[solar_dave]

In reality it's not so simple because people are forever confusing "How much did my bill go up?" with "How much does it cost to charge my Volt?". These are entirely different questions and I was just pointing that (a) it's best to understand the distinctions and that (b) the answer to the first is not the answer to the second.

More or less the same for the solar. Electricity generated by your solar system is not "free". In fact it may or may not cost him more to charge the Volt after getting solar. You'd have to compare the AVERAGE cost per kWh before and after the solar to know. Part of that computation is deriving the cost per kWh of electricity generated by the solar system.

That is one way to look at solar, another is the cost avoidance that solar gives. If I would have went along my merry way and continued to pay APS the $5500 annually before the Volts and solar over 4 years I would have a $22,000 pay out (actually more because the Volts add about ~3600 kWh annually). I install solar for an out of pocket expense of ~$18,500 after tax breaks and utility rebates and now have about a $250 annual cost for electric, post solar and with Volts added. I am break even at ~3.5 years and the electrons generated are now at no (extremely low) cost because I continue to avoid the $5500 annual cost plus any increases granted the utility. One could also argue that my annual cost avoidance for gasoline could be factored in, I didn't do that with my analysis. One bummer with APS net metering is I can only get kWh credits within my TOU, I don't generate much off peak kWh so I actually load shift to on peak to consume my solar kWh and minimize the off peak expenses. The pay back at year end for excess on peak kWh is only $0.065 per kWh. This year my credit will be under $300. That is enough to cover my fees with the utility until mid year. BTW my on peak TOU is 9AM-9PM Mon-Fri which is a grandfathered plan and unavailable to new customers, I suspect that plan will get dropped at some point, maybe soon but I hope not.

Now one needs to consider the longevity of the electronics involved as a replacement cost at some point and any maintenance cost for the system as well, but fortunately my system has been cost free on both fronts so far and I will cross that bridge when the time comes which could be well after year 10 when the inverter warranty runs out.

In California is gets even better as the utilities pay in dollars for watts generated. Peak TOU solar generation gets accounted for at the higher TOU rates while loads shifted to the off peak rates get bought back at the lower dollar rate. A smaller solar system can actually get you to net zero $$$$ much easier, you avoid those really high tier rates and back feed the grid at those medium high dollar rates. Then load shift what you can to the off peak rates and buy it back from the utility for a much lower cost per kWh.