank or utility can charge for "stabilising" of grid multiples of that price.

so customers incentive should be to have hot water from PV on his own roof. and when they do not have enough solar energy they can charge rest from grid. and lowering need for importing from grid by 80+% per year... for hot water energy.

"2)dryer "

how much is that kWh ? can it run during day when there is availability of PV ? Or atleast one of those cycles can run during day?

" 3) electric car "

I am one of them but unfortunately i am working from home and have nonstandard schedule (20-45 miles per day + once per week trip to buy groceries in town 130 miles ) so i can charge my car from PV, not many people can do that. but they can have water tank on PV and car on grid... or if they use one car only sporadically, then that one can maybe charge from PV ?

my electric car can be charged by 2kW from standard outlet for 10 hours to add 62 miles of range, in summer when i do not want huge loads or i can connect it to faster charger. one car takes daily roughly same amount of energy as 2 people need for hot water...

"4) appliances "

how much is that kWh ? starting current can be higher, sustain power can be lower. starting power can be lowered by using "starter circuit" - bunch of capacitors connected to motor, but lot of motor apliances already have it. coffee percolator is essentially water tank so you are already doing it ;) 20A is not much, some appliances can be connected to 240v if it is available. or adding more circuit breakers if you have slot for them, and spread loads between circuits.

"5) rest" not waste, save, use on site first, then grid. most people live grid first... i do not mind grid

im not saying everyone should go off-grid, because high-rises can not. but everyone who can, should atleast be able to have 5-10 kWp PV on roof just for hot water, and it can be used in emergency for other things (not necessarily same lifestyle). such small pv + hot water tank as a predictable load connected to well sized PV can make PV be payed sooner. and having connection to grid, with possibility of getting payed for export of excess in future for powering highrises...

my system got payed in 6 years because i use a lot of energy directly. lifetime of inverter is presumably 10 years and panels 20 years so i have presumably next 4 years energy for free. then i have to replace inverter,... if those devices last longer, saving is even bigger.