Help me scale up my back-up solution

[Adeptus Mechanicus]

Earlier in the year I put together a small backup system for my house, mainly to ensure I had uninterrupted power during working hours/evening hours for everything in the house aside from geyser/stove (or any other high wattage appliances)

However with higher levels of load shedding its become pretty apparent I need to scale up. The old system will not go to waste as I'll donate it to my folks.

My primary intention here is not to save money on my electricity bill, BUT if that's a happy by-product then so be it!

What I have:

• Mecer 3kw/24v unit
• 4x180ah AGM batteries (2x2 config)
• Powers everything except the geyser and electric stove
• Caution applied during loadshedding hours to ensure no kettles/hairdryers/dishwashers are used
• No solar

What I want:

• A 5kw+ inverter (mostly to avoid the inverter tripping out when load is exceeded when on AC)
• Approx. 3000-4000w of solar panels:
  • To ensure batteries get charged during lengthy periods of no AC
  • To ensure batteries are not utilized/not exclusively utilized while the sun is shining and there's no AC
• The ability to "blend" power. e.g. during the day system can draw from either AC or battery if solar is not sufficient.
• Enough battery to power approx. 800w of load for 10 hours (8kwh) . This is somewhat of an overspec given my typical load/typical loadshedding is less however:
  • Less DOD should improve overall battery lifespan
  • Will cater for any tightly spaced loadshedding sessions where the battery cannot fully recharge
  • Will cater for lengthy, non-loadshedding outages (e.g. cable theft)
• Bonus, but not a must: The ability to power essential and non-essential loads separately. The only way I see (aside from smart switches/home automation) from ensuring the geyser/stove can take advantage of solar, but will not use my batteries.

 

[DrJohnZoidberg]

How much are you budgeting for this?

You'll need something very similar to what I'm getting, so you can see the approximate prices:

8kW Sunsynk Inverter (~R40k) or 4kW (~R25k)
2 x 5kWh Sunsynk batteries (~R36k each)
10 x 450W Canadian Solar/JA Solar panels (~R4K each)

You'll also need to include the cost of installation. For splitting the loads, that's just something you'll need to electrician to do for you.

 

[Adeptus Mechanicus]

How much are you budgeting for this?

You'll need something very similar to what I'm getting, so you can see the approximate prices:

8kW Sunsynk Inverter (~R40k) or 4kW (~R25k)
2 x 5kWh Sunsynk batteries (~R36k each)
10 x 450W Canadian Solar/JA Solar panels (~R4K each)

You'll also need to include the cost of installation. For splitting the loads, that's just something you'll need to electrician to do for you.

Budget wise I'm somewhat flexible. I'd toyed with the idea of simply upgrading the battery and inverter for around R60k to R70k, but it then it got me thinking about spec'ing this upgrade properly, making it somewhat future-proof.

So even if I end up splitting it up into 2 phases, i.e. Battery/inverter upgrade first, panels later, the first first phase should be done "right".

Loads are currently split with the existing system, but this may need re-work if I follow through with the "bonus" of having an inverter that splits essential/non-essential loads.

Question regarding your choice of inverter: What do you need from the R40k 8kw Sunsync that a R20k 8kw Axpert (or other cheaper option) isn't providing?

 

[ADrunkTeddyBear]

Budget wise I'm somewhat flexible. I'd toyed with the idea of simply upgrading the battery and inverter for around R60k to R70k, but it then it got me thinking about spec'ing this upgrade properly, making it somewhat future-proof.

So even if I end up splitting it up into 2 phases, i.e. Battery/inverter upgrade first, panels later, the first first phase should be done "right".

Loads are currently split with the existing system, but this may need re-work if I follow through with the "bonus" of having an inverter that splits essential/non-essential loads.

Question regarding your choice of inverter: What do you need from the R40k 8kw Sunsync that a R20k 8kw Axpert (or other cheaper option) isn't providing?

You can message @DuracellBunny to put a system together for you

 

[B-1]

I went from a similar setup and also donating it to my parents to the one below.

Before: 3kw mecer inverter, 4 100a vision batteries, 2 305w panels.

Now:
8kw sunsynk inverter, 5kwh greenrich battery, 7x460w panels.

So far I am really happy with it. I've cut my electricity use from 450-500kwh per month to roughly 200kwh. I have my entire house all electric geysers, stoves, oven etc on it with only one of the geysers on non essential load.
One more battery will make a significant difference though and the plan is to get to 3 batteries and add another 2-3kw PV string.

I do have home automation which does help a lot in controlling the geysers.

The sunsynk is worth getting over the axpert style inverters as you have quite a bit more control(essential/non essential split, battery control etc) and the blending works really well.

 

[furpile]

Budget wise I'm somewhat flexible. I'd toyed with the idea of simply upgrading the battery and inverter for around R60k to R70k, but it then it got me thinking about spec'ing this upgrade properly, making it somewhat future-proof.

So even if I end up splitting it up into 2 phases, i.e. Battery/inverter upgrade first, panels later, the first first phase should be done "right".

Loads are currently split with the existing system, but this may need re-work if I follow through with the "bonus" of having an inverter that splits essential/non-essential loads.

Question regarding your choice of inverter: What do you need from the R40k 8kw Sunsync that a R20k 8kw Axpert (or other cheaper option) isn't providing?

There are lots of people with more knowledge on these systems here, but the Sunsynk is a true hybrid that can blend battery, solar and grid at the same time. The cheaper inverters cannot always do this. Also they have the Aux port which can be used for non-essential loads or a generator input, as well as all the software controls and safeties.

 

[Adeptus Mechanicus]

There are lots of people with more knowledge on these systems here, but the Sunsynk is a true hybrid that can blend battery, solar and grid at the same time. The cheaper inverters cannot always do this. Also they have the Aux port which can be used for non-essential loads or a generator input, as well as all the software controls and safeties.

Let's forget the aux port for a moment: What can they (the cheaper hybrids, e.g. LUX/Growatt) not do in terms of "blending" though?

Looking through the manuals they all claim to be able to set up a priority for charge of battery and supply of AC through combined solar/utility/battery configs.

Now:
8kw sunsynk inverter, 5kwh greenrich battery, 7x460w panels.

So far I am really happy with it. I've cut my electricity use from 450-500kwh per month to roughly 200kwh. I have my entire house all electric geysers, stoves, oven etc on it with only one of the geysers on non essential load.
One more battery will make a significant difference though and the plan is to get to 3 batteries and add another 2-3kw PV string.

I do have home automation which does help a lot in controlling the geysers.

The sunsynk is worth getting over the axpert style inverters as you have quite a bit more control(essential/non essential split, battery control etc) and the blending works really well.

I take it given you have just the 1x 5kwh battery at the moment those loads that are on essential side, but are heavy you've got set up to "not work" while on battery power via automation?

 

[B-1]

Let's forget the aux port for a moment: What can they (the cheaper hybrids, e.g. LUX/Growatt) not do in terms of "blending" though?

Looking through the manuals they all claim to be able to set up a priority for charge of battery and supply of AC through combined solar/utility/battery configs.


I take it given you have just the 1x 5kwh battery at the moment those loads that are on essential side, but are heavy you've got set up to "not work" while on battery power via automation?

Firstly its difficult to talk 1 to 1 as there are many variations of the voltronic aka mecer/kodak manufactured inverter vs the deye aka sunsynk/etc which is pretty common across the rebrands.

At the heart of it the two were designed for different purposes. The voltronic is an offgrid inverter first and the deye is designed as a hybrid. The deye as a result is more efficient when using grid or blending vs the voltronic. From battery alone I believe they should be around the same efficiency wise.

Then getting into all the variations of the voltronic some don't blend at all and when the PV input can't carry the load they switch to battery. Others like the king versions are better at blending but have the higher conversion losses. I ran through a lot of info as I also wasn't sure if paying the premium on the sunsynk was worth it but for my use case it made sense to spend the extra money.

For the automation side I still need to add an esp32 module to the inverter to make my automation smarter and based on SOC/weather/load shedding schedule.

For now I base it on the geysers only. I have the geysers set up in primary/secondary config and the secondary can't be on when the primary is on. They also have a time range from 10:30 to 16:00 where they are allowed to be on. Since the secondary is on non essentials the power is off during loadshedding so there is another rule that the primary can't be on when the secondary is not available(when there is loadshedding)

The greenrich battery is also 1.5c so can technically take the geyser load. Part of why I took a chance on them.

 

[furpile]

Let's forget the aux port for a moment: What can they (the cheaper hybrids, e.g. LUX/Growatt) not do in terms of "blending" though?

Looking through the manuals they all claim to be able to set up a priority for charge of battery and supply of AC through combined solar/utility/battery configs.


I take it given you have just the 1x 5kwh battery at the moment those loads that are on essential side, but are heavy you've got set up to "not work" while on battery power via automation?

B-1 gave a good answer, I am not fully clued up on the cheaper inverters but some of them do not really blend, they switch from solar to battery or grid when the solar dips, instead of just taking the extra that is needed and combining it with whatever solar is available.

Maybe @RonSwanson can give a better answer. There is also the generator/inverter thread and the battery thread with lots of info.

 

[itareanlnotani]

What you should want is some Lithium batteries.
My quick 2 cent suggestion

5KW Sunsynk
2 x 5KW of LFP of whatever brand you feel like (the variety available here is all much of a muchness) to get your 8KW of usage / 10hrs

As much solar PV as you can fit for that inverter (5 x 1.2 = 6KW odd)


The Axperts are just not as good as the Sunsynk/Deye. The hardware is better, plus, and an important plus, the Sunsynk/Deye are legal to use as they have NRS97-2 certification. The Axpert/Mecer don't, so aren't legal to use on the grid.

 

[RonSwanson]

B-1 gave a good answer, I am not fully clued up on the cheaper inverters but some of them do not really blend, they switch from solar to battery or grid when the solar dips, instead of just taking the extra that is needed and combining it with whatever solar is available.

Maybe @RonSwanson can give a better answer. There is also the generator/inverter thread and the battery thread with lots of info.

I can't actually, I know far too little about Growatt for starters. But I do know that the more expensive Luxpowers do everything that the Sunsynk / Deye can, for less. That said, there is a cheapy 5K Luxpower that does a whole lot more than a typical axpert type, but not all, because some axperts do have limited blending capabilities. If I were @Iwojima I would call Steve from the Powerforumstore and set aside an hour (at least) to discuss. He really knows a lot about inverters, and is a reliable and trustworthy source of information.

Looking at his needs very quickly, I'd say that he would want an 8K Sunsynk to be safe, 16-20kW batteries and as many panels as he can afford (up to 10400kWp). The generation capacity will go wasted 60% of the time, but he will be very grateful when there are consecutive cloudy days, and it it takes long to charge 20kW.

He could also get by with a 5k Sunsynk, 16kW batteries and 6500kWp on the roof, but I would need to confirm his monthly kWh, and what he uses for hot water.

He could easily swop the 10K Luxpower for the 8K Sunsynk, it is cheaper and at least he would have wider latitude for more panels, or the 5K Luxpower for the 5K Sunsynk.

He really needs to give Steve a call.

 

[jdido87]

B-1 gave a good answer, I am not fully clued up on the cheaper inverters but some of them do not really blend, they switch from solar to battery or grid when the solar dips, instead of just taking the extra that is needed and combining it with whatever solar is available.

Maybe @RonSwanson can give a better answer. There is also the generator/inverter thread and the battery thread with lots of info.

The Luxpower blends, check their Youtube channel where it is demonstrated.

 

[Adeptus Mechanicus]

Reviving my own thread. Have not moved on the upgrade yet as I've been out of the country.

So I found the following Kodak model: OG-PLUS6.2
Spec sheet: https://cdn.shopify.com/s/files/1/1...Axpert_King_II_TWIN_20220531.pdf?v=1662651846
Manual: https://cdn.shopify.com/s/files/1/1776/7837/files/KODAK-KINGII-TWIN-manual-20220111.pdf?v=1662652003

If I'm understanding correctly this has the ability to control two loads, essential/non-essential albeit at a much lower price-point for the size of the inverter. The only caveat appears to be that the only control you have over the non-essential side is via battery SOC (no time/source priority logic included like the more expensive Deye/Sunsynk)

Would it then be feasible if I never want to use my battery capacity for these non-essentials to set the cut-off at say 95% SOC, thereby not giving that load any chance to actually drain the battery significantly.

 

[leon.davibe]

Earlier in the year I put together a small backup system for my house, mainly to ensure I had uninterrupted power during working hours/evening hours for everything in the house aside from geyser/stove (or any other high wattage appliances)

However with higher levels of load shedding its become pretty apparent I need to scale up. The old system will not go to waste as I'll donate it to my folks.

My primary intention here is not to save money on my electricity bill, BUT if that's a happy by-product then so be it!

What I have:

• Mecer 3kw/24v unit
• 4x180ah AGM batteries (2x2 config)
• Powers everything except the geyser and electric stove
• Caution applied during loadshedding hours to ensure no kettles/hairdryers/dishwashers are used
• No solar

What I want:

• A 5kw+ inverter (mostly to avoid the inverter tripping out when load is exceeded when on AC)
• Approx. 3000-4000w of solar panels:
  • To ensure batteries get charged during lengthy periods of no AC
  • To ensure batteries are not utilized/not exclusively utilized while the sun is shining and there's no AC
• The ability to "blend" power. e.g. during the day system can draw from either AC or battery if solar is not sufficient.
• Enough battery to power approx. 800w of load for 10 hours (8kwh) . This is somewhat of an overspec given my typical load/typical loadshedding is less however:
  • Less DOD should improve overall battery lifespan
  • Will cater for any tightly spaced loadshedding sessions where the battery cannot fully recharge
  • Will cater for lengthy, non-loadshedding outages (e.g. cable theft)
• Bonus, but not a must: The ability to power essential and non-essential loads separately. The only way I see (aside from smart switches/home automation) from ensuring the geyser/stove can take advantage of solar, but will not use my batteries.

Tripping when on ac
Enable bypass in the settings

Inverter then meets the need with eskom instead of tripping overload

 

[Adeptus Mechanicus]

Earlier in the year I put together a small backup system for my house, mainly to ensure I had uninterrupted power during working hours/evening hours for everything in the house aside from geyser/stove (or any other high wattage appliances)

However with higher levels of load shedding its become pretty apparent I need to scale up. The old system will not go to waste as I'll donate it to my folks.

My primary intention here is not to save money on my electricity bill, BUT if that's a happy by-product then so be it!

What I have:

• Mecer 3kw/24v unit
• 4x180ah AGM batteries (2x2 config)
• Powers everything except the geyser and electric stove
• Caution applied during loadshedding hours to ensure no kettles/hairdryers/dishwashers are used
• No solar

What I want:

• A 5kw+ inverter (mostly to avoid the inverter tripping out when load is exceeded when on AC)
• Approx. 3000-4000w of solar panels:
  • To ensure batteries get charged during lengthy periods of no AC
  • To ensure batteries are not utilized/not exclusively utilized while the sun is shining and there's no AC
• The ability to "blend" power. e.g. during the day system can draw from either AC or battery if solar is not sufficient.
• Enough battery to power approx. 800w of load for 10 hours (8kwh) . This is somewhat of an overspec given my typical load/typical loadshedding is less however:
  • Less DOD should improve overall battery lifespan
  • Will cater for any tightly spaced loadshedding sessions where the battery cannot fully recharge
  • Will cater for lengthy, non-loadshedding outages (e.g. cable theft)
• Bonus, but not a must: The ability to power essential and non-essential loads separately. The only way I see (aside from smart switches/home automation) from ensuring the geyser/stove can take advantage of solar, but will not use my batteries.

A little update on what I went for eventually:

Installed:

• Kodak OG6.2 Twin (6.2kw off-grid system with 2 separate AC outputs)
• 2x Pylontech UP5000's installed in a 3x slot cabinet
• Raspberry PI running SolarAssistant and connected to the inverter
• Additional comms cable to connect RPi to batteries for additional stats in SolarAssistant
• Additional db with separate bypass breakers for both inverter loads as well as lights to indicate supply to these loads from inverter and Eskom supply.

Ordered:

• 8x JA Solar 550w panels
• Surge arrestors for inverter

To come:

• Another Pylontech UP5000
• Move the geyser to the secondary inverter output when the solar panels arrive

 

[Adeptus Mechanicus]

Got the additional cable from the Pi to the batteries going. Extra nerdy stats are now available

 

[wingnut771]

Got the additional cable from the Pi to the batteries going. Extra nerdy stats are now available

Cell voltage 3.4V x 16 = 54.4V
50.5V cannot be 100% SOC. That is 3.15V per cell, or about 50% SOC.

 

[Adeptus Mechanicus]

Cell voltage 3.4V x 16 = 54.4V
50.5V cannot be 100% SOC. That is 3.15V per cell, or about 50% SOC.

Yeah, I was wondering about that.

Along with the constant 25w drain on the batteries and the min/max charge and discharge rates which I certainly have not hit on these Pylontechs

Even here at 8am today SOC is indicated at 100% but voltage is 50.4v

 

[wingnut771]

Yeah, I was wondering about that.

Along with the constant 25w drain on the batteries and the min/max charge and discharge rates which I certainly have not hit on these Pylontechs

Even here at 8am today SOC is indicated at 100% but voltage is 50.4v

Not sure how it works. Maybe you need to drain them completely then charge to max voltage for BMS to reset? Is the drain not the inverter load?

 

[Adeptus Mechanicus]

Not sure how it works. Maybe you need to drain them completely then charge to max voltage for BMS to reset? Is the drain not the inverter load?

Would it be drawing directly from the batteries even when there is AC? Seems to be 25w-30w per battery.

Before I had the cable from the Pi to the batteries (ie just the Pi to inverter) this was was not reflected in the "Battery Power" section of SolarAssitant. It was a flat 0 mostly while on AC.

In fact I have the exact moment logged where I plugged the Pi to battery cables in and the 25w draw per battery becomes apparent.