The Prius principle: What worked for cars can work for trains

Here's an idea I had a bit ago: put solar cells between rail tracks and make the trains electric.

Also, with the advent of robotically-driven cars, a robotically-driven train should be much less of a technical problem.

Is the locomotive engineering industry really this conservative, or is it just a lack of appropriate battery technology? Because diesel electric locomotives have been common place for ages, and according to wikipedia they already use dynamic breaking they just bleed it off in heat instead of store it in battery banks.

It's seems like a pretty small jump that should have been made already to hook batteries up in a DE locomotive.

I don't get what's so new about this. Trains have been diesel-electric for decades.

They've already had hybrid shunters built since 2004 http://en.wikipedia.org/wiki/Railpower_GG20B and you can see some more that were scheduled to be in use in 2007 and 2009 http://en.wikipedia.org/wiki/Hybrid_locomotive