Invertors are used to convert DC electricity, created by solar panels or batteries, into AC electricity, used by many appliances. A Belgian company, Red Electrical Devils, managed to pack 142.9 watts per square inch into a 14 cubic inch box. The company ended up winning $1 million in Google's Little Box Challenge.
Smaller invertors means more portable power, which helps spread the non-polluting solar power.
Greentechmedia seems like a good source for green power news. The site is well-organized into subcategories.