Appropriate Technology DIY plans at Instructables

From Engineering for Change:

In off-grid communities where lights at night could improve grades and keep businesses open later, and where a homemade bicycle trailer can become a small delivery business, a little know-how may be the only thing missing. The right skills can turn low-cost materials into moneymakers, but learning to build, or just having the idea, is a challenge. To help, we've rounded up Do-It- Yourself guides to making energy, transportation, coolers, water filters and more. This is the best in appropriate technology from the legion of creative projects at Instructables.

They include:

How to make a solar panel from broken solar cells
Solar panels are expensive, but manufacturers may part with a sack full of broken solar cells for just a few dollars. Here's how to combine the broken shards into a working, power-generating solar panel.

and

How to build a high-efficiency LED desk light
In many off-grid communities, lights at night are all it takes to improve students' grades and families' incomes. Students can study and businesses can stay open later.

More here