ac coupling

[bahnfeldt]

i see the sunny island inverter off grid type can be connected to a ac bus

has any one had any experience with this i want to couple mains power ac and inverter ac with a ac output from a grid tie inverter so there is 3 ac sources , i presume it all revolves around the mains power frequency. this would greatly simplifies things , seems to good to be ture  

[Phil Timmons]

Let's see if I can make sense of what you are asking . . .

First, yes, I have used Sunny Islands as you are describing -- the output is tied to the grid.  It is rated to be grid tied.  It does this by shifting and checking the base 60 hz frequency.  If the steady 60 hz of the grid is not present, it disconnects its output from the grid.

Does your other AC inverter source have such a frequency detector?  If not, it is probably not suitable to tie its output to the grid, as it could backfeed power onto the grid during grid fault condition.  (dangerous for linemen and your neighbors).

You could still use the additional inverter as a back-up power source with the use of a transfer switch, if you would like.

[bahnfeldt]

cool so can these inverters the sunny island can be used to increase the power supply form say 30 amps per phase on the mains max to 46 amps per phase in total to load

our situation is our main grid power supply is to weak for our peak load we need 46 amps per phase in peak times so are looking for the extra 16amps per phase from the inverter battery supply for only peak times normally 3 hours per 24 hours, we also have a 30 kva 3 phase genset as back up

i have been told you can do it, i have seen this done with gensets but not the inverters before , with gensets there is alot of expensive equipment required to tie and laod with the grid, that why it seems to good ot be ture cheers arny