Getting a little solar to bring down my base usage

[gtojohn]

Although my energy usage has been down, partially from this site, I've been using a the Efergy kw meter, getting real time feedback on the whole house and its making me want to do something more. The house is pretty big, there's 4 of us and I can only cut our usage so much. Our base usage is about 16kw in the winter. That translates to quite a bit more for warm weather.
We are billed with 5 tier levels at 500kwh each. The top 3 tiers really ratchet up the rate. Thats great, i'm all for it, it'll help others want to conserve too. After doing a lot of research I've hatched a plan. If I hit tier 3 usage my rate after fees and tax is $.14 per kw and tier 4 is $.16. 5, I've never hit 5.

I figure if I go with a small enphase grid tie to cut back my base while the sun shines I'll get the fastest payback by keeping out of the higher tiers. I'm starting with at least 4x maybe 6x 240 watt sharp panels and enphase m215 inverters. The pay back before government rebates could be within 5 years if I do it myself. The enphase really seems the simplest for dyi, and expansion. I'm still gathering the pieces but really hope to get this going before it gets any warmer. 8 panels could really help make up for the a/c. The biggest hurdle I see is I will need to swap out my breaker panel for more circuits to add my enphase supply circuit.