Advanced Inverter Control, Is It Possible to Make It Peak Shave?

[Orski]

Around a year ago my cousin implemented a solar system in our place, and it's been great. As of lately the battery isn't holding out all night when using it after dark, we have a grid power system up to 1320 W, and our after dark usage is being around 1700 W and as our inverter doesn't support peak shaving we manually switch the grid off and rely solely on the battery, which in most cases drains it. As I was looking around I found that I can connect a Pi Zero to my inverter and send advanced commands, but my cousin later explained that it will only send commands that are already supported, so automating a peak shave using home assistant won't be possible. The inverter we have is a Voltronic Power rebranded to SunEnergy, though I couldn't find the specific Voltronic model but I think it's the Axpert VM III 6KVA variant which doesn't exist on Voltronic's products page (1.5/3/5KVA variants exist and are here). I attached pics to the sticker on the side of the inverter that has the specs.

I thought about flashing a custom firmware, but my cousin said that it might not be physically possible to peak shave, and it's risky.

If you guys have any suggestions, on what I can do to use the grid and peak shave at 1320 W which should save power usage on the battery and protect it from drainage.

Thank you.

 

[Orski]

I should probably mention that the grid isn't always connected to the inverter, we only switch it on when we want to charge the battery from the grid. Which makes it seem like using both at the same time should work, but it doesn't?? It's really confusing, this seems to be software limited but it might not be. If you have any insights, that would be greatly appreciated.

 

[BentleyJ]

Yes it takes much more sophisticated hardware and software for an inverter to be Grid-Interactive. That's part of the reason products like. Sol-Ark, Outback and Schneider cost more. We use a Schneider XW+ 6848 and the Peak Load Shave function is absolutely seamless and fully automatic. (except for the lack of battery recharge with AC coupling) Starts at 4pm and ends at 9pm without even a flicker of an LED.

 

[zanydroid]

I should probably mention that the grid isn't always connected to the inverter, we only switch it on when we want to charge the battery from the grid. Which makes it seem like using both at the same time should work, but it doesn't?? It's really confusing, this seems to be software limited but it might not be. If you have any insights, that would be greatly appreciated.

Inverters that only list SBU/SUB etc modes often cannot charge and invert at the same time / in rapid succession of switching. Hardware limitation if the topology is not inherently bidirectional.

Also even if you can math out using unidirectional topology, it may not have the control loop implemented (and it needs to be a tight one not one on order of seconds which is what one implemented on an external API is generally limited to), or have the feedback sensors necessary to do so. Think about it. If something reacts on the order of seconds, how would it avoid pushing to grid for a second (wastes battery)? How would it sync to grid voltage & frequency with the right phase control if it does not have the right feedback circuitry?

 

[Hedges]

Around a year ago my cousin implemented a solar system in our place, and it's been great. As of lately the battery isn't holding out all night when using it after dark,

Same load as before, shorter run time?
Sounds like a lead-acid battery losing capacity. After 365 cycles.
Possibly not being charged/maintained/discharged optimally, possibly that's all the cycle life it has.

we have a grid power system up to 1320 W, and our after dark usage is being around 1700 W and as our inverter doesn't support peak shaving we manually switch the grid off and rely solely on the battery, which in most cases drains it.

Consider a separate battery charger powered from grid. Could be set to put a floor on battery voltage.
While PV is producing you would use all power available from PV, also grid power if more needed.

I suggest not drawing battery down at night unless grid fails.
Chances are, battery replacement costs you more than grid power. So you want to use all PV power, grid when necessary and available, only use battery during grid failures.

 

[Orski]

Thank you all for your replies, from what you said my inverter won't be able achieve what I want. which begs the question, can I add a piece of hardware and control it to do what I want?(I don't mind doing one DIY)

Same load as before, shorter run time?
Sounds like a lead-acid battery losing capacity. After 365 cycles.
Possibly not being charged/maintained/discharged optimally, possibly that's all the cycle life it has.

No it's a greater load, with the summer heat we're using air conditioners. We usually use one at a time, one has a built-in inverter and draws around 700W the other which is in the bedroom draws around 1100W at night we usually use the 1100W AC. It's a Lithium battery, I don't think it's been running for enough time to lose capacity.

I suggest not drawing battery down at night unless grid fails.
Chances are, battery replacement costs you more than grid power. So you want to use all PV power, grid when necessary and available, only use battery during grid failures.

The grid fails at 1320W and our consumption at that time is barely above 1320W as I mentioned above, maxes out at 1700W. Which is why I was looking for a way to peak shave with my inverter.