Solar PV battery options

DrPhilG

championc wrote: »

Both drawings are correct

Yeeeaahhhhh. Its oddly satisfying to realise that I've taken something on board lol. And probably a relief for the rest of you.

DrPhilG

Of course an easier solution again would be a 10kw hybrid inverter. Everything in the one "box".

Such a thing doesn't seem to exist though.

graememk

DrPhilG wrote: »

Of course an easier solution again would be a 10kw hybrid inverter. Everything in the one "box".

Such a thing doesn't seem to exist though.

There is if you have 3 phase!

championc

DrPhilG wrote: »

Yeeeaahhhhh. Its oddly satisfying to realise that I've taken something on board lol. And probably a relief for the rest of you.

Just one minor point in your terminology used. You mentioned the ME3000 being on-line between the PV inverter output and the grid. In-line to me (and possibly others) would imply that if it failed or was knocked off, that your PV inverter output would not reach the house or grid.

Your diagram was 100% correct - the Storage inverter is a separate device, on it's own separate fuse, located anywhere on your side of the meter. If you get two PV inverters, I would expect both of them similarly to be on their own fuses and, as was mentioned previously, could also be installed at separate locations (loft and shed).

But, as I mentioned previously, going OptionB with the ME3000, you would need to read the combined export if you had 2 PV inverters

graememk

championc wrote: »

But, as I mentioned previously, going OptionB with the ME3000, you would need to read the combined export if you had 2 PV inverters

Which is measured from the main tails between the meter and your consumer unit

DrPhilG

championc wrote: »

Just one minor point in your terminology used. You mentioned the ME3000 being on-line between the PV inverter output and the grid. In-line to me (and possibly others) would imply that if it failed or was knocked off, that your PV inverter output would not reach the house or grid.

Ah OK, gotcha.

Back to the BMS, is this what I need? Or the Daly equivalent.



The 80a version is €57, and I think the ME3000 (and also the Solis hybrid if I went that option) charge at 63a?

graememk

DrPhilG wrote: »

Ah OK, gotcha.

Back to the BMS, is this what I need? Or the Daly equivalent.



The 80a version is €57, and I think the ME3000 (and also the Solis hybrid if I went that option) charge at 63a?

Me3000 can charge at 70 amps.

DrPhilG

graememk wrote: »

Me3000 can charge at 70 amps.

So the 80a model will still do the trick?

championc

DrPhilG wrote: »

So the 80a model will still do the trick?

In theory, yes, but as Will Prowse would advise, you are better going with a decent amount of headroom, for the sake of the few quid extra, for the 100A model.

So that's that bit. The next is with the connectivity. I went with the BT dongle, which is perfect for looking at the health of all cells, and calibrating 100% by setting the capacity. HOWEVER, you cannot have BT and Canbus. So if you went for Canbus, I have absolutely no idea as to how you would watch or set these things.

There is something about the internals that they change from model to model. It's not just a case of swapping over the external adapter.

So you'll need to ask them how things work if you go with Canbus

DrPhilG

I was worried about sounding thick, but then figured that shop probably sailed a long time ago...

BT = Bluetooth?

And this is referring to how the inverter communicates with the battery? The Solis hybrid in one option, or the Sofar ME3000 in the other.

Which I suppose means that I need to address that question first of all, which option I'm taking.

Winterman1234

DrPhilG wrote: »

I was worried about sounding thick, but then figured that shop probably sailed a long time ago...

BT = Bluetooth?

And this is referring to how the inverter communicates with the battery? The Solis hybrid in one option, or the Sofar ME3000 in the other.

Which I suppose means that I need to address that question first of all, which option I'm taking.

Following with interest and thinking about my own setup. If I was to bite the bullet with such a setup I would rather place batteries in garage approx 15 metres from house. For the sofar inverter I would need a current clamp on pv and mains. Anyone any ideas of the length limit of cat5 twisted pair to connect the current clamps to inverter out in garage. Or maybe there is a smarter way to do it. Do you plan to house your batteries in attic.

championc

DrPhilG wrote: »

I was worried about sounding thick, but then figured that shop probably sailed a long time ago...

BT = Bluetooth?

And this is referring to how the inverter communicates with the battery? The Solis hybrid in one option, or the Sofar ME3000 in the other.

Which I suppose means that I need to address that question first of all, which option I'm taking.

The bluetooth is only to allow YOU to connect your phone to the BMS. Canbus would "potentially" allow an inverter to connect to the BMS.

But if it was Canbus linked, then how do you monitor the batteries yourself ????????

championc

Winterman1234 wrote: »

Anyone any ideas of the length limit of cat5 twisted pair to connect the current clamps to inverter out in garage.

100m

graememk

Winterman1234 wrote: »

Following with interest and thinking about my own setup. If I was to bite the bullet with such a setup I would rather place batteries in garage approx 15 metres from house. For the sofar inverter I would need a current clamp on pv and mains. Anyone any ideas of the length limit of cat5 twisted pair to connect the current clamps to inverter out in garage. Or maybe there is a smarter way to do it. Do you plan to house your batteries in attic.

The ct for the grid on mine would be about 20 meters

The solar ct is about 100m! (If not more, I'll do a rough step tomorrow, ) it's not a data signal, it's a analog signal (voltage)

I have grid ct, solar ct and the rs 485 all running on the one cat6 cable.

I think it should work without the solar ct clamp. Must test that sometime, as it really only cares about the grid import/export.

Currently our Sofar inverters don't "talk" to the batteries at all, just run off voltage settings etc.

Once the battery is sitting idle for an hour, it takes the current resting voltage of the batteries and recalculates the SoC. Up until then when charging or discharging it's using dead reckoning, ie its at 100% of a 10kwh battery, we took 5kwh out, it's at 50% sort of thing.

I'm currently running a settings that would have the 20-50% range accurate but the top end is way off if it has to recalculate there. Which is fine for right now. Might need to change that in the summer.

Today it stopped at 35%, and recalculated to 34% an hour later (still putting some night rate in on predicted bad days or high load days)

It bounced up to 37 overnight, it's usual behavior, as the voltage in the batteries settles

unkel

Winterman1234 wrote: »

Following with interest and thinking about my own setup. If I was to bite the bullet with such a setup I would rather place batteries in garage approx 15 metres from house. For the sofar inverter I would need a current clamp on pv and mains. Anyone any ideas of the length limit of cat5 twisted pair to connect the current clamps to inverter out in garage.

The length of the current wires doesn't matter, but you need to have as short a cable between the Sofar and the batteries as possible. From memory max. 2 meters. So your Sofar would have to be in the garage too. And FWIW, I prefer to have all these outside of the main house myself too. In my case the inverters are mounted on my outside wall with nothing but stone walls and a steel cabinet around them. My batteries are in said steel cabinet. Belt & braces maybe as my battery is LiFePo4, so not combustible / flammable. But you never know. It also leaves the path open for me to install a bigger battery of less safe chemistry from say a scrapped EV at some point in future if I came across one for very good money.

Deagol

championc wrote: »

100m

Cat5 for TCP/IP is 100m. For other uses it varies. For instance, the Inverters use an RS485 signal from the CT clamp in my setup. At 9600bps, you'd be safe to use Cat5 up to ~2km possibly - though I'd not want to try that length you'd certainly be safe up to 500metres.

Deagol

Winterman1234 wrote: »

Following with interest and thinking about my own setup. If I was to bite the bullet with such a setup I would rather place batteries in garage approx 15 metres from house. For the sofar inverter I would need a current clamp on pv and mains. Anyone any ideas of the length limit of cat5 twisted pair to connect the current clamps to inverter out in garage. Or maybe there is a smarter way to do it. Do you plan to house your batteries in attic.

You can use a CT clamp remote from the inverter. I'm using a CT clamp in my consumer unit, it connects via a short analogue cable to an Acrel AC10R digital ammeter. That Acrel unit is connected then to a Lorawan radio link that goes to another Lorawan radio in the garage (20 metres away) and that Lorawan sends the current information to the inverter.

If you want to use Cat5 though, if it's a Solis RS485 you'd be safe up to several hundred metres.

graememk

Deagol wrote: »

Cat5 for TCP/IP is 100m. For other uses it varies. For instance, the Inverters use an RS485 signal from the CT clamp in my setup. At 9600bps, you'd be safe to use Cat5 up to ~2km possibly - though I'd not want to try that length you'd certainly be safe up to 500metres.

Only the solis hybrids use rs485 for their meters.

Sofar uses a simple ct.

Edit, just seen your other post!

Deagol

graememk wrote: »

Only the solis hybrids use rs485 for their meters.

Sofar uses a simple ct.

Edit, just seen your other post!

Never simple to decide to answer in two seperate posts or combine

Found this on myenergi about CT clamps:

https://myenergi.com/wiki/zappi-v2/installation-3/#:~:text=The%20cable%20can%20be%20extended,connection%20at%20very%20low%20currents.

What I would expect on current loop, 100m on twisted pair.

This link is also interesting: https://www.se.com/ww/en/faqs/FA212605/

I would expect that the key is to keep the resistance of the wire being used as low as possible - so use good quality, heavy gauge cable if you have to extend.

Another link that seems to support using good quality cable etc, allows up to 100m without issues.

https://ctlsys.com/support/current-transformer-ct-wire-extension/

I think maybe if it was me I'd use STP (shielded twisted pair) like Cat5 Shielded.

championc

Deagol wrote: »

Never simple to decide to answer in two seperate posts or combine

Found this on myenergi about CT clamps:

https://myenergi.com/wiki/zappi-v2/installation-3/#:~:text=The%20cable%20can%20be%20extended,connection%20at%20very%20low%20currents.

What I would expect on current loop, 100m on twisted pair.

This link is also interesting: https://www.se.com/ww/en/faqs/FA212605/

I would expect that the key is to keep the resistance of the wire being used as low as possible - so use good quality, heavy gauge cable if you have to extend.

Another link that seems to support using good quality cable etc, allows up to 100m without issues.

https://ctlsys.com/support/current-transformer-ct-wire-extension/

I think maybe if it was me I'd use STP (shielded twisted pair) like Cat5 Shielded.

Exactly. The likes of bell wire is a far heavier gauge than Cat5. So I certainly wouldn't suggest the use of Cat5 beyond 100m, since a weaker signal arriving at the inverter could lead to inaccurate readings

graememk

championc wrote: »

Exactly. The likes of bell wire is a far heavier gauge than Cat5. So I certainly wouldn't suggest the use of Cat5 beyond 100m, since a weaker signal arriving at the inverter could lead to inaccurate readings

To be fair I used cat 6 and my readings are fine

Deagol

graememk wrote: »

To be fair I used cat 6 and my readings are fine

More than 100m?

graememk

Deagol wrote: »

More than 100m?

By the time it gets from the garage, into the house, down to the yard, and then into the shed where the inverter is, not going to have much change from 100m!

Forgot to step it today. I did have a plan b, to put the ct on the feed to the yard, or not use it at all.

Grid ct isnt too long

lightson

What’s the actual delivery time from China for batteries right now? Has anyone had a recent delivery. Price goes right up when you select Poland. Anyone had delivery from Poland was it fast?

graememk

lightson wrote: »

What’s the actual delivery time from China for batteries right now? Has anyone had a recent delivery. Price goes right up when you select Poland. Anyone had delivery from Poland was it fast?

You dont select poland, they are shipped via poland.

I ordered mine at the end of oct, and got them end of dec, just before xmas, so id budget 2 months.

Once they land in poland, its only a few days.

DrPhilG

I'm thinking that the most cost effective option for me is to keep the Solis hybrid and connect the LiFePo4 batteries to it. So I don't need to buy too much more for now, and only need to add another inverter for additional panels down the road.

championc wrote: »

The bluetooth is only to allow YOU to connect your phone to the BMS. Canbus would "potentially" allow an inverter to connect to the BMS.

But if it was Canbus linked, then how do you monitor the batteries yourself ????????

So there isn't really any need for the inverter to connect to the BMS, the inverter will just charge/discharge based on need and if the BMS detects any problems it will shut it down?

Ubbquittious

graememk wrote: »

You dont select poland, they are shipped via poland.

I ordered mine at the end of oct, and got them end of dec, just before xmas, so id budget 2 months.

Once they land in poland, its only a few days.

This seems to be a big thing now. Chinese sh1te first lands in Poland or the Czech republic and from there it's spewed on to other European countries. A relatively recent development I think. Where is the advantage in it for China?

graememk

Ubbquittious wrote: »

This seems to be a big thing now. Chinese sh1te first lands in Poland or the Czech republic and from there it's spewed on to other European countries. A relatively recent development I think. Where is the advantage in it for China?

It gets it into the EU, once its cleared it can move freely throughout the EU without any customs or VAT implications.

championc

DrPhilG wrote: »

So there isn't really any need for the inverter to connect to the BMS, the inverter will just charge/discharge based on need and if the BMS detects any problems it will shut it down?

Correct, the BMS will do it's own thing and manage everything to do with the batteries.

graememk

DrPhilG wrote: »

I'm thinking that the most cost effective option for me is to keep the Solis hybrid and connect the LiFePo4 batteries to it. So I don't need to buy too much more for now, and only need to add another inverter for additional panels down the road.




So there isn't really any need for the inverter to connect to the BMS, the inverter will just charge/discharge based on need and if the BMS detects any problems it will shut it down?

Yep, only disadvantage of no communication, is that the inverter has to "guess" the State of Charge. So you could see some wiggles in it when its sitting resting for a while, (ie if its full and not discharging, or at the low end and not charging.)