Am I understanding this right?

[dudeinthewoods]

I'm upgrading my entire system. I've got 48 new cells coming, batrium BMS and going to probably replace my makeskyblue controllers. They're treating me well but I figure get some victron that can talk with the batrium.

I have 10kw in panels (probably add another 10kw)

1200ah @48v of lifepo4

Anyways. Debating upgrading my SCCs and going higher voltage.

I'm thinking either color or venus which basically just control the SCCs right? Batrium talks to it.

Then the part I'm confused on. The 250/100 controller. So its up to 250v or 100 amps going in to it whichever is more.

So if my panels are 250w 30voc I could throw 8 in series and be at 240v and if that's 2kw I'd only be looking at 8.3a

Now I've got 40 panels so could I do 5 sets of 8 in parallel?

Here's the part I'm lost on. That's 10kw (less in reality) but it's going to step down to 48v so that SCC would be pushing 208a out to the batteries. Is that the bottleneck?

Should I be running two controllers and 8s2p on each and I guess a 3rd that's 8s?

Maybe I'm thinking about something wrong here or should look at a different solution for the SCC. Maybe get bigger than 250/100. Or more smaller. I've got a decent run so rather not run a ton of wires but could.

Thanks!

 

[snoobler]

250/100 is 250Voc maximum cold weather input. 100A is maximum charge current to battery. The unit can only accept 70A in PV current. It has power output maximum of 5800W on a 48V system. All of this information is available from the datasheet. I suggest you consult it.

240Voc may be way too high if you experience cold weather. Victron recommends a 22% margin for cold, i.e., about 200Voc.

The only advantage to crazy high voltage is a reduction in losses from wiring. Extremely high Vmp vs. battery is actually less efficient than about 50% above the battery voltage. This has to do with additional losses in converting higher voltage to lower voltage. In many cases, these two conditions negate each other.

If you have a 10kW array, and you want to use more than 5800W of it, you need 2X 100A charge controllers. You might be able to get away with 150/100 and save about $200 each by doing 4S5P per array. Depends on your PV to SCC cable length/gauge.

 

[dudeinthewoods]

Thanks. I saw the datasheet and 5800w. I wasn't sure on where the 100a came in.

Did you get the 70a from the short circuit number? I didn't realize that was the input max but makes sense.

Thanks. I'll probably just get a bunch of controllers but it adds up fast. I've currently got 3 60a MSB that are working fine. Just wanted to upgrade

 

[snoobler]

Yes. 70A refers to the panel Isc value.

You're a brave man. I've seen too many cheap Chinese power supplies housed in those cases with defective fans to place any faith in them.

In any case, those have a 160V input limit.

How is your array currently wired?

What is the record low temperature for your area.

 

[dudeinthewoods]

Haha well I made sure to at least get legit MSB. Bad enough on legit so didn't want to get knockoffs.

I should clarify I have 40 panels. I'm only using 4 per controller right now. It gives me enough power and I haven't built my rack so no rush.

I was debating more MBS vs victron or whatever with the batrium. I'm going through their list that batrium plays with and making a decision. Victron is good no question just hate spending thousands I don't need to.

Thanks for your thoughts. I've been doing my homework just get a bit confused some times. I've learned a hell of a lot from these boards.

 

[snoobler]

IMHO, 4S5P each on 2X Victron 150/100. About $1500.

 

[dudeinthewoods]

IMHO, 4S5P each on 2X Victron 150/100. About $1500.

Makes a lot of sense. I may double up on panels can double up on the SCC too.

Your opinion is it worth doing the venus or color and integrating with the batrium? Seems like it might be flashy bells and whistles but it is slick.

 

[snoobler]

I have the CCGX, and I love it so hard. Even if you don't use a compatible BMS, VRM is so worth it.

VRM Portal - Victron Energy

vrm.victronenergy.com

I'm very mixed on the Batrium. I'm considering it for my Lithium-fire bank, but I really don't like a company that wants to charge me for sales material or to answer my pre-purchase questions.

 

[Hedges]

Another approach is AC coupling, if your battery inverter supports that.
10kW of PV could be connected as < 600Voc strings feeding a single 10kW grid-tie inverter.
Quality grid-tie inverters probably cost less per watt than quality charge controllers.

 

[dudeinthewoods]

I have the CCGX, and I love it so hard. Even if you don't use a compatible BMS, VRM is so worth it.

VRM Portal - Victron Energy

vrm.victronenergy.com

I'm very mixed on the Batrium. I'm considering it for my Lithium-fire bank, but I really don't like a company that wants to charge me for sales material or to answer my pre-purchase questions.

I got my pre sales questions answered. From what I've heard their email support is decent if you dont abuse it and the voice support is great if you want to pay / need it.

 

[dudeinthewoods]

Another approach is AC coupling, if your battery inverter supports that.
10kW of PV could be connected as < 600Voc strings feeding a single 10kW grid-tie inverter.
Quality grid-tie inverters probably cost less per watt than quality charge controllers.

Interesting. My brain is running out of capacity I'll probably keep going the way I have haha. Thanks though.

 

[snoobler]

I got my pre sales questions answered. From what I've heard their email support is decent if you dont abuse it and the voice support is great if you want to pay / need it.

Yeah, I got a handful of questions answered. I was strongly encouraged to pay for a session though. As answers prompted more questions, subsequent responses were clipped or non-existent.

One thing I HATE about Batrium is the lack of ACTIVE balancing. It's all passive. For that kind of cost, active should be a part of the package.

I'm still considering REC-BMS, Orion and ZEVA.

 

[Hedges]

Interesting. My brain is running out of capacity I'll probably keep going the way I have haha. Thanks though.

Well, what brand and model inverter do you use?

I have SMA Sunny Island (48V battery inverter) and it uses frequency shift to control grid-tied inverters when running off grid.
One of my PV inverters is Sunny Boy 10000TLUS-12. It produces up to 10kW AC.

SMA is probably the original AC coupled system, but several brands including Outback and Schneider now have battery inverters supporting it.
They suck down power from AC to charge the battery (just as they would with grid connected to their output), and raise frequency above 60 Hz so signal a reduction is power is desired.
An upside is while the sun shines your AC loads can be up to 100% of what the battery inverter can drive plus 100% of what the AC are producing at the moment.

The AC coupled inverters that support frequency shift can be found in 3kW to 10kW models, between $300 and $2000 new/used/surplus. I've paid $400 to $500 for new in the box Sunny Boy of 5kW and 6kW, also $1200 for a used 10kW one.

 

[dudeinthewoods]

Yeah, I got a handful of questions answered. I was strongly encouraged to pay for a session though. As answers prompted more questions, subsequent responses were clipped or non-existent.

One thing I HATE about Batrium is the lack of ACTIVE balancing. It's all passive. For that kind of cost, active should be a part of the package.

I'm still considering REC-BMS, Orion and ZEVA.

Damn, I thought it was active. Maybe I'll just sell it for cost if someone wants it when it arrives. That's frustrating. I saw someone say active somewhere and I didn't confirm it.

I agree with everything you're saying. I had considered the others too. Might switch.

 

[dudeinthewoods]

Well, what brand and model inverter do you use?

I have SMA Sunny Island (48V battery inverter) and it uses frequency shift to control grid-tied inverters when running off grid.
One of my PV inverters is Sunny Boy 10000TLUS-12. It produces up to 10kW AC.

SMA is probably the original AC coupled system, but several brands including Outback and Schneider now have battery inverters supporting it.
They suck down power from AC to charge the battery (just as they would with grid connected to their output), and raise frequency above 60 Hz so signal a reduction is power is desired.
An upside is while the sun shines your AC loads can be up to 100% of what the battery inverter can drive plus 100% of what the AC are producing at the moment.

The AC coupled inverters that support frequency shift can be found in 3kW to 10kW models, between $300 and $2000 new/used/surplus. I've paid $400 to $500 for new in the box Sunny Boy of 5kW and 6kW, also $1200 for a used 10kW one.

Awesome. I was actually looking at picking two of those up a few hours ago. It also seemed like a good way to get 220v.

I'm currently using a Chinese generic inverter one of the "reliable" brand. Honestly it's been nothing but great. I was just upgrading. I'd keep it around as a backup for sure if I do upgrade.

I'd probably do 2x 5k or 2x 10k on those guys.
Great suggestion I'll dig in more before I ask questions. Thanks.

 

[snoobler]

Yep. She referred me to this doc:

https://s3.amazonaws.com/helpscout.net/docs/assets/5af3b7ec0428631126f1e589/attachments/5df41bf52c7d3a7e9ae51d65/BMon-and-LMon-LeafMon-Data-Sheet-Ver-2.0.pdf

"bypass" current is "bleeding off through a resistor"

It CAN be disabled. I already have the 4A active balance modules, so it's still on the table for me.

 

[dudeinthewoods]

Yep. She referred me to this doc:

https://s3.amazonaws.com/helpscout.net/docs/assets/5af3b7ec0428631126f1e589/attachments/5df41bf52c7d3a7e9ae51d65/BMon-and-LMon-LeafMon-Data-Sheet-Ver-2.0.pdf

"bypass" current is "bleeding off through a resistor"

It CAN be disabled. I already have the 4A active balance modules, so it's still on the table for me.

So I'll blame myself for this but them a little bit. Also whoever said it was AB before..not happy I didn't dig more.

Per their site:

"For large capacity cells this is only achievable when there is plenty of balancing power to remove or relocate the energy from one cell to another. For example a 14kWh battery at 52v nominal battery has 270Ah cells."

OR RELOCATE to me implies it does AB even though it doesn't specifically say it does and if you dig you'll find that out.

I may have to throw these in the for sale NIB and look at the others. I was excited for it.

 

[lynhnn]

Extremely high Vmp vs. battery is actually less efficient than about 50% above the battery voltage.

Do you have some statistics or numbers or table to show some data? I'd like to know.

 

[snoobler]

It will take some digging on your part. Look up the efficiency curves published in several charge controller manuals. Higher voltage is about 1-2% less efficient than about 50% above battery voltage, but that's often about the same improvement in voltage drop you get with higher voltage PV wiring.

Meh. I did it for you:

https://www.outbackpower.com/downloads/documents/charge_controllers/flexmax_6080/owner_manual.pdf

PDF page 104.

 

[rhino]

Yeah, I got a handful of questions answered. I was strongly encouraged to pay for a session though. As answers prompted more questions, subsequent responses were clipped or non-existent.

One thing I HATE about Batrium is the lack of ACTIVE balancing. It's all passive. For that kind of cost, active should be a part of the package.

I'm still considering REC-BMS, Orion and ZEVA.

I'm genuinely curious why is it that bad it is passive instead of active? Are the passive implementations inherently more reliable/less complicated than the active ones?