i.e. some power then momentarily, for a small fraction of the cycle, flows the wrong way (from grid to inverter in our case) like we do with normal inductive or capacitive loads?
Exactly that happens -- this is the whole basis of the active power factor correction.

It does need a deliberate  inverter/ "active rectifier"  design that allows the switching transistors to conduct in either direction, not just from DC bus towards the output (the inverter bit), but also to recharge the DC bus from the supply (the rectifier bit). This in effect means that in some designs  flywheel diodes need to be replaced with transistors as well, so perhaps a bridge with 2 diodes and 2 transistors becomes 4 transistors,  or pairs of anti-series transistors allowing separating of switching in each direction.
However, with modern devices and the ability to control the individual switching times under software control, it is not  anything like as as hard as it would have been a few years ago to switch active devices at close enough to the right point in the cycle to conduct like  rectifier diode would have if required.

Mike.

Okay, thanks for your reply. So your own generation (PV/wind etc) gets preference over the the grid. As other's have said by raising the voltage slightly higher than grid ?

Thanks all for your replies, still trying to take it all.

It does need a deliberate  inverter/ "active rectifier"  design

So possibly not what we have with a typical domestic PV inverter?

   - Andy.

Most newer domestic ones, and all those models that support the addition of a storage battery have been made that way for a while, and in Germany at least you cannot  install one that doesn't allow active power factor correction without a load of justification and paperwork, Not sure about the UK legal position - I suspect that it becomes the standard fitment.

Mike

mapj1 said:

allow active poetry factor correction

Has you smell checker gone a bit Pete Tong?

yep 'poetry factor' should read 'power factor', well spotted. Fixed now.

Not so sure about VDE approach to German poetry - mind you there probably is a DIN standard somewhere. 'The Poet shall ....'

if so it would have to be approved in conjunction with  the Gesellschaft für deutsche Sprache

M.

share your doubts to know the true  energy transfers  Perhaps also missing is any account of all the gadgets that are consuming your energy just to get to the point of "spilling over" back to source  or does some of it  leak next door  first ? ?However you quantify it  Volta amps Kirchoff : Could a better starting point be if units of energy ( joules)  were used   Akin maybe to Fusion power research  Vital breakthrough is energy out is greater than energy in . (Still not there ) .  Perhaps the simple approach of measured  energy in vs energy out would be much clearer if applied over and above the mystic solar claims ?  ciao Ms O 

Anne Otis said:

Vital breakthrough is energy out is greater than energy in . (Still not there )

If only! But then the Universe would have boiled over millennia ago. Are you serious?

In relation to nuclear fusion, energy break-even, i.e  more out than we put in was achieved a couple of years ago, and not just in a run-away explosion, but also in terms of heat out of a controlled plasma higher than the energy put in to restrain it from burning out of the containment fields. Some US papers describe this as self-ignition which sounds much sexier, but is a bit misleading. Even so this is a long way from commercial break-even, where the electricity sold pays for the machine, and a 'long' run is seconds or minutes, not the  years of controlled operation that would be needed in a real power station. Equally things in this arena seem to jump a factor of ten per decade more or less, so it may not be as far away as it looked.

Mike.