SOLARWIND

Hi Plonkster
 
The ones I was looking at is called Hoymiles, you buy a DTU (Data Transfer Unit) with a current clamp that measures the load and stops the exporting. Have a guy in the area who has this setup and he says it works well. You can add panels and inverters as you need or have funds for.

Last time I checked those two things are mutually exclusive. Grid limiting/power control is not common on the microinverters I've looked at, they don't even support power reduction via frequency shifting. Of course this might have changed, but not that I heard of.

A clear, hand drawn single line diagram is all that is needed with your application. It must show the change-over switch and clearly show how it safely chooses between your inverter output and the utility mains supply. According to SANS10142-1 the change-over switch must be an approved type with a centre-off position and this fact should be confirmed as a comment on the test report section of the CoC for the installation. 
 

A very simple way to get the same result, would be to install a simple mains operated relay and use the N.C. contact on it. Then use inverter power in series with this contact to supply your remote indicator or whatever. 

Right. Cause at 54V a Pylontech battery is switching off already on overvoltage, while a lead-acid bank is hardly getting a good float 🙂

If the inverters' outputs are paralleled, then there has to effectively be only one battery, so the actual batteries would have to be paralleled. But paralleling lead acid and LFP, especially 15S LFP, isn't going to work.
What you could do is split the loads, putting half on one inverter and half on the other, keeping the systems separate. That solves the problem of the separate settings.
But then it will be like a computer with two hard drives; you've forever running out of space on one when you have space on the other, and you wish you could just make one big hard drive. I think you'd hate having to manage the loads all the time.

Because you are feeding the inverter from an E/L circuit in your grid DB, and you have connected N-E on the outputs which is an earth fault.
I hope the attached sketch is legible, my CAD skills are a touch lacking (I can do it but it will take the whole day!)

Grounding vs Earthing. That will be a good thread.
Sincerely
Jay

Victron inverters are isolated... but I still don't think it is a good enough excuse 🙂

In most of the new Victron MPPTs this is the case. In some of the older ones the current sensor was in the negative line. Because this is a hall-effect sensor you won't see it by measuring it with a DMM, but if you earthed the panels and the battery on the negative side you would bypass the current sensor and blow up the MPPT. I've seen it first hand too. But that was the old ones... the new ones have current sense in the positive line.

It's called corruption. Stage 4 load shedding was announced today. Yesterday our neighbors sat without power between 12:00 and 15:00. Yes, there is something VERY VERY wrong here. I could have supplied some electricity to someone else. In fact, most of us, just on this forum, could have contributed a bit to the grid. But they fat cats want to get rich off your efforts.

With all the labour unrest caused by ESKOM unbundling, I hear the unions are threatening to turn the lights back on.

Right... so you have to be a big consumer with an even bigger PV-array. It has to be "just so" to work. Still, the numbers turned out to be better than I expected.

And that future will be soon, now that the government has managed to add labour unrest to ESKOM's woes.

Thanks for the graph,
I draw the conclusion that an SSEG residential solar user is penalized for low usage, and only once he starts conforming to a normal usage quota is he not discriminated against.
And that in turn creates a financial incentive that for a band of potential solar export that its better for residential solar to throttle back and stay on the home rate.
The graph indicates in break even around  300kWh, for the realistic conditions given. 
And we can't really neglect the R10K meter cost either. So effectively there is this economic wall, where it either you stop or you crash through it by a mile.
Unfortunately, capacity limits also dictate you will have to stop and throttle your inverters on the home rate.
 
On the other hand, if you are a high rate grid user already, every self-consumed unit that can be generated saves at the high rate unit price.
So there is actually, a much greater incentive to install solar to reduce your usage down to 600kWh /pm, and a less incentive to cover the next 600kWh/pm, and a wall before you can contribute to the social good. To my mind, that's the wrong trend.
 
 

I'll go along with this, a maximum demand charge is fairer though, (but subsidizing the less well off is an social justification).
 
This is the charge I am rebelling against, this extra charge, not the standard connection charge.

That paper speaks to residential solar as target group, not to typical South Africans.
So the unit price will go down, once unbundled? 
Will it affect everybody based on the size of their supply connection.
Or because some people electrons can flow in a different direction do the wires needs more maintenance and therefore they warrant an extra charge?
That's patently untrue.
I think the paper is clear, the driver for the charge is they'll sell your extra on at a profit, but whatever shortfall they lose in lack of sales to you they charge you for anyway.
 

I am still of the opinion that this is the wrong approach for a long term sustainable win win situation. I would make it as attractive as possible to buy and sell as much electricity to the City as possible. Offer very attractive low demand purchase and high demand selling prices to the consumers. This would encourage households to invest more in storage capacity and reduce the need for expensive grid peak load and distribution capacity. As long as Cape Town is not officially allowed to purchase electricity this is obviously going nowhere and will drive more and more customers off grid.

True, IF there are 100's or 1000's of grid-tied inverters in a specific area, and IF the ESKOM supply to the WHOLE area is ISOLATED WITHOUT EARTHING AS A PRECAUTION, THEN and only THEN will there be a local "grid" which could be live. I agree, there should be safety regulations in place to be 100% safe and I agree that they should rather be strict on the Certificate of Compliance by a duly Authorised person and that the CoC makes provision in the Test Report section thereof that the signatory thereof certifies the safety of the system as a whole. It is ESKOM or the Municipality that should brush up on safety and KNOW that there is nowadays always the possibility of reverse power on the system.THEY are the ones that should make their equipment safe before touching it. (This is the reason for EXISTING safety rules which state that they should TEST, ISOLATE AND EARTH. - NOTHING NEW).

I interpreted the meter reversal mentioned in the paper to mean the reversal that happened when someone with an illegal solar installation generated power and because the meter reversed he was essentially selling power back at the same price he was paying for it. And that was the concern, not actual meter tampering.

It is quite amazing how much thought goes into just fleecing people for the right amount of money to avoid illegal connections.
(And how illegal connections are not considered from a safety perspective, purely a financial one).

I also think that the safety aspect is overemphasized. Whenever we have a power failure here in Plattekloof (because of the shifting ground we have a lot of them) I go and speak to the repair crew to find out what the problem is and how they fix it. What struck me is that they ALWAYS short the live wire they work on to ground with a big heavy duty cable and earth spike. They also told me, that they never had a problem with an inverter back feeding power into a dead grid. I am however in favor of registering/checking grid connected PV systems but the process should be MUCH quicker and simpler. I think the city is seriously paranoid about this and that it has more pertinent challenges it should channel its scares resources and money to.

That's akin to rearranging the deck chairs on the Titanic.
 
Yes, I have heard the talk of deregulation, that might be interesting for solar.

Meter tampering I am sure is rife, but that is the type of meter tampering that can happen with or without solar.
However, when a meter runs backwards because of correct power flow all that happens is your power gets sold to someone else by the authorities at full price.
It just that the authorities want to insert themselves into that transaction for an extra piece of the action.
It quite clear from that paper that they are carefully considering how much they can skin you for, while still keeping you working for them.
That's exploitation on their behalf.

Because the PC at the end of long lead will see rectification sag + cable drop - close pc sees only sag.