Which Victron inverter should I install?

Inverters Victron
1

At my workplace we’ve currently got a Kodak OG5.48 (Voltronic Axpert VM III) 5kW inverter hooked up to 10 x JA Solar 460W (JAM72S-20-460) solar panels in a 5S2P configuration. The loads on the essentials side is a fairly constant 3.5kW to 4kW during the day. We have 6 x Pylontech US2000B batteries. We have a 3 phase supply, but given that is a single phase inverter the essentials are all on one phase.

The issues that we would like to address are:

  1. We would like to add an air conditioner to the essentials side to keep all the servers cool during loadshedding. (It’s a 12000BTU inverter type air conditioner, so roughly 1kW.) This will push the Kodak beyond its limits.
  2. We have a generator to deal with extended outages, but the Kodak inverter will not accept its input without switching it from UPS mode to Appliance mode, which means downtime every time we want to use the generator.

We’ve decided that we’re going to relegate the Kodak to the role of a battery charger, permanently hooked up to the generator on one side and the batteries on the other. We might also continue to use it as a solar battery charger, or that role could be taken over by a Victron MPPT. (A potential complication is the fact that the panels are 50Voc, so 250V total, which likely limits our options to the MPPT RS or Multi RS.) How much pain am I in for if I attempt to continue using the Kodak as a solar battery charger together with a Victron inverter and Cerbo?

The options currently on the table are:

  1. Install two Multiplus II 5kVAs. It’s the most expensive option, but it gives us some redundancy. The downside is that if one of them fail we might end up having to replace both anyway, due to imbalance issues.
  2. Install a single 8kVA Multiplus II. At current pricing this is the cheapest option, provided we keep the Kodak hooked up to the solar panels.
  3. Install a Multi RS Solar. I’m not sure this will be suitable for a continuous load of 5kW during loadshedding. It is also not currently NRS approved, so if for some reason it does not get approval then we would be in trouble. Apparently its ESS is also not as polished yet, and I’m not keen on a downgrade from the bliss that I currently experience with my Multiplus II. The upside is that we can hook the solar panels to it instead of Kodak.

Noise is a consideration, since it is an open plan office and the inverter(s) will have to hang on a wall above someone’s desk. We’ve grown used to the fan noise of the Kodak, but would prefer it not to get any worse.

Which option would you recommend, or is there a better option I have not considered?

Thanks!

2

Fwiw, the multi rs is quite far along the grid code, nothing official yet but it’s probably in the order of weeks rather than months now. But, you are quite correct that a continuous load of more than 4kVA is not advisable. The solar charger and inverter also shares the cooling so using too much of one ends up throttling the other. So if you expect a load on f 5KVa I’d go with the 8kVA option.

3

Thanks for the advice. Would it be a safe option to keep the Kodak connected to the solar panels to charge the batteries, or will that confuse the inverter and/or Cerbo? The alternatives would be to risk using a SmartSolar 250/85 with 50Voc solar panels in a 5S arrangement, or to buy an MPPT RS at twice the price. Neither are very enticing.

4

I’d say bite the bullet and go for option 4, a Quattro either 8 or 10k, then you can connect the generator directly to the system.

Failing that, option 1.

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5

It’s not NRS approved, and there’s no indication that it will be anytime soon, so that’s pretty much a showstopper… that and the price.

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6

“Noise is a consideration, since it is an open plan office and the inverter(s) will have to hang on a wall above someone’s desk. We’ve grown used to the fan noise of the Kodak, but would prefer it not to get any worse.“

I would caution on the 8kVA MPII when fan noise levels are a concern. Maybe try and visit a unit that is drawing an expected load under LS conditions to evaluate before taking the plunge.