Solar Panels Query

[Nix]

(10 September 2013, 17:50)Skvez Wrote: The Grid-tie inverted is trying to output as much power as it can, what's not used by the house is (normally) exported to the mains.
In the scenario you describe the mains is no longer there to accept the difference between local generation and local load.

If the load is greater than the output of the array the Voltage will collapse and the array will 'notice' the loss of the mains and cut off (probably no damage but no power either)
If the load is less than the output of the array the Voltage will rise and either the array will notice conclude a loss of the mains and cut off (probably no damage but no power either) or run at too high a Voltage resulting in probable damage to your load, your original inverter that you uses to 'jump start' the system and the grid-tie-inverter too.
These systems are just not designed to work without the mains present.

Very difficult trying to get info on this stuff without talking to the designers themselves it seems!

Had a look around. Very differing opinions on even how a grid tie works, let alone if you can use an off grid with it. But apparently it all depends on what equipment you are using. I heard some off grid inverters can be bi-directional in their power flow. This means that the off grid inverter can then potentially charge your battery bank from the grid tie but only up to fully charged status and then there's a danger of overcharge without a dump load. In this scenario some off grid inverters change the output frequency to trick the grid tie to shut down thereby saving overcharge problems. So, yes, it looks like it can be done but only if you have intimate knowledge of both the off grid inverter and the tie grid inverter.