Greetings all. I have just been asked to assist a local (Zim) animal sanctuary with some upgrades to their existing solar system, given the parlous state of our local supply.

At present they are running 3 x Mecer 5kW inverters in single phase parallel, off what was a 900 Ah battery bank, but has just been cut down to a 450Ah bank, due to a number of failed units.

They would like to switch this all to lithium, which is great. At the same time, they have just been donated a Phocos Anygrid 5kW inverter, complete with panels and a single Pylontech US3000c battery.

Obviously the issue I have here is to provide a sufficient depth of discharge capacity for their loads (mainly freezers, and a borehole, with some light power and lighting) Night-time use is minimal from this perspective, but their bank of old freezers can take a bit of starting-up.

I then wondered if I could help them with the capacity on all fronts by creating one battery bank of US 3000's that both inverters can respond to. We have the wonderful situation of plenty of roof space, and of course 3 - and maybe 4 - mppt controllers for a really good spread of PV input throughout the year.

The Mecers have performed well over the last 4 years, and there is no need to change them out. This Phocos has been donated specifically for the volunteer house, which is great, as that is where the visitor centre and refreshment kiosk is located.

My thinking is to add a minimum of 4, and possibly (if their donors assist) 5 batteries to the brand new single unit, which would give them about 8-10kW discharge capacity on 17-20kWh of battery.

I don't see too many complications here other than being very careful with the voltage settings on the Mecers

 

Any observations will be gratefully accepted. Thanks for the input

I see no technical reason you would have any problems, just make sure the batteries and inverters are fused correctly. Only thing is you would not be able to run battery coms to both sets of inverters. Personally on the Axperts I don't like battery coms anyway so I wouldn't even worry about it.

Both mecers and the phocos' link their output voltage to incoming voltage and this can create problems where your loads might be receiving as low as 180VAC. Voltage monitoring might be needed to drop out incoming power (solatek AVS units are typically used I know)

Phocos' and mecers also has an annoying setting (bug) in if it is set to SUB and there is still some power from the solar panels it will drain from the batteries rather than switch to utility until solar power drops out completely...at least it used to, we use the kings which blend power much better so they may have fixed it in a firmware update.

Thanks for the input.