Superb. Found the solar page first http://www.geocities.com/dieret/re/Solar/solar.html By far the best overall presentation I have seen. Nothing is overly technical - probably aimed at teenage students. BUT it has a vast wealth of material, good numerical data, and covers the subject reasonably comprehensively. Gets down to wavelength distribution at atmosphere edge and planet surface, insolation levels with latitude and time of year, water and air heaters, cookers, ... . Even compares solar heater types by application and season. Superb. THEN the top level page covering Solar, Wind, Biomass, Hydro, and units. It's a Geocities site and exceeded its data bandwidth mid-viewing so I don't know how good the other pages are. Also available on CD. Superb ... -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist