I think you're missing my point; if everyone went net zero, and the minimum charge rate increased to compensate, the current payback calculations of solar will

I think you're missing my point; if everyone went net zero, and the minimum charge rate increased to compensate, the current payback calculations of solar will go out the window. If everyone were to buy solar (ignoring production issues) at today's price and technology, the seven year payback rate of the OP would not hold. That's why it is unsustainable. I think it's unlikely that net metering will be maintained with an increase in fixed rates; eventually the price of power at peak solar will be negative, and it makes no sense to credit households for feeding even more in. Residents building useless solar panels, overproducing at peak so they can charge their Teslas for free at night, and power companies building massive resistors to burn that power of during the day and coal plants for the night is Kafkaesque. The right thing to do (long term) is to treat those feeding power back into the grid as commercial customers/producers, where they're compensated and charged based on current market rates. Anything else distorts the incentives significantly. Edit: And this isn't some pie in the sky theoretical situation I'm talking about - South Australia has already experienced negative power prices at times due to solar, see http://cleantechnica.com/2014/10/23/negative-electricity-prices-middle-of-day-south-australia-renewables/ http://cleantechnica.com/2014/10/23/negative-electricity-pri...