Low voltage can a power wall be a UPS?

[Davidksa10]

Hi everyone,

Some background first. I have retired to rural Thailand, I am last on the power line getting the leftovers. My house is 4-500m away from my meter. We are waiting for an upgrade and the meter to be placed by the house but that is a year plus away.

The supply is 220v, but as I have found out can briefly drop to less than 140v when someone further up draws a load. It recovers after a few seconds.

I recently bought a 30kw stabilizer and from watching the digital display is how I know how low the voltage can drop. The stabilizer can handle 145-260v input to give a steady 220v output. The problem is when we get the sudden drop the stabilizer cuts out for a few seconds leaving the house without power. Without the stabilizer it is impossible to run AC at night during the hotter months.

I have been looking at solar for a while now but I don't want to go off grid, I don't want huge banks of batteries that need changing every 10 years or less.

Solar and day time no problem, I am looking at 36-48 panels, enough to power the house and the excess back to the grid. It is night that is the problem.

My primary question is:

Can I use a lithium power wall (or equivalent) that is topped up by the panels in the daytime and use it as a kind of UPS?
They claim a switchover time of 0.01sec. It would only need to provide power for a few seconds at a time (quite a few times during the night) I would be running 2 or 3 AC units, fridge, freezer and some other very small load items.

Any advice or alternative suggestions gratefully received.

On a separate note have any of you first hand experience of Zinc Bromine batteries? They would be my ideal choice from reading about them but it is availability.

https://redflow.com/products/redflow-zbm2/

Many Thanks

[SunEagle]

I would say that any type of battery could be considered as a UPS system depending on how it is wired and how big it is to power your loads.

I have no experience with either the Zinc Bromine or power wall batteries but I imagine the power wall can be used to "ride through" a short or moderate power dip. The key will be how your loads are affected by even a short change in power quality before the battery takes over.

I have 2 small 500watt UPS systems in my house that power my wireless either-net system and my CCTV system. Both do experience a transfer because I can hear them cycle when our lights sometimes flicker. Still I have had to replace the small battery inside them more than a few times due to our power being so unstable during the summer so be aware that any battery system you use may not last long if the number of cycles start to exceed the manufacturer's daily specification.

[bcroe]

Without the stabilizer it is impossible to run AC at night during the hotter months.

I am going to suggest, if you used a late technology variable speed compressor AC unit,
the AC could ride through the dropouts without an issue. With SEER in the 20-30 range,
they could also save considerable energy compared to older technology. With their own
internal small energy reserve and inverter driven motor, I believe they would adjust to the
line dip without noticeable loss of service.

Best consult the mfr as to if this proposal is legitimate. I might try one AC unit just to save
energy and test the concept, change out the rest if it proves out. good luck, Bruce Roe

[Mike90250]

you can always make your own solid double conversion UPS, with a big battery charger, charging your battery bank ($$$) which runs your inverter ($$$) which powers your critical loads.
Charger output has to be larger than your than the load your inverter input draws