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MPP Solar MPI 5.5kW Hybrid/Grid-Tie tripping my Conlog meter


Clive
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Hi guys,

I installed my 5.5kW inverter six months ago without solar as i didn't have the panels back then.

Everything has been running great as a backup when the grid goes down.

I now have connected my 20 x 325Watt solar array to the inverter and my Prepaid meter is tripping every 30 seconds or so.

I have also tried to set my inverter to “Grid-Tie with Backup (II)” and un-selected “Allow to feed-in to the grid”

The problem is still the same….

When i contacted Conlog this morning they advised me to change to the new pre-paid meter model BEC23(09) range.

Has anyone else also had this same problem and tried one of these pre-paid meters?

 

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Welcome Clive.

Yes. Some prepaid meters have a problem. There are posts on that on the forum, all over, but someone will be around shortly to sort you out.

This is one of the issues CoCT is dealing with ito having to register ones system.

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4 minutes ago, Clive said:

Has anyone else also had this same problem and tried one of these pre-paid meters?

It's come up a few times. The first time was @Wetkit's post some years ago, which had a follow-up here. He eventually gave up, not sure what he did after that. Then more recently @Chris Hobson has a similar issue with a Goodwe, after which we discovered you can use an arduino-based energy-diverter,  based on hardware you can actually buy and firmware you can download, that diverts excess power into a dump load (usually a water heater). No idea how far Chris got with that idea, but since we're usually talking only a few hundred watts for a few seconds, you only need to dump this load into a couple of incandescent lamps or something similar. Its a bit hacky but the best answer so far. Don't know if anyone has done it yet.

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26 minutes ago, plonkster said:

... since we're usually talking only a few hundred watts for a few seconds ...

I was waiting for one of these to come up again.

How does this effect, in CoCT, the connection to their grid? 

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Just now, The Terrible Triplett said:

How does this effect, in CoCT, the connection to their grid? 

Not sure if you mean on a technical level, or what. On a technical level, your power factor goes negative for a couple seconds, but it gets canceled out by other consumers on the same phase, and since this is a tiny amount of power (remember our discussion about the 3.5kw limit for a 60A breaker) it's all within the right margins.

Regarding tripping prepaid meters, the city will likely replace your meter with a new SSEG capable meter, at your cost. I believe the cost is around 5k.

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17 minutes ago, plonkster said:

I believe the cost is around 5k

Ja, thereabouts. 

If you want to connect a Victron inverter legally to the grid, you need to spend on a new inverter or as on your previous solution, on a Ziehl.

Ziehl is about R5-R10k depending on what you buy. 

Now if ANYTHING goes back, no matter how little, and there are a lot of those happening during a day, would it not make sense to them to say nope, not allowed, have to install this or that to not feed anything back, I wonder.

 

@Clive , we are chatting about this here, for in CoCT it is now law to register all solar installations, and grid tied needs a engineers signature for them to accept. We have a grace period till 28 Feb 2019 to make it happen, and there are a lot of sharks in the water, wanting to milk solar owners.

How this affects Axperts, we don't know yet. Therein my musings above.

I presume you are not in Cape Town or surrounds, but keep in mind Cape Town has been the pilot site for solar connecting to the grid, since 2008, in SA.

So from where I sit, the more people being made aware of this potential pending change everywhere in SA, is to get it as close to right as one can, and not get a shock later. I would be terribly annoyed to install a solar system to only find out later the bylaws require another few thousand K's to be legit.

Here is some more info:

 

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Thanks for the replies guys. What is confusing me is the fact I have just had MPP Solar in Taiwan assuring me that there is absolutely no “Feed in” in “Off grid” mode. So my question is then what is the meter “complaining” about then?

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Just now, Clive said:

What is confusing me is the fact I have just had MPP Solar in Taiwan assuring me that there is absolutely no “Feed in” in “Off grid” mode. So my question is then what is the meter “complaining” about then?

Ja, therein my question, same as you.

What I have learned these last few days, "off gird" and "grid tied" are being confused by even engineers, engineers whom are supposed to sign off the "grid tied" system. No jokes.

Off grid is off the grid as in there is no connection anywhere to the grid. Your prepaid meter cannot then trip.

And if you want to grid-tie you have to replace your meter, pre-paid and the old mechanical ones, with a new bidirectional meter, as Plonkster said, that can measure in and out.

But, if you are not Cpt, just check your local municipal bylaws.

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11 minutes ago, Clive said:

MPP Solar in Taiwan assuring me that there is absolutely no “Feed in” in “Off grid” mode

 

1 hour ago, Clive said:

I have also tried to set my inverter to “Grid-Tie with Backup (II)” and un-selected “Allow to feed-in to the grid”

The inverter is not in off-grid mode. It is running grid-interactive, and attempting to avoid feed-in. In other words, it continually adjusts its own power level to match that of your loads.

The trouble is that adjusting the power is a slow process that essentially plays catch-up the whole time. Simple example: Suppose you have a 2kw kettle going in the house and the inverter is pushing 2kw into the grid. This means nothing is fed into the grid, as it cancels out. Then the water reaches boiling point and the kettle turns off. If the inverter is really fast, it pull back production within a couple hundred milliseconds, but until it does: You are feeding 2kw into the grid.

The speed at which it adjusts differs between inverters, but is generally in the order of seconds rather than milliseconds.

The prepaid meter works on an average window, so it will trip if you feed back more than 20w over a 15 second window or something like that (depends on the meter). So for example, a 1500W feedin that lasts for 1 second is considered the same as a 100W feed-in over 15 seconds and will trip most meters that detect reverse feed.

Your only solution is to replace the meter, run in actual off-grid mode (disconnected from the grid), or use a PV-diverter.

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4 minutes ago, Clive said:

Thanks for the replies guys. What is confusing me is the fact I have just had MPP Solar in Taiwan assuring me that there is absolutely no “Feed in” in “Off grid” mode. So my question is then what is the meter “complaining” about then?

Hi Clive I like you was told by Conlog to get the municipality to install a BEC23(9) and request a voucher to switch off the reverse line protection - problem solved. Except our municipal ou has it in his head that we are trying to gypo the system and taken foot dragging to new depths (I was going to say heights but that has a positive connotation). I ordered  various Triacs and current transformers and Arduinos which got stranded in the post whilst the post office employees took a well deserved break.

I received the parcel on Saturday and in between my own solar upgrade and a upgrade in town I have been fiddling but have got anything working. Should be relatively simple. I can build you one if you are not happy programming a Arduino.

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Hi Chris, thanks for that. I might take you up on that. Please let me know how it goes?

so it sounds like I shouldn’t bother with the new meter then?

Does Conlog give the bypass voucher? Or is it a municipal thing?

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Try and get the new meter and the token (I think they call it a token rather than a voucher - my mistake) to switch off the reverse line protection. That is the simplest solution (and the most elegant). If not then you will have to build a diverter.

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59 minutes ago, plonkster said:

 

The inverter is not in off-grid mode. It is running grid-interactive, and attempting to avoid feed-in. In other words, it continually adjusts its own power level to match that of your loads.

The trouble is that adjusting the power is a slow process that essentially plays catch-up the whole time. Simple example: Suppose you have a 2kw kettle going in the house and the inverter is pushing 2kw into the grid. This means nothing is fed into the grid, as it cancels out. Then the water reaches boiling point and the kettle turns off. If the inverter is really fast, it pull back production within a couple hundred milliseconds, but until it does: You are feeding 2kw into the grid.

The speed at which it adjusts differs between inverters, but is generally in the order of seconds rather than milliseconds.

The prepaid meter works on an average window, so it will trip if you feed back more than 20w over a 15 second window or something like that (depends on the meter). So for example, a 1500W feedin that lasts for 1 second is considered the same as a 100W feed-in over 15 seconds and will trip most meters that detect reverse feed.

Your only solution is to replace the meter, run in actual off-grid mode (disconnected from the grid), or use a PV-diverter.

This is very interesting. Thanks Plonkster

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3 minutes ago, Chris Hobson said:

Try and get the new meter and the token (I think they call it a token rather than a voucher - my mistake) to switch off the reverse line protection. That is the simplest solution (and the most elegant). If not then you will have to build a diverter.

Great, will do. Thanks. 

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Hi Clive,

If you switch your inverter into mode Off-grid III, then there's absolutely no chance of feeding back into the grid. Spikes will be sent to the battery.

In the modes Off-grid I and II, the internal grid relay in the inverter is still connected,therefore spikes can hit the meter.

Just try it.

Regs,

Youda

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13 hours ago, Youda said:

Hi Clive,

If you switch your inverter into mode Off-grid III, then there's absolutely no chance of feeding back into the grid. Spikes will be sent to the battery.

In the modes Off-grid I and II, the internal grid relay in the inverter is still connected,therefore spikes can hit the meter.

Just try it.

Regs,

Youda

Hi Youda,

Thanks, ill give it a test.

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Just let us know how it worked :)

Sidenote - this mode won't blend the PV power with the grid power, so when the load is bigger than what panels+battery can deliver at the moment, then infini will auto-switch load to the grid and PV power will be used for charging the battery only. After couple of minutes, infini will auto-switch load back to the solar power (once the load drops to a lower level and battery voltage will be above re-discharge voltage value as specified in infinis settings).

 

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Hi guys,

Just thought i would give a quick report back on my meter tripping problem.

I have had my new pre-paid meter installed (BEC23(09)) and i also managed to get the 2 unlock tokens for this meter.

I'm pleased to report that there is no more tripping !!!

I would like to find out from you guys, should i now be able to export to grid and have the units on the meter add up?

When i export to grid my units are actually counting down.

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28 minutes ago, Clive said:

I would like to find out from you guys, should i now be able to export to grid and have the units on the meter add up?

No. For that you need a meter that accounts for the import and export separately. This is necessary because they don't generally pay you the same for power you export than you pay for power that you import.

29 minutes ago, Clive said:

When i export to grid my units are actually counting down.

That sort-of answers the question then :-)

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33 minutes ago, Clive said:

When i export to grid my units are actually counting down.

On pre-paid meters, some, I have heard warnings that they actually measure what you feed back as usage.

You have to get a bi-directional meter as per Plonkster. 

Just make sure that when you do, and you feed back, that you are not looking at a +-R11 per day connection fee.

End of 12 months, you must be a Nett user, used more than you sold.

That is the regulations in Cape Town, if you want to sell back to them. as the law does not (yet) allow anyone but Eskom to sell electricity.

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1 minute ago, Clive said:

Oh ok,

Do Conlog supply bi-directional meters?

If you are Cape Town based,off the top of my head, the company who installed the approved inverter (as per "The List" and Axperts are not on it), after having done a CoC (Few rands here), after a engineer has signed off the connection (R2.5k to R10k or more), after a bi-directional meter has been installed (R2k), you are good to go.

Anything else is problematic ...read illegal.

More info here, if I was you, wanting to sell back, I would follow the regulations to the last T, even if you are outside CoCT, to be as safe as you can be:

 

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31 minutes ago, The Terrible Triplett said:

On pre-paid meters, some, I have heard warnings that they actually measure what you feed back as usage.

It makes things much simpler to just assume that current can only go in one direction. In software, simple is good. Less bugs.

31 minutes ago, The Terrible Triplett said:

Just make sure that when you do, and you feed back, that you are not looking at a +-R11 per day connection fee.

You either

1. apply for the SSEG tariff, pay the R13/day connection fee, and get the new meter

OR

2. you fit a grid limiting device, you don't feed in (other than they tiny bits that used to trip your meter during load changes... which is of no concern, it is not going to kill the wallet), and you remain on your current tariff with your existing meter.

There is no point in fitting the fancy bi-directional meter if you choose the second option.

25 minutes ago, Clive said:

Do Conlog supply bi-directional meters?

I don't think so. The city has one that they like to use anyway, so you don't have much of a say.

31 minutes ago, The Terrible Triplett said:

End of 12 months, you must be a Nett user, used more than you sold.

Well... nothing will happen if you are not a nett-user. If you accidentally gave them more power than you used... they are simply not going to pay you for it. That is all. You will still have a R400/month bill (the connection fee) at the very least. In addition, you pay more than twice for imported power than they rebate you for exported power, so the absolute best you can do is offset half of your evening power. And not even that.

It does however still make more sense than battery storage. At least I think so, haven't done the math recently.

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