Using grid tie inverter with backup system

[Norman Webb]

I intend installing a 240v AC 2500W grid tie inverter on a new house. The
inverter needs a supply voltage in order to operate so when the grid power
goes down you are left with all that power on the roof with no where to go.

If you have a back up power supply (either petrol generator or
solar/inverter) will the grid tie sync to these type of power supplies.

The main power grid can soak up any power generated by your grid tie system
but what about a small generator??

My electronics engineering 101 has long since left me, but my guess is that
the two systems should sync.

Any thoughts out there?

Norman Webb

 

[[email protected]]

I intend installing a 240v AC 2500W grid tie inverter on a new house. The
inverter needs a supply voltage in order to operate so when the grid power
goes down you are left with all that power on the roof with no where to go.

If you have a back up power supply (either petrol generator or
solar/inverter) will the grid tie sync to these type of power supplies.

The main power grid can soak up any power generated by your grid tie system
but what about a small generator??

My electronics engineering 101 has long since left me, but my guess is that
the two systems should sync.

Any thoughts out there?

Norman Webb

http://www.xantrex.com/web/id/25/learn.asp

http://outbackpower.com/applications/residential/grid_interactive/

Wayne

 

[Ed]

But so far as the OP's request for backup power during a grid outage, I
don't think either of us can make an intelligent recommendation without
more information. Some of the things we don't know are power usage,
length
of blackout, weather conditions at the time (is the sun likely to be
shining during the blackout), how long a blackout he wants to prepare for,
etc.

For example, we have a 2nd home in NH where we spend a good deal of the
winter. A winter power outage might be due to widespread blizzard and
icing conditions and might last four or five days or longer. Depending on
how many of our kids are visiting at the time, we might be using as much
as
50 kWh/day! And this would be at a time when the solar resource is
virutally nil. Battery backup with solar panels is not very practical in
that situation.
--ron

Try looking at it from a different angle... Grid tied with battery backup
only.....

hook up the 24 hours needed circuits to the auto switch over circuitry
(fridge, a few outlets, computer, etc)

As a back up for longer use... hook up the generator to the other circuits
you may need while you are home (early evening stuff... hot plates, hot
water if youdon't have solar thermal, etc with another set of switch over
circuits) Also hook it up to a battery charger that can charge your solar
batteries if you don't get enough sun.
Hooking up a generator directly to grid tied inverter will not be a good
idea for 2 reasons... one: the freq will not be stable enough and worse,
generators don't like to be fed excess power