I am now even more impressed with Victron. You start with their devices, and as your need grows, they just give you the solutions to expand, not need to sell and start over.

There are some limits to this. There is a 1:1 rule: You cannot tie a PV-inverter to the output that is larger than the Multiplus. So if you have a 1.6kva inverter like you and I do, you're limited to no more than a 1.5kva (ish) pv-inverter. Something like the small Fronius Galvo.

But most of this is moot as Victron isn't on the CoCT list of approved inverters. The Ziehl UFR-1001e is on the list though, and it makes absolutely no sense that an anti-islanding device is on the list unless it is means to isolate SOMETHING... so the possibility exists that adding that device to your setup might be all you need.

9 hours ago, plonkster said:

Yup. That is how a hub-2 system works (that's what Victron calls it). You tie the PV-inverter to the output of the Multiplus. If it makes less than you're using, the rest is taken either from batteries or from the grid. If the PV inverter makes more than you are using, it pushes back through the Multiplus/Quatro either into the grid, or the inverter may decide to use it to charge batteries. But what if the grid goes down? Then you need a way to throttle the PV-inverter, and this is done by pushing the frequency up. In this way, a Multiplus can work with a PV-inverter on its output, even when the grid is down.

This is exactly what an Infini does, in one box, NRS 097-2 approved, the lot. So why go with such a complicated system? I am not trying to knock any brand, least of all Victron - they have a certain appeal/design which is obviously really compelling for the technical/engineering type. But, why would you use such a complicated and expensive setup if a R16k box can do all of this plus some flexibility?

I get it that Voltronic does not have the reputation of brands like SMA and Victron but neither did Kia, Huyndai, Toyota, etc. Given their value proposition I cannot get the resistance against giving it a try?

Yes, there has been reported failures but given the amount of them in the market I am not sure that their failure rate is necessarily excessive. And other brands fail too, one of my brother's 25kW SMA's failed.

Just thinking out loud.

7 minutes ago, cvzyl said:

This is exactly what an Infini does, in one box, NRS 097-2 approved, the lot. So why go with such a complicated system? I am not trying to knock any brand, least of all Victron - they have a certain appeal/design which is obviously really compelling for the technical/engineering type. But, why would you use such a complicated and expensive setup if a R16k box can do all of this plus some flexibility?

I get it that Voltronic does not have the reputation of brands like SMA and Victron but neither did Kia, Huyndai, Toyota, etc. Given their value proposition I cannot get the resistance against giving it a try?

Yes, there has been reported failures but given the amount of them in the market I am not sure that their failure rate is necessarily excessive. And other brands fail too, one of my brother's 25kW SMA's failed.

Just thinking out loud.

I agree, but I think some users just have an innate need for flexibility to manipulate devices and usage to their liking. Problem is:

What IF somebody rocks up tomorrow declaring it illegal (with fine structures and such) to feed back to grid and they catch you? 

Then I am not even referencing meter tampering to get it to turn back and then if something goes wrong - laying a criminal charge against you such as reckless endangerment?

Principal is - everyone would like to feedback to grid. Not to get paid as such, but to nullify your usage and use the grid as battery. But until such time as this is legal, does not affect insurance claims, municipalities can cope without billing errors and such (I don't want a R50K surprise billing error...) I am just not prepared to take the risk on.

This is me going to the extreme, but my life has been full of extreme events from time to time...

Edmund

Obviously the legal requirements must be complied to such as NRS097 but there are equipment certified for this. With the Infini, if you don't want to grid feed you switch it off with a tick box. And then you install a prepaid meter and save the monthly availability fee.

C

16 minutes ago, cvzyl said:

really compelling for the technical/engineering type

Perhaps it is a personality thing, as you say. Just last night I was talking about this bulky printer/fax/scanner thing we have at home. I'm thinking of throwing it away, or rather, I am beginning to agree with the minister of internal affairs that we should throw it away. The scanner still works, but I cannot get it going, even on windows. The printer still works, but some rollers are damaged and it gets a lot of paper jams, and it needs new toner. That leaves the fax part... which is the only bit that still works perfectly, but is never used.

This printer confirms a bias I've had for a long time: I don't like Multi Function Devices.

So I prefer a printer that is a printer and preferably a damn good one at the same time. That might also be because of all the Linux influence: In the early days, while the windows people had their pick of cheap printers (the printer is cheaper than new ink, we all know the story) us communists had to buy the expensive Postscript printer.

The Laserjet 4P... still working. Getting a little hard finding something with a parallel port to plug it in to though... :-)

Similarly, I want an inverter that is an inverter. I want my charge controller to be separate. It would have been nice if the Multiplus had the anti-islanding built in, because then I could also boast that it is NRS 097-2 approved... but that's only in the most recent models.

The price point... well yes. That will always be the place where the MFD kicks ass, pure value for money, at least in the short term.

plonkster, very valid point and I agree with you, in a MFD if one component of it fails you have to replace the whole thing or might possibly loose all use of it.

With the Infini it is a viable option to use an external charger. This is something I am considering (don't tell my wife) for my battery experiment. Especially where "exotic" charging parameters are required it will be necessary to do externally as the Infini has a limited range of charge settings.

The power regulation and supply on the Infini is very flexible and hassle free. I am fiddling with mine just because I'm bored, currently I have it set to supply the first 1kW of demand from batteries (if PV not available) and the balance from grid. That reduces shocks of e.g. a microwave suddenly starting on your battery bank.

C

+1 re. Gird-tie - it is all fun till you are paid a visit one day out of the blue, or a accident happens and now there are questions.

 

@cvzyl, you have a very good question: Why would you use such a complicated and expensive setup?

From your perspective, yes, it is very complicated. From mine, it is actually quite simple. Here is why. 

I have the situation that I bought equipment at a very good price 5 years ago knowing full well then that things are going to change as solar matures, new ideas come out. So I bought a controller because I knew I wanted more options ito settings for battery types or maybe go and try wind power using same controller or add more / less panels without having to replace said controller, or I just get another one.

Bought a small 1300w inverter for the load was first reduced knowing full well that I can go parallel with up to 5 more of them if I needed more power one day, which will then be adding redundancy - if I wanted to /need to. 

So now I have two options:
Option one is to sell all my trusted equipment that can expand, be added to, and get new unknown devices.
Option two is to add parts to the said trusted equipment, equipment I bought knowing full well this was going to happen.

And lets say you ask me the question: If say lightning wipes it all out, will you then change to new equipment?
Let me think on that for a moment ... Nope, I will go with Victron / Morningstar again.

And that is probably the best advert for the equipment, once you have discovered over years that the supplier supports you on time, equipment has a 5 year warranty on the part (for they can also break), not the customer who bought it, it can be fixed locally by a pal if you where stupid, it last decades and you know you can expand your system for the supplier saw that coming and made it flexible, easy to do - even if it costs an arm and a leg to get started, why change all that if you can add if you ever want?

I do understand this is not everyone's cup of tea but for all these years now I have not regretted my decision once, and trust me, I have said O my, that is a cool new thing ... but never could I sell and change. These blue things are just solid, expandable.

So, for me to expand, is not expensive nor complicated at all.

I quote Plonkster, who again nailed it spot on: 
<quote> Indeed. That's something that came from my earlier investigations when I installed the first system, and also from Victron's self-consumption whitepaper: The real killer is often the baseline, the small loads. For example, when I started, I had a baseline of 450 watt. 10kwh a day essentially for NOTHING. I still have a baseline of about half that, around 230W.

If you take a chart of your daily consumption (watts on the vertical, time on the horizontal), the watt hours will by definition be the area under the graph, so the baseline essentially forms this flat but very wiiiide rectangle at the bottom. There is a lot of gains to be had from eliminating that rectangle. </quote>

 

If you want to stay at 20% or less DOD of your battery bank, to ensure the longest life, with larger inverters you cannot easily isolate these smaller base loads to power them 24/7. It is all or nothing unless you a) make the effort to switch things off at night at 20% DOD, or b)) get more batteries. 

By splitting the bastard base loads off, the main bank has more power if load shedding returns and because it never sees below 20% DOD the rest of the time, it will last the design life, best ROI.

And this boys and girls, is what Ed and I are busy with, splitting the small 24/7 base loads off by dealing with them cost effectively and without any major capital outlay, to ensure the main bank never goes below 20% DOD year in and year out.
 

3 hours ago, The Terrible Triplett said:

I quote Plonkster, who again nailed it spot on: 
<quote> Indeed. That's something that came from my earlier investigations when I installed the first system, and also from Victron's self-consumption whitepaper: The real killer is often the baseline, the small loads. For example, when I started, I had a baseline of 450 watt. 10kwh a day essentially for NOTHING. I still have a baseline of about half that, around 230W.

If you take a chart of your daily consumption (watts on the vertical, time on the horizontal), the watt hours will by definition be the area under the graph, so the baseline essentially forms this flat but very wiiiide rectangle at the bottom. There is a lot of gains to be had from eliminating that rectangle. </quote>

 

If you want to stay at 20% or less DOD of your battery bank, to ensure the longest life, with larger inverters you cannot easily isolate these smaller base loads to power them 24/7. It is all or nothing unless you a) make the effort to switch things off at night at 20% DOD, or b)) get more batteries. 

By splitting the bastard base loads off, the main bank has more power if load shedding returns and because it never sees below 20% DOD the rest of the time, it will last the design life, best ROI.

And this boys and girls, is what Ed and I are busy with, splitting the small 24/7 base loads off by dealing with them cost effectively and without any major capital outlay, to ensure the main bank never goes below 20% DOD year in and year out.
 

I switch off the microwave and induction plate every night. My wife also got used to it. The fridge gets turned down a bit, in winter at night. The pool pump only runs between 10am and 3PM. No washing dishes or clothes before 9am. These small loads do add a bit of unnecessary strain on the system. The one thing I can't quite kill yet are cellphone chargers, purely since we charge phones and tablets at night. I have been toying with the idea of a 10W panel + small lithium battery just for this purpose, but have yet to find some DOD stats for these smaller litium batteries. 

So, this makes me think, what about installing some extra contactors on some of the CB's which has devices which can absolutely be shut down every night? 

What is your base load that runs 24/7?

16 minutes ago, The Terrible Triplett said:

What is your base load that runs 24/7?

probably 150W?

Now get that 150w that is on 24/7/365, off grid. Can be done using a 12v system.

19 minutes ago, The Terrible Triplett said:

Now get that 150w that is on 24/7/365, off grid. Can be done using a 12v system.

Nope. My "48V system" can sustain 4KW when needed. on a 12V system the batteries will take a LOT more strain - i.e. more Ampere will be drawn to deliver the same amount of watts. 

 

Here's the thing: a 12V system wouldn't allow me to boil the kettle (I should probably get a 1KW version), use the dish washer, lawn mower, welding machine, or allow my wife to use a hair dryer / hot tongues. 

A bigger system which could allow that would need either 24V or 48V. At 48V I'm getting better efficiency. 

 

Silver, we are not on the same wavelength at all, not even close. 

I see where you guys are going. I would, for example, have a second inverter with a AGM/SLA battery in a box behind my television, for example, and that will then charge from the main source during times when these is excess power. Tonight, I'll watch TV from that battery rather than the main one in the garage. I might have more of these systems to run bedlamps in rooms, computers, etc. So this way I have more smaller batteries all over the place, each system is not connected to the house wiring, so no paper work, and old batteries from larger systems can do duty in te small system for a while longer. Those are the upsides.

The downsides will be absolutely horrible efficiency, as low as 50%. You can get that up to about 65% by specifically charging only during the day, and only when there is excess power (the main bank is full).

In some ways, this story reminds me of another funny story that was told about my grandfather. Don't know how much truth there is in it... but apparently it worked like this: When the oil was changed on the bakkie, that oil would go into the tractor. When it was changed on the tractor, it would go into the Lister engine. When it was changed on the Lister, it would go into the windmill's head. That was the end of the road :-)

I think there will be some kind of balance somewhere. Having more than two systems will probably add very little gain for way too much effort.

Doing the math, I would be much better off doing something about the pump in the fish pond. That runs 24 hours a day, at 50 watts. R80 per month or thereabouts.

The core idea is to spare the main bank at night by keeping it well above 20% DOD at all times during its lifetime, unless there are power failures.

Because of max 20% DOD, most of the large systems have ample spare power during the day to charge these smaller separate systems via 220v AC outlets that are fed by the main inverter.

Also suspect that with the planned Lithium batts that it may be possible to take i.e. a small Victron MPPT, set the bulk, absorb and float all the same, to charge said lithium batts from a separate smaller panel, if one wants to go there.

I'm interested to explore to run my TV / DSTV / signal boosters / alarm from a small 12v inverter from a lithium bank. Adding these loads to my current bank, just goes a little to far and to buy more batts is an overkill. I suspect it to be the case for a few other systems out there.

Obviously it must be done very cost effectively and Edmund plays a key part in this re. the 12v lithium battery bank. The 12v inverter must last 10 years plus to make it viable, lithium as cost effectively as can be, for I suspect if the sums are done by saving the bigger bank, it may be a no brainer ito difference in costs, and losses, when the main bank does not last full term.

On 7/2/2016 at 5:32 PM, plonkster said:

But note the input stages. In the green, you see a capacitor. That's a capacitive dropper.

[ Edit: my apologies; I somehow managed to not see about 100 posts between there and here, and I see that SuperDIY has addressed most of this already. ]

Err, no. They only use capacitive droppers in very small power supplies. Never with SMPS.

> From there it goes into the (rather small!) transformer in the red, 

It's rather small because it's switching at high frequency, 15-100 kHz. That's why it's powdered iron or ferrite (I never remember the difference with those two) core, not iron laminations that you always see with 50 Hz transformers.

> and then it is turned into DC by the four diodes also in the red. 

Those four diodes are turning direct 230 V mains to ~ 325 VDC. That's why it's rated at 400 V. There is another diode (or two or four) at the output.

> Big electrolytic tank to make it smooth. 

Well, if you call 68 uF big. This type of power supply can't operate over a wide range of input voltages, so this capacitor is needed to provide power while the mains is away from its peaks (~ 95% of the time).

> Then it goes into the SMPS, which is in the blue block. That is, two stage PSU, first drop the current with a cap, then drop the voltage somewhat with a transformer, then do the rest with an SMPS.

No, it's all done with the SMPS (Switch Mode Power Supply). Here is the first typical power supply schematic I found:

Note the fairly large capacitor directly across the mains (after the fuse, which the one in the photo doesn't seem to have). It would be the equivalent of the green capacitor in the photo.
That and the common mode choke (at the left, in red in the photo) are to filter out switching noise from getting into the mains. If it was to filter out mains from the mains towards the power supply, the capacitor would be on the other side. They probably care about this switching noise exactly as much as regulations force them to.

Sorry about the non-English text; it was the first one that had the features I wanted (it's amazing how many SMPS topologies there are). These days,the switching would probably be controlled by a SMD (Surface Mount Device) chip under the board. This one mentions 0.7 mm, probably the size of the air gap. So this one would be a fly-back type. That's why the turns ratios would indicate about 50 V at the output - the control circuit makes sure it never gets that high, by pulse modulating the drive to the transformer (which is more like an inductor, but let's not go there).

So the issue in this case, as far as running from modified sine waves (= square waves with the right peak mains voltage) is the input capacitor. If it wasn't for that, the circuit would be rather happy with the square waves. There would be a peak of current into the capacitors, as with mains, but a smaller magnitude, and after that peak, the square wave would actually supply power to the load with a better power factor that from a sine wave mains. I suppose you could just remove the capacitor, and take the risk that high frequency switching pulses won't get into the inverter or other 230 V loads. [ Edit: or add an inductor to the input, where the fuse is in the schematic above.]

[ Edit 2: I forgot to add that I don't think that a 1:1 transformer, as someone else mentioned, would solve any of these issues. The transformer would pass the square waves through essentially unchanged, and it would risk running into saturation. ]

[ Edit 3: I believe that the 2n2 capacitor above is being used as a dropping capacitor, to provide power for the control circuit. It's a bit obscure, but I couldn't help mentioning it, to point out the contrast. The drive circuitry uses only a few percent of the total power; it's all losses. ]

9 hours ago, plonkster said:

I see where you guys are going. I would, for example, have a second inverter with a AGM/SLA battery in a box behind my television, for example, and that will then charge from the main source during times when these is excess power. Tonight, I'll watch TV from that battery rather than the main one in the garage. I might have more of these systems to run bedlamps in rooms, computers, etc. So this way I have more smaller batteries all over the place, each system is not connected to the house wiring, so no paper work, and old batteries from larger systems can do duty in te small system for a while longer. Those are the upsides.

The downsides will be absolutely horrible efficiency, as low as 50%. You can get that up to about 65% by specifically charging only during the day, and only when there is excess power (the main bank is full).

In some ways, this story reminds me of another funny story that was told about my grandfather. Don't know how much truth there is in it... but apparently it worked like this: When the oil was changed on the bakkie, that oil would go into the tractor. When it was changed on the tractor, it would go into the Lister engine. When it was changed on the Lister, it would go into the windmill's head. That was the end of the road :-)

I think there will be some kind of balance somewhere. Having more than two systems will probably add very little gain for way too much effort.

Doing the math, I would be much better off doing something about the pump in the fish pond. That runs 24 hours a day, at 50 watts. R80 per month or thereabouts.

@plonkster

That is basically it yes. Efficiency - yes it is a concern, but at the end of the day it is a bit of a statistic that can be interpreted multiple ways - total efficiency, isolated efficiency, etc. etc.

But to dig into that and for me to wrap my mind around it - let's take me as an example:

I have 1 x 5kVa Axpert and a 360Ah 48V pack. So that gives 48V nominal * 360Ah = 17.28kWh * 20% usable = 3.456kWh usable. (Ideally yes....)

For me despite best effort (and believe me I have gone to town on parasitic loads and such) it is too little and I seem to be using (measured) about 1.5Kwh, yet I deplete my bank with 3kWh....

Now: It is known that inverters becomes very INefficient at low power - as low as 20% dropping fast below 10% usage. I suspect something like an Axpert might be very guilty in this category... (although my standby consumption is a measured 25W) but at night my baseload is oscillating between 100W and 150W.

Question now is:

Is this the same for transformerless vs transformer based inverters?

Is it then not thus a LOT more efficient to have small inverters hover at 30-40% usage than one big tank hovering at 9-14% for 95% of the time?

And back to my point - is it then not MORE efficient to have the big tank as close to zero as possible during 0 solar generation and pass the punishment over to the micro systems (micro systems driven by big tank during daytime?)

What are your thoughts? I am seriously starting to feel like a watt/bean counter, but it all adds up. And with a battery bank replacement cost of R4100 * 8 - this is serious business.

13 minutes ago, edmundp said:

For me despite best effort (and believe me I have gone to town on parasitic loads and such) it is too little and I seem to be using (measured) about 1.5Kwh, yet I deplete my bank with 3kWh....

How are you calculating the 3kWh?

6 minutes ago, viper_za said:

How are you calculating the 3kWh?

BMV 700 statistics.

11 minutes ago, edmundp said:

BMV 700 statistics.

Can you please be more specific as to what values you use to calculate?
I would like to do the same on mine

4 minutes ago, viper_za said:

Can you please be more specific as to what values you use to calculate?
I would like to do the same on mine

Sure - I use an average of 80Ah per night to get to 80%DOD. (360Ah * 20% = 72Ah with Peukerts law added)

80Ah * 48V nominal = 3.84kWh. Yet only 1.65Kwh consumed...

This is actually worse than I thought....

48V is about 50% already. 

50%: 48.4V ::  3872Kwh

60%: 48.96V :: 3916.8Kwh

70%: 49.49V :: 3959.2Kwh

80%: 50V :: 4000Kwh

90%: 50.48V :: 4038.4Kwh

100%: 50.92V :: 4073.6 Kwh. 

So you can't calculate 80Ah * 48V, over a period of time. The calculation will change every few minutes. 

These values are average battery level values taken when the batteries have rested for about 2 hours.

IF, on the other hand, the batteries are being charged at the same time, the values will be much higher. 

7 minutes ago, SilverNodashi said:

48V is about 50% already. 

50%: 48.4V ::  3872Kwh

60%: 48.96V :: 3916.8Kwh

70%: 49.49V :: 3959.2Kwh

80%: 50V :: 4000Kwh

90%: 50.48V :: 4038.4Kwh

100%: 50.92V :: 4073.6 Kwh. 

So you can't calculate 80Ah * 48V, over a period of time. The calculation will change every few minutes. 

These values are average battery level values taken when the batteries have rested for about 2 hours.

IF, on the other hand, the batteries are being charged at the same time, the values will be much higher. 

Indeed but  we are still comparing apples with apples - working with 48V nominal across the calculation. The range of difference between 50.92 and 48.4 cannot explain a discrepancy of 3.8kW and 1.65kW?