I'll stop now.
Probably because that generation of solar panels sucked, efficiency-wise, and IIRC several models also lost a large percent of their functionality after a few years.
Repeat this for every generation of panels referencing the previous generation, and we all know efficient solar panels will be here Very Soon Now.
"People should not be afraid of their governments. Governments should be afraid of their people".
Top Ten Things Overheard At The ANSI C Draft Committee Meetings: (7) Well, it's an excellent idea, but it would make the compilers too hard to write.