Getting in the power production business

Since I got my PowerWall I've been semi-seriously considering intentionally producing more PV energy than I can possibly use.  There is good indication that the electric utility, BlueBonnet Electric Coop, will be willing to buy at $.05-$.055/kwh though recently, under an their old PV rate structure, they've paid only a bit more than $.04.

Rough numbers are that a ~245 watt panel costs me about $110 to get into production.  A not very long term average indicates that each panel might produce a bit more than 1 kwh/day.  About $.05/day.    About $18/year.  Around 6 years payback.

I'm in the process of installing about 50 panels within the next few months.  In the area of that install, 150-200 panels are possible.

3/18/19 Update
I now have about 50 panels installed and working; that is above the 26 roof top panels.
And, I'm having trouble.  With good sun, my ac voltage rises and shuts down some micro inverters.  After considering several possible trouble sources, I am beginning to suspect that my service from the transformer has insufficient capacity.  My static, no production, voltage is around 247.  With production, it starts rising and up around 8-11kw, voltage is around 260v and inverters start shutting down.