Need advice on a system for a 2 bedroom apartment

[Olorin]

I got a response back from Geewiz regarding the S-100 2nd life cell issue :

Quote

 

Hi Vaughan,

 

Thanks for your email. 

 

The older S100 units were indeed 2nd life units. 

 

Our new range is the S100a which are the latest batch, and now come with first life cells. We no longer sell the older, S100 with 2nd life cells

 

Regards, 

Ari 

 

 

 

[Clivevan]

12 hours ago, YellowTapemeasure said:

 

 

 

 

 

 

I recall that the OP, in the first post of this thread, indicated that he/she needed 2000W max. and further stated that he/she was looking at a 3kW Axpert, which, considering the 2kW load, seems fair. It does seem a bit low to me, for instance I don't know how he/she makes hot water for showering and bathing, but then again, what do I know about the OP and his/her usage?  It's not for me to either presume, nor prescribe.

 

Nope. The particular model which the OP pointed to is the UP2500, and for which I provided the spec sheet and warranty. It is 5 years, extendable to 7 years on registration. 

let us just try and understand what is going on here. He GAVE his needs:

55" LED TV, AV receiver, subwoofer, router, notebook, PC, fridge and LED lights in 2 rooms and a bathroom. If I go into the specs of each item and look at the max power and add everything up it would amount to +- 2000 watts max. Now there is no way I'll ever come close to 2000 watts. I reckon I won't even come close to 1000 watts. 

So we do not presume or prescribe. 

It is a GIVEN. What do I miss here?

Moreover, he lists his exact needs and based on that he is quite entitled to infer that he wont come close to 1000 watts. In fact he will average about 300 watts. Then with spikes from the fridge etc he will need max 1000 watts but the inverters have surge capacity more than double normal usage rating.

Hot water geyser kettle Microwave etc etc hairdryer - ALL OF THESE PRODUCE immense heat and CANNOT BE used off a battery during a loadshed UNLESS you completely tone down on wattage and then you need a new set of equipment etc. Your geyser is still hot during the loadshed; a gas cooker makes your tea and warms you food etc. 

So you place your essentials on a critical circuit and feed that with the below: 

A pure sine wave inverter rated to produce 1000 watts.

Personally I would get a premium product at that specification but lets just say we go for an Axpert. Then the following models all meet the grade:

 

INVERTERS/CHARGERS

1.  R4,950.00    1Kva VM 1000w MPPT Inverter https://www.diygeek.co.za/product/1kva-vm-1000w-mppt-inverter/

2.  R5,495 incl. VAT Axpert Type 2000VA (2000W) PURE Sine Wave Inverter (KS-2K) - 50A PWM (1200W) (Hybrid) [see at geewiz]

3. R 6,755.00incl. VAT RCT Axpert VM2 1K12 1kVa 1kW 12V Hybrid Inverter [see at sustainable] 

4. R 5,749.00incl. VATRCT Axpert VM 1K12 1kVA 1kW 12V Hybrid Inverter  [see at sustainable]

5. R5,109.99RCT Axpert VM 1000VA/1000W Inverter Charger -12V 500W PV [https://3mos.co.za/product/rct-axpert-vm-1000va-1000w-inverter-charger-12v-500w-pv/]

 

So pick one. To be super safe and to allow for future expanded needs you may want to scour the Net and get something a touch larger. Approx 1500 watt/kva so that you can purchase and run a camping kettle (750 watts) or possibly a small microwave (750 watts)

So in the region of 

R 8000.00 max for an inverter.

 

BATTERIES

Here I would take a bit of a risk on a cheap LifePo - LifePo is inherently lower failure risk than lead acid and has become very affordable and reliable - so eg:

 

Champion 12.8V 200AH LITHIUM

https://onlineshop.gcsolar.co.za/product/champion-12-8v-200ah-lithium/

R9,470.25  

There are other low price choices around.

So total load shed solution to run your critical items and some more:

Approx R 17 500.00

BUT you need to install and prepare that critical circuit - so add electrician/installer fees, wiring, tripswitch etc

Then you will have 4 to 6 hours of normal living during a load shed and 10 hours or more if you skimp it. You can use a small kettle/microwave.

If you want cheaper still, you can perhaps do it but you may have to take your fridge off the circuit, find a used 1000watt inverter,  use a 100ah Lifo battery and hold onto your hat - but it should still be OK.  Your usage is VERY low and provided you only use the TV OR x2 PC's  etc a 100Ah battery = 1000Wh useable = 250Wh every hour so it is viable.

Then maybe as low as 10 or 12k for the components.

 

So there you have it.

You run the risk of buying twice of course - and I would have attempted my level best to get eg a 

Victron MultiPlus 12/1200/50-16 230V Sine Wave Inverter Charger VE.Bus   R12,647.01 incl.

But the Axpert vendors are reputable, give you some kind of warranty and the Axpert (despite my terrible experiences) may do the thing especially if you do not burden it with solar panels for now.

Hope this helps and apologies to anybody who felt offended at my feelings about Axperts - with the maturity of daylight I realise I may have overstated the quality issue. And my sample is small.

[Clivevan]

Sorry re this product I referenced:

R5,495 incl. VAT Axpert Type 2000VA (2000W) PURE Sine Wave Inverter (KS-2K) - 50A PWM (1200W) (Hybrid) [see at geewiz]

I notice now it requires a 24 Volt battery so there we go again - it looks cheap but you need TWO batteries (to connect in serie and get up to the required 24v)

[Scorp007]

23 hours ago, Olorin said:

I got a response back from Geewiz regarding the S-100 2nd life cell issue :

 

 

Thanks a stack for the reply from Geewiz. This way we all learn about the S-100-A. Did not know about it. 

Luckily you found numerous answers and can choose what suits you. 

All I can mention is I have never read anyone with a 4yr journey with PV finding that their inverter was too large and scaled down. We all go larger when changing. We always find new loads to run partially free from sun. 

Thus spare capacity even at a low 1kW load puts you in a good position not to have to go larger in future. 

Also we would see a lot of post estimating a newish TV at about 55W. Recently I had to size a battery and I refused to give an answer until I measure the loads. The TV used 155W when measured on the DC side to the inverter. Inverter on its own at no load about 8W.

[Olorin]

So I discussed the matter with another installer and he said .... I must get a battery with BMS and the Hubble S-100/120 do not have that. He said it's crucial the inverter and battery have solid communication.

2nd he told me that the Axpert inverters are NOT compliant inverters for solar use (you can use them for solar, BUT....)  and said that should anyone install them you could be fined by the City of Cape Town or some such? He said there are list of compliant solar inverters and I need to stick to them.

Do you guys know anything about this???

[Don]

30 minutes ago, Olorin said:

2nd he told me that the Axpert inverters are NOT compliant inverters for solar use (you can use them for solar, BUT....)  and said that should anyone install them you could be fined by the City of Cape Town or some such? He said there are list of compliant solar inverters and I need to stick to them.

Axperts don't need to be compliant, as they are not feeding power back to the grid. Only if you are planning to feed power back to the grid, i.e. grid interactive Inverters that are cable to feeding power into the grid, need to be NRS 097-2-1 approved.

[GreenFields]

27 minutes ago, Olorin said:

So I discussed the matter with another installer and he said .... I must get a battery with BMS and the Hubble S-100/120 do not have that. He said it's crucial the inverter and battery have solid communication.

2nd he told me that the Axpert inverters are NOT compliant inverters for solar use (you can use them for solar, BUT....)  and said that should anyone install them you could be fined by the City of Cape Town or some such? He said there are list of compliant solar inverters and I need to stick to them.

Do you guys know anything about this???

The Hubble S100 battery has an internal BMS to limit the charging and discharging of the battery. It will not be able to communicate directly electronically with the inverter, but not every inverter needs that, it's also possible to set the voltage parameters on the inverter. It is specifically designed to be a drop-in replacement for traditional lead-acid batteries that can run without electronic comms to the inverter.

Regarding the CoCT list - go with what Don said. You'd swear there are no people in Cape Town using Axpert inverters. You may need conformance or certification, but it's a stretch to say it's illegal.

 

[Olorin]

And this installer said if I were to connect the fridge to the inverter the power could spike 10 times the average consumption in a very short duration so he recommended i go with a 5kva. 

And this is a guy I was told could be trusted from one of my clients. So I dont know if this guy is talking BS or not.

[Olorin]

1 hour ago, GreenFields said:

The Hubble S100 battery has an internal BMS to limit the charging and discharging of the battery. It will not be able to communicate directly electronically with the inverter, but not every inverter needs that, it's also possible to set the voltage parameters on the inverter. It is specifically designed to be a drop-in replacement for traditional lead-acid batteries that can run without electronic comms to the inverter.

Regarding the CoCT list - go with what Don said. You'd swear there are no people in Cape Town using Axpert inverters. You may need conformance or certification, but it's a stretch to say it's illegal.

 

Thank you for the clarification! It seems there is so much BS and misinformation out there.

[Scorp007]

9 minutes ago, Olorin said:

So I discussed the matter with another installer and he said .... I must get a battery with BMS and the Hubble S-100/120 do not have that. He said it's crucial the inverter and battery have solid communication.

2nd he told me that the Axpert inverters are NOT compliant inverters for solar use (you can use them for solar, BUT....)  and said that should anyone install them you could be fined by the City of Cape Town or some such? He said there are list of compliant solar inverters and I need to stick to them.

Do you guys know anything about this???

You are fed BS. 

CoCT only list on grid like full hybrids not off grid inverters. 

Also again refer to the information from Hubble icw is the S-100/120 fitted with a BMS or not. I have not seen a single 12V drop in lithium that is being sold without a BMS. 

 

[Olorin]

And regarding his fridge consumption comments? 

[Don]

24 minutes ago, Olorin said:

And this installer said if I were to connect the fridge to the inverter the power could spike 10 times the average consumption in a very short duration so he recommended i go with a 5kva. 

I have 3 fridges and 2 freezers and about 18 months of data. I have never recorded any spike when one of those unit's kick in.  

[Olorin]

6 minutes ago, Don said:

I have 3 fridges and 2 freezers and about 18 months of data. I have never recorded any spike when one of those unit's kick in.  

I'm so sick of people trying to scare me into buying crap I don't actually need. Thank you for confirming this. 

I think my plan for a 3kva inverter with 1 x 24v ah100 or 2 x 12v is looking more and more attractive. I can always expand on the battery and I don't need solar. 

[Olorin]

Just now, Olorin said:

I'm so sick of people trying to scare me into buying crap I don't actually need. Thank you for confirming this. 

I think my plan for a 3kva inverter with 1 x 24v ah100 or 2 x 12v is looking more and more attractive. I can always expand on the battery and I don't need solar. 

The question really is... what makes more sense 2 x 12v ah100 or 1 x 24v ah100? I'm  still undecided on that - I might save R1000 if I go for one bigger battery. 

 

[Don]

2 minutes ago, Olorin said:

Thank you for confirming this. 

My mom came to visit us during Christmas. I monitor her system from my home via Solar Assistant. While she was here, the only thing running was the inverter and her fridge. Here are the graph showing what happens when her fridge kicks in. 

[Don]

6 minutes ago, Olorin said:

The question really is... what makes more sense 2 x 12v ah100 or 1 x 24v ah100? I'm  still undecided on that - I might save R1000 if I go for one bigger battery. 

Same capacity. I would go with the 1 x 24V battery. 

[Olorin]

13 minutes ago, Don said:

My mom came to visit us during Christmas. I monitor her system from my home via Solar Assistant. While she was here, the only thing running was the inverter and her fridge. Here are the graph showing what happens when her fridge kicks in. 

So the red spikes are like maximum 230-240 watts? Thats not much at all. 

I just don't understand why so-called electricians would claim that the initial start up consumes SO much power - i swear I spoke with 3 separate guys all repeated the same crap. I'm sure there are plenty of folks who don't know better (like me) who will then proceed to buy wayyyy more than I need based on some bogus claims. 

I'm just happy I found this forum.

Edited January 23, 2023 by Olorin

[Don]

In general, Electricians can wire a DB Board and fit a plug, but they know very little about Inverters and solar installations. . It is a totally different animal. Now I am waiting for the back lash, haha. 

[GreenFields]

1 hour ago, Olorin said:

And this installer said if I were to connect the fridge to the inverter the power could spike 10 times the average consumption in a very short duration so he recommended i go with a 5kva. 

And this is a guy I was told could be trusted from one of my clients. So I dont know if this guy is talking BS or not.

There really is such a thing like a short-time transient surge when you start up a fridge compressor, or basically any appliance  with an ac electric motor. It could be five to ten times what the normal consumption of your fridge is, and it can last for a couple of seconds. Your fridge might be rated at say 200W for normal running, but on startup you can expect maybe a 1000W or more for argument's sake. You might not see it if your measuring devices does not take samples fast enough, but if your inverter cannot handle the surge, it will trip.

But your inverter also has a surge capacity. The Axpert 3000VA can handle 6000VA of power for 5 seconds. That's probably enough to start a fridge, but it could struggle with bigger motors. This would be why someone else earlier in this thread was saying his Axpert couldn't run his pool pump or aircons, but the Victron he bought can handle a bigger surge so he was happy once he replaced it. Your needs are different though.

Long story, but I don't think your installer is genuinely full of BS on this point, I just think he's playing it safe. And the 3kVA with 24V battery is probably a fair solution, because going for a 5kW is going to push you over to a 48V system and then you're talking R25-30K for a battery.

[Olorin]

12 minutes ago, GreenFields said:

There really is such a thing like a short-time transient surge when you start up a fridge compressor, or basically any appliance  with an ac electric motor. It could be five to ten times what the normal consumption of your fridge is, and it can last for a couple of seconds. Your fridge might be rated at say 200W for normal running, but on startup you can expect maybe a 1000W or more for argument's sake. You might not see it if your measuring devices does not take samples fast enough, but if your inverter cannot handle the surge, it will trip.

But your inverter also has a surge capacity. The Axpert 3000VA can handle 6000VA of power for 5 seconds. That's probably enough to start a fridge, but it could struggle with bigger motors. This would be why someone else earlier in this thread was saying his Axpert couldn't run his pool pump or aircons, but the Victron he bought can handle a bigger surge so he was happy once he replaced it. Your needs are different though.

Long story, but I don't think your installer is genuinely full of BS on this point, I just think he's playing it safe. And the 3kVA with 24V battery is probably a fair solution, because going for a 5kW is going to push you over to a 48V system and then you're talking R25-30K for a battery.

Thanks for the reply!  Appreciate it. Your comments make complete sense. I forgot that these inverters can handle much higher peak loads. 

My folks need a system similar to what I need, except they aren't connecting up a surround sound amp and sub so even less consumption than me and they were thrilled when one of their close friends recommended we reach out to a company called Greensun who recently completed an install for them. No solar panels. They are nearby - so I gave them a call, explained to them my folks needs and best guess consumption and... their solution is  R80k! But they tell me they only use the very best of the best Victon inverters etc etc. I mean R80k! For 2 TVs, one fridge, one freezer, router. Maybe a fan? My dad almost had a heart attack when I told him the price and he's 74.

Edited January 23, 2023 by Olorin

[Scorp007]

Some facts and not thumb suck have been provided. Yes I have shared a picture of the 98A drawn from 12V battery when a bar fridge starts. This is real short term. This bar fridge only uses 7A @ 12V when running. These kinds of currents cannot be measured by power meters that have long periods before sampling the value. I belief the same is true on monitoring software. Not the ideal instrument to measure peaks. 

Sometimes one must get advice from those that have measured vs thumb sucking. 

And yes I have a 3kVA with good batteries. The key is batteries that CAN supply the peak. Yes I do start a bar fridge, medium fridge combo and a chest freezer at the same instant. The Axpert does not even shown a battery low alarm when they start. On the other hand when I start my micro my battery low warning light from the Axpert does come on but goes out after a minute or 2 as the battery voltage recovers. This start is when I have taken the inverter off line to check that all connections are tight. The last thing wants is loose connections on the DC side. 

In normal use over 9 months or more the 3kVA is not bothered by the 3 fridges. They run permanently on the inverter. 

Edited January 23, 2023 by Scorp007

[Don]

18 minutes ago, Olorin said:

I mean R80k! For 2 TVs, one fridge, one freezer, router.

You can probably do it with a 3kW Axpert and Lion Battery for R35k-R40k in total, including splitting the DB. I have been using Axpert inverters since 2017. I have never had a problem with them, very reliable. Even with the latest technology available, I have no reason to change.

[Olorin]

1 hour ago, Don said:

In general, Electricians can wire a DB Board and fit a plug, but they know very little about Inverters and solar installations. . It is a totally different animal. Now I am waiting for the back lash, haha. 

The scary thing is that if what you say is true then how can they be expected to set up the inverter/battery settings correctly? If they don't know how then I'm screwed.

Edited January 23, 2023 by Olorin

[Don]

1 hour ago, Scorp007 said:

Yes I have shared a picture of the 98A drawn from 12V battery when a bar fridge starts.

Huge amps for only 1 174W and lots of batteries required. 

That is exactly why I don't like 12V systems and to a certain extent, even 24V systems. The amps drawn on those systems are huge. You need thick cabling to handle the amps. 

Load on 12 Volt Inverter: 1000 Watt       230 Volt       83 Amps (Discharge Amps)

Load on 24 Volt Inverter: 1000 Watt       230 Volt       42 Amps (Discharge Amps)

Load on 48 Volt Inverter: 1000 Watt       230 Volt       21 Amps (Discharge Amps)

Here is something I posted in 2017 on the forum: 

 

12 Volt system (2 Stroke System - High Revving System) - High Discharge Rates, Thick Cables, Lots of Heat to Dissipate:

                8 Batteries:  8 x 12 Volt batteries in Parallel = 960 Ah / 83 Discharge Amps

                                                                                          = 11.6 hours

 

24 Volt System (4 Stroke System - Moderate Revving System) Moderate Discharge Rates, Moderate Cable Sizes and Moderate Heat to Dissipate:

                4 Batteries:  4 x 24 Volt Batteries in Parallel = 480 Ah / 42 Discharge Amps

                                                                                           = 11.4 Hours

 

48 Volt System (Diesel System - Low Revving System) Low Discharge Rates, Smaller Cable Sizes and Lower Heat to Dissipate:

                 2 Batteries:  2 x 48 volts in Parallel = 240 Ah / 21 Discharge Amps

                                                                             = 11.4 hours

All three systems do exactly the same thing, the choice is yours.

 

[BritishRacingGreen]

1 hour ago, Scorp007 said:

Some facts and not thumb suck have been provided. Yes I have shared a picture of the 98A drawn from 12V battery when a bar fridge starts. This is real short term. This bar fridge only uses 7A @ 12V when running. These kinds of currents cannot be measured by power meters that have long periods before sampling the value. I belief the same is true on monitoring software. Not the ideal instrument to measure peaks. 

Sometimes one must get advice from those that have measured vs thumb sucking. 

And yes I have a 3kVA with good batteries. The key is batteries that CAN supply the peak. Yes I do start a bar fridge, medium fridge combo and a chest freezer at the same instant. The Axpert does not even shown a battery low alarm when they start. On the other hand when I start my micro my battery low warning light from the Axpert does come on but goes out after a minute or 2 as the battery voltage recovers. This start is when I have taken the inverter off line to check that all connections are tight. The last thing wants is loose connections on the DC side. 

In normal use over 9 months or more the 3kVA is not bothered by the 3 fridges. They run permanently on the inverter. 

Thanks 007, @Don and @Olorin, you will want to revisit the perception that surges are not a reality re freezer/fridges. The typical solar datalogging subsystem is not equipped to provide hard realtime high resolution measurement. In fact only snapshots of values are taken at undeterministic and slow intervals, and on top of that there is further gearing down  on database recording. The end result is good enough for power profile monitoring but poor for high resolition short surge pulses.