Safety mechanism for power outage use of solar.

It sounds like you are describing a generator interlock kit but that is not intended for solar as you are describing. A typical grid-tie inverter will not supply stand-alone backup power to your home during a grid outage because they must detect that the grid is up and stable in order to be able to operate. There are some home solar inverters that allow limited emergency power in such situations but I don't think that is what you really have in mind.

This gadget forces you to turn off the 200A main breaker to the entire home before it would allow the generator 30A breaker switch to be connected to your home circuits.

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What you are looking for is called a generator interlock. All the main residential panel manufactures sell some version of it.
Others with more knowledge than me can chime in but your average run of the mill UL approved solar install will not produce during a power outage without additional $$$ components.

As others have mentioned, what you described sounds like generator interlock. A typical home solar system is grid-tied so it won't produce power unless it sees a grid-like independent power reference. So, just have an interlock won't enable a grid-tied solar system to produce power by itself during grid outages.

Unless you have a hybrid inverter that can charge batteries, solar panels will not work if the grid is down. So no interlock is going to work for the OP

Thanks folks! This is exactly what I was looking for. Apparently it works if set up right. The one I saw some years ago allowed for 4 to 6 breakers you deemed most important. Usually lights to certain rooms, the refrigerator, and so on.

I appreciate all of your help and wisdom. I was going nuts trying to find it!

Sounds like it would send power to a critical loads panel.

As I remember it, you had to rewire your panel to put the breakers you wanted at the top, inside the generator interlock. It was pretty much a complete redo of your breaker box. So yes, it seemed very much like a sub-panel, or a critical loads panel in that it only powered a portion of your breakers. Basically, what do you absolutely need running in a power outage?

If you just want to run some loads in blackouts then generator interlock in a critical loads subpanel is one easy solution. However, back to the OP, it does nothing to allow use of solar in blackouts.

We did that with our home when we had the hybrid system designed. We have a sub-panel with 50 amps of what we deemed critical circuits in the house (refrigerators, freezers, heating/cooling, a couple central outlets). Our inverter SHOULD automatically knock over to battery backup in the event of an outage. It was tested once when they set up the system.

In my understanding, the main reason that solar can't be used in a power outage is that most systems are required to see the utility grid as 'up' in order for them to operate. This is a safety mechanism to keep power from being sent back to the utility lines in case a line is cut somewhere, but the problem is that if a line is cut somewhere it also prevents us from using our own solar panels for power.

Most manufacturers system require an expensive battery and transfer system to operate when there is no power, but even then it is like the generator interlock and sub-panel--just a few circuits.

It would be nice if there was a way to have a system automatically lock to 'solar only' when the utility grid is down and trip all breakers except the ones dedicated as 'critical load'. Then once the grid is back up, it may be a manual process to switch back to utility grid power, but at least there is a way to have power when the sun is out and the utility grid is dead. I don't know enough about how to design such a system, but I'm sure someone has done it.

Maybe some type of Hybrid inverter that will allow you to use your panels to charge batteries and only power critical loads. That will work if the grid is down but that type of arrangement may get expensive

Yeah, and I think that's why most systems that are available to go into 'microgrid mode' are expensive. The amount quoted for just 1 battery to be added to our enphase is more than the original purchaser paid for the whole system.

We have a maxed out PWRCELL backup (18kW) on our home and that ran us about half of the cost for just the designed solar rig. We did it all at once. Where we live (East Bay of Rhode Island), we rarely lose power for any more than a few hours, so this should be sufficient to protect what we need to survive during an outage. During outages, we get the wonderful opportunity to hear the symphony of un-muffled propane generators echoing across the neighborhood like a fleet of lawn services mowing every lawn all at once. We did not want that here and that is why we went for the battery backup.

Now our upside was that over the summer when the days were long, we rarely used any grid power. We kept our inverter set in what they call "Self Supply" mode - meaning that the arrays charge the batteries, and after the sun sets, the batteries would power the house until the batteries reached 30% depletion (a metric I can adjust) before shifting over to power from the grid. Over the summer, we had about 6 weeks where we never pulled power from the grid at all. The batteries lasted all night even with the AC running. The arrays charged the batteries first thing in the morning while powering the sundry necessities of the house. During that time, dawn was sometime in the 4AM hour and sunset was after 8PM, and the sun arced directly above the property.

It takes a 2 hours to recharge the batteries when the sun is strong. As the planet is shifting in it's orbit, the suns arc is further south, it's now taking 3 or more hours. This month the light does not hit the arrays until almost 8AM, and if I use the batteries for something (pre-dawn laundry), it takes most of the morning to fully recharge them. Last month, I put our inverter in "Clean Backup" mode, meaning that the batteries are just kept fully charged and any energy we get during the day above what the house uses is pumped back to the grid for a credit. We still are banking energy credits each month, just not as many as May - August.

Such is winter life in Rhode Island.

Thank you for sharing your experience in detail--I never thought about the self-consumption mode of the battery offsetting nighttime grid use. That is something that would help the batteries pay for themselves over time if they last.