In reply to <a href="https://electrek.co/2016/04/28/i-was-wrong-about-the-limits-of-solar-pv-is-becoming-dirt-cheap/#comment-26825">Daniel Brooks</a>. There are lots of chemistries for batteries. Lithium is popular for mobile applications because of its light weight. For industrial sized batteries, sodium-sulphur or sodium ion don't require lithium.