Off Grid - What happens when power is not sufficient?

[JToby]

Hi,

As you can tell, I am very new to Solar, but want to get a setup going this coming year 2024. I am working through all the scenarios for grid tied \ off grid, etc. One question that I have is what happens if your solar off grid setup runs low in power? Will the inverter have enough tech to shut down the flow of power so that it does not damage the components (fridge \ water pump) etc? (brown outs). As I do not have an Inverter, this is why the question. A few items:

* Does the Inverter (All in one) shut the flow of power off if not enough power to prevent brown out's?
* How is this accomplished? Is it a set safety limit inside the controller itself?
* Is this something that would be different from one manufacturer to another? Or do they all work in the same manner, is it a standard for all?
* Is this something that the home owner would set? If it is not a set limit on the controller?
* What about surge requirements? What happens if a surge of power is required? Like a compressor or water pump initial start? What happens if it wants to draw too much then available?

Thanks for this, great appreciated.

Yes - Newbie.. But will learn as needed.

Great forum..

 

[pollenface]

they usually have low voltage shut down around 10/20/40v

You should choose an inverter capable of supplying the surge required for your load (eg. 5-7x the continuous rating).

I have a 6000w/12000w inverter and it starts a 2.5hp (1800w) belt driven air compressor and runs my welders and pretty much anything I plug into it. My only regret is that I don't have two of them.

 

[Texican]

people that have a fully off grid system, meaning no grid connection avbl at all, will have a generator to power loads and charge batteries when solar is not enough.

most of what we all call off grid systems are actually more accurately called a grid assist system.
in this case a grid connection is avbl which can be connected to the off grid AIO and grid power can be added as needed to cover loads or charge batteries. this is pretty much an automatic option and brownouts will not be an issue.

 

[JToby]

Thanks for the help with this.

 

[chrisski]

In my case, for low batteries, I manually shut the inverter down and plug in a generator that will run my AC circuits and recharge the battery.

Exact details of my RV build are on my signature block.

 

[Browse]

In my case, for low batteries, I manually shut the inverter down and plug in a generator that will run my AC circuits and recharge the battery.

Exact details of my RV build are on my signature block.

You can also get a Chargeverter to power the batteries directly from the generator without having to turn off the inverter or have to depend on the generator for surges and loads beyond its capabilities. This works great when I need to power my HVAC where the generator can't handle the startup inrush current but the LF 12k inverter can.

 

[Hedges]

"load shed" and "dump load"

If battery gets too low, inverter shuts off and nothing is powered.
Some systems have relays configurable to switch at some battery state of charge, or when surplus power is available from PV.

Discretionary load, perhaps air conditioning, could be shut off ("shed") when battery drops below some SoC, leaving enough power for more important loads until there is more PV production. Possibly two stages for discretionary loads, important loads like refrigeration, critical loads like communications.

When there is more production than you have use for and battery is full, something like water heater can be enabled to consume the surplus ("dump load").

For a grid tied system or grid-backup system, there are grid-interactive inverters which synchronize to grid voltage and supplement with power from PV or battery. They can also backfeed grid if you have net metering, or backfeed only enough to supply other household loads but not backfeed the grid ("zero export" with current transformers.)

There is a range of prices and capabilities. Some like SolArk can be configured for almost any use: with or without battery, with or without PV, backfeed or not, etc.

Surge capability was mentioned. Motor starting surge is typically on the order of one second, so look for something like 3 to 20 second surge rating; don't be misled by inverter specs giving a 30 millisecond surge. That can be useful to trip a breaker in the event of a short (if inverter can deliver 5x breaker rating) but doesn't help for motors. It would also be useful for inrush of transformers or capacitors on front end of SMPS, but such specs aren't usually available to consumers.

 

[JToby]

Wow, what a great site for knowledge.

There are certainly some who know Solar \ Power setup.

Thanks for all of this.