Battery backup first-then grid tie????

[bighoss]

I have been using solar panels for partial power for 15years. I can do AC and DC wiring without electrocuting myself or burning everything down.
Recently looked into buying a grid-tie system, but way expensive.
Found 740 watts of Evergreen (3 190W n 1 170W, all have 36Voc and 8plus Isc) panels for what they're worth (80cents/watt).
Here's the problem: Everytime I try to get MC3 cables or a 24V inverter, or any parts to put MY stuff together, I end up arguing with some DA salesperson about what HE thinks I should do.
Here's my plan: If anyone has any comments or suggestions for improvement... O.K. .
Mount panels in 24 or 48VDC config. I'm thinking 24VDC for now because I already have a Xantrex C35 PWM charge controller and enough 6V batteries to make that work. The C35 won't do 48V
Find a Xantrex XW inverter of at least 4KW
Hook it all up to the AC in the barn and leave the Utility breaker to the barn open.
As I add panels I will feed more loads from the solar and less from the grid.
I'm on dialup so please don't send large pics or pdf files.
Thanks, bighoss

[Mike90250]

You have a good recipe for using up batteries @ $1 KWh vs purchase from grid at $0.2KWh.
If you have reliable grid power, skip the batteries. If you have loads that must be backed up (fax, computer, night light) use a small computer UPS. Big loads need larger UPS. Doing this via Solar PV, large battery bank, and XW inverter will cost you a LOT of $$ to save pennies.

What exactly do you want to do or backup ?