Noob inverter question


As per title, I am a noob in the space and researching my options. Will appreciate any and all advice :slight_smile:

So. Choice of inverter:

  1. I like the modularity and (from what I have read) the quality of the Victron 5kva MP II.
  2. With the required Cerbo GX and a suitable MPPT, the MP II price is not THAT much more (I hope!) than a 8kw Deye/Sunsynk.
  3. BUT then I guess the Deye/SS gives you 8kw vs the Victron 4kw?
  4. So in real operation, would you see double the load that can be supported by the Deye/SS than the MK II? Jumping to a 8kva Victron pushes it a bit out of my budget…

Am I missing something? Maybe there is something ITO real world performance that makes the Victron 5kva compete on almost the same level as the 8kw Deye/SS? Or is this just wishful thinking? Lol!

Thanks for any insights, much appreciated!

It is a little like asking why a Haval (or insert a car brand here that doesn’t have a 50 year track record of reliability) SUV that can drive a family of 7 around as a Toyota RAV that can only drive 5 around but costs the same.

Real world performance is also measured across time. Victron’s products have proven themselves to be highly robust. Their warranties are amazing as well.

In some respects the Sunsynk is more “advanced” than the Victron. When it comes to grid-tied operation, it is more efficient. However, for off-grid operation (read Eskom is down), I don’t think many would suggest the Sunsynk ahead of the Victron. Maybe I’m wrong. The Victron MPII just has a more robust (and expensive) design and can take a lot more punishment. The software and integration capability of Victron is also much better and more user friendly.

The other day, I had more than 8000W on my Multi. Luckily I was monitoring my HomeAssistant and noticed it. The Multi didn’t even give me a warning. Eskom was down, so it probably thought it’ll power through until it overheats and has to shut down for safety. I did go and turn off the culprit, but I’m not sure a high frequency design would be able to do the same. But then again, you can buy an 8kW HF design for the price of the 5kVA Multi, so maybe the point is moot. Anyways, I have no personal experience with Sunsynk, but I hear very good things about it. Victron isn’t going to complete on price, just like Toyota isn’t going to be the same price, like for like, than a cheaper brand. They complete on proven reliability.


Thanks for your response, much appreciated :grinning:

Especially the experience about the MP 5kva handling up to 8Kw.

My plan is to have the below installed as a start, then scale out wrt inverter, batteries and panels as it is required, based on my actual needs:

  1. Victron 5kva MP II
  2. Cerbo GX
  3. MPPT (not sure, probably 250/100, will have to take advice and take future potential growth into account).
  4. 1 x 5kw eTower Freedom Won OR 1 x 5kw Hubble AM 2. (OR Pylontech 3000c ). Batteries to be expanded with additional units as need is determined more accurately. I was thinking these are the best battery brands to pair with the Victron? Any advice/opinions welcome.
  5. ± 2-3kw solar panels.

Just don’t expect the MPII to do 8kW continuously, I had to go turn off the load as soon as possible. It will cover about 4kW on the AC side while grid tied. When the grid goes down, it’ll try its utmost to keep everything on that was coupled on the non-essential side.

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The Multiplus can give more power that it’s label for short bursts. That is great for things that have a high start up current (anything with a motor like pumps, fridge, washing machines, etc.)
You can also get a model that have the GX device built in (Multiplus II GX). It cost about the same so if you want simpler wiring that is a nice option.

For the MPPT you select one that fits your panels. The 100, 150, 250 and now 450 is the max PV voltage of your string. Depending on which PV panel you use this will then give you the max panels you can have in series(S) in a PV string.
If your panel voltage is around 45V that would have you 1 panel for each 50 you can divide into the number e.g. 2S for 100, 3S for 150 or 5 for 250.
If your panel voltage is around 49-51V like these newer 450W+ panels, that would have you 1 panel for each 55 you can divide into the number e.g. 1S for 100, 2S for 150 or 4 for 250. These are the safest options to use.
The 250/100 is a great MPPT option and will give you up to 5kW PV power for a 48V/50V battery. You can add more PV strings later, but the total voltage of your new string should be very close to the current strings so that the MPPT will have an easier time.

For the battery I would say that your might want to double the size you are looking at. 10kWh would be a much better size.


If the choice is between the 5kVA Multiplus and the 8kW Sunsynk, the Sunsynk wins every time, except on after sales support.


Thanks. I am open to any inverter at this stage. Would like to know why you say the Sunsynk/Deye is better? Honest question, I am trying to determine my best course of action for stability, quality, future expandability and the option that will give me the least problems/worries down the line :grinning:

I’m a huge Toyota fan. But, if you look at how much power the engine makes, the price, the creature comfort in the cabin, the Ranger wins every time. I will however keep buying the Hilux, because that’s just who I am :slight_smile:


I think the comparison would be a bit more apt if you compare say a GWM Steed to the Toyota Hilux. The one is cheaper but ticks all the same boxes. Comparing the 8kW Sunsynk to the 5kVA MPII is confusing, perhaps better to compare the 5 Sunsynk to the 5 MPII. Then the above analogy makes it easier to understand why some people might still opt for the Hilux (in fact the majority of the country).

Price isn’t the only factor when you make a decision. Sometimes a product is cheaper, and ticks all the same boxes on a spec sheet than a more expensive product, but still people buy the more expensive one.

That said, I’ll not try and convince someone to get a Victron over a Sunsynk, because they might not value the same things I do.

For the OP, just keep in mind an 8kW inverter probably should get a minimum of 16kWh of battery capacity (not 10 as a 5kW inverter would). Not sure how many panels you plan on having eventually, but to make use of the 8kW as intended, you really would like that amount of PV available as well otherwise your batteries will have to pick up the slack all the time, or if they are already drained, you’ll anyways just be running the 8kW inverter at 2/3kW…


I have been running a 8KW Deye for 6 months. I have been building home automations and find that it integrates really well. The Deye was designed to be able to use grid power to supplement your power needs and can blend solar, battery, grid and generator without too much drama and correctly setup I will save a large portion of your energy bill. The Deye can as an example use the solar power, lets say 2KW, then supplement 1.5KW (setup to limit the draw at a certain time of day)from the battery and fetch the remainder 800W from the grid all at the same time (of your current 4.3KW load). If you need a mix of grid and solar energy then the Deye is a brilliant piece of kit. If you are planning to go off-grid with no grid connection and like the idea of a modular design and have the bucks then a Victron would be a solid choice. There is also microcare that is made locally and can be serviced and repaired which is a solid choice but I have not had the opportunity to see it in action, they have been in business for more than 30 years

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Just keep in mind that the Victron mixes the grid, batteries and PV as well. It is a true “hybrid” inverter as we seem to be referring to inverters with the ability to sync with the grid. And remember that we are technically “off grid” many times - most people are getting these systems for loadshedding, which is in fact “off grid”.

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The grid has become irrelevant to me, I use on average between 5 and 15 units per month from the grid these last few months.

Victron is a modular design, you build your system up from modules so you can mix/match. All Power is first converted to 48V and then back to 230V which means that if you use most power during the day directly from the sun there will be some conversion losses as you go down and up again. Then it would be better to combine it with a string inverter which is something both inverters do. To get more advanced time of use schedules some of the victron pro people will need to explain as I do not know.

Deye is a packaged design, you get the battery charger/ solar MPPT together with your unit, no need to buy anything else. If you have severe shading on the roof then this might be a downfall for the MPPT that wants a minimum of 4 (unshaded)panels in series. Normal sunny roofs the 300-400V from the panels will be efficiently converted to be used during the day (for your loads) and there will be more losses stepping the power down to charge the batteries. The out-the-box time of use schedules makes the deye stupidly easy to setup without a complex home automation setup so that you can easily make the biggest possible saving on your bill

If you want to compare it to cars then I would say the first being like a toyota and the second like a tesla. The axpert type of inverter I would compare to one of those old land rovers

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The time of use schedules are the one selling point for Sunsynk/Deye that I just don’t get. Why is it a feature you need? You want the SoC to be X% at some time of day. It makes no sense. If you are planning for loadshedding, set your min SoC to always be what you need to get through loadshedding (or do something fancier with the ESP API and Home Assistant as many of the blue people on the forum have done).

The LF and HF designs have pros and cons when it comes to efficiencies. I don’t think it should significantly influence your decision of which to buy.

I don’t understand your car analogies. Victron makes a HF design as well if you consider that to be the future (i.e. Tesla), the Multi RS. So I’m assuming you’re comparing only to the LF design. Perhaps the next step is rather the HV designs but whether that makes financial sense is up to the reader to prove.

Anyways, as I’ve said, Victron has a proven track record of reliability and quality products. Sunsynk/Deye works great so far I can tell, but most of them are about 2/3 years old at most? That is not even old enough to be out of a Victron warranty period yet. Whether they are robust enough for the SA grid after 10+ years, time only will tell.

I don’t think we need to bring Voltronics inverters into this discussion, and should probably not bring them into a car analogy at risk of offending any automaker we choose as analog.

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That analogy is completely packed with flaws. For one, the Hilux is much nicer than the Ford. And secondly, the Victron is not a Toyota.

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Too keep it simple, the Sunsynk is IP65 rated - the magnetics are potted, the design is elegant. From a technical POV, there is no reason the Victron should cost more per watt.

I used to be a big fan of Victron until I opened one up - it’s not a pretty design. Lot’s of design choices don’t make any sense - it looks like a university group project taped together. This is not what I experienced from higher high-end inverters like SMA or Studer.


Let me attempt to explain. I use it to reserve a certain percentage of battery, if the battery is below then it switches to grid. On most solar days the battery gets to 100% and only goes down to 30% before the sun is out the next morning and never needs to switch to grid (so it is not used). On bad solar days I might get it only charged up to 65%, since the percentage at 9pm needs to be above 70% around 6pm it switches to the grid and runs on grid power, at 9pm it switches back to battery since my next time of day schedule specifies 50% to midnight once it reaches 50% it switches to grid again. By 12 there is enough power for the remainder of the night. I have lowered the percentages in such a way that I can go as low as 20% at 7am (and have enough battery to run the heatpump at 4am just in time for morning showers). There is no need to adjust the inverter day to day, it will switch back to grid if the battery goes below the “time of use” percentage, and if the battery will last then it always runs from battery. I can easily boil the kettle, reheat food during loadshedding, and if there is no loadshedding then I continue without a worry as the grid is my backup. The time of use schedules are brilliantly thought out, they save you the maximum money possible, you always have enough reserve left to face the loadshedding. If you have more than enough battery power they make no sense but who can afford that?

And one last thing, I never charge my batteries from the grid, only solar. I simply run from the grid where the batteries are below the specified percentage. I once charged from the grid at 7:45am, it was raining and I was only getting 60W from solar and the battery was down to 22% with loadshedding from 8am to 12am. I only charged about 1.3KWh before the loadshedding kicked in, luckily the dark clouds passed and by 10am I was getting enough to power the house plus charge the battery again.

I understand how it works, it just seems to be pointless. Does it save you money? No, your PV still generates what it would have (in fact, due to inefficiencies of charging vs immediate use on the high voltage strings, you are losing power this way). Does it make you more resilient against loadshedding, arguably, but it seems marginal if anything.

Put another way, your PV is the only thing that generates power. The battery that stores for later use. As such, why do you need the battery to be high enough at the end of the day to take you 100% through the night? If there wasn’t enough PV to charge the batteries full, just use it straight in the house and keep the batteries at the minimum you need to get through loadshedding, say 30% SoC. If you are expecting a 4 hour slot, put it at 40%. The method implemented by forcing charge to the batteries is inefficient and actually doesn’t save you the maximum amount of money. You store the PV in the batteries at a loss and use it at a loss again later. Your inverter is much more efficient when using PV in the house immediately and not first putting it into the batteries.

Technical design aside - From a longevity perspective they seem to last? That should surely count for something.

Otherwise, hardware aside, from what I’ve seen, Victron’s software and support is superior, both of which also costs money. So strip it all away and then you can argue you are paying extra only for proven durability vs a good but yet unproven product when it comes to long term reliability.

Electronics doesn’t care about these aspects. I liked Philips products for the same reasons but they went bust nevertheless.

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I would actually argue that it does. For me, I can cycle my batteries down during the night and still ensure that I have enough battery capacity should a power station decide to blow. Loadshedding is just one aspect of it and if I have to plan for a 2 hour cut vs 4 hr vs a whole night outage, the requirements are very different. So cycling the battery daily means I use less power from grid, saving me money. With this, I can also use battery to power my non essential loads when grid is available so you could have a zero reliance on grid.

It also means that batteries don’t need to be overspecked if you know your load pattern.

For me the sunsynk is a simple solution to achieve backup / solar power but if you plan to tinker a lot in the future, then victron is probably better.

I have sunsynk and I went with it because it was a simple solution. They were still relatively small that that stage and support was great. Unfortunately, support is now horrendous and it seems like they are will look for any way to get rid of warranty support.

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