I've been looking at that Rivian, but realised that with the full size 180KWh battery to get the longest range, to have that on-tap in a house battery, it will take an equivalent to 13 or so Tesla Powerwall-2 batteries for a full charge, which at $12k a pop = $156K   !
You may not want a full charge every time, but that would be worst case.
Also, if you were using an average 5KW solar array, it would take 36 hours of charging, which assuming you could get 9 hours of charging a day, would be 4 days to charge it. All this while the array is not used for any other household power. 
However, you could potentially charge it using off-peak power, if that is permitted,  at a rate of roughly 10c per KWh (is that about the off-peak rate?) .  Standard GPO in your house is good for about 2.5KW (10A) , so you would need the equivalent of 180/2.5 = 72 x 10A circuits over however long the off-peak runs for.... Not sure how long off-peak runs for overnight, but assuming you get a 8 hour window of off peak power, then you would need a 90A circuit to completely charge up the 180KWh battery overnight on off-peak. But it would cost less than $20 to charge.   
Could somebody please check my man-maths ? 

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