The estimated energy cost with the solar system including use of PowerWall to store solar energy collected during the day would be reduced to about 7.9 cents per kWh. And the electricity usage offset by solar production for my household as you can see below would only be around 58% with existing solar system technology:
My current rate in the DFW area of Texas is only 8.4 cents per kWh. And the energy rate over the last year has seen a downward trend as you can see from the screen shot from PowerToChoose.org. The current rate for new annual contracts is around 7 cents per kWh.
The estimated lifespan of a solar system with a good maintenance program (a.k.a. additional cost) is only about 20 years. If the current electricity rates persisted at around 7 cents per kWh over the next 20 years, I would loose money from the investment. Given these data points, it was a no brainer to put the brakes that project for now.
On a related but separate topic, the biggest concern that I have with Tesla's PowerWall is the risk it poses on making a house fire much worse since Lithium Ion batteries are well known for their explosive potential if charging is not properly regulated and retention guidelines observed or if the batteries catch fire from external factors. But even that risk may be mitigated over time as aluminium-ion batteries improve and make their way into main stream.
Time will tell. Here's hoping that Solar finally becomes economically viable for the masses in the next 5-10 years.