>They do, all the time.
In fact, they never do at all! If you look at the market statistics, you will notice that >80% of the market is crystalline silicon. And while there are different ways to manufacture crystalline silicon solar cells, companies have been extremely reluctant to introduce new technologies. In fact, almost all solar cells today are still made with the same manufacturing process steps as 10 years ago. Conversion efficiencies have improved simply by tweaking these process steps.
>Why do you think the cost of solar has decreased by 90% over the last 30 years?
I know why the cost has decreased
- Manufacturing cost reduction by scaling effects
- Very significant cost reduction in raw materials
- Reduction of material consumption by process optimization
- And to a smaller part, improvement of conversion efficiencies by process optimization.
News about surface plasmonic effects, black silicon and the like are surface every other weak. However they have not inched any closer to production than they were 5 years ago.
Photovoltaic modules are a commodity. The technology and science behind it is of limited depth and not comparable to the semiconductor industry. Look elsewhere if you want to innovate in technology.
What is needed is innovation on the system level, products and marketing.