This is a link to a blog by Tom Moriarty that works for me.
In particular, his summary on Solar PV and Wind from a Practical Project point of view underlines the fact that raw solar and wind are low density forms of energy:
Some points to consider
What would be the consequences of covering 6 million square kilometers of land with PV? This would be like completely covering an area the combined size of Arizona, Nevada, Colorado, Wyoming, Oregon, Idaho, Utah, Kansas, Minnesota, Nebraska, South Dakota, North Dakota, Missouri, Oklahoma, Washington, Georgia, Michigan, Iowa, Illinois, Wisconsin, Florida, Arkansas, Alabama, North Carolina, New York, Mississippi, Pennsylvania, Louisiana, Tennessee, Ohio, Virginia, Kentucky, Indiana, Maine, South Carolina, West Virginia, Maryland, Vermont, New Hampshire, Massachusetts, New Jersey, Hawaii, Connecticut, Puerto Rico, Delaware, Rhode Island with solar panels. Of course, this would be spread out over the about 100 million square kilometers of land at latitudes lower than about 50 degrees.
This plan would also require a distribution system that could move energy from daytime areas to nighttime areas, or at least a few days of storage for every person on the planet. Such a distribution system is not feasible at this time, and the massive amount of storage is prohibitively expensive.
Two days of storage would be 200 kilowatt hours of stored energy per person. Probably the best mass storage option today (2015) is with Tesla’s Powerwall, which stores 7 kilowatt hours, costs $3,000, and weights 220 pounds. So we would need about $90,000 and about 6,600 pounds of storage for each of the 7 billion people. That adds another $630 trillion to the cost.
These calculations serve simply to give a feel for what could be done with solar photovoltaics and what the limitations might be. I am not suggesting that the world should be powered solely with PV. With other energy sources in the mix less money and land would need to be devoted to PV (but more to those other sources). For example, if you did the same calculations for wind, then you would find that about twice as much area (about 12 million square kilometers) would have to be covered by wind farms to get the same amount of energy. But at least you can grow corn are graze cattle below the turbines in a wind farm.
I have led you to water. It is up to you to drink up your own conclusions about the viability of using solar energy to bring the world up to a reasonable level of energy consumption.