The amount of light and intensity of the light is important, but so is the amount of heat.
e.g in some really sunny climates in the height of summer the heat actually reduces the efficiency of photovoltaic panels, so on a really hot summers day you may not generate as much PV power as you would on a relatively cool yet clear winters day.
So you have to choose your solar techs carefully.
Basically, in a hot sunny country you're better looking at solar furnaces than at PV panels.
The best power storage that we currently have is hydro electric power.
E.g power stations that spend the night time (when everyone is in bed and not using power) pumping water to the top of a hill (therefore allowing the energy surplus from coal/gas/nuke stations [which as you point out don't respond to instant demand situations very well] to be used). and then in times of high drain from the grid these stations can typically turn on in time scales of less than a few minutes generating massive amounts of instant power.
I'm not sure that there could be a better storage medium than that.
carbon nano tube news seems to be a bit quiet nowadays, I'm sure that people are still researching it, and more breakthroughs will come,