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Budget off-grid set-up


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Hi All,

I'm hoping I can get some advice here. I am looking to install a solar system for under R20,000. For the time I can also connect to mains if the panels and battery is not sufficient however I would like to remove the system when I move next year and be completely off-grid. I have searched everywhere and the solar kits do not seem to offer any real value (please let me know if you came across anything better than below) My appliances that run 24hrs total about 350 watt (excluding geyser that I run during the day as required)

Here is the equipment I had in mind:

Axpert PS3K 24V Inverter (3Kva/2400w) - Sold by Takealot and what seems heavily discounted to R5650. It is not clear if this particular model can be connected in parallel should I wish to expand the system, is this sufficient, any advice?

Mercer 200A 12v lithium battery for R6077 from PC link shop, they do mention that this can not be set up in parallel, I don't really see why not, if it cant and the inverter can then I can increase my battery capacity right? if not what is the solution?

Canadian Solar panels - 335 WP Poly Hiku MC4 at R1924 each from Sun Store so that's R5772 total for panels, any comments?

Total brings it up to R17499, was hoping to get an electrician to help with the installation and connecting to DB and getting away with R20k, is that possible. Is there another better set-up that will allow me to use a lot less Eskom power (if any) and still be easily up-gradable?

 

Thanks all

Lawrence

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2 hours ago, LawrenceJ said:

Axpert PS3K 24V Inverter (3Kva/2400w)

The 3kVA Axpert type inverters are normally not able to parallel. And the cheaper 5kVA also not, just the more expensive versions.

3 hours ago, LawrenceJ said:

Mercer 200A 12v

You will need 2 in series to get to 24V for the 24V inverter. Lithiums all have a BMS (Battery Management System) circuit and this must be able to handle the series or parallel connections. If the BMS stop the one battery the other one that is in parallel will take the full brunt of the power draw and this will be double what it normally can do, so not the best way to do this. If you don't want issues get a battery that is matched to your inverter.

3 hours ago, LawrenceJ said:

Total brings it up to R17499

You also need some breakers, fuses and thick battery & solar cables to handle the amps these devices push at low voltages. This is going to push you over your limit before you even get an installer.

 

Perhaps look at something portable like the FlexoPower like this

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Same setup as above just a tad cheaper from Takealot. The gurus will have to advise if this can be hooked up to the DB to supply loads, my 2c worth...... not worth it as its a complete unit consisting of battery and inverter unit in one sealed unit.

My thinking is when battery packs up or inverter packs up or charger or mppt? what do you do? Dump the whole unit???

this unit Vs an inverter separate battery bank setup where atleast if one or the other packs up you can replace damaged unit as apposed to another 15k for another unit 

Screenshot_20200805-200622_takealot.jpg

Edited by Gelo
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23 hours ago, LawrenceJ said:

when I move next year

The problem with any normal suggestion is the move next year. That's why I suggest the portable option. I'd even not do the Flexopower with panels, but just get a Flexo as a UPS only. 

Or just get something very small like those DC UPS for a router only and only do the full inverter setup after the move. They are only R1000. (Not sure what is all included in the 350W usage)

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5 hours ago, plonkster said:

Swap the battery. It very likely uses something standard, NMC chemistry I would guess.

Based on the 500 cycle number probably more likely LCO (Li-Cobalt). Cell voltage is indicated in the flexo manual as 3.7V (and 120 000mAh total capacity). These guys who have close to identical product actually specify their battery as LCO and they use identical battery graphics (nano ceramic diaphragm) to what appears to be the Flexo manufacturer (the images could also be from the Chinese bid-or-buy site itself as opposed to the actual manufacurer...). Not that it matters much, swapping it out will likely be beyond the average weekend warrior, like myself (tri-angle security screws, components generally glued down etc.). Sourcing a battery could be somewhat tricky I think in sunny RSA (alluminium case dictates very specific dimensions - I could not find something that closely resembles the dimensions from this fairly long list of options) and if wanting to use another battery, one probably has to hope (or know your stuff) that the BMS will play along.

Flexo_Guts.jpg.afdfddc981c3649172a98b16a8d978b3.jpg

Btw, I counted 12 "rows" of these (whether internally there are a number of smaller capacity cells paralleled I have no clue)

Flexo_Cells.jpg.ee2da4c5da22819eb08249b69acff1bb.jpg

 In terms of running the flexo as a UPS wired into the DB I can't see it being worthwhile - as a mobile power source that you take out of the cupboard when you need it, yes.  (the AC charger gets quite hot...I will personally not leave a load and the AC charger permanently connected).... and keep in mind what, and for how long you will run from 400Wh capacity ....and then wait 6 hours to charge again. I have not used the solar charge side, but you are still limited to the same charge rate etc as on AC (max 120W panel, 6A)

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16 minutes ago, Gelo said:

Quite like the "all in one box" type (plug points etc.) setup, and using lithium from the get go. For the money (R19k) I would probably try DIY... 200Ah second LiFePO4 + 12V 1kVA Axpert (PWM though, not MPPT) inverter should get you at around R12000-R14000... double battery capacity and some change to add some battery cables and fuse  and something like a ready board (R1200?), if needed for a plugpoint. (a 12V 100Ah bluenova / freedomwon LiFePO4 + 12V Axpert inverter will probably land you in the R19k ballpark.... ).  My 2 cents...

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