Solar Flare said:
I believe we already went through this previously.
Although it sounds impossible, and is, if you have no co-generating source
in your house, by correcting PF you reduce the VA load to your
co-generating system and allow more reserve VA capacity to backfeed your
grid-tie, thereby reducing your kWh bills.
Generating sources usually do not care what your watt load is, only VA.
Thay are rated in VA except the units created by Engineers that do not
understand the technology.
But when operating a grid-tie inverter, the inverter doesn't *care* what the
load pf is. Because it is operating in parallel with the grid supply, the
distribution of VAR load between the inverter and grid is *not* simply
share-and-share-alike. The inverter is pumping power to the grid, and the
pf that it operates at is determined *completely* by the internals of the
inverter.
Take the extreme case, run your loads when the inverter is off, then shut
off all the loads and run the inverter. The pf of the loads doesn't affect
the kwh meter when they are running since the meter only registers the w and
not the va. The inverter pumps power to the grid when it's running, and
(hopefully) outputs power at near unity pf. The kwh meter registers the W
component of the inverter output.
If you combine the two (run both loads and inverter at the same time), then
the inverter continues to supply power at near unity pf and the utility
supplies all the VAR load. Net result is the lower W load on the utility
and the same VAR load means the kwh meter is running with a very low pf.
But the meter still only registers the kwh drawn through it, even at very
low pf (unless Jim has a bad meter, but that's unlikely).
If the inverter runs at a high pf when pumping power to the grid and all
loads are switched off, it will run with the same high pf when the loads are
switched on. And it will run with the *same* pf when the loads are switched
on *and* a pf correction network is connected to the loads.
daestrom
