Critics have long dismissed rooftop solar as a niche product for wealthy homeowners who want to feel good about going green or are looking for security against blackouts. And it is conventional wisdom among utilities and regulators that large solar farms have an inherent cost advantage over the rooftop alternative because they benefit from economies of scale.  Chris Clack sees things differently.  In a fascinating report released last month, Clack and his coauthors estimated that eliminating nearly all planet-warming pollution from electricity generation would be $473 billion cheaper with dramatic growth in rooftop solar and batteries.

That calculation is based on Clack’s exhaustively detailed model of the U.S. electric grid, which he says includes 10,000 times more data points than traditional models and allows for a better accounting of rooftop solar’s costs and benefits to the grid. The model is such a complex beast that Clack built his own computers to help run the simulations, which can take five days to complete.

Researchers...looked out to 2050 and projected how electricity costs would change under a national policy requiring emissions to fall by 95%. When they mimicked traditional models that favor large solar and wind farms, they found that consumers would collectively pay $385 billion more for power over the next 30 years. Not an unreasonable price tag for taking a huge bite out of climate change, but still not the preferred direction if we can help it.

When they optimized for smaller-scale solutions...they found the cheapest way to reduce emissions actually involves building 247 gigawatts of rooftop and local solar power (equal to about one-fifth of the country’s entire generating capacity today). In this scenario, consumers would save $473 billion, relative to what electricity would otherwise cost.

The results come down to simple dollars and cents. - LA Times