Off peak grid tied storage with ac coupled inverter

[Gareth79]

It's good that you can weld and use metal. I had to use some plywood for compression.

It seems nobody still really knows exactly how much is needed, but from what I've been reading plywood would be good enough really. I mainly wanted something I could easily move around. Plan is to make some rails with skateboard bearings so I can slide it into a narrow area at the bottom of a computer rack under the stairs.

I can't say I'm any good at welding though - I can make it spark and occasionally join metal though!

 

[CrossStreet]

The manual says that compression is good, but I am likely compressing too much as I cannot guess what force those nuts apply.
I've built my battery as two rows of 8 cells vertically to nicesly slide under the stairs. I've also made a simple trolly on 70mm furniture rollers. This proved to be very usefull as I could rotate the 90kg battery during construction easily and I was doing that a lot.

 

[CrossStreet]

The castor wheels I bought:

https://www.amazon.co.uk/gp/product/B0773QVGCZ

6 of those on a 18mm plywood make a smooth trolly

 

[israndy]

I have been trying to build a solar generator out of my old electric motorcycle (Vectrix) batteries that I upgraded to lithium a year ago. Was gonna wire it into the circuits that run when the solar goes away so I could charge them from solar and power lights and TVs after dark.

Then I saw an ad for this:

https://www.kickstarter.com/projects/zendure/superbase-v-first-plug-and-play-home-energy-storage-system

I purchased two base stations (for under $5000+shipping) and a Home Panel, that should give me about 10kWhs to use overnight and enough power to run the oven for a time. The Home Panel allows me to run 10 circuits off the batteries and to charge the batts off my solar during the day. It's got a lot of extra functionality that I might not use immediately, but I can wheel them out to the RV or take one up to the cabin. Each unit has 3800 watt at 240v and 120v outputs and a ton of DC outputs too. If I add solar to the cabin I just plug it into one unit and it'll charge up to 3000 watts of DC in addition to up to 3800 watts of AC charging, so you can charge the 4.6kWh battery in an hour at max input.

I watched Will's video this week of how to build a cheap solar generator with just two components, and was thinking seriously that it might be a good idea, but my wife asked me, "Is it plug and play", and I think the Zendure is going to be the best bet for someone that wants some of the functionality of a PowerWall, but also a Bluetti that can be wired to the house, and wheeled away to be used elsewhere. Heck you can even take it to a public EV charger to plug it in and fill it up.

Hmm... Didn't mean for this to be this much text, perhaps I should have posted this as it's own thread...

 

[MisterB1959]

@Gareth79


Is the Seplos BMS the only BMS that will work with the Sofar inverter and home made battery bank, or has anyone else used a different bms with success?

i assume the Seplos BMS is used by pylontech batteries, so it's easier to configure?

 

[CrossStreet]

I bought a 200a 16s Seplos, which I am planning to connect to the 8kW Deye inverter. Reading this forum this should be possible (and there is a diagram in one post).

 

[Gareth79]

@Gareth79


Is the Seplos BMS the only BMS that will work with the Sofar inverter and home made battery bank, or has anyone else used a different bms with success?

i assume the Seplos BMS is used by pylontech batteries, so it's easier to configure?

I don't think Pylontech use Seplos, but it's possible.

It's not the only BMS that will work, the CAN protocol seems to be fairly common between models so I'd think anything that supports the Pylontech protocol would work. I can't remember the other main one, I'm sure it is mentioned elsewhere on here. In. When I had mine set to Pylon it worked fine but had the wrong make/capacity in the inverter's info screen, and it would not discharge below 20% SOC (neither would be a huge problem). You do need an RS485 USB adapter and the Windows utility to change the settings on the BMS, for example the default battery capacity is 100Ah and the SOC would never work correctly without changing to the correct.

I bought a 200a 16s Seplos, which I am planning to connect to the 8kW Deye inverter. Reading this forum this should be possible (and there is a diagram in one post).

If it has a CAN interface and supports Pylon (or the generic protocol) then it should be fine.

 

[cajocars]

So an update - the system is mostly set up and working ok!

The Seplos BMS is working well. The only real issue I had was that my sytem is set up in 2x packs and the link cable between them was too long, and causing a higher voltage on the first cell of the second pack. I rewired the pack (flipped the busbars) so that the cells linked at at the front, and switched the 25mm cable for 50mm, and now it works perfectly.

The ME3000SP is very good too, the KEY thing when setting one up is to "freeze" the CT direction. I didn't with mine, and it all worked ok when the solar exported it detected it as a load and tried to export to match it!

I am using Home Assistant and have the Seplos BMS linked in using ESPHome. The ME3000SP didn't have any ESPHome integration but I am writing a Modbus configuration to monitor and control it (currently a WIP). There is an MQTT bridge for it, but I try and use ESPHome wherever possible. Then it will be possible to directly control the charging/discharging from Home Assistant, eg. as a timer, and also shut it off before a full charge based on solar predictions for the following day.

I'm doing a very similar project to yours (I'm on Octopus Go) and I've just bought 16x EVE 280Ah cells and a JBD bms; I just need to buy the inverter (or AC charger) and I was thinking about the Sofar ME3000SP; am I right it can work even without communicating with the BMS (mine doesn't have an RS485 port)? And what do you need to do to communicate/control it with Home Assistant?

 

[Gareth79]

I'm doing a very similar project to yours (I'm on Octopus Go) and I've just bought 16x EVE 280Ah cells and a JBD bms; I just need to buy the inverter (or AC charger) and I was thinking about the Sofar ME3000SP; am I right it can work even without communicating with the BMS (mine doesn't have an RS485 port)? And what do you need to do to communicate/control it with Home Assistant?

The M3000SP can be used without a BMS, but I believe you need to run it in lead-acid mode and manually set the various parameters, there are guides online. This is a very inferior setup to having a BMS with CAN/RS485 though, and others have mentioned that it's a bit of a pain to manage. With the Seplos you just plug it in and the inverter defers almost all control to the BMS, there's nothing to configure except the work mode (eg. when you want to charge, what maximum power and to what SOC %). I bought a Daly and then sold it on when I realised it wouldn't be great.

For HA sofar2mqtt is what most people use I think. I am still working on my ESPHome configuration, I haven't hurried because right now with winter sun there's no need to shut off charging early!

 

[cajocars]

The M3000SP can be used without a BMS, but I believe you need to run it in lead-acid mode and manually set the various parameters, there are guides online. This is a very inferior setup to having a BMS with CAN/RS485 though, and others have mentioned that it's a bit of a pain to manage. With the Seplos you just plug it in and the inverter defers almost all control to the BMS, there's nothing to configure except the work mode (eg. when you want to charge, what maximum power and to what SOC %). I bought a Daly and then sold it on when I realised it wouldn't be great.

For HA sofar2mqtt is what most people use I think. I am still working on my ESPHome configuration, I haven't hurried because right now with winter sun there's no need to shut off charging early!

I’ve ordered the ME3000SP
So if I run it in lead-acid mode, would it estimate SOC based on pure voltage?

 

[Gareth79]

I’ve ordered the ME3000SP
So if I run it in lead-acid mode, would it estimate SOC based on pure voltage?

I'm not sure to be honest! I'd strongly recommend not even trying though, a BMS with inverter communications will take a huge amount of guesswork and risk out of the equation. The main reason is that if the BMS detects a cell or temperature out of spec it shuts off and tells the inverter which will then shut off power. I assume in lead acid mode the inverter will just keep supplying power and the BMS will deal with it, which doesn't sound ideal.