We often hear solar PV systems promote job growth, but conveniently overlook where the bulk of capital is flowing. Solar PV modules, inverters, and racking systems all consume the lion’s share of a solar system’s capital investment. Adding a solar tracking system, can increase a solar system’s energy yield by as much as 45% or higher, while also benefiting the local economy. Most solar trackers can be designed by local machine or steel fabrication shops – thereby increasing local content. The additional Operational & Maintenance effort, usually reduced to an annual lubrication visit, also increases the local labor component.
You are absolutely correct about car batteries which can become a grid stabilizer. As with anything, there’s got to be an economical advantage, and somehow there has to be an incentive for you to participate in this system. Surely no electric car owner would let the utility company charge/discharge ones battery at will given battery degradation per such cycle. With large scale hydro pump-up, you loose about 15% energy per cycle. Thus, for car batteries to be viable, they have to match that loss rate, and hopefully also be able to squeeze out a small profit for the car owner. If not, I just don’t see this happening.