Respectfully, 30kWh is not much in this context. In 10 years every modern 2-car home will have 200kWh on the driveway just from the EVs; add a 100kWh whole home battery at a price point close to a 10kWh battery today and the calculus changes in most of the world.
The cost of materials going into modern batteries easily leaves room for another 10x reduction in price, IMO where this all is heading is obvious. Zero marginal cost will win every day of the week.
FWIW we run our cabin on 15kWh battery today year around, though we do run a small wood stove to supplant the heat pump on cold winter days.
I bet you didn't even see the tragic farce when writing your solution. Land development requiring ”2-car homes" is the driver of the problem! An apartment only has to heat one or two walls facing the outside instead of 4. That's 50-75% right off the top of your energy usage, with the mean closer to 75%.
40 kWH of storage and 9 kW of solar panels is all I need personally to live a 1st world lifestyle in the bay area mostly off-grid except for water and internet.