[RE-wrenches] AC Coupling

[Kent Osterberg]

Larry,

The Sunny Island is a solid solution.

Supposedly, the Magnum MS PAE inverters will wiggle the ac frequency to 
disconnect the grid-only inverters when the batteries are full. I think 
Magnum requires the diversion control as a backup. For a large system, 
the diversion load ends up being a major expense.

Outback's new Radian inverter looks like another good possibility. 
Internally it is supposed to be the same topology as the FX inverter, so 
ac coupling should work fine. It is also supposed to wiggle the ac 
frequency to disconnect the grid-only inverters. As with the FX 
inverter, the manual says nothing about ac coupling so I guess we are 
still on our own on that.

Kent Osterberg
Blue Mountain Solar



Larry Brown wrote:
> Wrenches,
>
> After Hurricane Irene left a lot of people without power here in the 
> Northeast, customers who have grid-tied systems are asking about some 
> battery backup to power some essential loads.
>
> We have used Sunny Islands but they require either 2 Sunny Islands or 
> a step up transformer to get 240 volts for the well pump.  Schneider 
> Electric  (Xantrex XW) inverters look like they would work  for this 
> application and do 120/240 volt output as well and we have used these 
> in off grid applications but not as AC coupled.  I have considered 
> Magnum because they also do 120/240 volts but they need battery 
> diversion to ensure the batteries are not over charged.
>
> None of these systems are going to be rewired as a DC system so I am 
> looking for any feed back on what others are using to AC couple to 
> existing grid-tied systems to provide some battery backup.
>
> Thanks
> Larry
>
> Larry Brown
> Sun Mountain_______________________________________________
>
>