The DOE of all bureaucracies is skewed here in their study. When talking the power grid, it is being accepted that means the utility scale energy generation that affects prices on the wholesale energy market, but does NOT have a large effect on the retail electricity costs. The IOU electric utilities are “allowed” by law to an “assured” rate of return. This means these entities are “allowed” filing electricity rate increases if the utility doesn’t sell as much electricity as they used to, referred to as a rate case for “lost revenues”. These IOU utilities also get preference of filing a rate case when old fueled generation plants are decommissioned and there are “stranded assets”. Yes, it is good one can install large scale solar PV and wind farms in the GW generation range and even drive down wholesale electricity rates to 1 cent/kWh; $10MWh generated. This will not make that much difference in the retail electricity rate. To reach this 40%, 50%…80% decarbonization of the grid is going to start at about 4% retail electricity increase (per year) every year for the next 10 years. Meaning on average, retail electricity rates will increase such that an electric bill of $200/month will cost a ratepayer, $280/month for the same electricity use in 2030. That last 20% will cost much more and become more difficult to implement in the grid, I do not see retail electricity rate declines until there’s about 25% excess energy is stored than the country as a whole needs every day. Without excess on tap, just in time will become a more expensive alternative in a system that could only be described as EaaS, Energy as a Service.

“A clean grid requires massive, equitable deployment of diverse, sustainable energy sources — The U.S. must install an average of 30 GW of solar capacity per year between now and 2025 and 60 GW per year from 2025-2030. The study’s modeling further shows the remainder of a carbon-free grid largely supplied by wind (36%), nuclear (11%-13%), hydroelectric (5%-6%) and biopower/geothermal (1%).”

Once again, it all depends where this energy generation is installed. It seems to be a “practice” that residential, small business, even C&I solar PV systems and energy storage are not added to the tally sheet. IF one uses the 2016 NREL Lidar study for solar roofs in the U.S. there are about 67 million solar PV viable roofs and of these some are large 25,000 to 1,000,000 square feet of available panel space. Many are smaller homes with less than 5,000 square feet of roof space. With ‘just’ 600 square foot of roof space available, one could install about 10kWp on 67 million roofs, just a conservative assumption of (4) sun hours a day average, you could generate, 2.68TWh a day in just those four sun hours. Adding energy storage of ‘just’ 20kWh to these 67 million systems, leaves one able to control another 20kWh per home “as needed” every day. Solar PV and energy storage is the (most) efficient installed on the (property) of the building it will power.