These reductions stem in part from the limited ability of electricity grids to absorb PV. The long-term limit is based on the capacity factor limit of grids to absorb intermittent sources. We are far from this limit, but short term constraints are showing up at very low levels of PV penetration. China’s current limit is the lack of long distance transmission capacity to take the power from the deserts in the west to the users in the east. As discussed in this blog post, California is hitting problems due to the inability of fossil generation to ramp up and down quickly enough to compensate for rapidly changing PV generation as the sun sets.
Advocates for PV are focused on the falling cost of PV generation and seem to assume that once PV becomes the lowest cost of generation the world will magically switch to solar energy. The reality is far from this rosy scenario. The real cost of PV electricity will increasingly have to factor in the additional costs needed to incorporate it into the electricity supply system. California is showing the need for storage at very low levels of penetration and China is showing the need for long distance HV-transmission. Both technologies are expensive and in need of development, particularly electricity storage. They are both additions to the current grid and both exceed the cost of PV generation. Add to this the geographical variability of solar, particularly at northern latitudes and the economic case for solar to be a large scale, economically viable supplier of electricity is far in the future.
StratoSolar is low cost generation with low cost, fast response storage built in and no need for long distance transmission. It has no daytime intermittency problem and it works well at northern latitudes. It needs relatively minor short term development to prove its viability. In contrast, the storage and HVDC transmission technologies needed to make ground PV viable are in many ways more speculative, unproven and longer term than StratoSolar.
By Edmund Kelly