Lourens78

Indeed. If we take the common-as-weeds Axpert systems that switch on low battery, then one could say that Axpert's do "trip". Trip, in this context, is when the system transfers the load back onto the grid. Axperts do transfer their loads back onto the grid, and they do so in a pattern (after dark, or on a rainy day), and this would cause some pick-up. This pickup is however spread over a much longer period and does not contribute to the same kind of event that you'd get witih a grid-tied setup that trips. So I maintain that applying grid-tied limits to such off-grid setups does not make sense, but 1) there are no alternative rules, and 2) the guys who do the sign off follow the rules, they are not allowed to add their interpretation into it.

Agreed. I mention it merely for fairness (so people cannot say I did not consider this characteristic). 🙂
 

Is the idea to go completely off grid? That's expensive. You need enough battery to contend with a period of sustained gloomy weather, enough solar panels to get them charged up in good time, and an inverter that can handle that. Plus probably a generator as a last resort.

use the first two years for learning what your property draws and when, and how long your system can run the essential circuits. Also use the various apps to identify high loads on the property and decide what to do about them. Consider going to gas for cooking and solar or heat pump for water heating as they are two of the biggest loads in your house. 

A point I always make. Get a COC (or amendment to your existing COC) from a competent person and make sure your insurers get a copy and know that you have a solar system. Otherwise if the worst comes to the worst they will send out a loss adjuster who will very quickly notice that there are wiring changes that they weren't told about or is not described on your COC and so you have misdeclared the risk to them and so the policy is voided.

Yes, but I'm saying that you should keep your insurer informed. It shouldn't affect your premium unless you specifically insure some internal components, but it is wise to be in a position where the risk is accurately described. Probably a valid COC signed by a competent person will prevail in the end, but a claim may be held up.
 

You will get monitoring tools with the Goodwe, and you will very quickly get a good picture of what is happening when. And you will very quickly see the impact of any changes that you make. 

Man... I would say let sleeping dogs dogs lie. The official reason for the 25% limit is that they want to limit the "pick up". When an embedded generator trips, whatever it was powering needs to be picked up by the grid. When some anomaly on the grid (low voltage event for example) causes the entire neighbourhood's embedded generators to disconnect, the grid has to pick up all of that. So they are not at all concerned about how much is being fed in, they are concerned about the spike that results of all those feeders go away.
So while one would think you can build a system that generates 10kW, but you carefully control it so no more than 3.5kw goes into the grid... that would not be allowed, because that has a potential pick-up of 10kw... not just 3.5.
Now one would also think that if you put a 5kVA hybrid inverter (eg a Multiplus-II) on the grid, with 3.5kW of PV modules... that inverter can supply the difference from the batteries, so it could potentially push as much as 4kW from the combined DC sources, and therefore the pickup for that combo is in actual fact 4kw (and not just 3.5). But CoCT looks only at the PV modules (the PV module is the generator, not the inverter)... and so you can get it approved if the PV array or the inverter is small enough... disregarding the battery component completely.
🙂
 

Is the 25% not limited on the feedback side of things?

I have a 60A main breaker and a 5kVA Axpert installed - but only 2.8kW of PV panels. My system was approved by COCT last month.
But also would like to install more panels in the long run - so am also interested about trying to find a way to be able to put more than 3.5kW on my roof...

60A breaker will give you close to 14kw at around 230v.... much more than the 5kw inverter can handle. Your inverter will probably switch off due to overload before you breaker will trip

I think he means in he CoCT context of 25% of that 60A breaker. The 25% rule applies to inverters that grid-tie. The 5kw axperts everyone installs is 1) not a hybrid, and 2) not always installed in Cape Town. For a long time CoCT even said outright the Axpert cannot be legally installed. For an equally long time, I personally argued that they don't even comply fully with SANS... but the truth is I simply don't know anymore. Apparently you can install them and declare them off-grid.

have a look here:
https://powerforum.co.za/topic/5165-circumventing-the-coct-35kva-limit/

Technically this is called "Current Level Discrimination" and is a technique linked to the staging of the Long Time (LT) tripping curves of two serial-connected circuit-breakers. (Quoted from the Schneider Electrical installation guide)
An interesting point is that overload protection of a cable can be implemented either at the source or at the load side but short circuit protection has to be implimented at the source.
@plonksteris spot on.

No, for two reasons.
The breaker is there to protect the cable. Without the breaker, the cable could get hot and set something on fire. If the cable is not rated for 80A, you cannot just upgrade the breaker.
Even if the cable can handle 80A, you have to remember there is usually also a breaker on the other end of the cable, one you don't have easy access to. This one is usually larger than the one on your end, because that adds specificity to the system: The one on your end will trip before the one on that end. If you upgrade it, then you may need to call the municipality each time it trips on the wrong end (plus, they will probably start to look for the reason too).
You have to apply to have the breaker upgraded. CoCT has already indicated they will not upgrade it if your sole reason is that you want to install a larger SSEG.