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8 minutes ago, The Terrible Triplett said:

Goes against the R&D account if you know how to claim Co expenses. :-) 

Indeed! I forgot about that :-)

Speaking of expenses... Meter Taxis in Europe are EXPENSIVE. I took a couple of trips, each one between 4km and 5km, and each one costing me almost exactly 15 Euro, or R50/km. Local metered taxis are around R10/km. We don't know how cheap some things are in SA...

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On 2018/10/02 at 7:05 PM, plonkster said:

When the inverter tests its relays. So basically when the power comes back after an outage, the inverter goes clickety-clickety-clack and then the RCD on the output trips.

Hi Plonkster

I'm new to this forum but have been following this thread with interest, since I am planning on installing the Mutliplus-II (which I understand to be a re-named Multigrid). I'm hoping that I do not run into similar earth-leakage issues, otherwise I might also be doing some tool-buying 😉. One question - what earth connections do you have to the Multigrid on the mains-input side?

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1 minute ago, NigelL said:

One question - what earth connections do you have to the Multigrid on the mains-input side?

It's earthed to the earth bar in the main DB (which is earthed to the supply cable going down to the transformer, since this is a TN-S system). I have a 300mA/25A RCBO on the input side too. That's because (I think?) SANS require RCD protection on the input side as well, and 300mA is sufficient for equipment-level protection.

The problem I'm having has to do with my appliances, but it's a combination problem: There is more than one appliance "working together". In fact, in my office/guest bedroom I have an ultra-weird situation, where the total standing loss actually comes DOWN when I plug in a second appliance. It appears that the air conditioner unit has a high leakage, but the computer monitor on the other side of the room cancels out some of it.

I have now also determined that my RCD trips around 17mA.

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That is a tricky one to pin down!

As you know, an RCD will trip if there is a defined imbalance between the currents in Live and Neutral (in your case 17mA). Although this imbalance is typically when Live "leaks" to earth, one can also get a trip where there is a current flow between Neutral and Ground. Neutral is normally at the same potential as ground (due to the Neutral-Earth link at the main breaker) - but I understand that the Multigrid's Neutral output can "float" if the chassis is not properly connected to earth. The internal relay connects the Neutral output to Chassis during a mains power failure (after disconnecting the Neutral input).

Basically I am wondering if your nuisance tripping may not be related to a Neutral-Earth problem rather than a Live-Earth leakage problem?

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I think I have a combination, that maxes the controller without danger.

3 x 150w panels on a 75/15 is perfect. Problem is, 150w panels are seriously expensive per watt.

So if I should ideally not go over 2kw array with a 225ah 24v bank, the goal being to take a cheaper smaller controller and match the panels optimally, as smaller arrays are cheaper to mount and one can make them face N/E/W, as needed, manually changed per season.

Array 1: (my very 1st set of panels - 2011/12)

image.png.65bc40ef4ccd73b8581718a9b41ed055.png

Array 2: (Then not being able to get more 200w, was early days so no mixing brands, my 2nd set of panels - 2012)

image.png.1220a25f9fed51abbf0b883ec70374ec.png

 

Array 3: To bring it to 2kw, with option to expand by adding same ...

image.png.2ab34cb2b3834881ca7556d3cc6298dd.png

 

Any comments, suggestions?

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29 minutes ago, NigelL said:

Basically I am wondering if your nuisance tripping may not be related to a Neutral-Earth problem rather than a Live-Earth leakage problem?

That is a good suggestion. I have disassembled and repaired a smaller Compact Multiplus, so I know that the earths are all interconnect as well as tied to the case (it only removes the N-E bond when running off-grid). There should be no reason to tie the case to earth if you already connected the earth connection to the screw terminal. So unless there is a major departure in how the Multigrid handles this, I don't think that is it. But I will check it when I mess with this again.

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22 minutes ago, plonkster said:

removes the N-E bond when running off-grid

Aaaand the edit function is gone again.  I meant to say when it runs on-grid.

57 minutes ago, NigelL said:

current flow between Neutral and Ground

I've got some of this too. Turn off the breakers and it still trips. Remove the neutrals and it stops tripping. It's a honeypot of issues...

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So, I set the system to re-charge fully once a week. This morning, I died twice, one time per controller and array.

No PV at all:

image.png.3b9e7e1db651cb0c4bb016a9a5d7aa50.png

 

Turns out, if I use the Scheduled Charging, that the array input is ignored till it is done. So I changed it, to charge every Mo morning from 1-7am.
Being summer, I switched it off.

I'm getting an itch to consider a thought to ponder on an idea that maybe I should be getting slightly ticked-off with the lack of info on all the options for newbies.

 

Good news for me, I see that the array is being used to the max now like on the 6th:
Shows one clearly that evening loads, which is, as my wife says, why we work so we can pay for Eskom to use stuff, is currently uhm ... interesting (I'm treading carefully).
Spikes are kitchen use, there are 2 on the property ... best I do not go there see.

image.png.1397c707d3f2a40be9916a6a1bf3ffc4.png

 

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10 minutes ago, The Terrible Triplett said:

Spikes are kitchen usage, there are 2 on the property, and best I do not go there see.

I know what you mean 😁! I see you are not using your batteries at all if consumption is > solar. What is the reason? I thought that moderate cycling will give you the best return on your battery investment.

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Just now, Fuenkli said:

I see you are not using your batteries at all if consumption is > solar. What is the reason? I thought that moderate cycling will give you the best return on your battery investment.

I am using the batts in self consumption, set to 95% SOC. Going too low with the SOC a lot of loads are "missed" that come and go all the time, whilst the batts are "recharged".

Batts are pushing out 50Amps at times, receiving 40+amps back in at times, as I have lifted all the checks and balances, therein also the high SOC. Playing it so that the meter does not charge me units for over production. ;-)

Am also noticing for the first time how "late" the panels start producing in the mornings ... and why they keep powering so well late afternoon. They are ever so slightly more North-West, the small array favouring winter production, the large one summer.

I'm eyeing adding 2 x 355w Canadian's on a 100/30 so I can "grow" the array in 700w chunks. One more controller and I am at 2kw in total, not that I have seen 1330w yet. Why I am not getting the full 1330w from the current array, as I have seen 1100w and 440w coming in in the past? It is not summer yet, panel degradation or wires - to be determined.

Having multiple smaller controllers are cheaper (off-set with added wire costs) and has the possibility of better harvesting by placing their arrays strategically. Still deciding that, East / West or North and at what angle, favouring summer or winter, or make them ground mounted and adjust as needed.

... all that till someone blows the idea out of the water asking a obvious question I have missed asking myself.

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25 minutes ago, Fuenkli said:

I thought that moderate cycling will give you the best return on your battery investment.

I think the Trojans can take this, for short periods:

image.png.7019c1477929764e657944423124cef7.png

image.png.3c38952e4d3da4f6d93707220f3cd98a.png

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Batteries being used, system is running "open taps" , yet seldom "feedback" noticed, does happen now and then.

image.png.d1ace7f363a007fce9a31af9abc2c87f.png

 

Like here I can see when it "fed" back ... the teeny weeny red parts. That is cheaper to "pay" than pay Eskom if the setting is "off". Helped when I switch on the Consumption setting. ;-)

From WHY are you boiling the kettle AGAIN!? 
To BOIL that kettle NOW! :D (thinking it, not really happening)

image.png.3287ee1d67fd4e36118643302303d43c.png

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7 minutes ago, The Terrible Triplett said:

I think the Trojans can take this, for short periods

interesting graph. What is causing this rapid cycling? Would it not be better to let the SOC go lower in order to harness as much solar energy as possible. Looking at the below graph I think you could have harnessed more energy between 11:30 and 14:00.  

image.png.1397c707d3f2a40be9916a6a1bf3ffc4.png

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5 minutes ago, Fuenkli said:

I think you could have harnessed more energy between 11:30 and 14:00

Yes, if the power could be fed back. But if the AC incoming is toiling around zero, loads fully powered by the panels, batt fully charged, nothing more can happen.

Like now, Grid fluctuates from -X to +Yw ... unless something is switched on, only then will more be generated.
If that load then exceeds the panels max potential at that time, batts are used, if load continues and 95% is hit, then Eskom is requested to assist.
Load goes off, batts are re-charged, and cycle starts again.

image.png.d04116e1011f0762bb3dc2736982a637.png

 

6 minutes ago, Fuenkli said:

interesting graph. What is causing this rapid cycling?

Kitchen, geysers. Induction plates makes for quite a interesting display, like 0w AC, 2000w AC, 311w AC, 2000w AC, 0 AC.

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What I find quite interesting, the Carlo gives quite accurate readings, the Effergy meter is FAR out compared.

Either the clamp is positioned incorrectly in the DB or it has become a useless way of measuring it all. 

Measuring over a day the Efergy is quite good though. It served a big purpose the last few years.

 

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Perfect example of system working in balance. Kettle.
No, I don't watch it all the time, I can hear the inverter when it uses the batts. Lovely comforting electronic sound.

image.png.cbaf0cfc4540c5f4f1ee3a01c650e8c3.png

 

Next moment, load goes off, panels supply all.

image.png.51851865f7f43a408fdbbda7e811340d.png

 

FWIW: Fan seldom comes on, it is very quiet. Therein me being able to "hear" when it is using the batts.
When fan does come on, and not for long periods either, it is quite well controlled, slow, or faster or at full speed. At full speed it can get noisy, come this summer, I will share the aircon between inverter and me. ;-)

Will need more panels for that.

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9 minutes ago, The Terrible Triplett said:

Fan seldom comes on

There is a heat sensor that plugs in at the top of the control board. If you unplug it the fans come on full speed and the CCGX logs an overtemperature error. So if you're in the mood for playing... I've had to do it once to test a software feature.

The unit is fairly quiet up to around 1600W. Then the fans slowly pick up speed.

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2 hours ago, The Terrible Triplett said:

Yes, if the power could be fed back. But if the AC incoming is toiling around zero, loads fully powered by the panels, batt fully charged, nothing more can happen.

I agree. I have the same problem. That is why I am still looking for an automatic power diverter solution to switch on stuff like pool pump, aircons, geysers, borehole pump etc. if there is excess power available.

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14 minutes ago, Fuenkli said:

That is why I am still looking for an automatic power diverter solution to switch on stuff like pool pump, aircons, geysers, borehole pump etc. if there is excess power available.

I work it the other way. Have X panels, looking at the results, not 100% convinced I need a lot more.

Yet I am toying with adding just 700w more, right now in summer, and see the results.

In winter we ALWAYS need more but then we have clouds too ... no matter how much panels I have then, they are wasted. Not the EV tubes, they work in winter too. ;-)

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@plonkster here is what I don't understand. What is the logic behind each, to limit AC usage?

Settings like this, I lose a lot of Solar power that is not off-set against AC in.

image.png.027eb87cc36f03c0310ee425c514596b.png

image.png.279574a2179d1b1de10245a0c65b278a.png

 

Versus, like this, which removes all limits. Yet still not there, batts seems to be the bottle neck, why I'm not sure.

image.png.657f26542b869a21c889e3d1760c5e16.png

image.png.35b3519fdf16a904dfa85d37d5a35ae1.png

 

Versus this, which is what I want.
Would be great if I can have batts fully charged, no feedback, with this AC.

image.png.ba947cfff5ac7410eb35f710a6e0af2e.png

image.png.0c5be225fbe364d28d33614470e0b421.png

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@The Terrible Triplett, there is a small issue with calibration that's being worked on. Some time ago the decision was made that 400mV (for a 48V system, 200mV for 24V) is sufficient of an overvoltage IF ALL THE DEVICES ARE CLOSELY calibrated. But then the mechanism used to sync them up showed a few issues and got dropped. Now it turns out that a Multi can be as much as 0.2V off (in a 48V system, half a percent), and the solar charger can also be a little off, and then there's the voltage drop on the cable. So essentially the 0.4V offset is too small. This offset is required whenever you're feeding the excess into the grid or keeping the batteries charged while using the excess for loads, and until this is figured out your best bet is to run optimised mode with MinSOC=100%.

You can also just increase the offset -- as previously discussed -- and set it to something nice and high, like 1V. If you're feeding into the grid (and there are no restrictions), then the Multi will hold the voltage down and you will get perfect feed-in at full power. There is however no regulation on this (and attempts at regulation doesn't work on a very full lithium battery, trust me), so whenever there is nowhere to go with the power, the battery voltages goes up.

So long story short... yes there is an issue. Just hang on a while longer.

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19 minutes ago, plonkster said:

So long story short... yes there is an issue. Just hang on a while longer.

100% ok with that. Thank you.

Am happy to be a test site for Matthijs and co, seeing as I run on the edge.

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