If you put enough panels on your roof to produce your annual electricity you will be producing about five times what you need when the Sun is shining. (4.5 average sunny hours / 24 hours = 19%).

If one out of five households is producing solar then they are, during the sunny hours, producing about what all households can utilize.

If half of all households and half of all businesses installed solar we would not be able to use all the electricity produced. (Assuming no additional storage installed.)

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Installing on east-/west-facing roofs does produce a bit less electricity but it also lengthens the solar day. Right now Germany has enough solar on line to wipe out their midday peak and lower wholesale prices to the level of nighttime power. But they still have pre-solar morning and post-solar afternoon peaks. Mounting some panels facing the rising and the setting Sun could wipe out those cost peaks.

I severely doubt that. Please don’t keep repeating it. Read Joe Romm about the power of repetition.

This figure is very suspect and was probably achieved by things like:

– excluding east and west facing roofs. They are perfectly suitable for solar, but generate a little less energy (like 20%). Still can be very profitable with today’s low solar panel prices. I have an installation facing west, and it has good yield, although I’ve had it for less than a year, so I can not draw any solid conclusions.
– excluding rental homes. The house can be perfectly suitable, but what needs some work is perhaps landlords’ attitudes.
– excluding apartments. An apartment building has a roof. Each owner could use a part of the roof for his own solar installation, or you could combine forces and put up a shared installation. This happens in the Netherlands. But it is true that apartment dwellers will have difficulty generating enough to cover 100% of their energy use.

A four year real-time study showing a major US grid could run on almost 100% renewables at an affordable cost.
Budischak, Sewell, Thomson, Mach, Veron, and Kempton
https://docs.google.com/file/d/1NrBZJejkUTRYJv5YE__kBFuecdDL2pDTvKLyBjfCPr_8yR7eCTDhLGm8oEPo/edit
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Powering New York State with only wind, solar and water.
Jacobson, et al.
http://www.stanford.edu/group/efmh/jacobson/Articles/I/NewYorkWWSEnPolicy.pdf
and
http://www.scientificamerican.com/article.cfm?id=how-to-power-the-world&page=2
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An all renewable Australian grid…
Elliston, MacGill, and Diesendort
http://reneweconomy.com.au/2013/baseload-power-is-a-myth-even-intermittent-renewables-will-work-92421
and
http://www.ies.unsw.edu.au/sites/all/files/profile_file_attachments/LeastCostElectricityScenariosInPress2013.pdf

And from the Elliston, et al. paper –

“Numerous scenario studies have been published that model the potential for
countries, regions, and the entire world, to meet 80{100% of end-use energy
demand from renewable energy by some future date, typically mid-century. Na-
tional scenarios exist for Australia (Wright and Hearps, 2010; Elliston et al.,
2012b), Ireland (Connolly et al., 2011), New Zealand (Mason et al., 2010), Por-
tugal (Krajacic et al., 2011), the Republic of Macedonia (Cosic et al., 2012), 
Japan (Lehmann, 2003), the United Kingdom (Kemp and Wexler, 2010), the
United States (Hand et al., 2012), Germany (German Advisory Council on the
Environment, 2011) and Denmark (Lund and Mathiesen, 2009). More broadly,
regional studies have been produced for Europe (European Climate Foundation,
2010; Rasmussen et al., 2012), northern Europe (Srensen, 2008), and several
studies of the global situation have been produced including by Srensen and
Meibom (2000), Jacobson and Delucchi (2011), Delucchi and Jacobson (2011),
Teske et al. (2012) and WWF (2011).”

More likely renewables + storage or geothermal or tidal will fill the role now played by nuclear. To the extent we actually need some “always on” generation rumbling along in the background. Budischak found we don’t.

Additionally AltaRock was able to create heat collection fields at different depths in a well which multiplies the amount of heat that can be extracted from a single set of bores. And they did the rock-shearing with biodegradable materials rather than fracking chemicals.

What is valuable in the report, like others before it, is that it shows you can solve the alleged “intermittency” problem of mass wind and solar under conservative assumptions, not the most probable ones.