Are there inverters that do programmable SBU

[Dinobot248]

Are there any inverters (AIO or piece meal approach (Victron?)) that have a programmable SBU function?

I know the question is vague so here is my use case. I want my system to run on solar, a certain amount of battery, and utility covers the rest.

For example, there is a 6kw load ( eg dishwasher, microwave, blow dryer are causing the short term spike in use)

1. Solar supplies 1kw
2. Battery is configured / programmed to supply max 4kw
3. Utility supplies the rest 1kw

Normally the combination of Solar and battery is sufficient to cover nearly all loads.


My reasons are

1. Battery does not drain down to empty level before the next day. System does not shutdown.

2. I can leave town for a week and not worry as much about “Murphys Law”

3. If the a grid account is required for any reason (local ordinance, convenience, etc) might as well make use of it.

4. I can reduce my battery bank size.

5. I can get better utilization of my system eg shift batteries or PV over to another place. Maybe quicker ROI. Maybe get a better inverter while I am at this.



I read the Solar 15k and watch how Victron power assist work. Both appear to treat the grid as your primary power source. Solar and/or battery can be configured to supplement and covers any peak demand.

I want to treat Solar and battery as the primary power source and have the grid supplement when necessary.

I thought about maybe having two inverters connected say two 5k Quattros. It gets kind of silly to have one inverter act as the grid for the second inverter.

 

[timselectric]

A typical AIO in SBU mode will use solar and battery to power the loads. Until a set battery SOC is reached. Then it switches over to AC input. And remains until solar recharges the battery to another set SOC. At which time it switches back to solar and battery.

 

[wildbillpdx]

A typical AIO in SBU mode will use solar and battery to power the loads. Until a set battery SOC is reached. Then it switches over to AC input. And remains until solar recharges the battery to another set SOC. At which time it switches back to solar and battery.

That's the way I have my EG4 6000ex configured. Low SOC is 30% (EG4 batteries show percentage rather than charge). Utility power charges the battery to 95% (along with solar if available) and then goes back to solar and battery.

 

[timselectric]

I never want to charge from utility.
That's what my solar panels are for.

 

[wildbillpdx]

I never want to charge from utility.
That's what my solar panels are for.

Agreed. However, my system isn't big enough to go off-grid and never will be. Not enough room for solar panels. I've got 4kW of panels (20x200 watts from an old grid-tied system) and that's about all the space I have. This supplements my main grid-tied system (9.6kW on the roof) and even between the two, not enough for all the usage.

 

[timselectric]

Agreed. However, my system isn't big enough to go off-grid and never will be. Not enough room for solar panels. I've got 4kW of panels (20x200 watts from an old grid-tied system) and that's about all the space I have. This supplements my main grid-tied system (9.6kW on the roof) and even between the two, not enough for all the usage.

If you are AC charging from a grid-tied inverter.
I'd still consider that solar charging.

 

[400bird]

Are there any inverters (AIO or piece meal approach (Victron?)) that have a programmable SBU function?

I know the question is vague so here is my use case. I want my system to run on solar, a certain amount of battery, and utility covers the rest.

For example, there is a 6kw load ( eg dishwasher, microwave, blow dryer are causing the short term spike in use)

1. Solar supplies 1kw
2. Battery is configured / programmed to supply max 4kw
3. Utility supplies the rest 1kw

Normally the combination of Solar and battery is sufficient to cover nearly all loads.


My reasons are

1. Battery does not drain down to empty level before the next day. System does not shutdown.

Does your system currently "shut down" as it BMS disconnect?
That's a programming/settings problem you probably can and definitely should fix with your current system.

2. I can leave town for a week and not worry as much about “Murphys Law”

I'd hope that was how every system operated.

Maybe get a better inverter while I am at this.

10/10 idea of you can't program something like this into your current inverter.

 

[wildbillpdx]

If you are AC charging from a grid-tied inverter.
I'd still consider that solar charging.

It's a grid-tied inverter but I'm charging at night. During good days, the batteries discharge to about 35-40% overnight and recharge via solar the next day.

 

[timselectric]

My system started very small. As I tested proof of concept. If the weather didn't cooperate, I would run on grid for a couple of days, sometimes.
I didn't see any benefit from charging from the grid.
I was already powering my loads from it.
And I didn't want to miss out on solar production. Because I had already charged the batteries, from my wallet.

 

[Dinobot248]

Thanks for the responses.

Probably some more context is helpful. It’s probably going to sound more like complaining


My EG4 6500EX shuts down from time to time for about a second. All charts like PV input, AC out, battery out drop to zero / near zero. This totally annoying and appears somewhat common based on forum discussions. I can see the drops from SA

My house only has led lights and they flicker randomly

Still have not been able to upgrade firmware on liefpower4 batteries. Maybe a bad cable and don’t have the time during the day to wait 2 hours with SS. The BMS program can connect to the com port and that’s it.

Still working on the system. Just went back to a single inverter. Parallel single phase 120v had too high idle power consumption about 80w for each. I knew this going into the purchase but I can still complain about.

Need to deal with a household who may not appreciate what is installed. No one besides me knows how to restart the system. High voltages are dangerous and prefer spouse / kids to stay away.

Yard / house not ideal for solar. Good solar that charges the batteries is from 12 - 4pm if the weather cooperates

Willing to learn a $3k lesson and drop the 6500s altogether if I can find a more stable AIO

 

[timselectric]

Sorry for what you are dealing with. But I guess that the answer to the original question is.
Yes, all but the ones you have.

 

[SeaGal]

Are there any inverters (AIO or piece meal approach (Victron?)) that have a programmable SBU function?

I know the question is vague so here is my use case. I want my system to run on solar, a certain amount of battery, and utility covers the rest.

By programmable, do you mean dynamically programmable from a micro-controller or similar?

I thought most battery systems allow the configuring of a max-charge and discharge current, which is signalled to the inverter over CAN/RS485 bus.

 

[Dinobot248]

I never want to charge from utility.
That's what my solar panels are for.

I feel the same and don't want to charge from the grid. That's why I want to have some type of "Solar / battery shaving" where grid will be configured to shave off the peaks for the solar / battery. The concept is similar with grid shaving or victron power assist, but flip flops the grid and battery sources.

I like this better than having to charge battery at a specified SOC %. That really forces me to use more grid power.


I don't know how well the 6500 handles certain programmed functions. With their track record, I cannot assume it will work and I don't have the time to be a tester. For example, will the 6500 initiate a charge at low SOC % and stop at a higher SOC %. Will it shutdown and properly restart if overloaded or temp is too high.

 

[Dinobot248]

By programmable, do you mean dynamically programmable from a micro-controller or similar?

I thought most battery systems allow the configuring of a max-charge and discharge current, which is signalled to the inverter over CAN/RS485 bus.

The max charge and discharge current for a battery serves a different function. I would consider those to be stop gap / safety related items.


I'm referring to having your inverter share or split the house electric load between solar, battery and utility. The inverters can handle sharing or supplying the house load between solar and battery. My inverter EG4 6500EX does not share or split the load among all three (solar, battery, and utility). I want "utility" to cover the solar and battery during certain peak times and want to configure that peak KW threshold.

Other brands do have a grid assist or power assist that will allow the solar / battery to shave off the peak demands from the grid. I want the same concept except flip flopped. I want the grid to assist the solar and battery at lower thresholds. Its difficult to test the scenario when I have only one system to power the house and cant take it offline to do test different scenarios.


I know the grid assist or power assist are features on higher priced inverters so I was asking if anyone knew of a better inverter (and likely more expensive).

 

[timselectric]

I feel the same and don't want to charge from the grid. That's why I want to have some type of "Solar / battery shaving" where grid will be configured to shave off the peaks for the solar / battery. The concept is similar with grid shaving or victron power assist, but flip flops the grid and battery sources.

I like this better than having to charge battery at a specified SOC %. That really forces me to use more grid power.


I don't know how well the 6500 handles certain programmed functions. With their track record, I cannot assume it will work and I don't have the time to be a tester. For example, will the 6500 initiate a charge at low SOC % and stop at a higher SOC %. Will it shutdown and properly restart if overloaded or temp is too high.

What you want to do (blending grid with battery) requires a hybrid AIO.
But then you have to deal with a utility company agreement. Or getting in trouble when it unexpectedly exports.

 

[Dinobot248]

What you want to do (blending grid with battery) requires a hybrid AIO.
But then you have to deal with a utility company agreement. Or getting in trouble when it unexpectedly exports.

I don't want to sell / export energy back to the grid. Never did and never will.

I probably want the functions included in a hybrid AIO but its not to sell / export energy.

First, I simply want my inverter to work reliably.
Second, I am willing to buy a new inverter that does work better and can program the grid to assist solar and battery.

I am keeping my grid / electric account open for now to minimize unwanted attention and feel the small monthly payment is worth it


I read the manual for the SolArk 15k (supposedly top of the line) and I was not impressed and did not find the functionality of the grid assisting the solar and battery. I refuse to look at the EG4 18K and don't want a $6k paper weight. Victron does things piecemeal so they don't have an AIO in the US market. The function of SBU does not appear to exist. They can do a SUB, probably better to say UB with their power assist but thats not what I want.

 

[Solar Guppy]

There is no Hybrid inverter that 100% will not sell to the grid, there is always the edge case that with large loads turning on/off the inverter can take a few seconds to adjust output which it will export.

 

[Dinobot248]

There is no Hybrid inverter that 100% will not sell to the grid, there is always the edge case that with large loads turning on/off the inverter can take a few seconds to adjust output which it will export.

I wanted to emphasize that I don't want to sell / export to the grid. It would have been better to say, I am reasonable and understand that the equipment may have "leakage" back to the grid. While its not good, that is probably reality and acceptable.

My main point is that I am trying to setup a reliable off-grid system. If I had unlimited or more funds, I would take brute force approach and buy another 100kw of batteries and this discussion would have never started. I have no desire to setup an on-grid system due to unwanted oversight and the utilities in the area discourage such systems with their residential solar programs.


Since I don't have unlimited funds, I wanted to build a slightly better solution that can withstand some of the unwanted / unanticipated high loads when I am away from home. Some people have kids, pets, plants, etc that prevent them from leaving for a couple of days. I have PV system that I want to make more reliable so it does not go down.

The grid assisting the solar / battery during high loads sounds like a good idea. Its probably not the ideal case for a hybrid AIO or off-grid AIO considering there is the option to charge the battery at a low SOC % and stop charging at a higher SOC %.

If I had the question, I'm sure others have a similar question.

 

[Adam De Lay]

Victron does things piecemeal so they don't have an AIO in the US market. The function of SBU does not appear to exist. They can do a SUB, probably better to say UB with their power assist but thats not what I want.

The way I have my Victron 5kVA system set up right now is when I get down to 15%, it switches back to grid. PV gets dumped directly into the battery to get you off grid faster (when your on grid power, it's only grid power). Once I hit 30% SOC, it switches back to battery mode.

In the event that my loads draw more than a set threshold (can't remember what it is right now because I've never actually hit it), the grid automatically kicks in and runs the load until the release threshold has been met, then the grid drops out and everything runs from battery again.

The Victron Power Assist is backwards of what you would want. It's more designed for generators being used for the AC IN. If the AC IN load exceeds a set value, then power would be pulled from the battery and added to the load.

I'm not aware of any way to successfully blend battery and grid power where battery is the main power source.

 

[timselectric]

I use a chargeverter to do it when my battery is low.
That's not exactly what is wanted here. But it could sorta accomplish the goal.
It's based on battery voltage. If the battery voltage drops below a set point, the chargeverter steps in. The chargeverter is powered by the grid.
This allows me to keep a certain amount of capacity in reserve.
I'm still using battery and solar. And there's no complete transfer.