Question: Tesla Power Wall

[bobalew]

5. That's not a "Limitation", but is the nominal continuous maximum output.

It can put out on an occasional surge, up to 60% more, if needed.
The Output is a continuous 2 KW per unit. If your house uses greater than 2KW, at any moment in time, double up. The 7 / 10 KW is the total CAPACITY of the Battery, or how much power it can supply over time. If you're are using , say 1.5 KW ( Roughly double your estimate) per hour in off peak (Night-time), then a single 10 KW capacity unit would yield you 10 KW/ 1.5 Kw per hour=6.66 hours of power. Better get 2, to get a 13 hour back-up when thee is no solar or wind (& I suggest investing in both, for Off Grid use) Being in the boonies myself, you never know when you might really need that extra wattage to run a pump from your well or stream water supply in an emergency.
The UL listing, BTW, at least portends that the units have been through some fairly rigorous safety compliance testing, but do note, Lithium batteries are inherently capable of some really spectacular failures. Keep them outside, away from flammable locations. Also, make sure you've located the inverters very close to the battery, to minimize Long runs of DC cables, & use the largest gauge of wire that you can. DC power over distance causes losses in the wiring & HEAT. AC voltage transportation is much more efficient. Do remember that when inverted to AC power, there will be some efficiency loss, and there will be more amperage when converted to AC 240/ 120Volts. This is why we work in watts as a metric. That is a constant.
I hope this helps answer some of your questions.