Are solar and wind energy systems suitable only when the sun is shining and the wind blowing?

no, you can make solar energy at night, and your wind turbine makes maximum energy when the wind has stopped.

Are you serious or did you not write you question correctly.

There are some options. For either, you can tie them to the grid, and hopefully one area will have a surplus when another area is in the doldrums. Electricity is already transferred long distances, so this is not new, but load balancing is an issue, and there are problems with new power sources being added to the grid.
For solar, first maximum energy load is during the day, particularly on hot days when the A/C is needed, so solar plants can take the place of natural gas “peaker” plants, used to help with a peak load. Second, if you have solar thermal (as opposed to solar photovoltaic), you can heat up a mass which retains its heat, and then use that heat later. This could work for several days of heavy clouds, but overall power production would eventually be reduced. Photovoltaics work rather well in light overcast situations, it doesn’t need a clear blue sky.

Here in Texas ,most of the time when the night comes and U need light the wind will quit.