Well there have been a few. One of the biggest has been new solar panel technologies. Now there are more choices for more efficient systems (more energy from a smaller system) and lower cost systems (save money but keep the system larger).
Many people also like the solar panels designed to look like ceramic tile roofing or asphalt shingles so that it blends. I'll post a photo of this type of system in the next few days)
It's not an improvement, but I also have to admit fluctuations in energy prices also have made people more aware that there are long-term cost benefits to producing your own energy.