I know I'll take a lot of good natured ribbing for this, but I must admit I own and use the kit the OP is referring to, and I can offer some thoughts on it.
I realize 45 watts is nothing when it comes to dry camping requirements for most people,but it has served me for about a year now.
My trailer has two 27 series battery's and I have no trouble making it thru a weekend trip including letting the kids watch one DVD both nites at bedtime. I definately head home Sunday afternoon with two depleted battery's..
The main purpose of my purchase of this kit is for when trailer is in storage at my workplace where we have no electricity. It allows me to take my lunch break in it if I choose, run the propane heat if I choose, even listen to radio or watch tv.
But as A Watts per dollar figure it's is a poor value compared to what else you can buy.