Bill;
I agree with Allan. Since you already have a good set of stuff going at a really good price. Continue on with the solar route.
If the solar charge controller is a good one, it should be able to handle three more of of the 15 watt panels. This will help with keeping the batteries charged up.
Depending on your abilites, you can google for some 12Vdc adapters for CFL bulbs and build them.
The little 400watt inverter is good for small lights and stuff but it does waste some of that power. By changing the FLs over to use 12v directly you'll cut out the power losses inherit with the inverter.
Go to a solar map and find the best possible alignment and angle those panels. A tracking system built will then pay for itself with the added extra charging time.
What are some of the things you'd like to do with the power?
Knowing what you're future plans for the gained power would help with the planning.
My plans did not include having enough power to keep our freezer up for more than 36 hours, but since loosing all our food in it from this past summers 4 day outage , my plans changed and I'm now making full use of the panels I have and working on making sure this doesn't happen agin.
Hope this helps.
Bruce S