It seems that all this fuss (e.g. the Guardian solar subsidy campaign) over installing solar PV panels is actually bad for the environment. Solar PV panels cause global warming! The best way to prevent global warming is by reflecting sunlight back into space using white and/or reflective surfaces. For example shiny white roofs! If one really wants to save energy, and stop using fossil fuel, the best contraption to put on one's roof is a solar water heater. Wikipedia has two articles on this: Solar radiation management | Reflective surfaces (geoengineering)
Alex Cannara: tell your friend that roof of his does more to damage climate than he gains from energy savings! Remember, the sun delivers 1kW/square meter. PV only converts ~20%. The pic shows what we should all do, as recommended for many years by The Heat Island Group , Lawrence Berkeley Labs,the CEC, Steve Chu.
Alex Cannara: your friend's panels aren't better than 20% efficient, no matter how he loves them. That means they radiate ~800 Watts per square meter back into air ... That waste of convection and IR radiation adds directly to local global warming. By the way, solar hot-water is good, because its collectors run at lower temps and transfer most heat to their intended target -- insulated water storage.
Alex Cannara: The fundamental point is that a 100 square meter, poorly-reflective roof/solar installation, generates about 100kW of waste heat/IR while the sun is on it, giving the physical effect of greater GHG concentration that actual. That waste dwarfs whatever savings the design & systems in the home can make, or cause to be saved, at a serving utility.
|Solar reflectivity increase||CO2 offset by 100 m²||CO2 offset globally|
|White Roof||0.40||10 tons (~ 2 cars)|
|Average Roof||0.25||6.3 tons||24 Gt|
|Cool Pavement||0.15||4 tons||20 Gt|
|Total potential||--||--||44 Gt|
|Value of 44 Gt CO2 at $25/t ~ $1 trillion|
100 gallons of gasoline/year => ~ 1 ton CO2
Global CO2 emissions in 2009 ~ 24 Gt
(Akbari, Menon, Rosenfeld. Climatic Change, 2008)
Alex Cannara: just increasing roof reflectivity around the world by 40%, would have the same warming prevention as parking all 700,000,000+ vehicles on Earth for a decade.