How to DIY electric bike modification - Schwinn 3-Wheel? I've come across a mint condition 3 wheel Schwinn bike (big tricycle) and I'd like to modify it to be electric driven. My main focus is an efficient electric system and I would like to integrate solar charging at one point.

I'm willing and able to build it myself. I don't need a kit although I'm interested in integrating the most technical advancement within the last few years. 

Recently, I spent some time in California and it appears the best and fastest electric bikes have the motor mounted in the front hub to pull the bike. This Schwinn bike has a very large basket behind the seat mounted over the rear axle where I could have larger battery packs. 

How can one modify this 3-wheel Schwinn to an electric bike?

Note: It will be used only on relatively flat terrain, in Florida.
Delta tricycles (trikes in which the two paired wheels are in the back) should either use:


A crank-based motor such as a Bafang BBS-HD (these are usually called 'mid-drive' but this designation makes less sense for recumbent trikes). This would take advantage of the rear differential (if available). If the trike doesn't have a differential, it will pull in the same direction as when pedaled. With a powerful crank motor, this can be quite dangerous as it will either you pull you into traffic (left) or off the road (right). So I would suggest you use mid-drive crank motor on a trike only if you have a differential.
A front hub-motor is better given the complexities of creating a differential for the two rear wheels. This has the advantage of not pulling to one side, but the disadvantage that you can easily lose traction, especially when going uphill (and especially if you have your batteries in the rear rack).


However, beyond this pithy answer, the actual complexities of installation are up to you and the particular motor/kit you choose. We're not a shopping site so asking "What's the best hub motor for a trike" would be ruled off-topic. You should instead ask "What characteristics of a hub motor would I look for if trying to install one in my trike" or "Which wheel should I put the hub motor in on my trike?" or "Should I use a throttle or pedelec for my trike electrification."

Finally, remember you can also always ask specific followup questions ("how would I install a Bafang BBS-HD given my recumbent's raised crank") once you've made the decision.