If you are running heavy current for 4-6 hrs a day, it won't matter if you have solar or not. Solar will not run heavy current (A/C's and the like).
If you are running light load, your fuel consumption will be a lot less. Example: you are running the A/C with the gen and using 1 gal/hr. If you turn off the A/C and just run small electronics, your fuel consumption might drop to just over a quart an hour. This changes the economics significantly.
That said, economics is not the only factor. Having no noise for the majority of those 4-6 hours can be a big deal (it is for me). Also, there is wear and tear on the gen that you have to take care of eventually.
QUOTE (sandhopper @ Feb 17 2010, 03:29 AM)

Thanks all for responces , generally I was thinking 1 gal per hour
Now at $3 a gal and 4-6 hrs a day I think it may put a dent in solar $