Jump to content

new UPS (Future Solar) advise


Recommended Posts

I need some guidance and advise if I am on the right track with approach and thinking. I have been looking at getting a proper inverter setup integrated into the main DB with solar, but usually it starts small and before I know it I am down the rabbit hole and looking at 100k setups. So the current loadshedding has been the final straw to kick start the process, unfortunately it is the worst timing, as budgets are tight due to Covid etc.

My thinking is to get an inverter and Battery setup that will be sufficient for my core needs to tide me over with loadshedding for the next 1 to 2 years and then maybe upgrade components as I go along. I dont want to waste money or buy double. So I have eliminated a portable type setup , it will be cheapest to an extend, but will need to move it around the house the whole time and there will be extension cables lying around etc, which is a risk with little kids.

My core electricity needs :
we have a home office for my wife's practice and I am working from home
It is mostly 2 laptops and 1 desktop with 2 laser printers
1 small bar fridge in office
2 routers
1 60L fishtank with pump and heater

Night time
Routers and fishtank still
2 x led tv (not on at same time) with tvbox etc
ability to put on lights (all globes are led)

So I figured I need to get my DB wiring sorted and setup, that will be needed regardless of the type of inverter or batteries I get.So I need to get an extra DB board, move out the lights circuit and the specific plug circuits that relate to my needs above. Leave the pool pump, geyser, kitchen etc off. Need all cabling and fuses and switches to get this ready.
What would something like this cost? I have an estimate of R5000 for parts and labour?

Inverter :
This is the tricky one, obviously a nice 5kw Axpert would be nice and ideal, but it will stretch the budget and the 48v battery adds to the dilemma. I like the fact of an all in one setup, so the Chinese inverter was an option , but getting a seperate charger and plumbing it into the DB just seems more complex. So I have settled on looking for a 3kva 24v inverter.
I am looking at an Axpert or Axpert like inverter.
I am looking for a 2nd hand model if possible.
I can get an Inkwenkhezi model for about R4000 , which looks decent and ticks the boxes . Is this a good make?
Should I rather look for an Axpert / RCT , they are 6500 ish and up?
The model I look at has PWM and not MPPT, is this an issue? I might look to add a few panels later (say to the 1500w max of the inverter)
Will the PWM part be able to supply the house with power after the batteries are charged ?
The inverter will be sold later and upscaled to a 5kw Axpert

I would like Lipo, but feel it is overkill for now, With the immediate need being load shedding and me not cycling / using them daily. Will upgrade to them eventually.
My thinking is i need 2 x 200ah batteries at least, this should give me 24v x 200ah = 4800kwh . Taking 80% efficiency it give me 3800kwh more or less and if I go down to 50% DoD it will give me 1900kwh usuable power. This will be about 950kw per hour for each 2 hours of loadshedding. this should be enough to drive my core needs easily.
seeing as I am going to upgrade later and looking for an interim solution of 2 odd years and for loadshedding mostly, I figured I could get middle of the road batteries, not the best and not the total worst.
Was maybe looking at getting 4 x 105ah Royal batteries? should add up to about R5000 in cost.
Should I rather look at getting 2 x 200ah batteries? I see you can get Ecco and Vision batteries for R3500 each, which would total R7000
I am looking at the batteries as "throw away" want to use them for the 2 years, and then they should be done, not really reselling( who would buy 2 year old 2nd hand batteries in any event), so trying to get the cheapest option that would last the 2 years.

Am I smoking my socks with the above setup ? or should I rather wait and get a 5kw/lipo setup. I reckon at worst I would lose the battery costs, the inverter I would be able to resell and recover some costs and the installation will have to be done regardless of the setup I choose.
Will this mean I can have a interim UPS setup for about R15000
Will electrician come and install the inverter and do the DB work if I dont purchase the inverter and batteries from them ?
Is it better to take a package deal, where they do the install and provide the products?

Link to comment
Share on other sites

  • 2 weeks later...

Is a late reply but what the heck...

any cost related to load shedding is to some extent going to be "throw away". You will likely recoup very little from selling on later, so leave it out of your calculations/decision making - in my opinion. 

Your core needs on the face of it should easily be met by a 3000W or so inverter (depending on realistic peak load probably even smaller but 3000 is a safe number that will allow wide use). The things to be weary of are those 2 laser printers (they tend to have a very high power draw, easily 1000W+ when starting up) and maybe the bar fridge (if keeping some cokes cold, take it off the list.... if keeping meds for patients at a required temperature then obviously not an option).

No idea what aquarium pumps draw but doubt it will be much (though running permanently)... the heater is bit of an unknown (you are not exactly running sea world but it could add up a bit for the battery requirement).

So, even though budget is tight, before spending money on inverters I would seriously look at buying/borrowing a watt meter (like this) to confirm actual power draw of things like the TV, aquarium pump + heater, etc.

I would personally not spend money on any clone/copy of the axpert type inverters - the money you save will probably be short lived. If going with an axpert type setup look for an actual voltronic produced version (I think the Mecers are voltronic)

Hopefully someone else will chime in on the solar part but for what you want PWM should be fine - and may be irrelevant since solar might happen only when you upgrade in the future some time? Overall I think MPPT will give you greater efficiency compared to PWM but I am not exactly all that clued up on solar.

Your battery calcs are technically incorrect 24v x 200ah = 4800Wh....or 4.8kWh (not 4800kWh).

Making some wild assumptions (and not really making much provision for the laser printers) I suspect your day time practice, home/office and Finding Nemo power requirement to be around 800W-1000W. Which will equate to 2000Wh for a 2 hour load shed (which will be [2000W/24V]/0.8= 105Ah... *2 (for 50%DOD) = ~200Ah).

2 x 12V 200Ah batteries should leave less issues around balancing etc. than 4 x 12V 100Ah batteries.

Btw, the inverters on the trolleys are exactly the same as what you will wire into the DB...someone just screwed them down onto a trolley....so if you get a good deal (better than buying a lose inverter) on a trolley for some reason (maybe 2nd hand one?), just remove it from the trolley and have the sparky mount it on the wall. If the only thing you can get/afford is a trolley you could also consider running an extension or two through conduit and route it in a creative way that keeps it mostly off the floor/out of the way so there is no need to push it all over the place...

If you want to avoid spending double, and seriously plan to expand in the future (by adding more loads on the backup side and potentially adding decent solar capability), go 48V from the start ...and depending where you are an inverter on the NRS approved list if wanting to add solar.

Link to comment
Share on other sites

You must look at how many times you experience power outages and the duration. 
To prevent spending double in future you need to go for a 48v system. 
The cheap and easy way out is to buy a generator. Many bargains can be had on the used market now. 
And you will not recoup the investment in a solar system unless you are young and will not move house ever again. 

Link to comment
Share on other sites

19 hours ago, introverter said:

Btw, the inverters on the trolleys are exactly the same as what you will wire into the DB...someone just screwed them down onto a trolley....

Correction to myself... SOME of the trolleys are the same as what you will put on the wall. The generally available ellies and mecer trolleys will lend them less to being taken apart to be mounted on the wall...

Link to comment
Share on other sites

If the actual base load was around 800W or less (maybe doable with some careful management) and this is an unavoidable temporary stopgap, for about R11 500 a 2nd Life 12V 200Ah LiFePO4 battery and a 12v Axpert 1000kVA (PWM) inverter could probably JUST get you through 2 hours load shedding without the seemingly high certainty that the lead acids in a trolley will not make 2 years. The battery should also be okay for more than one session per day in terms of recharge current/time...but the charger on the inverter is limited to only 20A... so you will need at least 10 hours for a recharge if using close to the full capacity of the battery..there exists versions with higher rated AC chargers but the 12V versions seem scarce. So you will have some change from R15 000 to allow for install, fuses etc. (a 24V option, i.e. 2 LiFePO4 batteries and 2kVA inverter will put you at R19500 before install and such).

When upgrading in the future all of this kit will be fairly redundant though... (btw, neither the stores or products are specific recommendations but should give you an idea of what can be done).

It might overall still make more sense to ride out the load shedding until circumstances allow for a more substantial  install. (maybe just get a small alarm type battery and inverter/charger  to at least keep Nemo alive). laptops should be okay if they are charged before load shedding starts (seems we at least get a bit more warning other than the very first session ... if in doubt, check the eskom twitter feed - seems often more up to date than the load shedding web site). eMail/whatsapp pdf invoices/receipts to patients (no printing). The routers could possibly run directly from a power bank (many routers are 5V or 12V). A jumpstarter/power bank like this could potentially keep the routers going and when load shedding is not around you can chuck it in the car to help some lady at the local mall who forgot her car's lights on...

Night time = router + netflix on the laptop.

Link to comment
Share on other sites

On 2020/07/20 at 2:54 PM, Reiniervd said:

usually it starts small and before I know it I am down the rabbit hole and looking at 100k setups

Been there, done that, got the T-shirt.

To give you an idea of my situation. I have been permanently working from home since April last year (and now my wife joined me from March) and I was in exactly the same boat as you where I essentially only need something to get me through loadshedding, but with the idea (when funds allows) to go bigger and get a proper inverter, battery & pv in the end.

After a ton of discussions here on the forum and with some friends I ended up getting one of the portable trolleys over a proper inverter and batteries or a generator. In my case this 2400VA Mecer one with the 100Ah AGM Deep Cycle batteries (which are Vision 100Ah 6FM100 batteries). I did this mainly because after doing the calculations on what I would need at the end of the rabbit hole I realized I should save quite a bit more and it's easier to have a portable inverter that's always on that immediately takes over without dropping power compared to a generator that needs to be started up, is noisy and needs a bit more TLC than sealed batteries. That was a quick win for me (was R8800 at the time) and it's been keeping me going through loadshedding for the last year and a bit.

In my case I have a TV, 2x routers, NAS, Pihole, 2x laptops with 2x monitors each and my gaming PC hooked up to the inverter (although the PC is generally not used in loadshedding, but helps for power failures). It started off being a messy extension cord + network cable running together through the house to the home office, but later on had a friend over who helped getting it there neatly be running the cables in separate conduits up the outside wall into the roof and into the home office. We just added 2x cheap lamps with led lights to have light in the TV room and the office at night time and we've had no issues with loadshedding (even the extended Johannesburg 7 hours due to trips days).

I'm just mentioning it as an option, because like I said it was a quick win to beat loadshedding without really breaking the bank and as the batteries won't really last I would guess more than 5 years it gives me time to save up to then get a proper 48V inverter with LiFePO4 batteries & pv later which sounds like the same as what you are planning with your setup.

As you've got the mini fridge & fish tank you'll need a pure sine wave inverter, so the modified inverter like I've got won't work. Something like this Mecer Axpert Type 3kVa inverter with (I'm guessing) the same Vision batteries should do the trick as long as you don't go over the recommended discharge Amps of the batteries although depending on the Watts used you might need 200Ah batteries as you mentioned (although you'll need a different trolley as they're bigger than the 100Ah batteries). I'm just linking them as that's where I got mine and that's an easy comparison, but you'll need to take delivery into account if you can't collect it.

If you are going to stay in the same house for when you hit the rabbit hole and really want your lights to also be on the inverter then I think your plan is also fine to then do a split in your DB to have your lights and the required plugs on the Inverter to keep it going during loadshedding, but it might cost you a bit more initially, but it is a start to the greater scheme in any case.
Or you can start with a trolley like setup for now to beat loadshedding (which magically disappeared now) and then when you decide to add some solar panels into the mix later you can get the same person who'll do the solar panels' installation to also mount the inverter to the wall (use the same trolley for the batteries) and do the DB rewire to get you started in that sense. I know nothing about the Axpert / Voltronic inverters and I'm too lazy to read up on it now, but I'm guessing that you should be able to add some solar panels to run the loads during the day and keep the batteries as a backup only for loadshedding, so you might get some more use out of the inverter and batteries after adding solar panels before pulling the trigger to replace both. (Again, not 100% sure about that, so someone should correct me if that's wrong)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...