1.5 KW is respectable and would run my house most of the time. One could not comfortably live off grid on 1.5 KW but it would keep the lights on, computer running and maybe power a small refrigerator too. But at what costs? At $4/watt that 1.5wk costs you $6,000.00 plus you only get that 1.5kw during daylight when it is nice outside. Also the system will degrade over time and have to be replaced in 15 or 20 years. All in all Solar is not yet a good investment for those of us watching our pennies.
I just bought panels on Amazon for a bit over a buck a watt. That said, it is still lousy payback for most folks including me.