tyler-pomerhn avatar image

Dirty Power on Island, 120V 10kW?

Long time Victron "appreciate-er" first time poster. ;) My apologies if these questions have been answered before or are too simple; I have to get this right the first time and need all the help I can get.

My wife and I are planning to retire to the Caribbean island of Dutch Sint Maarten and are in the process of building a villa on the island, which won't be ready for at least 3-4 years. We currently own a condo on the island and are unhappy, to say the least, with the power situation... frequent brownouts/blackouts (45m outage last night), clocks that "run slow" because the frequency is too variable (our clocks on the range/microwave are off by at least 1 minute worse each day), and several electrical devices (TV, Sonos, wine fridge) that I believe may have been damaged/destroyed by these power fluctuations. So I'm hoping I can build into the villa a "cleansing" system by Victron to smooth out at least the 120V power (230V AC, hot water, range, dryer, etc are not to be in this project and can stay dirty) and provide "whole-house" UPS for those systems.

I roughly estimate that the worst-case scenario will be around 6kW of load for 120V systems (averaging 250W per bedroom/bathroom, some for living room, one large-one small fridge, one microwave, general lighting in other areas, and a garage door opener) and initially I won't do solar but will likely want to add it later. I also may not be able to initially install this stuff and will have to temporarily feed 120V from the dirty grid for a period of time until all the equipment can be procured and shipped to the island. This solution also needs to be as "bulletproof" as possible because of the delays in sourcing gear to the island and lack of local support staff knowledgeable in Victron.

Island power is 120v/240v 60Hz 3-phase and does not support backfeed to the grid. The villa will have an ATS to a generator for emergency long-term outages and then then feed into a main panel. My plan, originally, was to have a 100A feed from that panel go to a manual transfer switch to a secondary panel with all the 120V loads, and have the other end of the manual transfer switch go to a 10kW 120V/48V Quattro, which could also have one of its AC sources hooked to the main panel for charging. However, in reading some responses on this forum, I'm having doubts. As in, I think a single Quattro "might" work - by tuning the sensitivity in the AC input to only charge/passthrough grid when it's clean, and charge no matter what (even with dirty power) when the batteries dip below a certain range, but I'm not sure this is enough protection for what I need.

1) Can a Quattro be configured so that when operating with functional, yet "dirty," grid power, it will still "clean" it by constantly inverting from battery (and charging the battery from AC in)? Or is it strictly a passthrough relay, which means my 120V will still get "dirty" power from the Quattro?

2) Can a Quattro be configured to never permit backfeeding to the grid, even if, in the future (and likely so, given that the Caribbean would be great for this) I add some SmartSolar MPPT SCCs to also charge the batteries so I can "off-grid" all my 120V? I read in some forum responses that certain failure conditions could result in some backfeed and I want to ensure there is never a situation in which the grid sees power from my system.

3) The alternative to an "all in one" Quattro, as I'm seeing it anyways, is to isolate the dirty power from the home power by means of a charger separate from the Quattro, and disabling the charger in the Quattro. However, I'd like to use the 10kW Quattro, which requires 48V batteries, and the only Skylla that does 48V does not look like it can be controlled/monitored with the Cerbo GX and other "smart" Victron components... given that I would potentially need isolation for dirty power and 48V, is there a "smart" charging solution for 48V now or on the horizon in the next few years? Or would I have to entertain parallel operation of multiple 24V Quattros and 24V batteries to achieve the same 6-10kW target (there _are_ "smart" 24V Skyllas)?

4) Are there Victron dealers/resellers who would work with me to design this, knowing they cannot actually install the system for me (given that it has to be installed in Sint Maarten, and nobody local can even spell Victron, let alone install it)? Perhaps charge for a few hours of their time to design/parts list something for me?

MultiPlus Quattro Inverter Chargerquattro 10kva
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3 Answers
Rob Fijn avatar image
Rob Fijn answered ·

Hi @Tyler Pomerhn , I am in Aruba. I know St Maarten, have been there many times.
I can help you. Send me an email robfijn (at)
Regards, Rob

1 comment
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Thanks, will do later today! :) I'm still verifying some particulars and want to put together a diagram of what I'm planning to do, and once I have that together and have some of these questions answered, I'd like to talk to someone about this and post my findings so others can also learn from this project.
Alexandra avatar image
Alexandra answered ·

@Tyler Pomerhn

The first question is easy. The quattro synchronizes to the grid so dirty power will pass through, up to a certain point. If it is too dirty or brownouts then it will disconnect and invert.

The victron is not an avr.

And the second, yes you can program it so there is no feedback to the grid. We also live in an area where feedback is not allowed unless you have a special license

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shaneyake avatar image
shaneyake answered ·

We have a similar situation with power in some parts of South Africa. What we have ended up doing is running a few multiplus-ii, depending on the client, that are only connected to the battery bank.
They are always inverting as an off-grid system would and have PV connected to the battery. If the SOC drops below our target SOC, we use the GX to trigger a Skylla-TG Charger or another multiplus-ii, with it's own GX to control charge rate, that is connected to grid. This provides perfectly clean power all year round and in the winter when there ins't great solar we charge the batteries from grid on those cloudy days but the power is always going via the battery.

We have a lot of sites running this setup in power 3phase and single phase.

As for your site, I would recommend 2 or 3 mutiplus-ii 48/5000 240V in parallel with a 100A victron autotransformer. This would allow up to all most 4kW of imbalance on the 120V phases before any problems.
I prefer the Multiplus-ii to the Quattro as they are cheaper per Watt.

You could connect your generator to the inputs of the Mutiplus-ii in your off-grid group. This would run those loads as well as charge the batteries.

This setup will provide clean, stable power, 24/7. Will not feed back and will optimize PV power over grid or generator power.

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