I agree with what Alan said.
In my case the math made sense for me.
My average monthly bill to Pepco was $160.
When i looked at the solar option, it would cost me $170 with the finance option. I reckon, I was paying Pepco about $160 per month anyway so paying an extra $15. was not a big deal to own the system and get ALL the benefits. I got the federal 30% tax credit plus an extra $1000 for MD. Plus i got Solar Renewable Energy Credit (SERC)s
At the time I purchase my system (10kWa), the SERCs were selling at $150 per credits unfortunately, that value has been reduced to about $15/credit, last time i check. Last year I got a $600 check which i used to further pay off the loan. At this rate, I would have payed off the loan years sooner. Now it will take a bit longer because of the decrease SERC value. But at the end of the deal the system is mine.
Yes, technology gets better, but its better than nothing. The panels now are about 20% efficient and they will only get better. But if you are going to have to pay Pecpo anyway, why not buy/finance the system anyway?
The Tesla battery will be a game changer once it is available. Then you will be able to live off grid and rely solely on the battery. It will certainly worth the cost of the battery because now enen though i make "free" power, when the grid goes down, i loose power too.
The other consideration about the generator too your carbon footprint. I want to be as green as possible. Remember, burning fossil fuel leads to increase CO2 and acidification of the water, increase water temp and ultimately coral bleaching which adversely affect the reefs and our hobby.
I am all about going green. Solar fits that bill