I'd be a bit cautious about using GDP PPP in isolation.
It's a good metric for a rough comparison/transformation, but has relatively weak prediction power. That said, the same holds for any economic metric used in isolation (eg. HDI, GDP, GDP Per Capita, GDP Growth Rate, GDP PPP Per Capita, Debt Rate, Median Income, etc.)
All metrics need to used together to gain a holistic view on economic development. It's the equivalent of driving and only concentrating on the odometer at the expense of the fuel gauge, speedometer, and tachometer.
Well, in this case we are talking about the Photovoltaic Sector within the PRC.
This implies that this is a microeconomics problem, not a macroeconomic one. This means that metrics like GDP PPP, HDI, etc are completely useless when investigating a subsegment of industrial production.
If I was analyzing the Photovoltaic sector, I'd probably look at
1. Current TAM, Future TAM, TAM growth rate (both past and present)
2. The price of the inputs used (wafers, polysilicon, cells, modules, labor, R&D, tariffs, subsidies)
3. The growth of comparable manufacturers globally
4. Adjacent markets/segments (if I am specialized in solar wafer manufacturing tools, can I potentially pivot into tools for IC wafer manufacturing)
This is a non-comprehensive list, but in general I'm not surprised with a collapse in the price of Photovoltaic Cells.
This was kind of the whole point globally of spearheading the industry - it helped build domain experience or subsidize the adjacent semiconductors sector as well as helped countries like the PRC and the US pivot away from foreign ONG dependency, and is why countries like Vietnam, Malaysia, and India also invest heavily in the sector.
It's a good metric for a rough comparison/transformation, but has relatively weak prediction power. That said, the same holds for any economic metric used in isolation (eg. HDI, GDP, GDP Per Capita, GDP Growth Rate, GDP PPP Per Capita, Debt Rate, Median Income, etc.)
All metrics need to used together to gain a holistic view on economic development. It's the equivalent of driving and only concentrating on the odometer at the expense of the fuel gauge, speedometer, and tachometer.