What’s most cost efficient for the duck curve at scale is single axis tracking solar systems. The added cost produces ~zero extra power at noon and significantly more power at sunrise and sunset. It doesn’t completely remove the issue, but you get about 80% of max capacity for about 90 minutes more in the morning and evening.

EX: http://ujsolar.weebly.com/uploads/2/1/0/4/21043846/9545485_o...

Currently the economics favor regular solar systems, but this will change long before large scale grid storage becomes viable.