Solar PV battery options

DrPhilG

So I wonder if using the Can cable and connecting them as PylonTech would be better after all?

garo

If the new BMS speaks the same language as Pylontech then yes it would be better to connect the Can cable to your HEYO BMS and inverter.

graememk

DrPhilG wrote: »

So I wonder if using the Can cable and connecting them as PylonTech would be better after all?

But they aren't compatible, inverter is expecting certain information from the bms in a certain way/format and if it comes even slightly different it would just error out.

Deagol

graememk wrote: »

But they aren't compatible, inverter is expecting certain information from the bms in a certain way/format and if it comes even slightly different it would just error out.

Yeah, you have to bear in mind that Canbus is a method of communication - it doesn't define the actual information that is sent / rec'd, only the encapsulation and delivery.

graememk

Deagol wrote: »

Yeah, you have to bear in mind that Canbus is a method of communication - it doesn't define the actual information that is sent / rec'd, only the encapsulation and delivery.

eg we both are using our voices to talk, but one of us could be speaking english and the other german.

DrPhilG

This came from the Solis guy on Facebook.

Not supported but should in theory work for the basics.

slave1

...so your warranty is null and void......

DrPhilG

slave1 wrote: »

...so your warranty is null and void......

Oh yeah I knew that much from the start. Goes with the territory sure with a DIY project.

DrPhilG

Good news for anyone else, batteries going on sale soon to celebrate the store's anniversary.



Sh*t news for me and anyone else who just paid about €150 per pack more than that...

Deagol

DrPhilG wrote: »

Good news for anyone else, batteries going on sale soon to celebrate the store's anniversary.



Sh*t news for me and anyone else who just paid about €150 per pack more than that...

I think I'll wait to see if your's actually arrives and works etc - thanks mr. guinea pig

DrPhilG

Deagol wrote: »

I think I'll wait to see if your's actually arrives and works etc - thanks mr. guinea pig

Ah I'm not the Guinea pig lol, 2 or 3 others have bought the same batteries from the same seller before me.

2 have already arrived and are working, one is on the way I think.

graememk

DrPhilG wrote: »

Ah I'm not the Guinea pig lol, 2 or 3 others have bought the same batteries from the same seller before me.

2 have already arrived and are working, one is on the way I think.

Neither of us have solis inverters though!

DrPhilG

graememk wrote: »

Neither of us have solis inverters though!

True but if I'm not going to try and connect the BMS via CAN, then I'm in the same boat as the rest of you, i.e. connecting as Lead Acid.

DrPhilG

A question for you smart folk who already have a LiFePo4 system set up.

Read this elsewhere, recommending AGAINST using a pack with the BMS not communicating to the inverter.

Your thoughts?

Some fella wrote:

LFP and lithium cells in general have extremely low resistance and they will practically take whatever current you throw at them. This, however, isn't great and there is an optimum charging current curve, particularly at the end of the charge cycle. Typically the primary purpose of the BMS is to handle the charging parameters in realtime by sending max current and voltage parameters every few hundred milliseconds to the inverter. By doing this, it's able to optimize the charging curve and taper the charging current at the end of the charging cycle.

There are 2 reasons to artificially taper the curve at the end. The first one is to settle the chemistry gently so that the cell retains the most amount of capacity for as long as possible. Otherwise, the internal resistance grows over time and the cell capacity diminishes.

The second reason is to keep from overloading the internal cell balancers. So as the first cell reaches the target voltage, the BMS sends instructions to the inverter to back down the charging current to an amperage that will keep that cell and subsequent cells from exceeding the target while not overloading the balancers burning off (passive) or shunting power (active) other cells.

Instructing the BMS to power-down is actually the last resort. For discharge for example, prior to that, it begins sending commands lowering the usable discharge current until the max discharge current reaches 0A. Then the inverter shuts down.

He did go on to say that it can still work fine, but those were his reasons to say that it wouldn't be the best option.

unkel

FWIW I have neglected my LiFePo4 battery, had it switched off for at least a month during the coldest bit of winter (as I used all PV directly anyway) and I have NOT been using a BMS for months now. Switched it back on a few weeks ago, hadn't checked the cells before

Yet when I checked the individual cells a few days ago, there was only 2mV between the highest and the lowest. These cells just love to sit at a bit under 3.3V no matter what

As I said before, DrPhilG, I really wouldn't have cells in parallel. I've you want to use a BMS, do it properly and have two 16S batteries with their own BMS each. Or parallel them and don't bother with a BMS

DrPhilG

unkel wrote: »

As I said before, DrPhilG, I really wouldn't have cells in parallel. I've you want to use a BMS, do it properly and have two 16S batteries with their own BMS each. Or parallel them and don't bother with a BMS

If I do that, how do the 2 separate batteries physically connect to the inverter?

championc

DrPhilG wrote: »

If I do that, how do the 2 separate batteries physically connect to the inverter?

Join the with the marine switches I recommended before. You can then isolate a string if needed.

The switch has 4 positions, at 3, 6, 9 and 12 o'clock. Off, A, A+B and B

DrPhilG

championc wrote: »

Join the with the marine switches I recommended before. You can then isolate a string if needed.

The switch has 4 positions, at 3, 6, 9 and 12 o'clock. Off, A, A+B and B

What I mean is, how does the inverter view the batteries? Is it basically connecting 2 16s in series and then connecting those 2 packs in parallel before connecting to the inverter?

There is only 1 set of connections on the inverter.

DrPhilG

What I mean is, in this sexy diagram...



Is it just a case of the outputs from each set of batteries with its own BMS joining inside the yellow circle there and going into the inverter as one?

If so, does the inverter just treat them as one battery?

graememk

DrPhilG wrote: »

What I mean is, in this sexy diagram...



Is it just a case of the outputs from each set of batteries with its own BMS joining inside the yellow circle there and going into the inverter as one?

If so, does the inverter just treat them as one battery?

Yes. Simple as that.

DrPhilG

graememk wrote: »

Yes. Simple as that.

Good, I like simple lol...

The worry is that I go with the basic option and connect as Lead Acid, and the Solis still turns its nose up at it.

Maybe I am the Guinea pig after all.

championc

DrPhilG wrote: »

Good, I like simple lol...

The worry is that I go with the basic option and connect as Lead Acid, and the Solis still turns its nose up at it.

Maybe I am the Guinea pig after all.

It's impossible that that will happen. The only thing that will constrict you is the upper voltage settings. You want to be able to set an over protection voltage of 58.5v and a max charging voltage of 58.4v.

That's the bit that would dictate whether you can go 16s or whether you could only go 15s which would have voltages much closer to that of Lead-Acid's.

And from your diagram. All you need is a marine switch / knob at the "yellow circle" point. That will join them perfectly and safely too.

DrPhilG

championc wrote: »

And from your diagram. All you need is a marine switch / knob at the "yellow circle" point. That will join them perfectly and safely too.

Lol, I had no sooner put that pic up and I thought to myself, "hang on, that marine switch that championc mentioned sounds like exactly what I'm describing..."

DrPhilG

We have a new contender in the BMS stakes...

The ZEVA BMS, built and shipped from Australia, was recommended to me by an installer on another forum. It is confirmed to be compatible with a number of inverters and battery types, and more importantly uses a compatible protocol for both PylonTech and LG batteries, both of which are happy to talk to the Solis.

I contacted the manufacturer and he emailed back to confirm that it should work. He hasn't had customers use it specifically on the Solis as yet, but he has offered a refund if it doesn't. Its a bit more expensive, about €200 including shipping by DHL, but it looks like the best of both worlds. A good reliable BMS, with compatible canbus protocol. And a much better level of support than the various AliExpress stores.

ZEVA wrote:

I don’t recall anyone trying that inverter with our BMS before, but I managed to find the user manual for the inverter and it sounds like it should work with our 8-16 cell Integrated BMS. It states “The CAN cable enables the communication between the inverter and the Li-ion battery from BYD, Pylontech, LG, Dyness, Puredrive.”

BYD and LG batteries use SMA’s CAN protocol, and Pylontech uses their own protocol which is only slightly different from SMA, and our BMS supports either of these. So by telling the inverter that it is connected to a BYD, LG or Pylontech battery, it should be able to communicate with the BMS correctly.

It’s always hard to be 100% confident about this with new inverters, but I’m happy to offer a money back guarantee on the BMS itself if it turns out not to work for some reason

graememk

DrPhilG wrote: »

We have a new contender in the BMS stakes...

The ZEVA BMS, built and shipped from Australia, was recommended to me by an installer on another forum. It is confirmed to be compatible with a number of inverters and battery types, and more importantly uses a compatible protocol for both PylonTech and LG batteries, both of which are happy to talk to the Solis.

I contacted the manufacturer and he emailed back to confirm that it should work. He hasn't had customers use it specifically on the Solis as yet, but he has offered a refund if it doesn't. Its a bit more expensive, about €200 including shipping by DHL, but it looks like the best of both worlds. A good reliable BMS, with compatible canbus protocol. And a much better level of support than the various AliExpress stores.

Time to share the link!

If it's emulating the batteries then it should work perfectly

DrPhilG

graememk wrote: »

Time to share the link!

If it's emulating the batteries then it should work perfectly

https://www.zeva.com.au/index.php?product=140

Small operation, but the guy who makes them is very responsive. Replied to me within a few hours with a comprehensive reply and a quote for shipping.

Drop him an email and see if it is compatible with the Sofar too. The Sofar works with Pylontech so I would imagine that it is.

PS the REC BMS is another that I'm told should support a wide variety of inverter connections, more expensive though.

graememk

DrPhilG wrote: »

https://www.zeva.com.au/index.php?product=140

Small operation, but the guy who makes them is very responsive. Replied to me within a few hours with a comprehensive reply and a quote for shipping.

Drop him an email and see if it is compatible with the Sofar too. The Sofar works with Pylontech so I would imagine that it is.

PS the REC BMS is another that I'm told should support a wide variety of inverter connections, more expensive though.

If it can pretend to be pylontech then it should work, will prob wait until the week so I don't get hit with currency fees on revolut.

It will stop me from having to trick the me3000 from recalulating when I don't want it to!

DrPhilG

I'm still waiting to confirm price and everything I need.

The unit with 100a shunt is $335 but do I also need a contactor? That's another $200.

The monitor for it is another $200 but if its going to communicate properly then I don't think I need that.

So need to confirm everything first. Could be anywhere from €250 to €550 depending on what I need but if it does everything I need then it's worth it.

The REC BMS is made in Slovenia and from what I could find would be closer to €1k which is crazy money.

graememk

DrPhilG wrote: »

I'm still waiting to confirm price and everything I need.

The unit with 100a shunt is $335 but do I also need a contactor? That's another $200.

The monitor for it is another $200 but if its going to communicate properly then I don't think I need that.

So need to confirm everything first. Could be anywhere from €250 to €550 depending on what I need but if it does everything I need then it's worth it.

The REC BMS is made in Slovenia and from what I could find would be closer to €1k which is crazy money.

That's a beefy contactor. 800v, 400a. You'd need that in a car though. Not so much in our 48v systems

Something like this would be adequate for what we're doing

https://shop.gwl.eu/DC-Contactors/DC-Power-Contactor-100A-Coil-48V.html - Has a duty life of only 8 hrs.. ours would be on all the time.

edit 2 : you could wing it without one as that should only ever be triggering if something goes drastically wrong and the inverter should cut off before the relay (basically what I have right now)

graememk

Actually everything should be working without one, (will still need a manual isolator for servicing)

As it would be instructing the inverter on how to charge /not charge/ too cold. Instead of just yanking the power.