Inverters

nadeem_k

Senior Member
Joined
Oct 1, 2009
Messages
635
Hi

I need some help figuring out which inverter to get.

The system I'm looking for is to have solar panels, batteries and eskom supplies. Where solar is primary and the grid is secondary to supplement the load.

The idea then is to rewire my DB so all essential loads are one phase and then use the solar system for that phase. In so doing I could save on my eskom bill and have back up during load shedding.

I know this is an expensive exercise so I'm thinking of installing the battery and inverter now and then adding the panels at a later time. From my understanding I need a hybrid grid tied inverter.

I've been looking at the mercer axpert inverter but was told that mercer dont make hybrid inverters. Please advise

Then in terms of batteries I was told that the gel batteries don't work well if used for longer periods of time. Apparently they last only a year a two. Does this mean li ion is the only option?
 

Chuckmyster

Honorary Master
Joined
Aug 2, 2016
Messages
15,535
yup pretty much what you just said
@Sinbad went all out for R180k but I'm sure you can do it in stages if you just start off with the correct future proof Inverter :thumbsup:
 

thechamp

Honorary Master
Joined
Feb 26, 2011
Messages
23,751
Hi

I need some help figuring out which inverter to get.

The system I'm looking for is to have solar panels, batteries and eskom supplies. Where solar is primary and the grid is secondary to supplement the load.

The idea then is to rewire my DB so all essential loads are one phase and then use the solar system for that phase. In so doing I could save on my eskom bill and have back up during load shedding.

I know this is an expensive exercise so I'm thinking of installing the battery and inverter now and then adding the panels at a later time. From my understanding I need a hybrid grid tied inverter.

I've been looking at the mercer axpert inverter but was told that mercer dont make hybrid inverters. Please advise

Then in terms of batteries I was told that the gel batteries don't work well if used for longer periods of time. Apparently they last only a year a two. Does this mean li ion is the only option?
People lie, Mecer do make hybrid inverters and gel batteries don't last a year or two, I have the common flooded lead acid batteries and they have been going for years, close to 5 years now, gel batteries a much better than those.

Looks like you have been getting bad advice.
 

Sinbad

Honorary Master
Joined
Jun 5, 2006
Messages
68,038
People lie, Mecer do make hybrid inverters and gel batteries don't last a year or two, I have the common flooded lead acid batteries and they have been going for years, close to 5 years now, gel batteries a much better than those.

Looks like you have been getting bad advice.
If you cycle daily which you want to do to optimize solar output, lead batteries will die quickly.
 

thechamp

Honorary Master
Joined
Feb 26, 2011
Messages
23,751
From my understanding I need a hybrid grid tied inverter.
You just need a hybrid inverter not a grid tied hybrid inverter, grid tied means it does not work when electricity goes off.
 

HavocXphere

Honorary Master
Joined
Oct 19, 2007
Messages
31,500
Yeah the axperts are fine.

If you cycle daily which you want to do to optimize solar output, lead batteries will die quickly.
Have you crunched the numbers on this? My gut feeling tells me even with Li batteries you'll come off worse financially vs going lead acid & running them only for loadshedding. See cellphone batteries...after like 1.5 years of daily cycles you can basically bin them.
 

Sinbad

Honorary Master
Joined
Jun 5, 2006
Messages
68,038
Yeah the axperts are fine.


Have you crunched the numbers on this? My gut feeling tells me even with Li batteries you'll come off worse financially vs going lead acid & running them only for loadshedding. See cellphone batteries...after like 1.5 years of daily cycles you can basically bin them.
I've got a 7000 cycle warranty.
 

Pho3nix

The Legend
Joined
Jul 31, 2009
Messages
27,734
Yeah the axperts are fine.


Have you crunched the numbers on this? My gut feeling tells me even with Li batteries you'll come off worse financially vs going lead acid & running them only for loadshedding. See cellphone batteries...after like 1.5 years of daily cycles you can basically bin them.
Glad to see you still around mate
 

Mars

Honorary Master
Joined
Feb 4, 2006
Messages
10,320
I wouldn't say the axpert/mercer is a great option. I have one and the battery management is terrible. I was going to dump it and get a SMA or Victron inverter but then with advice here and on PowerForum I found some software that runs on a Pi that takes over the management part from the inverter. Since I started using that its much better. Not perfect, but acceptable.

When it comes to batteries you need to consider what you want out of them.

A batterys life is measured in cycles (and time but cycles is more important), the reason people talk about time is to make it easier to gauge. Generally the year lifespan of all lead acid based batteries (SilverCal/VRLA/AGM/Gel) is based on an average automotive cycle use. Obviously that doesn't apply well to the backup industry.

My suppliers guarantee give different guarantee's based on the application. Your standard flooded 105a/h battery gets 2 years in an automotive application but only 1 year in a backup application, but technically the cycle guarantee is the same. They cant really enforce that because 99% of the time they dont know the application and cant tell from testing the battery, but it gives you an indication of the differences in application.

So, if you are planning on saving money through solar: SBU: Solar -> Battery -> Utility : Solar runs the house during the day and charges the batteries, when the sun goes down it cycles the batteries until they're flat and then switches to eskom then you would be best of with a Li-ion battery. Yes they are expensive, but they have the best ROI in this application.

If you are planning on using them as a backup only: SUB: Solar -> Utility -> Battery : Solar runs the house during the day and switches to utility at night and only uses the battery when both solar and utility are unavailable. Then you would be fine with lead acid or gel since the battery only cycles when there is both no solar and utility.

Thats not to say you could not use lead acid /vrla/agm/gel for a SBU application and save money, just that the best ROI is on the lithium.

As for the differences between Lead Acid/VRLA/AGM/Gel performance is all pretty much the same overall when you balance cost with usage. What I mean is, an AGM may get you 30% more than the VRLA but it also costs 30% more. Gel doesn't gas so if you have your battery in an enclosed space without ventilation (which is NEVER a good idea) then gel is the best worst option after Lithium.
 

thechamp

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Feb 26, 2011
Messages
23,751
The Axpert is not great but it's value for money for what it offers.
 

Geoff.D

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Aug 4, 2005
Messages
11,822
People lie, Mecer do make hybrid inverters and gel batteries don't last a year or two, I have the common flooded lead acid batteries and they have been going for years, close to 5 years now, gel batteries a much better than those.

Looks like you have been getting bad advice.
Bad installs will kill anything ... That is where the problem lies. people don't truly understand what they are taking on, screw up the install and then tell you xyz does not work. Batteries will all last, some way beyond their warranty period IF treated, charged and discharged properly.
 

FNfal

Executive Member
Joined
Jul 6, 2011
Messages
5,640
AFAIK Mercer do not make any thing they re brand and assemble .
The Axpert type inverters seem ok if that is all you can afford , buy the best that you can afford .
Solar panels i support the locally made ones , they are priced well to . https://artsolar.net/.
Batteries now there is the problem , if you program the Axpert correctly and do not exceed the DOD of the batteries you should get a few years out of lead acid or gell batteries.
Lifepo4 batteries are the ultimate at the moment but the price is the killer .
 

Mars

Honorary Master
Joined
Feb 4, 2006
Messages
10,320
AFAIK Mercer do not make any thing they re brand and assemble .
The Axpert type inverters seem ok if that is all you can afford , buy the best that you can afford .
Solar panels i support the locally made ones , they are priced well to . https://artsolar.net/.
Batteries now there is the problem , if you program the Axpert correctly and do not exceed the DOD of the batteries you should get a few years out of lead acid or gell batteries.
Lifepo4 batteries are the ultimate at the moment but the price is the killer .
Mercer and Axpert and all those brands are made by Voltronic Power.

Just beware that they are not designed to run lithium batteries, they doe not have the profile needed to manage these batteries properly.
You can use them together but then you will need to get extra software on a pi to do the management.

This is the software: https://iccsoftware.co.za
 

Neuk_

Expert Member
Joined
Jan 23, 2018
Messages
1,976
I am in a similar situation with the exception that my girlfriend bought a Victron Multiplus 3kVa 48v inverter and four Omnipower 12v 120ah AGM batteries last year after chatting to her family who are all electrical engineers. While she had good intentions, I wasn't happy with just having 3kVa available as my plan was to always start with a system to handle load shedding but be able to be expanded to handle PV and eventually get off the grid completely. I am waiting for a quote to install the existing 3kVa inverter and batteries with another 3kVa inverter for now with PV being an option in the future and as few changes going forward as possible.
 

falcon786

Executive Member
Joined
Jan 29, 2011
Messages
9,901
see cellphone batteries...after like 1.5 years of daily cycles you can basically bin them.
Those are Lithium Cobolt if memory serves me right, but regardless they are made for optimal size/power draw/capacity efficiencies.

For home storage we usually use lithium phosphate or similar which are safer than some lithium batteries but it does this and the higher cycle life by making sacrifices with size/watt ratios and charging/discharging ratios etc.

Basically you cannot compare the 2 as they were designed for very different use cases.
 

nadeem_k

Senior Member
Joined
Oct 1, 2009
Messages
635
I wouldn't say the axpert/mercer is a great option. I have one and the battery management is terrible. I was going to dump it and get a SMA or Victron inverter but then with advice here and on PowerForum I found some software that runs on a Pi that takes over the management part from the inverter. Since I started using that its much better. Not perfect, but acceptable.

When it comes to batteries you need to consider what you want out of them.

A batterys life is measured in cycles (and time but cycles is more important), the reason people talk about time is to make it easier to gauge. Generally the year lifespan of all lead acid based batteries (SilverCal/VRLA/AGM/Gel) is based on an average automotive cycle use. Obviously that doesn't apply well to the backup industry.

My suppliers guarantee give different guarantee's based on the application. Your standard flooded 105a/h battery gets 2 years in an automotive application but only 1 year in a backup application, but technically the cycle guarantee is the same. They cant really enforce that because 99% of the time they dont know the application and cant tell from testing the battery, but it gives you an indication of the differences in application.

So, if you are planning on saving money through solar: SBU: Solar -> Battery -> Utility : Solar runs the house during the day and charges the batteries, when the sun goes down it cycles the batteries until they're flat and then switches to eskom then you would be best of with a Li-ion battery. Yes they are expensive, but they have the best ROI in this application.

If you are planning on using them as a backup only: SUB: Solar -> Utility -> Battery : Solar runs the house during the day and switches to utility at night and only uses the battery when both solar and utility are unavailable. Then you would be fine with lead acid or gel since the battery only cycles when there is both no solar and utility.

Thats not to say you could not use lead acid /vrla/agm/gel for a SBU application and save money, just that the best ROI is on the lithium.

As for the differences between Lead Acid/VRLA/AGM/Gel performance is all pretty much the same overall when you balance cost with usage. What I mean is, an AGM may get you 30% more than the VRLA but it also costs 30% more. Gel doesn't gas so if you have your battery in an enclosed space without ventilation (which is NEVER a good idea) then gel is the best worst option after Lithium.
Thanks for this. So if I have the SUB config will the victron/mever/axpert invertes be good enough? I was recomended Goodwe but I found it to be expensive. Is the logic where victron is like a Tazz and Goodwe like a land cruiser?
 

falcon786

Executive Member
Joined
Jan 29, 2011
Messages
9,901
Mercer and Axpert and all those brands are made by Voltronic Power.

Just beware that they are not designed to run lithium batteries, they doe not have the profile needed to manage these batteries properly.
You can use them together but then you will need to get extra software on a pi to do the management.

This is the software: https://iccsoftware.co.za
I was under the impression the lithium ion batteries BMS or battery management system would do this,is this not the case and a BMS is just to balance load between different cells rather than managing the entire banks charging?
 

falcon786

Executive Member
Joined
Jan 29, 2011
Messages
9,901
Thanks for this. So if I have the SUB config will the victron/mever/axpert invertes be good enough? I was recomended Goodwe but I found it to be expensive. Is the logic where victron is like a Tazz and Goodwe like a land cruiser?
Are you perhaps confusing the names Victron with Voltronic?

Victron is probably the rolls royce in invertors from what I know so far.So top of the range.

Voltronic is the axpert type basic ones.
 
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