inverter

 

i have a xantrex GT3.0 grid tie inverter and was searching for a way to
trick it into working when the grid is down.  does anyone have a clue
as to how this could be done or maybe direct me to someone who can.

 



I assume that these types of grid-tie inverters would have to boost the
voltage significantly higher than line voltage in order to drive current up
the line.  That kind of voltage might be harmful for your appliances.  It
would also be difficult to provide the line signal and the special switching
configuration required.

I would say don't risk it, unless Xantrex has a special kit or procedure for
doing so.

 

JoeSP wrote:

I don't think that's how grid-tie inverters would work. More likely, they supply
the energy by
having their output phase shifted wrt the grid,  possibly only supplying energy
during the part of
the waveform where the voltage is relatively low.


So would I. Without the special kit, I don't think it would work anyway and a
battery would be
required, of course.

Furthermore, I believe that grid-tie arrays are usually wired in series for a
higher voltage.
To use a common non grid-tie inverter for emergencies, you would have to be able
to switch to a
paralled combination.

An emergency generator might be a better option.

Cheers

 

sam wrote:

Actually, both voltage *and* phase need to be exactly the same as the
grid or the grid will *force* them to be the same. If the inverter
resists, it will quite possibly be damaged or destroyed -- the grid is
much bigger and more powerful than a puny residential inverter. Picture
trying to turn the wheels of a car with a pencil through the axle while
the car's engine tries to rotate the axle at a different speed....

"Driving current up the line" is strictly a function of where the power
sources are and where the loads are. Power lines work in one direction,
so it's not like you're forcing some power to go one way and other power
to go in the opposite direction. If you're producing more power than you
need at your home, no power comes "down" the line into your home and the
excess power simply travels up the line to the first load it can find.

 



If you had for example, 2500 watts of power to sell to the grid, no current
would flow to the grid if both voltages were exactly the same on either
side. You need a voltage differential for current to flow.  The grid-tie
inverter must raise the voltage to the appropriate level for your power to
flow into the grid.

You're correct that the phasing has to be exactly synchronized, otherwise
the sine wave would be compromised on the grid. You can't combine two AC
circuits unless they are in phase.