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Inverter with off grid capabilities WITHOUT battery

Fardenco

New Member
Joined
May 18, 2022
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9
Hi,
I'd like to install solar panels on my house. My goal is to reduce my bills, carbon footprint, and dependency to the grid.
That last point is important to me, but not enough to make me buy an expensive battery.
Not knowing much about solar, I naively assumed that any solar installation would be able to power my house in the event of an outage.
I mean, I have solar panels, I have an inverter, what else would I need.
But from what I understand, the problem is that grid tied inverters are designed to draw as much power from the panels as possible ans send it to the their output. Then you use what you use, and the rest goes to the grid.
The solution would be to use an hybrid inverter, but many seem to only do what I want if you add a battery to the system, and I don't want that. Reading through the descriptions in online stores, it's never really clear whether the offline capabilities are available without battery.
For now the only system that seems to do what I want is Enphase IQ8 which is not available for now, or some overpriced inverters like the sol-ark.
But even with the IQ8, this is not perfect because it's a micro inverter and I really don't need that. My system will be composed of 16 405Wc panels, all on the same roof with nothing to make shadows on them except clouds. And from what I understand, micro inverters are less efficient, right ?
I think one common solution is to use AC coupling, but from what I've read it only works down to a certain power, if the load is too low then the frequency goes up too much and the inverter shuts off.
This is what I understand. Am I wrong ?
What I want is quite simple : a system that can produce electricity at full power and send the surplus to the grid when it is online, and that can also work off grid by giving me from 0W to full power depending on my load, without any battery.
Do you have any advice about that ? Should I look for an hybrid inverter or for micro inverters ?
Micro inverters are more expensive but my supplier gives me a 25 years warranty on them vs 10 years for classic or hybrid inverter
Thanks
 
Its only half a solution without a battery.

What if the grid goes down on a very cloudy day or at night ?
No matter how many solar panels you have, you will still be sitting in the dark.
 
Delta H6 hybrid inverter will supply 6kw as a grid tie inverter and will also supply 6kw to offgrid love ads without using a battery. I have one I’d be willing to get rid off. I used it for one month before I realized my electric company wasn’t 100% honest about their solar program.
 
Delta H6 hybrid inverter will supply 6kw as a grid tie inverter and will also supply 6kw to offgrid love ads without using a battery. I have one I’d be willing to get rid off. I used it for one month before I realized my electric company wasn’t 100% honest about their solar program.
How does it produce power to the loads with no battery, no grid, and no solar (night time or cloudy)

It can't.
 
Sunny Boy does that, 2000W 120V available when grid is down but sun is up from "Secure Power" feature of newer models.

I thought some of the MPP or GroWatt were batteries optional.
If you hook up something like four automotive batteries or small AGM, that should give it better starting surge for motors.
 
I have the MPP LV6548 and when in batteryless mode, with 6000w of solar connected to it and no grid connection, I was able to run 3x RV ACs consistently. (This was just for testing).

But as soon as the sun is down, its all gone. Doesnt matter what inverter you have.

So you have power during 6 or 7 hours of the day I guess.
 
Sunny Boy does that, 2000W 120V available when grid is down but sun is up from "Secure Power" feature of newer models.

I thought some of the MPP or GroWatt were batteries optional.
If you hook up something like four automotive batteries or small AGM, that should give it better starting surge for motors.
The 5000ES is battery optional.
But, clouds wreck the output without grid assist.
 
Without a battery, you can't get a stable output from solar. In a grid down situation. Due to clouds moving through the sky. It doesn't take much battery, but its necessary.
Is that true even if the solar installation is much more than I need ? I'll install 6kW and I rarely need more that 2 or 3kW
I could use a 1kWh deep cycle lead acid battery in the event of an outage, would that help ?

How does it produce power to the loads with no battery, no grid, and no solar (night time or cloudy)

It can't.
Its only half a solution without a battery.

What if the grid goes down on a very cloudy day or at night ?
No matter how many solar panels you have, you will still be sitting in the dark.
Yes of course but I can accept that. This is a compromise between cost and functionality, for now I think batteries are too expensive compared to my need for them

Sunny Boy does that, 2000W 120V available when grid is down but sun is up from "Secure Power" feature of newer models.

I thought some of the MPP or GroWatt were batteries optional.
If you hook up something like four automotive batteries or small AGM, that should give it better starting surge for motors.
I have the MPP LV6548 and when in batteryless mode, with 6000w of solar connected to it and no grid connection, I was able to run 3x RV ACs consistently. (This was just for testing).

But as soon as the sun is down, its all gone. Doesnt matter what inverter you have.

So you have power during 6 or 7 hours of the day I guess.
The 5000ES is battery optional.
But, clouds wreck the output without grid assist.
That's interesting, I'll look at those inverters, thanks

Delta H6 hybrid inverter will supply 6kw as a grid tie inverter and will also supply 6kw to offgrid love ads without using a battery. I have one I’d be willing to get rid off. I used it for one month before I realized my electric company wasn’t 100% honest about their solar program.
What did they tell you ?
 
Is that true even if the solar installation is much more than I need ? I'll install 6kW and I rarely need more that 2 or 3kW
I could use a 1kWh deep cycle lead acid battery in the event of an outage, would that help ?
A 1kWh lead acid deep cycle will actually only give you 500Wh of capacity, and considering the standby consumption alone of some of these inverters, like the LV6548, is 65 watts. If it sat idle all day, it would consume 1560Wh on its own. You need a much larger battery bank than that for it to be at all worth it.

To put a little into perspective, my system has been sitting idle for about 6 weeks since I moved into my home, and my 2x LV6548's have been consistently consuming 3.5kWh just sitting there.
 
How does it produce power to the loads with no battery, no grid, and no solar (night time or cloudy)

It can't.
Havnt seen an inverter yet that can do that. But if the array is over sized then it can power some loads when cloudy
 
Any small amount of battery will work. Just to smooth out the solar variations.
Yes.

But I’m thinking OP would enjoy life more and incidentally his wife much more if he just dropped off $600 at walmartha for 6 deep cycles or maybe $750 for a pair of 100Ah LiFePo amazonian batts the Will reviewed recently.
Furthermore, I’d be inclined to use an off-grid/hybrid thst can pass grid with no grid-feedback and at least get the stuff to pay for itself. If truly as over paneled as stated, $2000 of LiFePo would run a lot overnight.

So then you have ‘some’ backup power no generator required AND reduced average monthly electricity bills… it may not payback quickly, but it will payback eventually plus you get to use it in the meantime
 
Is that true even if the solar installation is much more than I need ? I'll install 6kW and I rarely need more that 2 or 3kW
I could use a 1kWh deep cycle lead acid battery in the event of an outage, would that help ?

Any small amount of battery will work. Just to smooth out the solar variations.

A 1kWh lead acid deep cycle will actually only give you 500Wh of capacity, and considering the standby consumption alone of some of these inverters, like the LV6548, is 65 watts. If it sat idle all day, it would consume 1560Wh on its own. You need a much larger battery bank than that for it to be at all worth it.

Motor starting surge is about 5x operating current, and only lasts a fraction of a second. Too long for most capacitors to support, however.
A very small battery, but capable of high current, should let a system start then run much larger loads.

If lead-acid, you would want low battery cutout to be quite a high voltage, keeping SoC above 80% or 90%, so it can give 10 to 20 year life. Voltage will drop low at high current, so inverter needs to allow some seconds before shutting down if it doesn't understand Peukert.

Possibly super-capacitor bank would also work. But I think used automotive batteries from the wrecking yard would be an economical first implementation. Handy as spare or jump starter for your vehicles too.



One link somewhere around here had video of a contractor who installed 6kW Sunny Boys for a customer, and they demonstrated that Secure Power was able to start a large angle grinder. That looked like one that might draw 15A full load, so I think Secure Power may deliver surge well over the 2000W rating they quote. System is sized for 240Vrms output, so when buck converter is delivering 120Vrms the capacitor voltage can swing a lot to release stored energy.

I think solar with large loads in the daytime is a reasonable goal. I run my central A/C with a fraction of PV output.
DC or AC powered LED lights and communications could be powered 24/7 from battery. Much of the gear is 12V, so separate AGM battery and charger could be used.
 
Yes.

But I’m thinking OP would enjoy life more and incidentally his wife much more if he just dropped off $600 at walmartha for 6 deep cycles or maybe $750 for a pair of 100Ah LiFePo amazonian batts the Will reviewed recently.
Furthermore, I’d be inclined to use an off-grid/hybrid thst can pass grid with no grid-feedback and at least get the stuff to pay for itself. If truly as over paneled as stated, $2000 of LiFePo would run a lot overnight.

So then you have ‘some’ backup power no generator required AND reduced average monthly electricity bills… it may not payback quickly, but it will payback eventually plus you get to use it in the meantime
Maybe but that would mean adding yet another feature to look for for my inverter, which is that it should be able to accept any battery.
I don't know much about all of this, and I know a battery is just a battery, but the 2 models of hybrid inverter my provider showed me both use only proprietary batteries, which is also probably why I have been with this idea that batteries are too expensive. Or maybe it's the price. About 1200€/kWh.
But you're right, if it can pay for itself it's a great solution
Motor starting surge is about 5x operating current, and only lasts a fraction of a second. Too long for most capacitors to support, however.
A very small battery, but capable of high current, should let a system start then run much larger loads.

If lead-acid, you would want low battery cutout to be quite a high voltage, keeping SoC above 80% or 90%, so it can give 10 to 20 year life. Voltage will drop low at high current, so inverter needs to allow some seconds before shutting down if it doesn't understand Peukert.

Possibly super-capacitor bank would also work. But I think used automotive batteries from the wrecking yard would be an economical first implementation. Handy as spare or jump starter for your vehicles too.



One link somewhere around here had video of a contractor who installed 6kW Sunny Boys for a customer, and they demonstrated that Secure Power was able to start a large angle grinder. That looked like one that might draw 15A full load, so I think Secure Power may deliver surge well over the 2000W rating they quote. System is sized for 240Vrms output, so when buck converter is delivering 120Vrms the capacitor voltage can swing a lot to release stored energy.

I think solar with large loads in the daytime is a reasonable goal. I run my central A/C with a fraction of PV output.
DC or AC powered LED lights and communications could be powered 24/7 from battery. Much of the gear is 12V, so separate AGM battery and charger could be used.
Do all hybrid inverter (or most of them at least) provide that kind of settings ?
 
Just need to do much much more research, before you spend any money.
There's many ways to skin a cat.
This stuff can be done very cost savvy.
 
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