SolarCity's announcement of 22% efficient PV got me thinking. What matters is having top efficiency at a cost efficient price point. 22% efficient solar panels can cost more per Watt than 15% ones, but it can't cost 50% more/Wp. Anyone cares to predict when 20%+ efficient solar panels will make the other panels obsolete (due to lower installation costs and better utilization of roof space) ? Ultimately getting rid of fossil fuels will require those that both have the money and have the inclination to invest to convert their houses into a mini solar grid generator. I mean at 200% over generation whole year, ideally 500% or more. Having 200kWp of solar panels (or bigger). Unless you have a mansion, you're likely to be roof space constrained. Oh, and at one PowerPack for each 100kWp worth of panels (ideally 3 PowerPacks for each 100kWp so one can sell electricity at peak demand hours). Ok, I'm writing from the seat of my pants. I don't live in the USA. I live in Brazil where most people live in buildings 4-20 floors high. The solution here would by ultra high efficient hybrid solar PV+Thermal or PV concentrating generation in order to just break even for buildings with 10+ floors. Any thoughts would be interesting. There is an Israeli Solar Hybrid system advertised to achieve 72% efficiency, but at what price point ? Zenith Solar Israel. Thanks for any thoughts.