If design specs are JUST met some massive passive cooling is needed. 2 kW at 95% =3D 100W losses. Max allowed outer temp - 65C If delta T for cooled air is say 30C then that's 30C / 200 W =3D 0.3 c/W cooling. As 50W / in^32 kW is 40 inch^3 If say 4 x 5 x 2 inches (100 x 125 x 50 mm) that's 0.3 c/W from a 4" x 5" heatsink. even doubling that to say 4" x 10" and 1" thick makes life hard [tm]. Increasing efficiency makes cooling easier (of course) Typical HV PV to AC inverters are getting 98% plus. With non isolated topologies as discussed here recently. Required sine purity is 'easy enough' except that it usually increases switching speed and or filtering 'costs'. R E&OE On 30 July 2014 15:42, Bob Blick wrote: > http://www.gizmag.com/google-little-box-challenge-power-inverter/33094/ > > 50 watts per cubic inch, no active cooling. > > > -- > http://www.fastmail.fm - Same, same, but different... > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .