Cheapest way to add Batteries to an existing solar system?

[Asthix]

Hi,

After spending a lot of time searching, i'd like to add some batteries(15kWh) to my current 6.4KW solar system, that's been running for a bout 2 years now.

• Using about 60kWh per day, my system is producing about 40-45kWh daily.
• 16 * TrinaSolar 405W
• 6KW Huawei sun2000-6ktl-l1 / Hybrid Grid tied but limited to Huawei battery
• I have space for 6-8 more panel that could be installed.

Using Luna Batteries is out of the equation, the price in Europe is crazy high, about 9000$ installed myself.
So i thought about few things:

1:

• Victron Multiplus II 48V/230V 5000VA 70A-50A
• Cerbo GX
• 16s EVE LF280K / LF304 / MB31
• JK / JBD BMS with active cell balancer
• + In the future, i could add either using MPPT or cheap Micro inverter kit if there is any discount

2:

• Changing the Huawei inverter to a hybrid one that we could find in europe?
• I've seen DAYE and Growatt.

The cost would be approximately the same as using the stuff from Victron but i feel Victron, must be more reliable?
Also i would be able to add more panel down the line, or at least, not as easily as i won't be able to find the same panel.


I've got few quote from Alibaba sellers name that i found here :

1. Luyuan : 16 * MB31 314Ah 1500$ DDP
2. Docan: 16* LF304 304Ah 1180$ DDP
3. Qishou: 16* LF304 304Ah 1384$ DDP from EU
4. EVE : 16*MB31 314 aH 1075$ not shipped ( waiting for quote)

Would you have any suggestion regarding what i offered?
Which BMS should i go for? Ideally, talking with the Converter would be nice, but if that comes at an extra $$$ i don't mind not having it.


Thanks!

 

[chrisski]

I'd like to know more details about the inverter you already have.

I'm assuming you have a grid tied inverter that will put out its max rating and you use this and any excess gets sold back to the grid.

If this is true I'd think that an AC coupled battery is what you want. This is really a second inverter that converts the AC power to DC for your batteries. This can work better if permitting is involved.

It does sound like this is a DIY project and you are thinking of scrapping your system to get a hybrid inverter. This may be a better inverter.

 

[Asthix]

I'd like to know more details about the inverter you already have.

I'm assuming you have a grid tied inverter that will put out its max rating and you use this and any excess gets sold back to the grid.

If this is true I'd think that an AC coupled battery is what you want. This is really a second inverter that converts the AC power to DC for your batteries. This can work better if permitting is involved.

It does sound like this is a DIY project and you are thinking of scrapping your system to get a hybrid inverter. This may be a better inverter.

It's a Hybrid grid tied inverter, that has the ability to use the Proprietary LUNA battery from Huawei.

Any excess is given for free, and if i give to much, i'll even have to pay extra

The AC coupled battery which would then be by the Victron, but is there any other brand that offer these type of converter?

Anything is possible as of now, i've installed it myself and i can basically do anything, if that make sense in regard to the budget/use.

Scrapping the actual inverter could be possible, but then, which hybrid converter would be good, and found in Europe?
I mostly see Growatt, Sofar installed with Pylontech here.

 

[chrisski]

The AC coupled battery which would then be by the Victron, but is there any other brand that offer these type of converter?

I don't know a whole lot about the AC coupled system, but every AC coupled inverter I looked at was made specifically for turning a grid tied inverter AC voltage to DC to charge a battery. I've never heard of Victron doing this. I would not recommend this, but an example of a AC coupled invertter is the Mojave made by Outback. THis shows the pathway for this:



IMO, Victron would work just fine as a primary inverter and interface with the batteries, you would simply lose the ability to export to the grid and depending on loads, would lose the ability to power loads once above the rating of the Victron inverter. You're looking for a system that would have grid zero, or zero export.

 

[wpns]

• system is producing about 40-45kWh daily.
• 16 * TrinaSolar 405W

You are getting 6-7 peak solar hours per day?

Anyway, IMHO AC coupled batteries just add more complexity. If you want to add more panels and non-proprietary batteries then you probably want to get away from your existing inverter which is the piece that’s holding back everything else.

 

[SeaGal]

Scrapping the actual inverter could be possible, but then, which hybrid converter would be good, and found in Europe?
I mostly see Growatt, Sofar installed with Pylontech here.

Bienvenue!

Check out Solis too, as well as Sunsynk/Deye, both popular in UK and Europe.

My recommendation, if you are adding additional panels would be to add a Solis hybrid in parallel with your existing system, e.g. S5-EH1P-6kW. Then split the panels between the Solis and the existing inverter. The Solis will charge not only from its own PV input, but also from excess AC generated by your existing inverter. And you can limit export too, if that is going to potentially cause you issues.

 

[Asthix]

I don't know a whole lot about the AC coupled system, but every AC coupled inverter I looked at was made specifically for turning a grid tied inverter AC voltage to DC to charge a battery. I've never heard of Victron doing this. I would not recommend this, but an example of a AC coupled invertter is the Mojave made by Outback. THis shows the pathway for this:

View attachment 229511

IMO, Victron would work just fine as a primary inverter and interface with the batteries, you would simply lose the ability to export to the grid and depending on loads, would lose the ability to power loads once above the rating of the Victron inverter. You're looking for a system that would have grid zero, or zero export.

I've read it works well, but i was wondering if there is any better solution to that, either financial or pratical sense

You are getting 6-7 peak solar hours per day?

Anyway, IMHO AC coupled batteries just add more complexity. If you want to add more panels and non-proprietary batteries then you probably want to get away from your existing inverter which is the piece that’s holding back everything else.

A picture is worth a thousand words right? As of today(you can see when my water heater got fully warmed up):

Why is that surprising? I'm seeing these value since about April, the Peak power is reduced with the heat, About 4.8Kw, as opposed to the Peak 6Kw in april-may.

Complexity isn't an issue if it is "worth" it in my opinion, i'm pretty satisfied with this inverter but i can understand why swithcing to a "All-in-one" unit make sense. Also the cost from Victron VS Inverter end up being the same, if not more expensive for the latest.
Is there anybrand you would recommend?

Bienvenue!

Check out Solis too, as well as Sunsynk/Deye, both popular in UK and Europe.

My recommendation, if you are adding additional panels would be to add a Solis hybrid in parallel with your existing system, e.g. S5-EH1P-6kW. Then split the panels between the Solis and the existing inverter. The Solis will charge not only from its own PV input, but also from excess AC generated by your existing inverter. And you can limit export too, if that is going to potentially cause you issues.

Thanks for the suggestion, i'll look into these brand and what i could find.
I like what you suggested, as i've put a screenshot of my production/usage, i don't have that much excess to charge the battery but mixing it that way would work.

Thing is, how can i prioritize what's being produced on one compared to the other. e.g: If the power is taken from the Solis with the battery instead of the Huawei inverter, i'll end up with excess energy being reinjected in the grid?

 

[Hedges]

Depends on how PV strings are wired for your present inverter, but "cheapest" way to add batteries is probably to remove existing inverter, connect the cheapest hybrid you can find that supports cheap batteries.

This could even be an offgrid inverter with AC input, if you put all loads downstream and it is able to start them.

Easiest way is to replace with a hybrid inverter that can backfeed house & grid, with CT at the meter connection for zero export, if desired. It can provide backup for select loads downstream. It does not have to start large loads upstream; the grid will do that.

Adding a battery inverter which AC couples to your existing inverter may be possible, may have issues. My system is like that, but the battery and GT PV inverters are designed to work together.

Read about issues and responsiveness of support before selecting "cheapest". Some companies have much better support than others. Some inverters are cheap enough you can buy a spare, but that only helps with failures not incorrect operation.

 

[SeaGal]

Thing is, how can i prioritize what's being produced on one compared to the other. e.g: If the power is taken from the Solis with the battery instead of the Huawei inverter, i'll end up with excess energy being reinjected in the grid?

So, the Solis will have a CT clamp at the grid connection and where possible will do what it can to keep the grid import/export to zero.

If there is spare from the Huawei (not being used by the house load), the Solis will charge its batteries from the excess.

If the Huawei is generating exactly what the Solis needs, the Solis will charge batteries from its PV, until the batteries are full. Only when it can't charge will it then export. But if you have limited export from the Solis it will reduce the amount it draws from the panels attached to it.

 

[Asthix]

Depends on how PV strings are wired for your present inverter, but "cheapest" way to add batteries is probably to remove existing inverter, connect the cheapest hybrid you can find that supports cheap batteries.

This could even be an offgrid inverter with AC input, if you put all loads downstream and it is able to start them.

Easiest way is to replace with a hybrid inverter that can backfeed house & grid, with CT at the meter connection for zero export, if desired. It can provide backup for select loads downstream. It does not have to start large loads upstream; the grid will do that.

Adding a battery inverter which AC couples to your existing inverter may be possible, may have issues. My system is like that, but the battery and GT PV inverters are designed to work together.

Read about issues and responsiveness of support before selecting "cheapest". Some companies have much better support than others. Some inverters are cheap enough you can buy a spare, but that only helps with failures not incorrect operation.

I don't really need to set it up as a Backup in case i loose grid, i may loose grid about 30 minutes per year maximum!
Thanks for the advice, i'm looking into it and even though not budget friendly Deye seems to be a good pick here.
I've seen few growatt, and other model but the GEN port is quite interesting to feed from another inverter or Micro inverter if added

So, the Solis will have a CT clamp at the grid connection and where possible will do what it can to keep the grid import/export to zero.

If there is spare from the Huawei (not being used by the house load), the Solis will charge its batteries from the excess.

If the Huawei is generating exactly what the Solis needs, the Solis will charge batteries from its PV, until the batteries are full. Only when it can't charge will it then export. But if you have limited export from the Solis it will reduce the amount it draws from the panels attached to it.

Yeah i see what you mean, but both Inverter will work together with there own clamp, so the most responsive might feed the power first to the load.
So let's say that the Solis is providing the power quicker than the Huawei by few ms, then the Huawei would backfeed to grid(or zero if setup), but the Solis wouldn't charge the battery. The EYE have a GEN port that is setup to be able to drive either Micro inverter and grid tied inverter and modualte the frequency to stop them if excess/ not willig to backfeed.
In any case, i don't mind either feeding back to grid or use it as a backup, but would be nice if possible .

Is there any brand that somebody would suggest as an inverter as Deye (2500$ for an 8KW!)