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Right, crossroads, after a deep dive into Solis, to the brink of purchasing.

NBEEF feedback:
- 60amp breaker, will not sign off more than 3kw.
- Panels will be earthed.
- Batteries must be ventilated - they are in a wooden box - even maintenance free ones, AGM's too.
- He does claim checks for select insurers. No CoC, no claim payout. 

Costs:
- If all is ok with DB, about R1k to get a CoC - excluding fixes. 
- "The Engineer" ... I'll be back on that price. I'm smiling very broadly at this point in time. :-) 

I have: 
- BMV700, VenusGX, Trojan batts and all the cables.
- 930w on a 150/35 in series (310w x 3) 
- 400w on a 100/30 in series (200w x 2) 

Additional parts required:
- Carlo Gavazzi ET112 and a RS485 cable +- R1500 odd
- New MultiGrid 24/3000/70-50 inverter. Worst case: R13 038.00 ex VAT.

Plan: Want to push all solar power into the house, with a few select circuits like internet, computers, lights, fridge, 1 small freezers on battery backup.
So will have the Carlo G energy meter installed after the main switch and before the earth leakage. As per Plonkster.

As Plonkster pointed out:

22 minutes ago, plonkster said:

Hybrid inverters means smaller battery banks. Battery banks are the largest part of your investment :-)

So, to max the controllers, yes, I know 24v has input limits, but Victron combinations do not. :-) 
100/30 can take max 880w - currently on 400w
150/35 can take max 1000w - currently on 930w
Total of 1 330watts.
Run as is, see what the numbers look like after a few months.

Assuming the numbers make sense, then BEST case thereafter:
Get another 150/35 controller with 3 new 200w panels added to the exiting 2 x 200w = 1000w
Get 4 new 220w panels on the 100/30 = 880w
Plus the existing 930w array on the existing 150/35
= 2810 watts in total from 2 existing controllers, and 1 new.

All the above on the assumption that ESS will allow this size array, on a small 24v 225ah bank.

What am I missing?

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28 minutes ago, The Terrible Triplett said:

All the above on the assumption that ESS will allow this size array, on a small 24v 225ah bank.

A bit of eye-candy for those who also rug up makeshift things to develop/test things. This was in December.

25440320_10155796672090619_4682538286571583616_o.thumb.jpg.bc5e4b11a1fc0485745ca12ccc6dc85a.jpg


The three little wires hanging out of the Venus-GX is attached to the serial debug header, in case you're wondering.

The CCGX distributes the charge current across the MPPTs. The limit is always distributed such that the limits of the MPPTs always adds up to the total requested. All that it does is shuffle some of the limit across so that all the chargers are the same distance away from their respective limits. If there is a shortfall in charge current, the rest of the limit is assigned to your  Multi.

We also add in the load before distributing it, so if you want to charge your batteries at max 30A, but you also have a load equating to 10A, we limit the MPPTs to 40A (so that the remainder is within the requested limit).

However, there are caveats. There always are. If you have fluctuating loads (your typical washing machine spinning this way and then that way), you cannot adjust your MPPTs up and down every two seconds. They don't like that. So the overall load of the Multi is chucked through a low-pass filter to smooth it out, and this value is used.

What that means is that for short periods we can and will charge more than the limit you set. In other words, the fact that this feature exist doesn't grant you the license to be an idiot and make things completely lopsided. It is still advisable to size your array towards a C/5 charge rate (with no loads), and maybe C/2 max for short periods. This is a gut feeling, I've done no work to prove it. So my gut feeling is that with a 225Ah battery at 24V, you'd better stick to <2kwp of PV to be safe.

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6 minutes ago, plonkster said:

So my gut feeling is that with a 225Ah battery at 24V, you'd better stick to <2kwp of PV to be safe. 

This changes completely once you change battery chemistries. LFP thinks nothing of 1C or even a 0.5C spike, so this allows you to make things a bit more lopsided, but you still have to keep things more or less in proportion.

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25 minutes ago, plonkster said:

... make things completely lopsided ...

I presume the same applies to all hybrid inverters?

 

3 minutes ago, plonkster said:

This changes completely once you change battery chemistry.

It is planned yes. Existing bank must stay in place until its replacement in a few years time.

Flips side to that, Eskom slips, run existing bank at peak level, after adding more panels, then upgrade to a bigger bank ... with a new chemistry 400ah 24v bank.

If Eskom stays within parameters, replacing a 24v bank is still cheaper than a 48v bank.

System sounds future proof?

 

33 minutes ago, plonkster said:

A bit of eye-candy ...

I'm very comfortable with that kind of setup. :-) 

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52 minutes ago, The Terrible Triplett said:

I presume the same applies to all hybrid inverters?

To a greater or lesser extent. Those who bring the PV in on the DC bus must be affected more than others. Those who bring it in on the high voltage DC side (and then buck it down to charge the battery) will be less affected. So that expensive Infini you talked about for example, with the high voltage DC mppt...

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16 hours ago, The Terrible Triplett said:

Right, crossroads, after a deep dive into Solis, to the brink of purchasing.

NBEEF feedback:
- 60amp breaker, will not sign off more than 3kw.
- Panels will be earthed.
- Batteries must be ventilated - they are in a wooden box - even maintenance free ones, AGM's too.
- He does claim checks for select insurers. No CoC, no claim payout. 

Costs:
- If all is ok with DB, about R1k to get a CoC - excluding fixes. 
- "The Engineer" ... I'll be back on that price. I'm smiling very broadly at this point in time. :-) 

I have: 
- BMV700, VenusGX, Trojan batts and all the cables.
- 930w on a 150/35 in series (310w x 3) 
- 400w on a 100/30 in series (200w x 2) 

Additional parts required:
- Carlo Gavazzi ET112 and a RS485 cable +- R1500 odd
- New MultiGrid 24/3000/70-50 inverter. Worst case: R13 038.00 ex VAT.

Plan: Want to push all solar power into the house, with a few select circuits like internet, computers, lights, fridge, 1 small freezers on battery backup.
So will have the Carlo G energy meter installed after the main switch and before the earth leakage. As per Plonkster.

As Plonkster pointed out:

So, to max the controllers, yes, I know 24v has input limits, but Victron combinations do not. :-) 
100/30 can take max 880w - currently on 400w
150/35 can take max 1000w - currently on 930w
Total of 1 330watts.
Run as is, see what the numbers look like after a few months.

Assuming the numbers make sense, then BEST case thereafter:
Get another 150/35 controller with 3 new 200w panels added to the exiting 2 x 200w = 1000w
Get 4 new 220w panels on the 100/30 = 880w
Plus the existing 930w array on the existing 150/35
= 2810 watts in total from 2 existing controllers, and 1 new.

All the above on the assumption that ESS will allow this size array, on a small 24v 225ah bank.

What am I missing?

The money????:D:D

Edited by Ronnie_V
Spelling error
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14 minutes ago, Ronnie_V said:

The money????:D:D

Is it really that expensive?
Additional parts required:
- Carlo Gavazzi ET112 and a RS485 cable +- R1500 odd - most would need a additional cost to become legit, most.
- New MultiGrid 24/3000/70-50 inverter. Better case: +-R11 000.00 ex VAT ... not THAT much more than a new Axpert.

Still waiting on a better price for the inverter ...already down by about R2k ... ;)

Adding panels and controller/s etc, can be a expense incurred on any system. So I don't count that.

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15 minutes ago, The Terrible Triplett said:

New MultiGrid 24/3000/70-50 inverter. Better case: +-R11 000.00 ex VAT

Where did you get THAT price!? That is exceptionally good. That is almost less than I paid for my 1600VA unit 5 years ago!

The Multiplus-II sells for the same price by the way (at least in Euro), and its NRS certification is only a few weeks away. Hopefully. The ultra low EMC value I referenced earlier was apparently dropped which moved things forward a bit.

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20 minutes ago, The Terrible Triplett said:

not THAT much more than a new Axpert

And I just have to say again... this is a really bad comparison. Its natural competitor is the Infini. You can't compare a Hybrid with an Off-grid inverter, that's not apples for apples :-)

Honestly, if that is what they sell for now, you'd be nuts to buy anything else.

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3 minutes ago, plonkster said:

... this is a really bad comparison.

Well, did the Infini not lose the price war on the other thread ... ;)

 

2 minutes ago, plonkster said:

Honestly, if that is what they sell for now, you'd be nuts to buy anything else.

Or maybe we are raising the bar when comparing a off-grid UPS with solar panels to a state of the art inverter, that is legal to connect to the SA grid, coupled with all the best battery saving techniques at your disposal, free firmware upgrades, 5 year warranty ... nuts! :D

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14 minutes ago, plonkster said:

Where did you get THAT price!?

Not done yet ... waiting on 2 more prices to come in.

Multigrid / Multiplus II ... that in itself is an opportunity presenting itself.

Maybe I wait for the Multigrid to officially become available, once approved. Unless I pay what I am prepared to pay, then basta with that.

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14 minutes ago, The Terrible Triplett said:

Well, did the Infini not lose the price war on the other thread ... ;)

There's a whole range of them. The high end ones are expensive and you're better off taking a Goodwe. I believe the lower 3kva models come in just a smidgen under 10k. In fact, PriceCheck lists one for around 7.5k right now. And remember that those come WITH an MPPT in the box. The point though is that we're apparently no longer in the "three times more" domain.

Edit: Just note though, the Infinisolar 3K plus is not on the Cape Town list.

Edited by plonkster
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1 minute ago, plonkster said:

And remember that those come WITH an MPPT in the box. The point though is that we're apparently no longer in the "three times more" domain.

True ... 

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1 minute ago, plonkster said:

But as I belatedly edited above: It's not on the approved list. I don't think the lower models have NRS approval.

Here is a suggestion: If it is not on the list, single or dual MPPT's ... no matter how good the specs are vs the price ... we do not speak of it not do we ever compare price.

Caveat: IF the unit can be made to conform to NRS regs and be signed off, then it is fair game.

 

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