Hi,
I don't think the rate of return for grid-tie systems these days is quite that bad.
For example:
If you put a 1000 watt system in a good sun location (I used Albuquerque), according to PVWatts it will generate 1830 KWH a year.
If you pay 12 cents a KWH, thats $219 saving a year.
Prices of grid-tie systems have been dropping lately -- the rule of thumb used to be about $8 per peak watt, but I think its at least down to $7 now, and may be a bit lower. A friend of mine got a bid on a large system at $6 per peak watt. I'm thinking about installing a 2KW system using the Enphase inverters, and the total parts price (no install labor) is coming out around $5 per peak watt -- this includes wire, racks, disconnects, ...
So, if you use $7 per peak watt, the system costs (1000 watt)($7/watt) = $7000.
Take the 30% federal tax credit off that, and its $4900. State incentives might lower it more -- some states offer as much as 50% rebates.
So, ($219/$4900)(100) = 4.5% first year return.
That's not earthshaking, but a lot of people are investing in CD's at less, and its a tax free return and the return goes up as electric rates go up.
Its a good enough return that I'm going to do it:)
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On the original question of a small grid tie system, I think the Enphase system that uses one micro inverter per panel might be a good choice. You could put in a 1 panel, 200 watt system to start with, and add panels and micro inverters to grow it over time.
Here is a good description of a DIY installation of an Enphase system:
http://www.arttec.net/SolarPower/index.htm
Gary