We ve been there, done that!
Costa Rica has generated consistently over 90% of its electricity from renewables over the past 15 years. Yes, even before climate change was sexy.
How do we do that ? Much in the line of what Rosana writes.
Some 75-80% hydropower, with a big reservoir providing seasonal storage, as we have a very marked "dry" season. Run of the river plants also have reservoir capacity of several hours and can help take our two daily peaks.
Some 10-15% geothermal power, used as base power.
Some 0-5% wind power, starting in the 1990s. And this fraction should grow markedly since we are in the process of contracting or building an additional 10% of our capacity from wind. Also complements hydro during our dry season.
Some <1% biomass from bagasse burning in sugar mills.
Some <1% solar. No matter how inefficient (low plant factors compared to hydro) it has the potential to cover us during the dry season. Will probably develop as distributed energy.
Along with that, our distribution network covers 99,4% of the population.
So thats how we do it. A sustained country effort from policy down. It can be done.