Solar or wind can't save the world alone, but all renewables together just might

A harsh but realistic article about renewable energy accepts what you hear so often from climate change skeptics and fossil fuel boosters: while there is a huge potential supply of solar and wind power, both sources of energy are necessarily intermittent and unreliable.
I think most fans of renewables would admit that is true, but that does not mean that it is not the right path to pursue. Every watt of energy produced by solar or wind, is a way that does not require carbon-heavy fossil fuels.
What, then, is the solution to this conundrum? The article suggests the following alternatives:

• Use fossil fuel plants as back up (rather than the mainstay of energy production).
• Oversize renewable energy production to be able to cope with peak demand (aware that much power will be wasted at other times).
• Connect geographically dispersed renewable sources (such as from different states, provinces or countries, necessitating improved or expanded transmission grids) so as to smooth out variations in power production.
• Store surplus energy for times when solar and wind power resources are low (requiring battery technology, which is improving fast but is still not everything we need).
• Adjusting the demand to the supply by improving building and vehicle energy efficiencies (so that less power is needed, even at peak times).

I would probably add one more option to this list: invest in other renewable energy sources, like tidal, run-of-river hydro, geothermal, etc. There is no reason why we need to limit ourselves to solar and wind, even though these are currently the most economical methods of green energy production.
How many times have you heard naysayers claiming that solar or wind can never replace coal because it is too unreliable? But no-one ever said that one renewable resource was going to save the world all on its own? We need as many different options as possible, all working together.