Understanding the development of the PV module, the size, configuration and production, I wonder what the next generation will be? Reduced footprint with similar or more generation? What is possible?
They are always making PV more efficient and you can buy 20% efficient PV from SunPower and a few other manufacturers. The thing about 20% efficient PV is it is more expensive than 15% efficient PV and most jobs use about 15% efficient PV as the cost effective compromise in order to make a reasonable return on investment. I expect the average PV efficiency to increase over the years.
Some of the ways that PV is expected to get more efficient is by making the PV with different layers of crystalline and thin film PV as you can read here:
Silveo was bought by Solar City.
Sanyo was also known for years as being super efficient and having 2 layers. Sanyo's PV division was bought up by Panasonic.
High efficiency is expensive! Ouch!!
Also, there has been a lot of news about First Solar modules (thin film CdTe) reaching a record efficiency that is beyond that of Polycrystalline:
The thing about record efficiencies, is that they are records and not the cost effective solution.
Here is the famous NREL record efficiency chart:
On this chart we see 46% efficiency! That probably cost more than your house to make a small cell that is that efficient. The record was made by 4-junction (4-layered) concentrating PV. Very not reasonable to install on your house.
If I had to take a guess, I would think that we would expect to get about a quarter of a percent efficiency increase per year for the average PV sold for the next decade.
They say Einstein said that you will never get over 50% efficient at turning light into electricity with PV.
Maybe in 100 years we will have robots that can make 46% efficient PV that we can put on rooftops, but by then will we have cold fusion reactors that fit into our phones?