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A little bit of advice needed for my ESS system


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*first off, apologies in advance if i ask a question that's been asked before, but i really have spent a ton of time reading as much as i can on the topic but i'm still unsure of a few questions that i have.

This forum is amazing, i'm really impressed with the amount of knowledge people have, and the helpful advice given here and the amount i've learned just reading the posts here, so i'm hoping i can get some of that advice to make sure i don't go down the wrong path.

I'm looking to install a system that allows me to give Eskom the boot, as much as is practically possible. So a hybrid system, PV array, with battery system to keep the lights (and other toys) on when the sun isn't shining, and most importantly, when Eskom's coal is wet / conveyer belt breaks / maintenance happens / <insert random reason for being loadshat>

Im looking at going the Victron route for the inverter and MPPT, with some Pylontech lithium batteries to store the little rays of sunshine in. (I've got the Victron MultiPlus-II 48/5000/70-50 in mind.)

I'd like to start with a medium-ish system, and expand a bit later on till i'm eventually fully (or 90%) off Eskom.

Turns out i use a lot of electricity. Around 40 kWh per day (based on my meter reading), and around 7000w at peak time. But this is theoretical, I don't have an electricity  / power consumption meter, so I'm not a 100% sure of my peak usage, i worked it out theoretically based on the appliances power consumption, and which appliances run simultaneously.

So i'm concerned about the inverter.

I can't go bigger on the inverter though, it seems that Durban (Ethekwini) has a limit on a 4.6kva inverter if you go grid tied.

So my questions are:

What are the options if i do need to be able to cater for more power than this inverter can provide?

E.g. If you run two inverters in parallel , I'm guessing that's not compliant anymore then, or is it?

thanks in advance!

 

 

 

 

 

 

 

 

 

 

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On 2020/02/28 at 10:40 PM, grapgat said:

What are the options if i do need to be able to cater for more power than this inverter can provide?

We had a long discussion about this elsewhere, about circumventing the 3.5kw limit in CoCT. Well, not really circumventing of course, but sticking to it in some way.

The suggestion I made is to use the AC input limit of the Victron inverters. This works in both directions (which may not be quite what you want but does the job). If you set this to 20A for example, the Multi will never feed in more than 20A, and will never draw more than 20A (the rest is taken from the battery). This makes the Multi appear like a 4.6.kw inverter to the grid, but you can have loads on the output that are larger than that. You essentially have an off-grid system that can be assisted from the grid (up to 20A), and can feed into the grid up to 20A (to your own loads of course), but the pickup will never be more than 20A.

Then, because the 8kVA Quattro doesn't have NRS097 compliance, you could put two 5kVAs in parallel.

Let me stress though: Best to check with your municipality whether such a software limit is acceptable.

To me it sounds however like you only peak at 7kW for short periods... so why not go with the 5kVA and just take the peaks from the grid. That would still get you mostly independent from Ethekwini.

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9 hours ago, plonkster said:

To me it sounds however like you only peak at 7kW for short periods... so why not go with the 5kVA and just take the peaks from the grid. That would still get you mostly independent from Ethekwini.

thanks plonkster. 

I've ordered an Efergy energy meter, so i'll be able to monitor for exactly how long my usage peaks past the inverter's capability.

If it is short enough periods, then I'll just draw from the grid as you suggest. If it's longer periods, then I'll see if the municipality will allow the software limit and go the parallel inverter route to get the most of my investment.

 

 

 

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