Guidance required

[Atti2de]

Hey guys,

OK so I am looking at pushing my system to about 8kW. This is for when my wife is busy with her hair dryer, and I decide to use the kettle & microwave, etc. It may be a bit overkill but I would rather cater for it now and know it is done.

Currently I have a Schubart (Axpert) 5kVA/4kW inverter, with 4x200Ah Allgrand Gel batteries. 

I will be adding some 12x270W Solar panels within the next month.

What I would like to do is to modify my setup, using the Pylontech (or better/ preferred) batteries, together with another Axpert unit (parallel).

Is there a better way to do this? The Pylontech units have the ability to feed battery information back to the inverter, and I feel that this is not being used. Can the Axpert take this feedback from the batteries or should I be looking at a different inverter setup? I can always sell my current stuff as it has only been running for a month without issues.

 

I have even been looking at the Tesla powerwall as an option. I am really open to a good & robust solution. Another thing that I would like is to monitor my systems' performance and see how much power we are using and what the state of charge, etc. is with all the relevant components. My main goal is to remove myself completely from the grid.

Another plan I am busy with is to change the stove and geyser to a gas system. The gas geyser will get assistance from a solar system which heats up the existing geyser using the sun's free energy and only use gas as needed.

 

Your ideas and guidance would be greatly appreciated.

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6 hours ago, Atti2de said:

Is there a better way to do this? The Pylontech units have the ability to feed battery information back to the inverter, and I feel that this is not being used. Can the Axpert take this feedback from the batteries or should I be looking at a different inverter setup? I can always sell my current stuff as it has only been running for a month without issues.

Axpert does not communicate with the battery, in for the most part it doesn't matter.

The BMS provides three groups of data, so to speak. The first set contains information about the voltage, current, temperature and state of charge. The second set contains warning and alarm flags: It can tell you if you're charging or discharging too fast, if the voltage is too low or too high, and so on. Useful to know, but offgrid inverters can't really do anything about other than switching off, which the BMS will do for you in any case. Finally, the third group provides information about battery limits: Maximum discharge current, maximum charge current, and the charge voltage. These values can change, for example if the battery temperature exceeds a certain value, it might lower the charge and discharge values, and if there is a high cell it might lower the overall charge voltage, and so on. This is useful to hybrid inverters (because they can take the shortfall from the grid), but again not really important to offgrid units.

I think what worries me more about your proposed course of action, is that to go to 8kw you'll need a second inverter. You're going to need two in parallel to do that... and do you really want to buy another oddly named copy? Also... we've been discussing NRS097-2-1 to death the last few days... maybe that should factor into your decision?

Tesla Powerwall is very expensive. I only know of one local combination, where it is sold with a SolarEdge inverter, and with the PV panels included it's on the other side of 200k. If you're looking at that kind of investment, you really should consider SMA, Goodwe and Victron too, combined with a locally-made battery such as the FreedomWon home units or even the mentioned Pylontech.

[Chris Hobson]

For a good 8kW install you going to be hard pressed to come in under R160-180k. 

I am busy with a 8kW install myself but my situation is differs from 95% of solar users. If my solar system cannot power something the gennie has to start. So I hear you about the hassle of the hairdryer and the microwave but that is peculiar to an Axpert. If you had a hybrid you would not notice this inconvenience as the shortfall will be powered by the grid.

Now I need to quote our friend TTT about needs and wants. To get good ROI on a solar system one needs to cater for the 24/7 loads. The other loads even the big ones, with the exception of the geyser, are usually on for short periods of time and are not major contributors to you electricity bill. Most households 24/7 loads would be covered by a 1000W inverter or at the outside a 1500W inverter. That is what you need. If you want energy independence by all means have a larger system but 8kW that is big and with the possible exclusion of Axperts from grid connections I would not advise buying another to parallel, let alone an Axpert clone which I think your Schubart is.

What are your alternatives if you are sold on Pylontechs? The Infinisolar 3kW Plus (on the smaller side),  Goodwe (there is a small one and a big one) or a Victron can be paralleled to achieve your 8kW. This is going to cost a whole lot more Tom than adding a second Axpert. The Infinisolar, like the Axpert does not communicate with the Pylontechs whereas the Goodwe and Victrons do.

 

[Guest]

Thank you Chris, was hoping not to get on my pedestal again. :-)

My 2 cents.

Batteries are more expensive per Kwh than Eskom, and need replacement every X years.
If you want to save on your bill, go grid tied, start smaller, can always expand, like a 3kw grid tied inverter and panels, later another one ... more panels.
Find the sweet spot of max savings with least amount of equipment.
If you want to deal with regular power failures, still go grid tied with selected circuits on a UPS, UPS is powered by the grid tied system.

And as Plonkster said, make sure you do it right from day one i.e. meet your local regulations and in the absence of them, look at the CoCT regs as a guideline.

Last thing you want is to spend a lot of money only to find out your system is illegal, get a fine and notice of removal, when the municipality gets their ducks in a row.

Edited July 27, 2018 by Guest

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1 hour ago, Chris Hobson said:

Axpert clone which I think your Schubart is

I mean, it's not even spelled correctly. If you were going for the composer, then Schubert is the correct spelling. Google tells me there was a poet called Schubart though. I have no idea what they were going for. It's like all these stencil piano brands from China... slap a German name on it and sell it!

(I personally own a 100 year old Carl Otto... a real one :-) ).

Earlier tonight I remembered an event from 1988: Lightening destroyed the 1.5kva inverter on the farm (it was absolutely huge and weighed a ton). My dad had insurance. I believe he had it insured for 5k, because that is how much a new one was. Now to put that into perspective, back then a good second hand car was around 10k.

[Atti2de]

Thank you all for the input!

Really appreciate it all!

So what I can gather is that I should not really go full out and build an 8kW system, but maybe a 6kW max; Use a proper inverter such as Victron/ Goodwe and the Pylontechs.

Just need to measure my roof later so that I can plan for the correct solar panels and the amount.

 

Where do you guys normally buy your equipment and decent prices?

2 or 3x Pylontech (I assume 2000B) 

1xGoodwe (4.6kW; or whatever combo)

Solar panels - I initially calculated 12 x 270W solar panels, but this may change.

Edited July 29, 2018 by Atti2de

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1 hour ago, Atti2de said:

Where do you guys normally buy your equipment and decent prices?

Current automation, Sonopsolar, or Rubicon. I buy from OnTrack as well as they are close to where I live and generally a bit cheaper than ExSolar. Most of these guys will ship to you as well. There is also SolarSolved somewhere in Cape Town, prices look generally good, but I have no personal experience with them.