Just really disappointed with my multiplusII 5000, it wastes around 21% on discharge/feed-in.
Can someone please tell me why this inverter is wasting so much power on discharge? Can I send it back bc I’m really getting sick of seeing this thing underperform.
Please help.
It’s 16%
loss is between 10 and 20% depending on load, exporting being less efficient.
Conversion isn’t 1:1
No converter is 100% efficient, losses are due to physics.
If you think that’s terrible, good luck..
Thanks for the quick reply Nick, but 5305/4321=1.22etc, that’s 22%, way higher than 16%, and even 16% would be unacceptable for these batteries. My Growatt inverters produce 50Hz waves just fine with 98%+ efficiency, and without noisy ventilators and heavy metal casings. Seriously thinking of building my own now,
First I’ll note, please keep it civil - this is a technical forum, not social media. I’ve modified a few things in your response to bring it in line with our community guidelines.
Second, you’ll want to re-check your calculations, as you’re missing a few things there.
Third, though, you absolutely should build your own inverter/charger! Granted it’d take a decade or so in production and certification and all the other stuff, but competition breeds innovation. Good luck!
Having worked with GW for years, i would challenge your claim of 98% or at least ask for the specifics of how you got to that number. I’ve never seen anything even close to 98% at any power point in the curve of a GW. I’ve seen some impressive numbers using the data from the GW itself, but those vanish when you actually measure with good quality tools.
The same with data from batteries - the numbers above don’t show whether that’s the MultiPlus or the battery shunt providing that measurement of 102A, but i’d put money on the fact that 102A will be wrong - its just a case of how far out is it ; 0.1% or 5%? The data is only as good as the fidelity and calibration of the shunt. The voltage is likely to be close.
I’d also second Justin’s comment - many great new products have been developed by someone saying “i can do better”. Granted; most of those who say that eventually fill in all the gaps in their understanding, and realise that the problem wasn’t that the original product designer was a moron, but that a better understanding of the problem was needed to see why it was done that way, but every now and then a diamond is found.
Would heat not be a factor in the calculations? As in the UK I can bet my 10kVA isn’t as efficient as with an exhaust temp of 50c I’m looking to automate a portable air con unit to keep the plant room and batteries happy, maybe automated from battery temp more than anything. If you can try early morning hopefully when cooler and see what you get.
I actually looked into my MP2 48/5000 round trip efficiency today, and concluded that it’s pretty good. About 1 MWh to the MP2 ESS system and about 0.8 MWh out of it during this year.
Ok, so efficiency is output power divided by input power, 4321/5305 * 100 = 81.44%. That’s a loss of 18.56%, not 22 as I miscalculated and also not 16% as Nick claimed, sorry for that.
But for any of those numbers, and mind you this is just the discharge, not even round trip. I can’t say it as I would be violating your community guidelines and you’d have to edit my post again, but you know!
I never double checked the efficiency of my Growatt inverters, I do know from the datasheet they claim a max efficiency of 98.4%, and well, they don’t weigh a ton, don’t sound like airplanes and you can’t fry eggs on them.
All jokes aside, cause it’s really not funny, does anyone here have a real solution or alternative? Or just an explanation of these very poor results?
Sure, building an inverter in compliance with all regulations would take me a decade or two, but a more simple DC/DC boost converter to feed my Growatts should be doable. And it would be way, WAY more efficient than what I’m seeing from this multiplus disaster.
@castleneva Search the forum for some simple cooling solutions that may help reduce the internal temperature and improve the derating especially when running at full rated power for prolonged periods.
check math one more time
its 4425/5305 = 83.41so 16.59%
but to your point max efficiency of 95% is only reached at under 25C or 77F
so the higher above that the lower efficiency.
assuming the battery data is accurate in your screen shot
Hi. I understand your frustration. Many uninformed customers are like that, but…
The Victron Multiplus II is a old school type inverter. With a massive/heavy toroidal transformer. The RS6000 on the other hand is lighter, more efficient, but also more expensive. Sort of a Growatt Inverter you have. Not the price but efficiency.
Also. The efficiency varies, depends on the type of the load. No. Victron isn’t sharing a charge/discharge curve. No idea why, but you could improve it a little by staying outside of the < 500 VA and > 2000 VA range.
Another thing is temperature. That has been mentioned here already, so I won’t.
Hope this helps to clarify things a little.
Edit: I checked my Victron Multiplus II 5000 test setup, and last month (June) 167 kWh AC was used to charge the battery and 142 kWh AC discharged. That is with 9 kWh (airco usage on a bloody hot day) for the next day, in July so we are talking about:
151 kWh / 167kWh =0,904 AKA a very reasonable percentage.
Note: I have a dedicated MID certified energy meter for this.
From an efficiency perspective there is a good argument to be made to go fully DC/DC for all internal power needs and only interface with AC where absolutely unavoidable, the grid foremost. For all DC power needs only a few voltage levels are required, say 12V, 48V and 320V+ with two bidirectional, isolated, high frequency, high efficiency buck/boost converters in between. The technology for that is maturing very quickly, nearing the limits of what is physically possible while seeing significant cost reductions made possible by mass adaptation driven by the EV market I suppose. So the idea to do a 48V to 400V DC/DC boost before using a dedicated DC to AC grid export conversion is not a strange idea at all. To do it safe, reliable and affordable in a DIY style manner, can be done by those with the right skillset, but only as a hobby where the time spend on R&D will not be counted towards the final solutions cost (not to mention certification cost if any of it ever needs to interface directly with the grid, or be sold). And that is where I think Victron shines with their low frequency, toroidal transformer based line of products, it is old school, reliable and affordable. With an enormous longterm track record, certifications base, community customer base and open source initiatives as well to boot. But indeed no not the highest state of the art efficiency. Unless of course you are willing to pay the premium for the new high frequency line of products. That is not said you need to ‘just accept’ the efficiency figures you are getting out of your system right now, the most direct way of improving that is not to run it at absolute maximum power and build the best (air) cooling around it you can manage, that will bring clearly noticeable improvements with a lot less effort than going early adapter towards the DC/DC grid world of the future (that, IMHO, will come soon enough)
In June our Multiplus II 5000 based system (that includes a 93.5% efficiency boost charger to fully use 9kW charge power on a single phase 40A main fuse) bought 990kWh for €287 and sold 1360kWh for €199 (tibber NL). If I assume 1/3 of the 370kWh to be our own consumption that leaves 247kWh ‘losses’ on 1360kWh ‘bought’ a roundtrip efficiency of 82% while driving the MPII at full power when selling, while the buying was mostly done by the boost chargers. I think that is not too shabby at all. With €88 + €13.5 (tax compensation) €102.50 profit, 10ct per kWh is high enough to cover the battery cycle cost and then some. In may the system did even more, screenshots here: Another Strange DESS behaviour - #40 by UpCycleElectric
Yeah, that 98.4% might be possible in a lab if you fiddled around and then cherry picked the points to measure.
You are doing yourself a disservice by taking a claimed efficiency from a Growatt spec sheet, and trying to compare it to a real world measurement.
I just ran a heat gun (so a purely resistive load) on one of my GWs, and collected the figures on the screen plus measured them.
on low = 780w / 920w = 84%.
on high = 1890w/2050w = 92%
Should i complain on the Growatt forum about this? - its nowhere near 98.4%
However … it gets worse. Those figures above were using the GW reported figures (on the LCD); using real figures from fluke testers; 83% and 90%.
And this is on a perfect, absolutely resistive load, so a power factor of 1.0
The GWs i run don’t export, but if they did, i would expect the power factor would be quite different and efficiency would be far far worse.
and conveniently forget to count the air-conditioning cost to keep everything at a narrow band 20 to 21 degrees Celsius for instance.
That said, I can say from experience that 97 to almost 98% efficiency is possible with common hardware, for 230Vac to ~48Vdc at least. See Huawei R4830S1 (up to 98% and max 2000W) for example, or for much higher power in the same form factor and a little less efficiency see R4875G5 (up to 97% and max 4000W). I know because I build my boost charger with R4875G1’s (not G5’s but close) that perform very close to their published efficiency curve. I measure about 94% where the curve says 95% (and that includes the fans running yes 
Yes, absolutely.
One thing that isn’t in the Growatt calcs is the multiple fans running 24/7
Does anyone on the list know (or can guess) the magnitude of the drop in efficiency that would occur when an inverter is exporting to a network with a power factor of say 1.0 vs 0.9 vs 0.5?
The network or the inverter? I would say for the inverter at a pf of 0.5, at least expect the same (heat) losses while running at half power, so double the losses per kW power
The network - say for example your neighbours are a data center with lots of switch-mode PSUs, or maybe a factory with all manner of induction motors and VFDs, so you can’t do anything about the PF
those will all run close to a perfect pf of 1 or they can’t cool their building anymore. idem ditto the VFD’s. But a toolshop with heavy use of direct grid connected 3-phase motors starting and stopping all the time to, lets say, run an overhead carry trolley to pick and place lots of real heavy stuff, yeah that will get to 0.8 regularly before they will get a visit from the liander. Probably alerted to a grid problem nearby by you due to the loud hum and resonation noises out of your multiplus. Still, I’m not even sure if you will see much of that low pf, 'm not sure how far that would actually propagate to ‘nextdoor’ neighbours instead of being ‘absorbed’ by the shared street transformer.
I had the ‘pleasure’ of installing a Victron setup…three days before 92 heat pumps were switched on. Customer complained about using 100-130 kWh more each month. Been searching high and low for the cause, for weeks. Customer told me to take ‘my crap’ home 
