Just reviewing this choice from 5 years ago. I was finally capable of given the panels a wash last week. Crutches and wheel chairs did not work for the roof 

 Its raining a bit so not out for a walk yet 
 
27.721  MWh is showing as total solar yield on the home Inverter. Its a little above  6000kWh per year solar power from the sun. 
Using a cost per KW at (work) of $0.28842 per kWh saving me a bit over $1700 every year. The two systems I put at work and home cost me after a few credits just shy of 10K each, The  27.721  MWh total is my home. Work is much likely to be higher for three reasons happily. As it has had new inverter to enable full off grid when the grid fails at times I do not have the exact total there sadly. I sold my work sunnyboy inverter. Its still working cheerfully.  Paid back fully 
 
 
I use over 80% of my power so
 I am not talking about you subsidizing me. Feedin credits do not give this number unless your under the really odd 
old FIT system where everyone else pays more to pay for you. Good luck to you if you have it 
 
As my systems are now free and have perhaps 20 years life left I have a choice- Some new panels are more than 100% more efficient and deal with shade and dirt much better.   Just tossing up the idea of either adding as many Q.MAXX-G2 345-360 or 400w SunPower Maxeon3  or similar that fit in any spare space I have or selling QPRO265-G4 x 20 (or 40 inc work) (PM me if your interested) 
I suspect payback time is sub 2 years with the much higher wattage and efficiency now. I am looking at now for work at first with the tax deductions possibly making it silly not to as the 2 years ROI is more likely just over a year if I factor that in. 
The prices now compared to 5 years ago is SO cheap.
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