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10kW Hybrid Inverters
#21
When it comes to efficient power consumption, does anyone know how this is achieved?

e.g.:

1. Is it just down to good design by Victron?
2. Is it down to poor components used by Chinese companies like MPP?
3. Are the builds similar but Victron uses more expensive versions of the same components?

The reason I ask:
Is to determine if its possible that as companies like MPP evolve and release new products, that they could close the gap in the future.

If the true high costs of the Victron are because all that extra $$$ is spent on better components, then MPP will not be able to improve without charging a lot more (like Victron already does) but I suspect only a portion of the Victron extra expense is added value, the rest is probably brand prestige Sad
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#22
Mpp wont improve. Its all about cost to decelop and Components choices. There Will Always be cheap choices
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#23
Oh, well, that's that then Smile

Here's a question I've been meaning to ask. If you planning on getting a load of solar but in stages, maybe 5kW initially and more panels later, is it better to get a big inverter, say a 10 or 12kW or get smaller inverters and parallel them up?
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#24
I phoned today again with greenakku.de
Thats the plan right now:
5 kwp connected to
1xVictron Energy MultiPlus-II 48/5000/70-50 connected with 
1x SmartSolar MPPT 250/100
plus 5 kwp conntected to 
1x SmartSolar MPPT 250/100
additional i need
Victron Interface MK3-USB
Venus GX
Costs:
1x -II 48/5000/70-50 = 1720 Euro
2x SmartSolar MPPT 250/100 = 910 *2 = 1820 Euro
Victron Interface MK3-USB = 70 Euro
Venus GX = 300 Euro

Hello, my first message.
I'am Eric from Nantes (France).
I'am building a 40 kW powerwall for my house with 8 trackers of 3 panels. Total : 9 kWc
My house have 15 kVa grid and 3 phases.
So, our solution is good for 3 phases ?
Sorry, I don't learn english at school ...

Eric
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#25
(03-03-2020, 11:48 AM)drh Wrote: When it comes to efficient power consumption, does anyone know how this is achieved?

1. Is it just down to good design by Victron?
2. Is it down to poor components used by Chinese companies like MPP?
3. Are the builds similar but Victron uses more expensive versions of the same components?

1. Yes and No
2. Yes and No - usually undersized components/design causes the issues
3. No - can be completely different depending on inverter

Inverters are split into two groups. A. High Frequency and B. Low Frequency

A. High Frequency : These take the battery DC and boost it up to over 300V into a capacitor via a high frequency step up transformer, which is smaller because it runs at a much higher frequency than the mains 50/60Hz. The >300V is then switched to create the AC output and it is the combination of the capacitor sizing and FET switch capability as to actual output. The high frequency units effectively use 2 stages of switching, which is one area where the efficiency takes a hit... small undersized high frequency stage (cheap) makes for more losses.

B. Low Frequency : These only have 1 stage switching the battery DC directly into a transformer with the 50/60Hz output the other side. However, the transformer type and choke implementation are critical for efficiency.

Toroidal transformers are a lot more efficient due to the design and shape which causes less iorn losses and less magnetic losses, so toroidal transformer based inverter is a good start.

E core laminated transformer based inverters I would try to avoid as they tend to be much less efficient.

The chokes (used to prevent the transformer from looking like a near short circuit) are critical and the larger the inverter capacity the more problematic (bigger) the choke becomes and overall inverter weight, which then makes shipping costs quite a significalt part of the unit cost. Any single phase inverter above about 5kW using only a single transformer starts to loose out on overall efficiency as you start to see I2R losses becoming quite significant.

Integrating mains charging, solar charging and UPS style switching between mains and battery make the whole unit cost 2-5x more and just tend to make overall efficiency lower.
Doin it likes this post
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#26
Wow, thanks for the detailed explanation!!

I asked this in another thread but I didn't get an answer yet.

If I'm planning on installing a large array (eventually but in stages), with the initial stage starting at 5kW, would it be better to buy a large inverter say 10-12kW with a view to future expansion or buy smaller inverters and parallel them up?
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#27
One size does not fit all..
My view is a little different to the normal here.
Inverter size is highly dependant upon the battery pack size and avaialble daily energy input, which would dictate the maximum draw.
Also depends a lot on if your inverter is grid attached or not.

If your grid attached and don't run off-grid then matching an inverter to meet your peak demand is massively uneconomical and a bit pointless. With my current setup of just over 2kW of grid tied capacity, 7kW of soalr and 36kWh battery I can meet over 95% of my energy use in the summer. Winter I don't have enough solar. Shoulder months in winter I can offset what energy I get with less than 500W because the majority of the load is actually on 24 hours a day or with lights and TV is never above 600W. Why try to match the kettle + oven + microwave + washing machine all at the same time.

Also, with smaller (cheaper) separate inverters you can split your load up.

Large inverters over 5kW also tend to use a lot of power just being switched on, like daromer's 240W on idle.

To counter this I made my own inverter setup with a cheap chinese board(s) and local transformer (oil cooled build thread details) and have a 4kW+ inverter that draws about 24W on idle and can cope with >10kW spikes from anything horrible I plug into it.

Plus, inverter efficiency tends to be viewed in my mind the wrong way a lot of the time and is actually two values.
First value is what energy are you willing to expend (opportunity cost) just to have the inverter available to service a load.
Second value is the incremental efficiency (removing the idle power) and is a lot higher.
For my unit if I take off the idle power losses the actual throughput efficiency starts off over 96%,
Idle losses are just the price your paying to have the unit available and not really part of the efficiency of the energy you are "choosing" to pass through.

Start a new thread for your build questions.
Doin it likes this post
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#28
Yikes, I'm even more convinced now, I have absolutely no idea how to spec a system.
I read what you're saying twice and it just won't sink in, maybe I need to have a few coffee's and try again later Sad

Sorry, that's no reflection on you, I'm sure its just me.
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#29
Idle load vs efficiency converting are 2 things but in overall the total loss running you Main load is important to calculated. Like in My case enda Up to be 7kwh cost per Day vs running grid only.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#30
I have AIMS and I notice that when idle, they do indeed burn 200w/hr (as the manual says).  However,  under steady load the efficiency averages 86%  (aims-watts-output / pv-watts-input) which is good for AIMS.     This makes me think that 'idle power consumption' is mitigated if there is a load >= idle power.
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