Hi all,

I've been lurking here a while and absorbing all the information possible, of which there is tons.

I currently have a very small backup system that I'd like to expand in a modular sense and keeping costs in mind.

I am presently running a 720w Mecer 12V inverter that powers a basic lights circuit and keeps my internet going during power outages and load shedding. I currently run 2x 12v260Ah batteries in parallel which gives me decent runtime, provided I keep the essentials on.

I would like to upgrade to something a bit bigger so that I can add another circuit or two, but I would like to try and keep it modular so that I can expand upon it when the need arises.

My plan is to upgrade to a 3kva 24v inverter that has MPPT charging so that I can slot it into my existing system and add solar at a later stage, and use my existing batteries until I can save up enough for a proper LiFePo4 battery.

1. [R10k] Upgrade to 3kva inverter that has hybrid support with MPPT charging functionality. If possible, parallel capability so that I can add another 3kva unit at a later stage.
2. [R30k] Upgrade to 24v LiFePo4 battery system (51v seems more popular but hopefully there are some 24v units that would work)
3. [R40k] Add solar - perhaps 6x 395w panels which should be well sized for my needs.
4. [R15k]At a later stage, convert existing geyser to either evacuated tube or PV collector design. Happy to run this off municipal supply for now.

I use around 380 units of prepaid electricity per month, but I am not intending on feeding back into the grid (I believe being prepaid makes this a pain anyway). I can swap #2 and #3 around as needed, but I figured since I already have batteries that I can use, maybe I can move this down the list of priorities.

Finally, budget. I was looking to see if I could keep the inverter under R10k, the batteries around R30k, and solar seems to vary wildly so I am not 100% sure on what my budget would be here. Perhaps around R40k. In short, I can possibly look at spending R40k within the next 12 months, and thereafter maybe another R40k for panels and getting some solar production introduced. I also want to convert my geyser so I've added that above with an estimated budget.

Is my plan sound and doable, or are there aspects that I should look at changing/avoiding? Been reading up on the Synapse inverters and their float bug, and with all the clones out there, it's a bit hard to discern which models are decent and which ones to avoid.

 

Thanks to all for reading!

33 minutes ago, PhireSide said:

I would like to upgrade to something a bit bigger so that I can add another circuit or two, but I would like to try and keep it modular so that I can expand upon it when the need arises.

modular is ok, specially if you want to go the route you're indicating, but... I do not suggest a 24V solution (28V closer to true peak voltage), if you want to run two 3kW inverters in parallel and you hit 6kW, at 24V (let's call is 25V for ease of maths), 6000 / 25 = 250Ampere? it is doable, but you'd need serious battery size and cabling to go with it, to cater for this kind of current... on the 48V side you'd be down to 120-odd Ampere, which is a lot easier to supply and cable up for...

so, ponder that before making any further investment into the direction you've indicated...

Going modular, maybe you can consider adding solar with a MPPT controller, that can cater for 12, 24 & 48V systems and for now, run it for the 12V side that you already have, then this can also be used if you end up upgrading to 24V or 48V and thus, won't really be money wasted...

HWC to evacuated tubes, is what we did, no heating element as backup and mostly its perfect (or too warm at the moment), on the odd winter morning here in the green Kalahari, with sub-zero temperature (which is not too often) is the hot water, not really hot and less than ideal for a shower... I've been thinking of running the hot water piping through a donkey, so for those rare winter mornings you can heat up the less than hot water though the donkey and have hot water after all, but its been two years and I haven't done this yet, so it probably lets you see that the less than hot water scenario is less off an issue, or rare enough for me not to have done anything about it as yet... (shower early evening and its hardly ever an issue).

Coming back to 3kVA, there are some 48V 3kVA units, but invariably probably on the higher end of the pricing scale, probably not exactly in the 10k or less range...

 

4 hours ago, PhireSide said:

Hi all,

I've been lurking here a while and absorbing all the information possible, of which there is tons.

I currently have a very small backup system that I'd like to expand in a modular sense and keeping costs in mind.

I am presently running a 720w Mecer 12V inverter that powers a basic lights circuit and keeps my internet going during power outages and load shedding. I currently run 2x 12v260Ah batteries in parallel which gives me decent runtime, provided I keep the essentials on.

I would like to upgrade to something a bit bigger so that I can add another circuit or two, but I would like to try and keep it modular so that I can expand upon it when the need arises.

My plan is to upgrade to a 3kva 24v inverter that has MPPT charging so that I can slot it into my existing system and add solar at a later stage, and use my existing batteries until I can save up enough for a proper LiFePo4 battery.

1. [R10k] Upgrade to 3kva inverter that has hybrid support with MPPT charging functionality. If possible, parallel capability so that I can add another 3kva unit at a later stage.
2. [R30k] Upgrade to 24v LiFePo4 battery system (51v seems more popular but hopefully there are some 24v units that would work)
3. [R40k] Add solar - perhaps 6x 395w panels which should be well sized for my needs.
4. [R15k]At a later stage, convert existing geyser to either evacuated tube or PV collector design. Happy to run this off municipal supply for now.

I use around 380 units of prepaid electricity per month, but I am not intending on feeding back into the grid (I believe being prepaid makes this a pain anyway). I can swap #2 and #3 around as needed, but I figured since I already have batteries that I can use, maybe I can move this down the list of priorities.

Finally, budget. I was looking to see if I could keep the inverter under R10k, the batteries around R30k, and solar seems to vary wildly so I am not 100% sure on what my budget would be here. Perhaps around R40k. In short, I can possibly look at spending R40k within the next 12 months, and thereafter maybe another R40k for panels and getting some solar production introduced. I also want to convert my geyser so I've added that above with an estimated budget.

Is my plan sound and doable, or are there aspects that I should look at changing/avoiding? Been reading up on the Synapse inverters and their float bug, and with all the clones out there, it's a bit hard to discern which models are decent and which ones to avoid.

 

Thanks to all for reading!

Take a quick look at this 48V for close to your indication of budget. They can also parallel. 

https://shop.thesunpays.co.za/products/sacolar-wifi-compatible-5kva-5kw-pure-sine-wave-axpert-type-inverter-100a-high-voltage-mppt-parallel?variant=39288282087495&currency=ZAR&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=Cj0KCQiA54KfBhCKARIsAJzSrdrQoBw_NlhyidpP7YqSIMVvPtMaMH9rm68uvPfOyA_EWjxspLGEZL8aAo_FEALw_wcB

Along those lines, rather spend R2k or R3k or so more on a 5kW 48V inverter, which gives you a much wider choice of batteries. Even some possibility to get a battery at R2K-R3K under your battery budget. Then when you later want to upgrade, instead of a second inverter, you could rather put that money to additional panels or more batteries.

Thanks for all the sage advice thus far! I really appreciate it.

@Kalahari Meerkat I may have to perhaps look at a 24v inverter for now, and keep my batteries as-is (I don't have the cashflow at the moment to get a 48v inverter and new batteries in one fell swoop), and then when I decide to scale up, look at replacing the inverter with a 48v unit and do the batteries at the same time. Not sure what your thoughts on this would be? My batteries are still good so it would make sense to use them while I still can?

With my base load I could even get away with a 1kva inverter as I rarely push 450w, but figured that the price difference between a small 1kva/1.5kva and larger 3kva is not really at all large so I may as well get something with a bit more headroom just in case?

Regarding the solar MPPT charger, I did also ponder this, but my current inverter isn't long for this world as it's already been in for a warranty job twice and I had had to hard reset it once or twice this year already due to a fault. Sadly, I think the inverter would be the first thing to be replaced as I don't trust the reliability thereof and it's a few years old at this stage. But I do like the idea and I can see how it can save some dosh down the line!

On the topic of a donkey, I had the best shower of my life with one a few moons ago when I was canoeing up the Fish River. We stopped at a cabin for the night, and there was gravity-fed water that we heated up with a donkey. The showers were rudimentary, but in the middle of the brush they had made a cordoned off area with some droppers as 'walls' and a soakaway for the waste water. I am not sure if it was just the desperation for a nice warm shower after the morning and afternoon's rowing, but I swear that water heated up by a donkey is just far superior🙂

 

@Scorp007 thank you so much, that is definitely within budget, and seems like a really decent brand as I've heard the name mentioned here before. I'll do some more research into them. I don't see any 24v inverters from them on that site that I could use for the time being, but they seem like a decent deal when I eventually expand.

 

@GreenFields definitely a plan if I could get the batteries and inverter at the same time, sadly budget isn't allowing for this at this point in time so I will probably have to do it bit by bit. I'd have loved for my current Mecer to hold on for just a few more months, maybe a year at most, then I could maybe get the batteries and an inverter as a bulk buy and then add solar the year after. Sadly it seems to be dying and forcing my hand sooner than anticipated, and I am a bit reluctant to get another one of the same type as they don't seem to be all that reliable for long-term operation.

Appreciate all the responses, thanks all!

49 minutes ago, PhireSide said:

On the topic of a donkey, I had the best shower of my life with one a few moons ago when I was canoeing up the Fish River. We stopped at a cabin for the night, and there was gravity-fed water that we heated up with a donkey. The showers were rudimentary, but in the middle of the brush they had made a cordoned off area with some droppers as 'walls' and a soakaway for the waste water. I am not sure if it was just the desperation for a nice warm shower after the morning and afternoon's rowing, but I swear that water heated up by a donkey is just far superior🙂

yup and you're showering out in the open, not in a bathroom that has moisture build up due to the hot water/vapour etc.

I was already thinking of putting up a shower outside as well, have a free air shower, obviously with privacy shielding and a dry area attached where one can undress and dress... 🙂

Heyo Phire, its a bit strange seeing your name without your usual avatar.

Mate my brother is going through a similar thing at the moment, he went from the 12v with LA/AGM batteries in parallel to an Axpert 3kw 24V system and used the same batteries in series. Everything was run into the DB etc by an electrician. 

Now comes the dilemma, he has been running on that system for a bit and the batteries are knackered and he wants to add solar. 

So we start looking at panels, hmmm max V/W on the MPPT is very low so that isnt ideal, now we need to start looking at lower rated panels which means more money for mounting hardware. Ok cool, no worries lets look at batteries... hmmm again, slim pickings in the 24V lithium space.

At this point the realization that the 3kw unit was a massive waste of money kicks in and its time to get a 5kw+ which plays nicely with all of the mainstream panels/batteries.

 

I fully get where you are coming from in terms of re-using what you have while upgrading incrementally, just be aware that it will most likely cost you more in the long run. Often its a case of spending just a little more to save yourself down the line.

Personally if I was looking in your situation I would go for an Axpert clone 5kw and something like a Pylon US2000 48V battery, you can always add more batteries later if needed. That would come in at around the R30-R35k mark.

5 hours ago, Kalahari Meerkat said:

yup and you're showering out in the open, not in a bathroom that has moisture build up due to the hot water/vapour etc.

I was already thinking of putting up a shower outside as well, have a free air shower, obviously with privacy shielding and a dry area attached where one can undress and dress... 🙂

My brother in law built an outdoor shower in his last house renovations and he likes it so much that he hasnt showered inside for the last few years. Im not sure what the appeal is but he loves it.

1 minute ago, RocketBoy said:

My brother in law built an outdoor shower in his last house renovations and he likes it so much that he hasnt showered inside for the last few years. Im not sure what the appeal is but he loves it.

Fresh air and a bit closer to nature... its like showering underneath a waterfall ... 🙂