Hello,

I've been around a year. There is still so much to learn and I don't want to make a mistake. 
I'm looking at the

Sunsynk 5kw hybrid inverter (https://www.sunsynk.org/_files/ugd/9350f7_db0c934c3cb84ad58fee44358212198a.pdf) and the

Luxpower 5KW Lux Power LXP-5K Hybrid Inverter (https://griin-e.co.za/wp-content/uploads/2022/02/Lux-Hybrid-Datasheet-3-5K.pdf)

My requirements:
Reduce eskom bill
Prevent feedback onto the municipal grid
No batteries (I think sunsynk requires a small one)
Solar PV only
Daytime loadshedding back up from solar panels
Use the generator during night time loadshedding
Blend Eskom and Solar when load is too high

My understanding (mostly lack thereof):
The inverter needs to be grid-tied, so that I can blend power, but if the grid is down I still want to use the power from the solar panels (in the case of the Synsynk, I'll need a battery), no idea what the Luxpower will do or what you even call this feature/problem/issue/use case, so that I can look it up. 
Preventing power going back onto the grid is an inverter feature? (I think). Again I don't know what the terminology of this is, so not sure if either the Sunsynk or Luxpower do this.
We currently have not split our board for the generator - we're just careful with the load - I'm not sure what the options are here with using the generator, it's only a 2.2kw - so not sure there will be an issue - we use it for the alarm system, fridge, wifi and laptops. Any concerns here, I need to know about?

I have a efergy monitor thingy, so have a fair idea of my power usage. 
They both have 2 x MPPT's - which I think means that they can potentially have solar panels on different parts of my roof ??
I think the Sunsynk can be set up in parallel, if I want to add more panels and capacity. Not sure about the Luxpower - I think the same.

I like the cost saving on the Luxpower and it seems not to need a battery - but I'm not entirely sure if that means what I think it means and will meet my needs. 

I'd appreciate some ideas and maybe some information to fill in the gaps, so I can make an intelligent decision.
 

Both inverters mentioned will require a battery to supply loads from solar when Eskom is down. The only inverter I know of that can supply load from solar without batteries is certain Kodak inverters. Even so this won't be reliable or constant with cloudy weather. The inverter will "brown out" and switch on and off. Never good for electronic equipment.

3 minutes ago, TimCam said:

Both inverters mentioned will require a battery to supply loads from solar when Eskom is down. The only inverter I know of that can supply load from solar without batteries is certain Kodak inverters. Even so this won't be reliable or constant with cloudy weather. The inverter will "brown out" and switch on and off. Never good for electronic equipment.

Thank you! 
So how do I calculate the minimum battery size I need?
I might just opt to use the generator during load shedding as I do now and use the solar set up to save my monthly bill and then buy batteries for storage.
I'm guessing my next question is:
Can I use the generator when the grid is down to blend with the solar panels and supply the house - if I'm careful with my load - and if I was not careful with my load - would it just trip? (given the okey who sets it up, sets it up properly... i'd also like to have enough information to know that s/he has set it up properly)

Edited August 10, 20223 yr by MKRandburg

Even if you find a reliable Inverter that can operate on Solar without battery, the concept is not recommended as there is no buffer when the cloudy weather sets in.
Here is an example of two days ago where we had a lot of cloud movement in between the glorious sunshine.
See how the battery served as the buffer every time the clouds dropped the solar below the required load.
Had I not had a a battery the Inverter would have shut down every time the demand exceeded the solar. This is neither good for your Inverter or the equipment.

 

19 minutes ago, MKRandburg said:

I have a efergy monitor thingy, so have a fair idea of my power usage.

 

5 minutes ago, MKRandburg said:

So how do I calculate the minimum battery size I need?

Check with your Efergy monitor, and see what your usage is. You also say your 2.2 kW generator gets you through load-shedding, therefor maybe a small 2.75 kW lithium battery will be enough for a start, to fill in the gaps when there are clouds.

6 minutes ago, MKRandburg said:

Thank you! 
So how do I calculate the minimum battery size I need?
I might just opt to use the generator during load shedding as I do now and use the solar set up to save my monthly bill and then buy batteries for storage.
I'm guessing my next question is:
Can I use the generator when the grid is down to blend with the solar panels and supply the house - if I'm careful with my load - and if I was not careful with my load - would it just trip? (given the okey who sets it up, sets it up properly... i'd also like to have enough information to know that s/he has set it up properly)

Obviously if your budget allows go for a Lithium battery - but if not and all you are really after is battery backup during load shedding, then there is nothing wrong with going for an AGM battery bank - 12v100ah x 4. You run the inverter in SUB mode.  Will cost you in the region of R10-11k. 

13 minutes ago, MKRandburg said:

Can I use the generator when the grid is down to blend with the solar panels and supply the house - if I'm careful with my load - and if I was not careful with my load - would it just trip? (given the okey who sets it up, sets it up properly... i'd also like to have enough information to know that s/he has set it up properly)

Most times I would say yes if you have a large enough generator with decent AVR control. With a small generator the Voltage and Frequency might fluctuate to much, and the inverter will disconnect the "supply". On the inverter you can open the range quite a bit, but still no guarantees with a small generator. 🤔

Maybe someone else with a 2.2 kW generator can give us some feedback?

4 minutes ago, TimCam said:

Most times I would say yes if you have a large enough generator with decent AVR control. With a small generator the Voltage and Frequency might fluctuate to much, and the inverter will disconnect the "supply". On the inverter you can open the range quite a bit, but still no guarantees with a small generator. 🤔

Maybe someone else with a 2.2 kW generator can give us some feedback?

Wouldn't the generator need to support autostart ?  Dunno if 2.2kw gennie will have this function unless its an electric start.

Also, now I am asking to learn 🙂 how would he connect the gennie and eskom - I assume these inverters have two seperate inputs or a mechanism of detecting eskom outage and starting up the gennie remotely - but this would not really work for the idea to use the gennie to fill the solar production gaps.  A battery is needed for this I would think.

Edited August 10, 20223 yr by Douw Gerber

9 minutes ago, Douw Gerber said:

Wouldn't the generator need to support autostart ?  Dunno if 2.2kw gennie will have this function unless its an electric start.

Also, now I am asking to learn 🙂 how would he connect the gennie and eskom - I assume these inverters have two seperate inputs or a mechanism of detecting eskom outage and starting up the gennie remotely - but this would not really work for the idea to use the gennie to fill the solar production gaps.  A battery is needed for this I would think.

With no battery on the inverter, the inverter would shut down. This would be a manual process of starting the generator, then switching the inverter on again when the generator is running. The generator can be connected to the Eskom feed via a change-over switch, or the AUX/ Generator port straight. I would not recommend the AUX port on such a small generator.

21 minutes ago, TimCam said:

With no battery on the inverter, the inverter would shut down. This would be a manual process of starting the generator, then switching the inverter on again when the generator is running. The generator can be connected to the Eskom feed via a change-over switch, or the AUX/ Generator port straight. I would not recommend the AUX port on such a small generator.

yeah I assumed you meant manually - but sounds like a lot of pt 🙂 I guess an ATS could possibly start the gennie if eskom is down (battery still needed during generator startup) but that still isn't achieving what you want with the infill when solar isn't generating enough.

I tested what @MKRandburg is looking for with my Axpert Hybrid inverter - solar and eskom only - no battery - supports the loads and fills in with eskom where necessary when in SUB mode. [EDIT]

Edited August 10, 20223 yr by Douw Gerber

3 minutes ago, Douw Gerber said:

yeah I assumed you meant manually - but sounds like a lot of pt 🙂 I guess an ATS could possibly start the gennie if eskom is down (battery still needed during generator startup) but that still isn't achieving what you want with the infill when solar isn't generating enough.

Yip, for me batteries are a definite, but everyone has different needs.

See the image attached @MKRandburg

sorry @TimCam LOL I was thinking you posted OP 🙂

OP asked for:

My requiremement
Reduce eskom bill - solar can help here
Prevent feedback onto the municipal grid - inverter should have this option
No batteries (I think sunsynk requires a small one) - you will need a gennie as eskom backup
Solar PV only - PV only systems are for grid backfeed solutions where backup is not required.
Daytime loadshedding back up from solar panels - your gennie will fire up if eskom is down - somehow you will pay - cannot guarentee panels will be able to supply load always
Use the generator during night time loadshedding - feasable but you will still need a battery to carry the loads during generator start
Blend Eskom and Solar when load is too high - can be done

So bottom line is I think what OP is asking for isn't practical.

You will be able to reduce your energy bill using solar but with no battery you wont have backup.  Well you could fire up a gennie but everything would go offline while that gets started if the load is higher than wht the panels can supply at that moment in time.

34 minutes ago, Douw Gerber said:

yeah I assumed you meant manually - but sounds like a lot of pt 🙂 I guess an ATS could possibly start the gennie if eskom is down (battery still needed during generator startup) but that still isn't achieving what you want with the infill when solar isn't generating enough.

I tested what @MKRandburg is looking for with my Axpert Hybrid inverter - solar and eskom only - no battery - supports the loads and fills in with eskom where necessary when in SUB mode. [EDIT]

Interesting I thought the Axpert's didn't blend. What model do you have?

53 minutes ago, TimCam said:

With no battery on the inverter, the inverter would shut down. This would be a manual process of starting the generator, then switching the inverter on again when the generator is running. The generator can be connected to the Eskom feed via a change-over switch, or the AUX/ Generator port straight. I would not recommend the AUX port on such a small generator.

Ok, I think I live with this - the system will only be to save monthly costs and when eskom goes down, I'll use a manual switch to switch over to the generator - seeing as I have to pull that cord anyways... no auto start on this puppy! 
Rather then save up and buy decent batteries for the long term. 

Edited August 10, 20223 yr by MKRandburg

24 minutes ago, Douw Gerber said:

See the image attached @MKRandburg

sorry @TimCam LOL I was thinking you posted OP 🙂

OP asked for:

My requiremement
Reduce eskom bill - solar can help here
Prevent feedback onto the municipal grid - inverter should have this option
No batteries (I think sunsynk requires a small one) - you will need a gennie as eskom backup
Solar PV only - PV only systems are for grid backfeed solutions where backup is not required.
Daytime loadshedding back up from solar panels - your gennie will fire up if eskom is down - somehow you will pay - cannot guarentee panels will be able to supply load always
Use the generator during night time loadshedding - feasable but you will still need a battery to carry the loads during generator start
Blend Eskom and Solar when load is too high - can be done

So bottom line is I think what OP is asking for isn't practical.

You will be able to reduce your energy bill using solar but with no battery you wont have backup.  Well you could fire up a gennie but everything would go offline while that gets started if the load is higher than wht the panels can supply at that moment in time.

Thank for this! I'm not too stressed about everything going down and firing up the gennie - doing it now anyways. I probably should have added 2 things to my initial post:
- no auto start on gennie and that's ok
- this is part of my modular plan - get ROI as soon as possible. But eventually add batteries so I don't have downtime

This is helping me understand the terminology and be able to articulate my needs better. 

12 minutes ago, MKRandburg said:

Thank for this! I'm not too stressed about everything going down and firing up the gennie - doing it now anyways. I probably should have added 2 things to my initial post:
- no auto start on gennie and that's ok
- this is part of my modular plan - get ROI as soon as possible. But eventually add batteries so I don't have downtime

This is helping me understand the terminology and be able to articulate my needs better. 

Have a look at Growatt SPF5000es, it works with small generators

 

15 minutes ago, hoohloc said:

Have a look at Growatt SPF5000es, it works with small generators

 

This was pretty cool. The only though is that he said it was an inverter generator - doesn't that mean it does something - smooth the wave - for lack of a better way of describing it. My little gennie definitely doesn't smooth anything, I'm pretty sure it fluctuates a lot.

So just to be clear - I can run either of these inverters with just solar and eskom - no battery? I only need a battery if I want backup for when Eskom is down?

1 minute ago, MKRandburg said:

So just to be clear - I can run either of these inverters with just solar and eskom - no battery? I only need a battery if I want backup for when Eskom is down?

Virtually all inverters will work as long as there is grid connected. It might not blend sources though - i.e. if draw exceeds available PV it'll switch over to grid only as opposed to one that blends which will only draw in the needed extra from grid.

7 minutes ago, MKRandburg said:

So just to be clear - I can run either of these inverters with just solar and eskom - no battery? I only need a battery if I want backup for when Eskom is down?

Yip, on the SunSync there is a "No Battery" option, under battery settings. It can run as grid tied, and supply essential and non essential from PV with grid available, so your bill should be reduced.

As @Speedster has just explained, the SunSynk will always be able to "blend" and save you money.

Edited August 10, 20223 yr by TimCam

1 hour ago, TimCam said:

Yip, on the SunSync there is a "No Battery" option, under battery settings. It can run as grid tied, and supply essential and non essential from PV with grid available, so your bill should be reduced.

As @Speedster has just explained, the SunSynk will always be able to "blend" and save you money.

And the luxpower also blends, doesn't switch over if the load is greater than what the solar is supplying? How would I check that on specs? Is it the word blend? Or is there other terminology? 

1 hour ago, MKRandburg said:

And the luxpower also blends, doesn't switch over if the load is greater than what the solar is supplying? How would I check that on specs? Is it the word blend? Or is there other terminology? 

Best to ask those with Luxpower inverters first hand.👍

3 hours ago, MKRandburg said:

Interesting I thought the Axpert's didn't blend. What model do you have?

Mecer/RCT Axpert MKS IV 5.6

Well I dont have it right now - LOL - its with Mustek as I write this...screen died... loooong story available in another thread - just search my name 🙂

Edited August 10, 20223 yr by Douw Gerber

So, I've learnt a lot since starting this thread. I think my options are now between the KODAK Solar Off-Grid Inverter 5.6kW 48V and Sunsynk Sun 5K Hybrid Inverter

On 2022/08/10 at 7:20 PM, TimCam said:

Yip, on the SunSync there is a "No Battery" option, under battery settings. It can run as grid tied, and supply essential and non essential from PV with grid available, so your bill should be reduced.

Both can run without batteries - which was part of my requirement (stage 5 loadshedding has me questioning this, had to listen to the alarm battery beep for hours on end). I will probably need to replace it now. If I go battery back up, this won't be a problem - but if I replace the alarm battery with 2 in parallel, I can probably solve that issue for a lot less money than a battery for an inverter. (4.5 hour loadshedding extended to 5.25 hours at 2 am - I don't mind a bit of PT but I'm not pull starting the gennie in those hours! )

Not sure if the SunSynk will run in "No battery" mode without grid though - can anyone confirm this? @TimCam?

Gennie is on a change over switch, so if there is day time loadshedding and not enough PV that trips the inverter, I will do what I usually do and run my house on the gennie - after reducing my loads. Assuming the reduction of loads is still too much for the PV - cloudy day for example.

These are my concerns:

On 2022/08/10 at 5:17 PM, zsde said:

Had I not had a a battery the Inverter would have shut down every time the demand exceeded the solar. This is neither good for your Inverter or the equipment.

On 2022/08/10 at 5:12 PM, TimCam said:

The inverter will "brown out" and switch on and off. Never good for electronic equipment.

Damaging the inverter - if it trips or shuts down every time the demand exceeds the PV (during loadshedding - no grid and no battery)- does it auto start up? Can I stop it from auto starting up? Is there some other way to protect it? 
@Steve87 can you confirm on the Kodak - is this something I need to worry about? 
Anyone that comment on a SunSynk? @TimCam

Passthrough/Non-essentials vs Essentials DB split  - I'm not sure how to ask this but this is my concern - I will be limited by the inverters passthrough capacity even when I have grid power available (remember to assume no battery). I guess my questions are something around this:
- do all inverters have essential and non-essential connections?
- I guess batteries normally supply essentials - would I need to put everything on essentials whilst I don't have batteries?  
- is passthrough something that effects all inverters?
- I've read about it being a limitation on the SunSynk but don't understand under what circumstances. I guess then my question is how does passthrough work on the Kodak and how will it impact me - given the set up I want?

Budget - the Sunsynk is approx. R10 more than the Kodak. I know that everyone is saying the build quality is so much better. I drive a Hyundai - the build quality isn't nearly as good as a BMW but it serves me well. Is this a similar issue? What else do I get with SunSynk - that I don't get with Kodak?
 

Looking forward to learning more and reading some lively debate backed with evidence and references 😂

7 minutes ago, MKRandburg said:

SunSynk will run in "No battery" mode without grid though - can anyone confirm this? @TimCam?

The Sunsynk cannot do this. Hence I suggested the Kodak Off grid. This is a game changer of note especially for my needs and the needs of many other folks. When the grid is not present ie. Loadshedding the Sunsynk will switch off without a battery. 

The only thing you can do is reduce the load to a margin where the machine can startup & stay on. There is no damage done to the inverter. I have inadvertently had mine do this for up to half an hour with the geyser constantly being on & the tripping did not ruin the machine. Its still in good operation. 

The other questions I won't answer because, to me your narrow set of requirement is to run batteryless. The Sunsynk wil not do this. The rest of the questions would relate to if you had a battery.