Hi All

Absolute beginner here with basically zero knowledge of inverters,solar etc. I’m (almost) set on getting a 5kva inverter installed. Brand-wise I’m considering Victron. 
 

2 questions-

1. What does your 5kva inverter power? 

2. This might be a silly question but can I assume that a 5kva inverter will produce 5000 watts? Will the output differ from brand to brand? 
 

Thanks in advance.

1. You can run a full house on a 5kva. It all depends on how many things you want to switch on and use at the same time. For 99% of the time I run my house of a 3kVA Multiplus II. I have scheduled the big items to try and minimize concurrent use of those, so my geyser (heat pump) switch on at times when the stove and oven would mostly not be used. If it is used it will fall back and add extra power from the grid. 

2. Most of the time 5000VA is not 5000W. There is a power factor at play and if there was no losses in conversions then it would be possible. But not in real life. For instance my Multiplus 3kVA give 2400W, but only 1700W if it is very warm (65 deg). The better the components used, the better the power factor, so don't expect to much from that cheap inverter you buy at that sale.

4 minutes ago, JK844 said:

1. What does your 5kva inverter power? 

I live in an apartment, so I don't use the solar charge controller.  I just use it as backup when Eskom fails.

My light circuit and a "red plugs" in ever room of the apartment are fed from the inverter.  Been running like that since roughly 2014, I switched to an Axpert King in 2018 (If I recall correctly) for the double conversion, I have a lot of computers and stuff I didn't want damaged by Eskom's sh!tty supply.

I power my TV, router, microwave, kettle, Nespresso, fridge, TV, amplifier for TV, NAS, home office from the Axpert, occasionally things like vacuum if there is load shedding and the place needs cleaning.

The Axpert King runs in inverter mode 24/7 and it has held up well, when I turn on the kettle or microwave the fan speed increases but it is pretty much drowned out by the noise those appliances makes.  Everything else it remains fairly quiet (so not much load).  I rarely go above 3.5kW.

4 minutes ago, JK844 said:

2. This might be a silly question but can I assume that a 5kva inverter will produce 5000 watts? Will the output differ from brand to brand? 

Different brands may have different models.  You can look at the models available here: http://voltronicpower.com/

Voltronic Power makes the actual inverter and then puts the badge on the seller wants.  There are companies that manufacture clone Axpert inverters, meaning they actually copied the design.  They took an already low cost inverter and went cheap on it, so you can guess the end result of that.

My 2c: Buy your inverter here https://www.fullcirclesolar.co.za/

I've bought a few from them, they are the cheapest I could find, respond quickly and they don't sell fakes.

11 minutes ago, Louisvdw said:

2. Most of the time 5000VA is not 5000W. There is a power factor at play and if there was no losses in conversions then it would be possible. But not in real life. For instance my Multiplus 3kVA give 2400W, but only 1700W if it is very warm (65 deg). The better the components used, the better the power factor, so don't expect to much from that cheap inverter you buy at that sale.

I mean they'll say the kW, for all the newer Axperts, 5kVA = 5kW.  But that said, the power factor does not come into play on the inverter...  Power factor is determined by the devices you power in your home.  So ultimately if you bought good quality stuff your PF is close to unity (1.0) in which case the extra power factor overhead is wasted.  But if you use a lot of things like florescent lamps, motors, very old switch mode power supply, your PF could be around 0.5 or lower in which case having an inverter with a higher kVA rating is sufficient.

That said, if the kVA and kW on an inverter doesn't match, I don't put much faith in it.

EDIT: My point was power factor is not an indication of quality of the inverter.  But I wouldn't buy an inverter based on kVA rating, you look at the KW and decide based on that.  The kVA is just gravy on top.

Edited September 28, 20204 yr by Gnome

I also run my whole house off a single 5kW inverter:

• Borehole pump
• Swimming pool motor
• Oven & hob
• Geyser element
• Kettle
• Wall plugs
• Lights
• Panel heaters
• etc.

Some of them are very high draw items (I'm looking at you, you 3kW oven!) and you may need to ensure that you do not run them at the same time as other high draw items (kettle or geyser element).

It also pays to spread the load...  Our home's base load is around 500 W (3x fridges/freezers, extensive alarm system, three desktop computers, fish tank, etc).  Every morning at 08:30 our automated sprinklers turn the borehole pump on (1.3kW) for 30 minutes.  When they're done at 09:00 the pool motor starts up (750W) and runs until 17:00.  If it's very cloudy the solar geyser's element (2kW) may kick in at 13:00 via a GeyserWise megafter to ensure that the water temperature is at least 65 deg C.  If my wife were to boil a kettle (another 2kW) during this time, my home automation (Nodered & Sonoff) would turn the pool pump off to ensure I stay below 5kW.

If you buy a grid-tied inverter like mine you can get away with peaks over its rated output (it will just supplement the difference from the grid), but I try to remain off-grid as far as possible.

Oh, and I agree that it won't hurt to chat to Paul at FCS when shopping for inverters!

1 hour ago, ChristoSnake said:

I also run my whole house off a single 5kW inverter:

• Borehole pump
• Swimming pool motor
• Oven & hob
• Geyser element
• Kettle
• Wall plugs
• Lights
• Panel heaters
• etc.

Some of them are very high draw items (I'm looking at you, you 3kW oven!) and you may need to ensure that you do not run them at the same time as other high draw items (kettle or geyser element).

It also pays to spread the load...  Our home's base load is around 500 W (3x fridges/freezers, extensive alarm system, three desktop computers, fish tank, etc).  Every morning at 08:30 our automated sprinklers turn the borehole pump on (1.3kW) for 30 minutes.  When they're done at 09:00 the pool motor starts up (750W) and runs until 17:00.  If it's very cloudy the solar geyser's element (2kW) may kick in at 13:00 via a GeyserWise megafter to ensure that the water temperature is at least 65 deg C.  If my wife were to boil a kettle (another 2kW) during this time, my home automation (Nodered & Sonoff) would turn the pool pump off to ensure I stay below 5kW.

If you buy a grid-tied inverter like mine you can get away with peaks over its rated output (it will just supplement the difference from the grid), but I try to remain off-grid as far as possible.

Oh, and I agree that it won't hurt to chat to Paul at FCS when shopping for inverters!

I understand that this is how a grid tie inverter should function. i.e. you use power as you want to and the grid provides a backstop if demand is too great.

You must have moved most of your load to daylight hours to maximise the use of your solar power? So effectively you are running your house on grid power at night?

My batteries carry me through the night

I have a 5kVA off-grid inverter, and I have it running my whole house except the geyser and stove.

i.e. All plug and light circuits

 

15 hours ago, Louisvdw said:

1. You can run a full house on a 5kva. It all depends on how many things you want to switch on and use at the same time. For 99% of the time I run my house of a 3kVA Multiplus II. I have scheduled the big items to try and minimize concurrent use of those, so my geyser (heat pump) switch on at times when the stove and oven would mostly not be used. If it is used it will fall back and add extra power from the grid. 

2. Most of the time 5000VA is not 5000W. There is a power factor at play and if there was no losses in conversions then it would be possible. But not in real life. For instance my Multiplus 3kVA give 2400W, but only 1700W if it is very warm (65 deg). The better the components used, the better the power factor, so don't expect to much from that cheap inverter you buy at that sale.

Thank you so much! Appreciate your response.

On 2020/09/28 at 8:18 PM, ChristoSnake said:

I also run my whole house off a single 5kW inverter:

• Borehole pump
• Swimming pool motor
• Oven & hob
• Geyser element
• Kettle
• Wall plugs
• Lights
• Panel heaters
• etc.

Some of them are very high draw items (I'm looking at you, you 3kW oven!) and you may need to ensure that you do not run them at the same time as other high draw items (kettle or geyser element).

It also pays to spread the load...  Our home's base load is around 500 W (3x fridges/freezers, extensive alarm system, three desktop computers, fish tank, etc).  Every morning at 08:30 our automated sprinklers turn the borehole pump on (1.3kW) for 30 minutes.  When they're done at 09:00 the pool motor starts up (750W) and runs until 17:00.  If it's very cloudy the solar geyser's element (2kW) may kick in at 13:00 via a GeyserWise megafter to ensure that the water temperature is at least 65 deg C.  If my wife were to boil a kettle (another 2kW) during this time, my home automation (Nodered & Sonoff) would turn the pool pump off to ensure I stay below 5kW.

If you buy a grid-tied inverter like mine you can get away with peaks over its rated output (it will just supplement the difference from the grid), but I try to remain off-grid as far as possible.

Oh, and I agree that it won't hurt to chat to Paul at FCS when shopping for inverters!

Thanks for the feedback!

Quick follow-up question: I'm assuming you use the inverter throughout the year (i.e. not only during load-shedding. If this is correct, what % reduction have you seen in your electricity bill compared to pre-inverter days?

 

On 2020/09/28 at 9:25 PM, Richard Mackay said:

You must have moved most of your load to daylight hours to maximise the use of your solar power? So effectively you are running your house on grid power at night?

Indeed, pool motor and borehole pump only runs only during the day, and we only use the oven during the day over weekends for roasts, etc.  Batteries are only charged via solar and we run everything off them at night.  Eskom is there as backup for very cloudy weather that lasts longer than a day.

We've used less than 500 kWh of grid electricity this year:

On 2020/09/29 at 6:24 AM, Stanley said:

I have a 5kVA off-grid inverter, and I have it running my whole house except the geyser and stove.

i.e. All plug and light circuits

 

Yep, running a normal (i.e. non-solar) geyser's element or an oven requires some care.  Both of these can run at 3kW or more, leaving little capacity to spare. We have a solar geyser with a 2kW element (only runs during the day if required courtesy of a Geyserwise switch), and generally only use the oven during the day (so that the sun pays).

I found that our hob (at 500-800 W per plate) is not an issue at all, unless you turn all 4 plates to their maximum setting simultaneously.  Luckily we don't cook that way 😁

On 2020/09/28 at 6:54 PM, JK844 said:

1. What does your 5kva inverter power? 

It is capable of running your whole house with the proper planning and due diligence by the occupants of the household. I had a 5kVa running for 3 years where we did not even know when the grid power was off most of the time. I did however split my DB into 2 and ran the whole house except for air-con, oven and back-up electric geyser.  The 5kVa can handle  these other loads as well, but the problem arises when you run the appliances concurrently. If you run the oven and the missus switches on the kettle, then the inverter would change over to grid feed.

The funny thing is that I now am running a 3kVa Multiplus and I am getting better effeciency than I did with my 5kVa due to the power assist function. I still have my DB split in 2, but whereas the air-con etc was connected to the grid on the 5kVa it is now the second output on my 3Kva....so during the day when my solar panels are putting out 3600W all the extra power is going to my second output. The multi can quite comfortably give an AC Load of +5000W  during the day, blending all the supplies.

It all comes down to proper planning and due diligence.

Hi there, another newbie here. How many panels of what output and  size batteries would I need for a 5Kva power system? 

10 hours ago, Shaun54 said:

Hi there, another newbie here. How many panels of what output and  size batteries would I need for a 5Kva power system? 

Hi the size of the pv panels will be stated on the inverter specs as it can range from 4000 to 6000 depending on the model within the same brand.

The battery size recommended for a 5kw inverter is 200ah, which is 200ah multiply by 48 volts = 9,6kwh or 10kwh.

@ChristoSnake- I have just read your post and would like to know what system for you have from the inverter type, batteries storage amount and the number of panels and wattage of the panels.

 

I would like to install a system and doing my research now on what I could do to maximise the benefit 

Nvm

Edited November 25, 20222 yr by madness_za

I've had small scale solar for a while, but have just upgraded to a Sunsynk 5.5 inverter and Hubble AM2 battery.

I'm slowly adding more and more load to the system, but at the moment I have the whole house including 2 freezers and a fridge/freezer (we're out in the country, this saves us too many shopping trips), washing machine, dishwasher, all the standard hifi, TV & computer stuff, plus hairdryer, vacuum cleaner etc when needed. Mind you we have been careful of the years to buy eco-friendly appliances. We use solar heating, but the geyser backup is connected to the inverter and works fine. We don't have a conventional stove, we cook on gas, including boiling water, but we do have a microwave, coffee grinder etc which are all on solar now.

I put in solar for my lights years ago, and I've kept those separate, because when all else fails you can do a lot of stuff if you've still got lights. That's just one small panel, one battery and a 600w inverter (I think - I've haven't looked at it for ages, it just sits there and works).

I just tried my house pressure pump on the new system - we have to pump our own water on the farm, so we need a pressure pump (as well as a borehole pump to lift the water). Very frustrating to have no water pressure when the power goes out. But no more - it's working fine on solar. I also just put our small irrigation pump on (about 2kw, I think. It irrigates our two house gardens and our two orchards, but not all at the same time!), temporarily just to see, and it was fine, but I've taken it off again because...

My limitation is PVs now. I only have a theoretical 1.8kw of panels, although they seem to only run at about 1kw (according to Sunsynk's monitor) A lot of people seem to forget that there's two side to this game - how much power you use, and how much power you generate. I look at it like this. The inverter limits how much peak power you can take, the battery limits for how long you can take that power, and the panels limit how often you can take that power. Very simplistic I know, and ignores some of the facilities in hybrid inverters, but I've used this to explain solar to a lot of people, and it helps them "get it". The other thing that people don't get is learning to "live solar". Like a shower in the early morning? Fine, but then either have a cold shower or pay money to heat the water. The solar way is to wait until the solar water is hot enough. Similarly with appliances. You may not be able to run your dishwasher, washing machine, coffee machine, vacuum cleaner and gaming computer all at the same time. Tough! If that's important to you, cough up and get a bigger system, or stay connected to what's left of Eskom.

Now I'm beginning to look at solarising the main farm, borehole and main irrigation pump etc. I wish I could do without the inverter and use a DC pump, but there are issues with that, one being theft if the system if out in the field! I'm stuck at the moment on sizing 3-phase soft-starters for pump motors. I know how they work, I know they do work, but it's difficult to size the inverter require because I can't find by how much they limit that in-rush current when you start up a motor.

Can't find it yet 🙂
 

BTW think carefully as to whether you want to go totally off the grid. Eskom will always provide a useful, if expensive, backup for me. And if you buy (and configure) the right system, then you will  be able to run all of your appliances at the same time, but like I said, learning not to is the key.

On 2020/09/28 at 6:54 PM, JK844 said:

Hi All

Absolute beginner here with basically zero knowledge of inverters,solar etc. I’m (almost) set on getting a 5kva inverter installed. Brand-wise I’m considering Victron. 
 

2 questions-

1. What does your 5kva inverter power? 

2. This might be a silly question but can I assume that a 5kva inverter will produce 5000 watts? Will the output differ from brand to brand? 
 

Thanks in advance.

I'll answer (2) first. Read the specs carefully. My inverter is marketed as "5kW", but really it's 4.6 on the backed up side, allowing short bursts (10 seconds) up to 5. 

What do we run on it? Pretty much the whole house, with the exception of the outbuildings, and there's only two really significant loads there - the 2nd geyser and the pool pump. So when Eskom are shedding as they currently are, the only indignity we suffer is that the pool pump might lose a couple of hours of running time a day.

But see the earlier comment: We can't run everything AT ONCE. In particular I have had to introduce a rule in the kitchen. If you have the kettle on and the microwave on, then you can't turn on the toaster or the dishwasher. 

NB! We have full gas cooking (oven & hob), and we have a heat pump for the main geyser.

Running my house off grid, by that I mean I have a change over to Eskom if really needed, but my Inverter is off grid, i.e. no grid connection there.
It runs 5kW no problem, will even sustain up to 5,5kW but I manage all high power items sequentially. i.e. when the Geyser is on I don't run the Dishwasher or Washing Machine. Mostly runs between 3 and 5 kW when high loads are required for short periods.
Took about a year for the others in the household to eventually realise to check first between 10 and 12 if they can switch on the other high powered stuff. My Geyserwise is set to start at 10. Geyser never takes more than 1 to 1:30 to get to max temp.
The whole house runs off the 5kW, just not at the same time. Sequential management and it can be done easily. 

Have a stove top with two electric and two gas. In the daytime the electric elements are used (it's free solar) and the gas is used in the evenings or when the solar is minimal. Saves on the gas too.

 

Edited December 10, 20222 yr by zsde

On 2020/09/28 at 8:18 PM, ChristoSnake said:

at least 65 deg C.

Wow. I just turned mine down from 55 to 50 because I thought "what a waste". Horses for courses, I guess. I wouldn't bother with power heating my water at all, but my wife seems to think 6:00 is the perfect time for a shower.

Hi there

So glad I Find this forum!

Can anyone assist with a table that shows what devices can run on inverters of 1KW up 10KW?

Pieter