Hi everyone, 

New user here, hoping to pick the brains of those more knowledgeable than myself 

Poked around a bit but haven't stumbled across any discussion on quite like what I want to do.

 

I'm looking to build myself a UPS system, but I currently live in a flat in an apartment block, so any kind of DB integration is out of the question. However, I'd like to buy components now such that I can meet my immediate needs in the flat, and then just move these components into a house and properly integrate into the DB when the time comes.

At this point, I'm thinking of a system 5kW inverter & 5kWh battery, installed in a portable server rack - plugged into a normal 15A wall socket to charge the battery via inverter. Some loads will be directly on the UPS at all times, and others will be added via extension cord as needed during loadshedding.

For the battery I'm looking at the Blue Nova 5.12kWh/48V LiFePO4 (the BP variant)

For the rack I'm looking at a simple 12U rack on castors

For the inverter I'm looking at the SunSynk 5kW/48V Hybrid Inverter (Looks to be a decent future-proof option for future 'Phase 2' plans)

 

I have two uncertainties:

1) On the inverter choice, I'm concerned that since this is a hybrid unit, I will have issues using the wall socket to supply the inverter and that this isn't a feasible option since I can/should never 'feed back' into the circuit in my flat. Reading the Sunsynk's manual leads me to believe that it'll always feed a bit back into the grid and that this inverter is only suited to an integrated type install? This bit is very fuzzy for me and I'd appreciate if someone could elucidate the functioning here.

2) The requirement of the BMAC unit so that the Blue Nova can communicate with the SunSynk properly. One would imagine that it's just a comms cable from battery to inverter but it seems that isn't enough with the Blue Novas?

 

Tried to keep things short, so let me know if you need any more info...

Kind Regards,
Kyle

Edited January 7, 20232 yr by SpankyZA
Spelling

I live in a rented apartment too, this created some difficulties dealing with load shedding.  I cannot make changes to my DB board or touch the wiring in the apartment.  I work from home so when we went into stage 6 my power trolley just couldn’t cope. I contacted Solar Installers, but they didn’t want to help since I could not make changes to the wiring.  

 

I did not know about this forum or anything about solar/backup electricity solutions.  In my desperation, after watching a Will Prowse video, I went to China Mall, bought a 5kw axpert clone inverter and a 4.8 kWh lithium battery.   This is the video that started it all https://www.youtube.com/watch?v=fdeZz4QvxG0&t=314s.

 

I wired them together, set the inverter to ups mode and set the voltages for LiFEPo4.  I run AC into the inverter from a wall socket.  As you can imagine, I have horrible extension cords running all over the show, it cannot be helped where I am.   It did solve load shedding, I run fridge, computers, network, lights, TVs and a gaming computer from this setup, I don’t even notice when load shedding kicks in. I can easily get 5 hours of runtime from the system, if I turn of a few things, I can get 8 hours.

 

Now that I know more, I wish I had spent more on the inverter, I will have to replace it when I move to a property I own.  At least the batteries I can reuse.  

 

Dangerous voltages etc.  You can kill yourself if you get it wrong.  

Thanks @JayGee for the comments. Your setup looks to be practically identical to what I envisage mine to be!

Which model inverter did you buy initially? Does it have feed-in capabilities at all? It would appear that you didn't run into any of the concerns that I thought might be an issue - does this simply come down to Inverter type/features?

Which inverter would you consider now that you know more?

Did you wire in any safety stuff such as DC fuses etc?

I'd appreciate any further insights.

More experienced members of this forum are better qualified to comment on inverters.   I bought a Fivestar inverter, it seems to be sold under the Must brand too.  It does the job,  it''s ok for a UPS but its not the type of product I would pay an electrician to come out to install permanently into my DB board.   As far as I can tell it does not have any grid synchronization or feedback so this was not a concern for me. 

I will most likely ask this forum for advice when its time to do a permanent installation.   I am sure there are COC requirements.  Other forum members has spoken highly of Sunsynk and Dye.   Those will be on the top of my list when its time for replacement.  

My batteries has both BMS current limiting and a breaker, I did not add an inline fuse between the battery and inverter.  Most server rack batteries come with over current protection.  

Ultimately, this is a hack job of note and only a temporary solution.  I tried to keep it as simple as possible to meet my needs for now and not set the house on fire.  There are really only two expensive components that can be carried forward, the battery and inverter.  

Good luck, it's awkward trying to deal with loadshedding in a rented property. 

 

 

 

Maybe have a look at the Revo Cube 800 or something like that.

So I've managed to get certainty on the my second question in the OP - The Blue Novas do in fact require the BMAC to communicate with the inverter. This knowledge has me moving away from the Blue Nova. Just seems like an unnecessarily complex and cost inefficient way to do things.

I'll likely just go with a Hubble AM-5 for the simpler comms and better C-rating.

The last bit of uncertainty now lies with the earthing situation, on inverter output, when using a wall plug as input, but I will hopefully get some certainty on this soon.

Managed to get some clarity on the wiring in the meantime, so

• 1x Sunsynk 5kW,
• 1x Hubble AM-5 &
• 1 x DC Isolator/fuse

in the post 😁

 

First time Solar-Shop.co.za user and so far, the experience has been good. The website is great and response to support email address is prompt.

Excited to receive the goods and complete the build! Just to source a sub-db or two as well as some professionally crimped battery leads.

Happy to report that the build went well and the system is working flawlessly! Took two full days to complete. Chuffed!!!

Worth noting that the Hubble AM-5 documentation doesn't really make it clear that a custom comms cable is a necessity - so I struggled to get comms going between inverter and battery until I made up a custom ethernet cable which was only populated with Pin 2, 4 & 5, on each end.

The physical manual received in the package is also outdated compared to the online version, and both, in my opinion, are a bit lacking in clarity on certain aspects. There are even some inconsistencies which creates uncertainty. It would also be have been great had the included comms cable been explicitly labeled "battery-to-battery comms only".

Anyway, bar these issues, it wasn't too hectic to build the whole UPS and I am glad to be rid of loadshedding at home  

This forum's historical threads also helped me a lot - a great reference when in doubt!