The numbers in your linked article are from 2000. The price of solar panels per watt is about 5% of what it was in 2000. Most of that cost reduction was from reduced energy use, so you need to multiply Jancovici's numbers by 5%.

You're also assuming that you have to store 100% of the energy to get to a green grid. But in a grid with a good mix of different renewable sources, grid ties large enough to cover areas with different weather, substantial amount of nuclear, hydro and a large number of EVs that can charge while energy is cheap means that very little energy needs to be stored. So you also have to multiply your storage numbers by about 5%.