It's lagging behind because energy developers operate on the economic margin. At the margin, solar is more profitable, up until the point that the grid is saturated with solar, then it flips. But only a small proportion of geographical locations are saturated, hence the marginal investment is still primarily in solar. This is not concerning, it is the market working as it should. The demand for storage will come and then the supply will follow only after the demand shows up.
It is surprisingly hard to find reliable figures. Best I could do was a global solar installation of 2-3 TW and global BESS of around 200 GW/500 GWh right now.
China is leading in both, but I'm more interested in local BESS and other storage deployments locally in northern Europe. I think for example Spain started getting more heavily involved only after their massive blackout. According to those links there is a very large overcapacity in battery production, but I don't see it reflected here. I'm sure it will happen at some point though.
https://ses.jrc.ec.europa.eu/storage-inventory provides European battery storage inventory, but to your point, it will take time for manufactured BESS to be deployed. Spain, only after the recent blackout, has moved towards mandating storage paired with renewables for grid services to improve reliability and health.