Grid-tied but grid down

[JimLudden]

I have an Enphase grid-tied system, with manual disconnect switch for the fire department.
When the grid fails, how can I use power from my panels to run my refrigerator or gas furnace? I have installed a generator transfer switch, but have no generator (other than the PV panels). No batteries, other than in my car (which I cannot use for this).

[solardreamer]

The conventional solution is add a hybrid inverter/battery system that supports off-grid AC coupling and frequency-shift control for grid-tied inverters. Search for "AC coupling" on the forum for more info. A generator would be cheaper but cannot connect to the grid-tied system by itself.

[Mike 134]

You cannot use the panels for power unless the grid is up. When the grid goes down so do the panels. Unless you lose power often and for extended periods of time it's not worth the $$ to utilize the panels for power. I have a 6500-watt generator just in case in the next 10 years I lose power and need the frig running. So far 9 years into owning it and have not used it.

[Rade]

We have a 18kW battery backup attached to our system. During the summer, I've kept the system in "Self Supply" mode and used the battery power to keep the house alive overnight (when the nights are short). We would use about 80% of the battery power. For several weeks, we actually pulled nothing from the grid; the sun would fire up the panels at dawn and start generating power, recharging the batteries while also providing power to the house.

That said; in "Emergency Mode", we have fail-over that will provide battery power to 6 specific circuits in our home if the grid power goes out. Since installation, we have not had anything worse than a >Bink!< power blip that just managed to cause every digital clock in the house to reset. Nothing that failed over. I am of the impression that, much like the multi-day outage we experienced 8 or so years ago, that in emergency mode, the panels would recharge the batteries as much as they could while the sun would be up.

[ray188]

I have an Enphase grid-tied system, with manual disconnect switch for the fire department.
When the grid fails, how can I use power from my panels to run my refrigerator or gas furnace? I have installed a generator transfer switch, but have no generator (other than the PV panels). No batteries, other than in my car (which I cannot use for this).

You would need an Offgrid inverter. Your house circuit MUST be disconnected from the grid at the Main Breaker Panel before connecting the Offgrid inverter. If you have many inductive loads (i.e., appliances with motors, like fridge, aircon, well pumps) you need a LF (low frequency) inverter that has 3x surge power. HF (high freq) will die easily if your loads are mostly inductive. I am using 3KW LF offgrid from Solartorrents website, think they will have 6KW soon. You can also ask their support to determine what/how to setup offgrid. Electricity is not very forgiving to persons and eqpts, so must know what you are doing.