Are grid tied inverters built under the assumption you have grid 24/7?

[mudk]

I would like my system to use solar where possible, use grid to cover any gaps and ONLY use battery when there is no utility,
Reason:
If my house is run on Solar 500kw system, I need no use for the grid. BUT we have many blackouts during the day. If the battery is drained under any of the two settings below, when I use the inverter during a black out, if the battery is too low and there is no solar, I will have no power.

So I have an inverter and it has the standard three settings:
UTL - grid until there is no grid, then solar +batteries.
SOL - grid only if 1. no solar OR low battery. (so if the solar power is not covering my usage, it will use the battery to cover it until it is too low to continue. e.g if i am using more than the solar can cover battery will also drain, so in a power outage I will have no power due to solar not covering my consumption and battery being dead)
SBU - grid is only used if battery is dead. So if i lose grid shortly after it being needed, I have no power)

Is this the correct understanding?

How do I make is possible that solar covers my needs until consumption is greater than the solar can provide. Then it uses grid to top up consumption. If there is no grid then and only then it uses batteries?

 

[Ampster]

How do I make is possible that solar covers my needs until consumption is greater than the solar can provide. Then it uses grid to top up consumption. If there is no grid then and only then it uses batteries?

Buy a hybrid inverter with the correct modes to do the above. That is exactly what Self Consumption Mode does in my Outback Skybox.

 

[mudk]

Buy a hybrid inverter with the correct modes to do the above. That is exactly what Self Consumption Mode does in my Outback Skybox.

there is no such think here in pakistan. Looks like I just need enough battery back up to survive this.

 

[Ampster]

Well if you actually mean no such thinking then it it's an opportunity. On the otherhand, if supply is the issue then you are limited to what is available

 

[mudk]

Well if you actually mean no such thinking then it it's an opportunity. On the otherhand, if supply is the issue then you are limited to what is available

*thing.
Well actually, both can apply. Although one is useless without the other!