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Off Grid Setup - Load Management

Eclipse

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Oct 11, 2021
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I am starting to plan an off grid solar setup to power critical loads at my house that has utility power. I will be using an all in one unit to power the critical loads which will be on a transfer switch. So no feeding back to the grid but the all in one unit will also be connected to AC power from the house when there is not enough solar/battery.

Anyways, I would like to be able to power additional certain circuits during the day when there is sunlight, but have them switch back automatically either on a schedule or by some other means when there is no sun. The solar array on the roof will be oversized and provide more power than what just the critical circuits need. I want to use this energy instead of it being wasted. I also don’t want these same loads using battery during an outage because they are not critical.

Looking for some sort of solution for a “smart” breaker or transfer switch. A breaker that can be on a schedule. Or maybe there is an entirely different solution I’m not thinking of. If I had a breaker I could put on a schedule, the loads would be connected to an auto transfer switch. The smart breaker being on or off would cause the transfer switch to direct the load where I wanted it, either on the grid or through the inverters. This seems logical in my head at least.

Hopefully what I’m wanting to do makes sense. If this solution doesn’t work, or I am completely missing something, please let me know. I am pretty new to this. My experience is doing a 24v system with an all in one unit and 1000w of solar on my trailer.
 
What would be wrong with just using the auto transfer switch ability of the all-in-one unit, when turned off, it switches into bypass mode, just powering the output off the AC input power?

Then just manipulate the on off switch with some control logic...

Or do we need a standalone ATS for some other reason?
 
What would be wrong with just using the auto transfer switch ability of the all-in-one unit, when turned off, it switches into bypass mode, just powering the output off the AC input power?

Then just manipulate the on off switch with some control logic...

Or do we need a standalone ATS for some other reason?

I didn’t want to do this because I wanted to continue to power critical loads with the battery bank even after the sun goes down, which means I need to leave the inverter on. Ideally, these lower draw critical loads, could be powered overnight through the batteries to save on electricity. Batteries would then charge the next day as well as power additional loads with the sun up. Hopefully this makes sense.
 
You can just power your critical loads thru the inverter .
Then run your grid power to the inverter , when the sun gos down just switch the inverter to by pass
And the grid will power the load and the inverter can be turned off .
You can add a transfer switch between your grid power and generator so you can recharge with out the sun
 
You can just power your critical loads thru the inverter .
Then run your grid power to the inverter , when the sun gos down just switch the inverter to by pass
And the grid will power the load and the inverter can be turned off .
You can add a transfer switch between your grid power and generator so you can recharge with out the sun
I am wanting to keep the inverter on so that critical loads will actually be powered through battery during the night to save on electricity. So I don’t want to shut the inverter off. Additionally, I want to power extra loads during the day when the sun is up that are not powered by the inverter when it switches to battery.
 
My out back unit has a mate programmer that will buy power from the grid , sell power to the grid
And switch back and forth on a built in timer .
I’m off grid and just run every thing thru the inverter
 
Hmmm , I use separate outlet timers that turn on and off at the appliance , just plug them in .
You could mount a timer next to your panel that will kill a Circuit and turn it on automatically .
Pool timers work like this
 
I’m wondering if maybe something like this would work:


I could have it switch on a schedule. During the day certain loads would be powered through the inverters and then switch to grid power at night.
I notice it's only 2 pole. For US, 240/120v you need 3 poles. You could do 120v only and 240v only but doesn't look like you can do standard US 240v/120v. And... they advertise 0.03sec switch-over but I wouldn't count on this being OK for computers/tivo.

I agree that all-in-ones like MPP Solar can take in grid (which can be ATS'ed such as in a generator) and battery and have UPS built-in. This is because they have a mode where AC(in) -> DC(battery) ->AC (out) is ongoing... so even if you ATS the AC(in) or turn off the AC(in), the DC -> AC is not interrupted as long as the battery can cope.
 
@Eclipse I am doing the very thing you want to do. I use a Victron solar charger and it has a cool programmable relay. I programmed the relay to turn on when there is sun and off when there is no sun. This relay triggers a bigger relay that moves my HVAC system from solar during the day, to city during the night. As an added feature, I put a switch on my relay control box so I can manually over-ride the mode the big relay is on. 20220403_193748.jpg
 
I’m wondering if maybe something like this would work:


I could have it switch on a schedule. During the day certain loads would be powered through the inverters and then switch to grid power at night.
That looks cool but I don’t want to have to set the time on my phone , in the individual timers can just be set in forgotten about , I kill my frig and chest freezer over nite for about 5 hours from 4am and on at 9am .
Well pump , pumps to a tank I can control the a mount of water by time 30min 6 gallons a min 180 g every 4/5 days .
Or I can use stand buy where the inverter turns on when it senses a load .
 
@Eclipse I am doing the very thing you want to do. I use a Victron solar charger and it has a cool programmable relay. I programmed the relay to turn on when there is sun and off when there is no sun. This relay triggers a bigger relay that moves my HVAC system from solar during the day, to city during the night. As an added feature, I put a switch on my relay control box so I can manually over-ride the mode the big relay is on. View attachment 94291
That is awesome, and pretty much exactly what I’m looking to do. Was just wanting to save a few bucks and use an all in one instead of Victron. The MPP and Growatt all in ones has a dry contact switch, but doesn’t look like it can be programmed based on sun/no sun.

Would you mind sharing the links or model numbers for the relay you purchased? Thanks!
 
I am starting to plan an off grid solar setup to power critical loads at my house that has utility power. I will be using an all in one unit to power the critical loads which will be on a transfer switch. So no feeding back to the grid but the all in one unit will also be connected to AC power from the house when there is not enough solar/battery.

Anyways, I would like to be able to power additional certain circuits during the day when there is sunlight, but have them switch back automatically either on a schedule or by some other means when there is no sun. The solar array on the roof will be oversized and provide more power than what just the critical circuits need. I want to use this energy instead of it being wasted. I also don’t want these same loads using battery during an outage because they are not critical.

Looking for some sort of solution for a “smart” breaker or transfer switch. A breaker that can be on a schedule. Or maybe there is an entirely different solution I’m not thinking of. If I had a breaker I could put on a schedule, the loads would be connected to an auto transfer switch. The smart breaker being on or off would cause the transfer switch to direct the load where I wanted it, either on the grid or through the inverters. This seems logical in my head at least.

Hopefully what I’m wanting to do makes sense. If this solution doesn’t work, or I am completely missing something, please let me know. I am pretty new to this. My experience is doing a 24v system with an all in one unit and 1000w of solar on my trailer.
The Enphase IQ8Plus Microinverters, with the Empower Smart switch and the IQ Load Controllers, are capable of being programmed when to turn loads on and off for up to 12 x 120V circuits, and you can control when your system is grid-connected or off-grid, by using the App. The solar panels use microinverters that can provide on or off-grid power as long as the sun is shining, without a battery. It's called Sunlight Backup. The IQ Battery 10T has 12 internal microinverters, that are also charge controllers. At night, the battery uses the internal inverters to power your backup load panel, but during the day, the solar and battery microinverters can combine to provide more peak power than either alone. Allowing you to run heat pumps, air conditioners, vacuum cleaners, etc. Also, once you have the smart switch, combiner box, and line-side tap completed, you can add more solar panels and/or batteries with microinverters very easily, as your needs increase. It's also UL Listed so you can pull a permit and pass inspection.
 
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