[GBlist] Inverters that both charge battery banks and the grid?

[Bill Dorsett <dorsett@interkan.net>]

    I have a client who is interested in a grid connected PV system which he can take with
him to a non-grid connected home when he moves or use as utility back-up now. So he wants
an inverter which can feed the grid now and be able to charge a battery later. Like the
Trace SW series. This must be a very common request given the rolling brown-outs across
the country. A 4000 watt system is an overdo for many conservative homes, and for this
client's PV array size. The ideal would be a 2500 watt 24V inverter.
   Most remaining SW inverters are 4000 watts or bigger and often require 48V inputs.
Inspite of smaller cabling for higher voltages, lower voltages have real advantages. From
a battery bank of 6V batteries (L16's) this would require 8 in series at each additional
bank size increase. So the inputs would be 8, 16, 24 ...batteries. Expensive steps and a
lot of corrodable connections bottle necking each string of batteries. Also the four
modules required to charge such a bank are bottle necked by the lowest power module in the
string. to say nothing of resistance in each of their connections. I tend to favor 24 and
possibly 36V systems. So again I'm looking for roughly a 2500 to 3000W sinewave grid
synchronous inverter at 24 to 36 volts.

Trace used to build the SW series of inverters which had a built in battery charger and
could feed back power to the utility. Since Xantrex bought Trace, Heart, and Statpower the
SW series is being phased out leaving a void for relatively small inverters that could
take the place of the SW2512 inverter. Now in mid-2001, is there any historically stable
company that builds a good sinewave inverter in that size range which both charges a
battery bank and feeds the grid?

Any thoughts or suggestions?   Thanks

Bill Dorsett
Manhattan, KS


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